WO2018011570A1

WO2018011570A1 - Wee-1 inhibiting pyridopyrimidinone compounds

Info

Publication number: WO2018011570A1
Application number: PCT/GB2017/052042
Authority: WO
Inventors: Frank Burkamp; James Samuel Shane Rountree; Adam Piotr TREDER
Original assignee: Almac Discovery Ltd
Current assignee: Almac Discovery Ltd
Priority date: 2016-07-12
Filing date: 2017-07-12
Publication date: 2018-01-18
Anticipated expiration: 2019-01-12
Also published as: GB201612095D0

Abstract

The present invention relates to compounds that are useful as inhibitors of the activity of Wee-1 kinase. The present invention also relates to pharmaceutical compositions comprising these compounds and to methods of using these compounds in the treatment of cancer and methods of treating cancer.

Description

WEE-1 INHIBITING PYRAZOLOPYRIMIDINONE COMPOUNDS

BACKGROUND TO THE INVENTION Cells are continually challenged on a daily basis, resulting in multiple lesions forming in DNA. The lesions, if not repaired, can lead to mutations or cell death, thus complex signalling networks exist which ensure that lesions are detected and repaired to maintain the integrity of DNA. Detection of DNA damage initiates a series of events which are key in maintaining the genome. Cell cycle checkpoints are designed to stop the cell cycle and allow repair of the lesion before allowing the cell to continue into mitosis.

Two key checkpoints have been identified, one at the end of the G1 phase and the second at G2, working in tandem to ensure all lesions are identified and repaired. In 50% of human cancers the G1 checkpoint is non-functional due to mutations in the tumour suppressor gene p53. However, the G2 check-point is seldom mutated and often found to be activated in cancer cells. Cancer cells exploit this to confer resistance to treatment modalities, including DNA damaging agents and radiation.

Three kinases have been identified as key regulators of the G2 checkpoint, namely Chk1 , Chk2 and Wee-1. Inhibitors for these kinases are currently being evaluated in clinical trials.

Wee-1 is a nuclear tyrosine kinase which negatively regulates entry into mitosis at the G2/M check-point by catalysing a phosphorylation of the cdc2 / cyclin B kinase complex. The phosphorylation occurs on the tyrosine-15 residue and leads to the inactivation of the cdc2 / cyclin B complex, ultimately preventing mitosis. Wee-1 function is intimately linked to that of Chk1 and Chk2 due to their phosphorylation and inactivation of cdc25 on serine- 216, as well as the reported activation of Wee-1 by Chk 1 & 2 (Ashwell et al., 2012, DNA Repair in Cancer Therapy, DOI: 10. 1016 B978-0-12-384999-1. 10010-1). Wee-1 is downstream of the Chk family and is a crucial component of the checkpoint signalling cascade as it prevents cells from entering mitosis if lesions are detected (Do et al., Cell Cycle 2013 12 (19) 3159-3164).

Commonly administered anti-cancer compounds induce DNA damage, including antimetabolites, platinum agents, topoisomerase inhibitors and alkylating agents. However, their efficacy is limited due to excessive toxicity, resistance and lack of tumour selectivity. Compounds which work in combination with these agents to prevent DNA repair selectively in tumour cells would be extremely beneficial. As the tumour suppressor gene p53 is commonly mutated in tumour cell lines, the administration of a Wee-1 kinase inhibitor, abrogating the G2 check point, may lead to increased sensitivity to DNA damaging agents. The potential for this has been reported, as silencing of Wee-1 activity was sufficient to sensitize HeLa cells to doxorubicin due to abrogation of G2 arrest. By contrast, in normal breast epithelium due to the fully competent p53 protein, the removal of Wee-1 function had little additional effect compared to doxorubicin alone (Wang et al. ,2004, Cancer Biology and Therapy, 3(3), 305-313).

It has been reported that cell lines harbouring mutations in the tumour suppressor gene p53 had increased sensitivity to DNA damaging agents when co-administered with Wee-1 small molecule inhibitors. Synergistic in vitro and in vivo efficacy has been reported when small molecule inhibitors were combined with gemcitabine, 5-fluorouracil, carboplatin, cisplatin (Hirai et al 2010, Cancer Biology & Therapy 9:7, 514-522), cytarabine (Tibes et al., 2012, Blood, 1 19(12), 2863-2872), for example. Other examples of chemosensitization upon Wee-1 inhibition include but are not limited to combination with irinotecan, topotecan or alkylating agent (temozolomide). Radiosensitization has also been demonstrated in multiple cancer types (Havelek R., et al. 2014 Biochem Biophys Res Commun., 24 (453), 569-75; Caretti V., et al. 2013 Mol Cancer Ther., 12 (2) 141-50; Bridges KA., et al. 201 1 Clin Cancer Res., 1 (17), 5638-48; PosthumaDeBoer J., et al. 2011 BMC Cancer., 29 (1 1 ) , 156) . Combinations with non-cytotoxic compounds have also been evidenced including for instance with Chk-1 inhibitors (Carrasa et al., 2012 Cell Cycle 1 : 11 (13):2507- 2517), (Russell et al., 2013 Cancer Res. 15; 73 (2) 776-784), Src inhibitors (Cozzi et al., 2012, Cell Cycle 11 (5), 1-1 1), PARP inhibitor (Karnak D., et al. 2014 Clin. Cancer Res., 1 (20), 5085-96), HSP90 inhibitor (Lokeshwar VB., 2012 Cell Cycle., 15 (11), 3722-3; Iwai A., et al. 2012 Cell Cycle 1 (11), 3649-55), HDAC inhibitor (Zhou L, et al. 2015 Leukemia, 29(4), 807-18). Interestingly, single agent apoptotic efficacy, independent of p53 status, has also been reported in various cellular models and contexts including sarcoma cell lines and in patient-derived sarcoma samples (Kreahling et al., 2012, Mol. Cancer Ther., 1 1 (1), 174-182) in a panel of cancer cell lines in vivo including lung and melanoma model cell lines (Guertin et al., 2013 Mol Cancer Ther, 12 (2) 141-151) or more recently in

H3K36me3-deficient cancer cell lines (Pfister SX., 2015 Cancer Cell., 28(5), 557-568).

Irradiation is known to increase phosphorylation of the Tyr15 and Thr14 residues of cdc2, leading to a radioresistant phenotype. Inhibition of Wee-1 activity by small molecule inhibitors (Wang et ai, 2004, Cancer Biology and Therapy 3(3), 305-313), (Caretti et al., 2013 Mol Cancer Ther. 12 (2) 141-150) leads to a reduction in phosphorylation and radiosensitization, with the effect being more pronounced in p53 mutant cell lines.

It has been reported in melanoma that over-expression of Wee-1 is correlated with poor clinical outcome (Magnusson et al., 2012 PLoS One 7; (6)e38254), indicating it may have a significant role as a biomarker and as a targeted therapy.

Compounds having a kinase inhibitory effect, for example a Wee-1 kinase inhibitory effect, are described in WO2002/090360, WO2007/126122, US2007/0254892, WO2008/1 15742, WO2008/153207, WO2010/098367, US2012/0220572, WO2012/161812,

WO2013/0018045, WO2013/126656, WO2013/059485, WO2013/013031 ,

WO2014/167347, WO2015/019037, WO2015/092431.

WO2015/092431 , Example 3 (page 87), describes the synthesis of a compound having the formula:

This compound is said to have a Wee-1 activity of less than 10 nM, and a CDC2 activity of more than 100nM but less than 1000 nM. Furthermore, WO2015/092431 , Example 18 (page 106), describes the synthesis of a

This compound is said to have a Wee-1 activity of less than 10 nM, and a CDC2 activity of more than 100nM but less than 1000 nM.

WO2015/019037, Example 38 (page 114), describes the synthesis of a compound having the formula:

This compound is said to have a Wee-1 activity of less than 100 nM, and a CDC2 activity of less than 500 nM.

WO2014/167347, Example 13 (page 66), describes the synthesis of a compound having the formula:

This compound is said to have a Wee-1 activity of less than 10 nM, and a CDC2 activity of less than 100 nM. WO2013/013031 , Example 174 (page 156), describes the synthesis of a compound having the formula:

This compound is said to have a Wee-1 activity of 0.1 nM.

Furthermore, WO2013/013031 , Example 207 (page 163) describes the synthesis of a

This compound is said to have a Wee-1 activity of 0.1 nM.

US2012/0220572, Example 65 (page 54), describes the synthesis of a compound having the formula:

This compound is said to have a Wee-1 activity of less than 10 nM. Furthermore, US2012/0220572, Example 66 (page 54), describes the synthesis of a compound having the formula:

This compound is said to have a Wee-1 activity of less than 10 nM.

WO2010/098367, Example 24 (page104), describes the synthesis of a compound having the formula:

The Wee-1 activity of this compound is not described.

It is one object of the present invention to provide compounds having an enhanced or similar Wee-1 kinase inhibitory effect compared to compounds known in the prior art.

It is a further object of the present invention to provide compounds which exhibit enhanced or comparable Wee-1 potency in cells compared to compounds known in the prior art.

It is a further object of the present invention to provide compounds which exhibit an enhanced or similar kinetic solubility compared to compounds known in the prior art.

It is a further object of the present invention to provide compounds which exhibit an enhanced or similar stability in human microsomes compared to compounds known in the prior art. Furthermore, it is an object of the present invention to provide compounds which exhibit more than one, most preferably all, of the above properties, i.e. to provide compounds having an enhanced or similar Wee-1 kinase inhibitory effect, and/or enhanced or comparable Wee-1 potency in cells, and/or an enhanced or similar kinetic solubility, and/or an enhanced or similar thermodynamic solubility, and/or an enhanced or similar stability in human microsomes, compared to compounds known in the prior art.

More generally, it is one object of the present invention to overcome at least some of the disadvantages of the prior art or to provide a commercially useful alternative thereto.

SUMMARY OF THE INVENTION

In a firs :

(I)

or a pharmaceutically acceptable salt or /V-oxide derivative thereof, wherein:

R¹ is an optionally substituted aryl or heteroaryl group;

R² is an optionally substituted alkyl group, an alkynyl group optionally substituted by one or more alkyl groups and/or one or more alkoxy groups, or a cyano group; R³ is an optionally substituted alkyl group, a cycloalkyl group, an alkoxy group or a cycloalkoxy group;

R⁴ is a hydrogen atom, an alkyl group or a cycloalkyl group;

X is a nitrogen atom or a CH-group;

Y is a nitrogen atom or a CH-group;

Z is a nitrogen atom or a CH-group; and

n is 1 when X is a nitrogen atom and n is 0 or 1 when X is a CH-group. Each aspect or embodiment as defined herein may be combined with any other aspect(s) or embodiment(s) unless clearly indicated to the contrary. In particular any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.

In a further aspect the present invention provides the compound of Formula (I), or a pharmaceutically acceptable salt or /V-oxide derivative thereof, and at least one

pharmaceutically acceptable excipient. In a further aspect the present invention provides a pharmaceutical composition comprising the compound of Formula (I), or a pharmaceutically acceptable salt or /V-oxide derivative thereof, and at least one pharmaceutically acceptable excipient.

In a further aspect the present invention provides the compound of Formula (I), or a pharmaceutically acceptable salt or /V-oxide derivative thereof, or the pharmaceutical composition as described herein, for use in therapy.

In a further aspect the present invention provides the compound of Formula (I), or a pharmaceutically acceptable salt or /V-oxide derivative thereof, or the pharmaceutical composition as described herein, for use as a medicament.

In a further aspect the present invention provides the compound of Formula (I), or a pharmaceutically acceptable salt or /V-oxide derivative thereof, or the pharmaceutical composition as described herein, for use in treating or preventing cancer.

In a further aspect the present invention provides the use of the compound of Formula (I), or a pharmaceutically acceptable salt or /V-oxide derivative thereof, or the pharmaceutical composition as described herein, for the manufacture of a medicament for treating or preventing cancer.

In a further aspect the present invention provides a method of treating or preventing cancer in a human or animal patient comprising administering to a patient in need thereof an effective amount of a compound of Formula (I), or a pharmaceutically acceptable salt or N- oxide derivative thereof, or the pharmaceutical composition as described herein. Other preferred embodiments of the compounds according to the invention appear throughout the specification and in particular in the examples. Particularly preferred are those named compounds having greater activity as tested. Compounds having higher activity are more preferred over those having lower activity.

The present inventors have surprisingly found that compounds of the present invention show an improved or similar Wee-1 kinase-inhibitory effect compared to known

compounds. The present inventors have also surprisingly found that compounds of the present invention show an improved or comparable Wee-1 potency in cells compared to known compounds.

The present inventors have also surprisingly found that compounds of the present invention show an enhanced or similar kinetic solubility compared to known compounds.

The present inventors have also surprisingly found that compounds of the present invention show an enhanced or similar stability in human microsomes compared to known compounds. In addition, the present inventors have surprisingly found that compounds of the present invention exhibit an enhanced or similar Wee-1 kinase inhibitory effect as well as displaying enhanced or comparable Wee-1 potency in cells, and/or an enhanced or similar kinetic solubility, and/or an enhanced or similar thermodynamic solubility, and/or an enhanced or similar stability in human microsomes, compared to known compounds.

Without wishing to be bound by theory, it is thought that the compounds of the present invention tend to show the advantageous effects discussed above due, at least in part, to the presence of a pyrido[4,3-d]pyrimidin-5-one (or a pyridazino[4,5-d]pyrimidin-6-one) in combination with an alkyl group, a cyano group or optionally substituted alkynyl group as R², an optionally substituted alkyl group, a cycloalkyl group, an alkoxy group or a cycloalkoxy group as R³, a nitrogen atom or methine group as X, and a hydrogen atom, deuterium atom, an alkyl group or a cycloalkyl group as R⁴. DETAILED DESCRIPTION OF THE INVENTION

Unless otherwise defined herein, scientific and technical terms used in connection with the present invention shall have the meanings that are commonly understood by those of ordinary skill in the art. The meaning and scope of the terms should be clear, however, in the event of any latent ambiguity, definitions provided herein take precedent over any dictionary or extrinsic definition.

As used in the specification and the appended claims, unless specified to the contrary, the following terms have the meaning indicated:

The term "alkyl group" (alone or in combination with another term(s)) means a straight-or branched-chain saturated hydrocarbyl substituent typically containing 1 to 15 carbon atoms, such as 1 to 10, 1 to 8, 1 to 6, or 1 to 4 carbon atoms. A "C_n alkyl' group refers to an aliphatic group containing n carbon atoms. For example, a C1-C10 alkyl group contains 1 , 2, 3, 4, 5, 6, 7, 8, 9 or 10 carbon atoms. Attachment to the alkyl group occurs through a carbon atom. Examples of such substituents include methyl, ethyl, n-propyl, isopropyl, n- butyl, isobutyl, sec-butyl, tert-butyl, pentyl (branched or unbranched), hexyl (branched or unbranched), heptyl (branched or unbranched), octyl (branched or unbranched), nonyl (branched or unbranched), and decyl (branched or unbranched).

The term "alkynyl group" (alone or in combination with another term(s)) means a straight-or branched-chain hydrocarbon substituent containing one or more triple bonds and typically 2 to 15 carbon atoms; such as 2 to 10, 2 to 8, 2 to 6 or 2 to 4 carbon atoms. Examples of such substituents include ethynyl, 1-propynyl, 3-propynyl, 1-butynyl, 3-butynyl and 4- butynyl.

The term "cycloalkyi group" (alone or in combination with another term(s)) means a saturated cyclic hydrocarbon substituent containing 3 to 14 carbon ring atoms. A cycloalkyi may be a single carbon ring, which typically contains 3 to 8 carbon ring atoms and more typically 3 to 6 ring atoms. It is understood that attachment to a cycloalkyi group is via a ring atom of the cycloalkyi group. Examples of single-ring cycloalkyls include cyclopropyl (cyclopropanyl), cyclobutyl (cyclobutanyl), cyclopentyl (cyclopentanyl), cyclohexyl

(cyclohexanyl). A cycloalkyi may alternatively be partly unsaturated or be polycyclic or contain more than one ring. Examples of polycyclic cycloalkyls include bridged, fused, and spirocyclic cycloalkyls. In a spirocyclic cycloalkyi, one atom is common to two different rings. An example of a spirocyclic cycloalkyi is spiropentanyl. In a bridged cycloalkyi, the rings share at least two common non-adjacent atoms. Examples of bridged cycloalkyls include bicyclo[2.2.1]heptanyl, bicyclo[2.2.1]hept-2-enyl, and adamantanyl. In a fused-ring cycloalkyi system, two or more rings may be fused together, such that two rings share one common bond. Examples of two- or three-fused ring cycloalkyls include

tetrahydronaphthalenyl (tetralinyl), indenyl, indanyl (dihydroindenyl) and decalinyl.

The term "aryl group" (alone or in combination with another term(s)) means an aromatic cycloalkyi containing from 6 to 14 carbon ring atoms, or 6 to 12, 6 to 10 or 6 to 8 carbon ring atoms. An aryl may be monocyclic or polycyclic (i.e., may contain more than one ring). In the case of polycyclic aromatic rings, only one ring in the polycyclic system is required to be unsaturated while the remaining ring(s) may be saturated, partially saturated or unsaturated. Attachment to the aryl group occurs through a carbon atom contained in the ring. Examples of aryl groups include phenyl, naphthyl, indenyl, indanyl, and

tetrahydronapthyl. The term "heterocyclyl group" (alone or in combination with another term(s)) means a saturated (i.e. "heterocycloalkyl"), partially saturated (i.e. "heterocycloalkenyl"), or completely unsaturated (i.e. "heteroaryl") ring structure containing a total of 3 to 14 ring atoms, wherein at least one of the ring atoms is a heteroatom (i.e. oxygen, nitrogen, or sulfur), with the remaining ring atoms being carbon atoms. A heterocyclyl group may, for example, contain one, two, three, four or five heteroatoms. One or more attachments to the heterocyclyl group may occur either through a carbon atom and/or one or more heteroatoms that are contained in the ring. A heterocyclyl may be a single-ring

(monocyclic) or polycyclic ring structure. A heterocyclyl group may be a single ring, which typically contains from 3 to 7 ring atoms, more typically from 3 to 6 ring atoms, and even more typically 5 to 6 ring atoms. Examples of single-ring heterocyclyles include furanyl, dihydrofuranyl, tetrahydrofuranyl, thiophenyl (thiofuranyl), dihydrothiophenyl, tetrahydrothiophenyl, pyrrolyl, pyrrolinyl, pyrrolidinyl, imidazolyl, imidazolinyl, imidazolidinyl, pyrazolyl, pyrazolinyl, pyrazolidinyl, triazolyl, tetrazolyl, oxazolyl, oxazolidinyl, isoxazolidinyl, isoxazolyl, thiazolyl, isothiazolyl, thiazolinyl, isothiazolinyl, isothiazolinyM oxo, thiazolidinyl, isothiazolidinyl, thiodiazolyl, oxadiazolyl (including 1 ,2,3-oxadiazolyl, 1 ,2,4-oxadiazolyl, 1 ,2,5-oxadiazolyl (furazanyl) or 1 ,3,4- oxadiazolyl), pyranyl, dihydropyranyl, thiopyranyl, tetrahydrothiopyranyl, 1- iminotetrahydrothiopyranyl-1-oxo, pyridinyl (azinyl), piperidinyl, diazinyl (including pyridazinyl (1 ,2-diazinyl), pyrimidinyl (1 ,3-diazinyl) or pyrazinyl (1 ,4-diazinyl)), piperazinyl, triazinyl (including 1 ,3,5-triazinyl, 1.2.4- triazinyl and 1 ,2,3 -triazinyl), oxazinyl (1 ,4-oxazinyl), morpholinyl, thiomorpholinyl, 1-iminothiomorpholinyl-1-oxo, azepinyl, oxepinyl, thiepinyl, and diazepinyl. A heterocydyl group may alternatively be polycyclic (i.e., may contain more than one ring). Examples of polycyclic heterocydyl groups include bridged, fused, and spirocyclic heterocydyl groups. In a spirocyclic heterocydyl group, one atom is common to two different rings. In a bridged heterocydyl group, the rings share at least two common non- adjacent atoms. In a fused-ring heterocydyl group, two or more rings may be fused together, such that two rings share one common bond. Examples of fused ring heterocydyl groups containing two or three rings include indolizinyl, pyranopyrrolyl, 4H-quinolizinyl, purinyl, naphthyridinyl, pyridopyridinyl (including pyrido[3,4-b]-pyridinyl, pyrido[3,2-b]- pyridinyl, or pyrido[4,3-b]-pyridinyl), and pteridinyl. Other examples of fused-ring

heterocydyl groups include benzo-fused heterocydyl groups, such as indolyl, isoindolyl (isobenzazolyl, pseudoisoindolyl), indoleninyl (pseudoindolyl), isoindazolyl (benzpyrazolyl), benzazinyl (including quinolinyl (1-benzazinyl) or isoquinolinyl (2 -benzazinyl)),

phthalazinyl, quinoxalinyl, benzodiazinyl (including cinnolinyl (1 ,2-benzodiazinyl) or quinazolinyl (1 ,3-benzodiazinyl)), benzopyranyl (including chromanyl or isochromanyl), benzoxazinyl, and benzisoxazinyl (including 1 ,2-benzisoxazinyl or 1 ,4-benzisoxazinyl).

The term "heterocycloalkyl group" (alone or in combination with another term(s)) means a saturated heterocydyl group.

The term "heteroaryl group" (alone or in combination with another term(s)) means an aromatic heterocydyl containing from 5 to 14 ring atoms. A heteroaryl may be a single ring or 2 or 3 fused rings. Examples of heteroaryl groups include 6-membered rings such as pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, and 1 ,3,5-, 1 ,2,4- or 1 ,2,3-triazinyl; 5-membered rings such as imidazolyl, furanyl, thiophenyl, pyrazolyl, oxazolyl, isoxazolyl, thiazolyl, 1 ,2,3-, 1 ,2,4-, 1 ,2,5-, or 1 ,3,4-oxadiazolyl and isothiazolyl; 6/5-membered fused rings such as benzothiofuranyl, benzisoxazolyl, benzoxazolyl, purinyl; and 6/6-membered fused rings such as benzopyranyl, quinolinyl, isoquinolinyl, cinnolinyl, quinazolinyl, and benzoxazinyl.

The term "amino group" refers to the -NH₂ group. The amino group can be optionally substituted (a "substituted amino") with one or more substituents, which can be the same or different. Amino group substituents may be, but are not limited to, an alkyl, alkanoyi, aryl and/or a heterocyclyl group.

The term "amido group" refers to the -C(=0)-NR- group. Attachment may be through the carbon and/or nitrogen atom. For example, the amido group may be attached as a substituent via the carbon atom only, in which case the nitrogen atom has two R groups attached (-C(=0)-NR₂). The amido group may be attached by the nitrogen atom only, in which case the carbon atom has an R group attached (-NR-C(=0)R). The term "alkoxy group" refers to an -O-alkyl group. The alkoxy group can refer to linear, branched, saturated or unsaturated hydrocarbon chains, including, for example, methoxy, ethoxy, propoxy, isopropoxy, butoxy, t-butoxy and pentoxy. The alkoxy group can be optionally substituted (a "substituted alkoxy") with one or more substituents. The term "cycloalkoxy group" refers to an -O-cycloalkyl group. The cycloalkoxy group refers to cyclic, saturated or unsaturated, hydrocarbon chains, including, for example, cyclopropyl, cyclobutyl, cyclopentyl, cycloheptyl and cyclohexyl. The cycloalkyl group can be optionally substituted (a "substituted cycloalkoxy") with one or more substituents. The term "hydroxy" refers to an -OH group.

The term "alkanoyi group" (i.e. acyl group) refers to an organic acid group wherein the -OH of the carboxyl group has been replaced with another substituent. Thus, the alkanoyi group can be represented by the formula RC(=0)-, wherein R includes but is not limited to an alkyl, aralkyi, an aryl group (an "aroyl group'), a heteroaryl group (a "heteroaroyi group') which in turn may be optionally substituted by one or more substituents. Examples of alkanoyi groups include an acetyl group, a propionyl group, a butyryl group, an isobutyryl group, a valeryl group, an isovaleryl group, a pivaloyl group and a benzoyl group. The term "halo group" refers to a group selected from chlorine, fluorine, bromine and iodine. Examples of halo groups include a chlorine atom (a chloro group) and a fluorine atom (a fluoro group).

An alkyi, alkynyl, amino, amido, alkoxy, cycloalkyl, aryl, heterocyclyl group can be optionally substituted with one or more substituents, which can be the same or different. A substituent can be attached through a carbon atom and/or a heteroatom in the alkyi, alkynyl, amino, amido, alkoxy, clyloalkyl, aryl, heterocyclyl group. The term "substituent' (or "radical") includes but is not limited to alkyi, substituted alkyi, aralkyi, substituted aralkyi, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, halo, cyano, amino, amido, alkylamino, arylamino, carbocyclyl, cycloalkyl, substituted cycloalkyl, cycloalkenyl, substituted cycloalkenyl, aryl, substituted aryl, nitro, thio, alkanoyl, hydroxyl, aryloxyl, alkoxyl, alkylthio, arylthio, aralkyloxyl, aralkylthio, carboxyl, alkoxycarbonyl, oxo, alkylsulfonyl and arylsulfonyl. If a group (for example an alkyi group) is "optionally substituted', it is understood that the group has one or more substituents attached (substituted) or does not have any

substituents attached (unsubstituted).

For completeness, it is also noted that certain chemical formulae used herein define delocalized systems. This definition is known in the art as a definition of aromaticity and may indicate the presence of, for example, a mono-, di- or tri-cyclic system that contains (4n+2) electrons where n is an integer. In other words, these systems may display Huckel aromaticity. In whatever aspect, the compounds of the present invention may possess some aspect of stereochemistry. For example, the compounds may possess chiral centres and / or planes and / or axes of symmetry. As such, the compounds may be provided as single

stereoisomers, single diastereomers, mixtures of stereoisomers or as racemic mixtures. Stereoisomers are known in the art to be molecules that have the same molecular formula and sequence of bonded atoms, but which differ in their spatial orientations of their atoms and / or groups.

In addition, the compounds of the present invention may possess tautomerism. Each tautomeric form is intended to fall within the scope of the invention. In addition, the compounds of the present invention may be provided as a pro-drug. Prodrugs are transformed, generally in vivo, from one form to the active forms of the drugs described herein. For example, a prodrug may be formed by protecting any -N-H groups with a hydrolysable group that gives -NH on hydrolysis. Any -NH group within the compound may be protected as a physiological hydrolyzable amide.

In addition, it will be understood that the elements described herein may be the common isotope or an isotope other than the common isotope. For example, a hydrogen atom may be ¹ H, ²H (deuterium) or ³H (tritium).

In addition, the compounds of the present invention may be provided in the form of their pharmaceutically acceptable salts or as co-crystals. For example, the compounds may be provided having protonated amine groups. The term "pharmaceutically acceptable salt' refers to ionic compounds formed by the addition of an acid to a base. The term refers to such salts that are considered in the art as being suitable for use in contact with a patient, for example in vivo and pharmaceutically acceptable salts are generally chosen for their non-toxic, non-irritant characteristics. The term "co-crystaf refers to a multi- component molecular crystal, which may comprise non-ionic interactions.

Pharmaceutically acceptable salts and co-crystals may be prepared by ion exchange chromatography or by reacting the free base or acidic form of a compound with

stoichiometric amounts or with an excess of the desired salt-forming inorganic or organic acid or base in one or more suitable solvents, or by mixing the compound with another pharmaceutically acceptable compound capable of forming a co-crystal.

Examples of pharmaceutically acceptable salts include, but are not limited to, mineral or organic acid salts of basic residues such as amines; alkali or organic salts of acidic residues such as carboxylic acids; and the like. The pharmaceutically acceptable salts of the present invention include the conventional non-toxic salts of the parent compound formed, for example, from non-toxic inorganic or organic acids. The pharmaceutically acceptable salts of the present invention can be synthesized from the parent compound which contains a basic or acidic moiety by conventional chemical methods. Generally, such salts can be prepared by reacting the free acid or base forms of these compounds with a stoichiometric amount of the appropriate base or acid in water or in an organic solvent, or in a mixture of the two; generally, non-aqueous media like ether, ethyl acetate, ethanol, isopropanol, or acetonitrile are preferred. Further reference is made to the number of literature sources that survey suitable pharmaceutically acceptable salts, for example the Handbook of pharmaceutical salts published by lUPAC.

In addition, the compounds of the present invention may sometimes exist as zwitterions, which are considered as part of the invention.

The present inventors have discovered that the compounds of the present invention are useful in the treatment of medical conditions associated with disordered cell growth, including, but not restricted to, cancer, in particular (but not restricted to) cancers associated with inactivation in the tumour suppressor gene p53. The compound may have utility and activity as a single agent exploiting synthetic or contextual lethality relationships as well as in diseases including cancers with enhanced susceptibility to increased replicative stress and impaired cell cycle progression. Wee1 inhibitors according to the invention may also be used in combination modalties including combinations with genotoxic agents, radiotherapy, targeted agents and immune-modulators including but not restricted to immune checkpoint inhibitors.

For example, cancers include cardiac cancers, lung cancers, gastrointestinal cancers, genitourinary tract cancers, liver cancers, bone cancers, nervous system cancers, gynecological cancers, hematologic cancers, skin cancers and adrenal gland cancers, and cancers such as adrenal tumors, bile duct, bladder, blood, bone and connective tissue, brain and central nervous system, breast, cervical, colon and rectal (colorectal), endometrial, esophageal, gallbladder, head and neck, Hodgkin's Lymphoma,

hypopharangeal, kidney, laryngeal, leukemias, liver, lung, lymphoma, mediastinal tumors, melanoma (malignant melanoma), mesothelioma, multiple myeloma, nasal cavity, nasopharyngeal, neuroendocrine tumors, non-Hodgkin's lymphoma, oral, oesophagus, oropharyngeal, ovarian, pancreas, paranasal sinus, parathyroid, penis, pituitary tumors, prostate, salivary gland, sarcoma, skin, spine, stomach, testicular, thyroid, urethra, uterine, vaginal and vulvar. Preferably the cancer is selected from colon and rectal (colorectal) cancer, head and neck cancer, lung cancer, oesophagus cancer, ovarian cancer and pancreas cancer. More preferably, the cancer is colon and rectal (colorectal) cancer. Alternatively, preferably, the cancer is lung cancer, more preferably non-small cell lung cancer.

The compounds of the present invention are also useful in preparing a medicament that is useful in treating the diseases described above, in particular cancer.

The present invention is further directed to a method of inhibiting Wee-1 activity which comprises administering to a mammal, preferably a human, in need thereof a

pharmaceutically effective amount of the compound of the present invention.

The compounds of this invention may be administered to mammals, including humans, either alone or, in combination with pharmaceutically acceptable carriers, excipients or diluents, in a pharmaceutical composition, according to standard pharmaceutical practice. The compounds can be administered orally or parenterally, including the intravenous, intramuscular, intraperitoneal, subcutaneous, rectal and topical routes of administration.

The present invention also includes within its scope the use of the compounds of the present invention in combination with a second or further drug in the treatment of cancer. The second or further drug may be a drug that is already known in the art in the treatment of cancer.

The present invention also includes the use of the compounds of the invention in a regime including the step of radiotherapy. The radiotherapy may be an ordinary method of treatment by x-ray, γ-ray, neutron, a-particle, proton or electron beam irradiation. The co- administration of compounds contained in this invention may lead to the potentiation of the radiation therapy, thus classifying them as radio-sensitizers.

In particular, cancers often become resistant to therapy. The development of resistance may be delayed or overcome by the administration of a combination of drugs that includes the compounds of the present invention for example in cancers which are known to be resistant to DNA damaging agents, radiotherapy or any other form of treatment agents and modalities. For example, drugs that may be used in combination with the compounds of the present invention may target the same or a similar biological pathway to that targeted by the compounds of the present invention or may act on a different or unrelated pathway. Depending on the disease to be treated, a variety of combination partners may be coadministered with the compounds of the present invention, for example genotoxic agents, targeted agents and immune-modulators. The second active ingredient may include, but is not restricted to: alkylating agents, including cyclophosphamide, ifosfamide, thiotepa, melphalan, chloroethylnitrosourea and bendamustine; platinum derivatives, including cisplatin, oxaliplatin, carboplatin and satraplatin; antimitotic agents, including vinca alkaloids (vincristine, vinorelbine and vinblastine), taxanes (paclitaxel, docetaxel), epothilones and inhibitors of mitotic kinases including aurora and polo kinases;

topoisomerase inhibitors, including anthracyclines, epipodophyllotoxins, camptothecin and analogues of camptothecin; antimetabolites, including 5-fluorouracil, capecitabine, cytarabine, gemcitabine, 6-mercaptopurine, 6-thioguanine, fludarabine, methotrexate and premetrexed; targeted therapies, for example protein kinase inhibitors, including imatinib, gefitinib, sorafenib, sunitinib, erlotinib, dasatinib, and lapatinib; proteasome inhibitors, including bortezomib; histone deacetylase inhibitors, including valproate and SAHA; cell cycle and checkpoint inhibitors, including CDK4 / 6, CHK1 and CHK2; DNA-repair- modulators, including but not restricted to inhibitors of PARP, DNA-PK, ATM, ATR;

antiangiogenic drugs, including bevacizumab; monoclonal antibodies, including

trastuzumab, rituximab, alemtuzumab, tositumomab, cetuximab, panitumumab; conjugates of myoclonal antibodies, including Gemtuzumab ozogamicin, Ibritumomab tiuxetan;

hormonal therapies, including antiestrogens (tamoxifen, raloxifen, anastrazole, letrozole, examestane) antiandrogens (flutamide, bicalutamide) and Luteinising Hormone analogues or antagonists.

With regard to combination therapy the compounds of the present invention may be administered separately, sequentially, simultaneously, concurrently or may be

chronologically staggered with one or more standard therapeutics such as any of those mentioned above.

The present invention provides a compound of Formula (I):

(I)

or a pharmaceutically acceptable salt or /V-oxide derivative thereof, wherein:

R¹ is an optionally substituted aryl or heteroaryl group;

R² is an optionally substituted alkyl group, an alkynyl group optionally substituted by one or more alkyl groups and/or one or more alkoxy groups, or a cyano group;

R³ is an optionally substituted alkyl group, a cycloalkyl group, an alkoxy group or a cycloalkoxy group;

R⁴ is a hydrogen atom, an alkyl group or a cycloalkyl group;

X is a nitrogen atom or a CH-group;

Y is a nitrogen atom or a CH-group;

Z is a nitrogen atom or a CH-group; and

n is 1 when X is a nitrogen atom and n is 0 or 1 when X is a CH-group. R¹ is an optionally substituted aryl or heteroaryl group. Preferably, R¹ is a substituted aryl or heteroaryl group.

In an embodiment of Formula (I), R¹ is optionally, independently substituted one or more times with a halo group, a hydroxy group, a cyano group, an amino group, a C C₆ alkyl group, a C₂-C₆ alkenyl group, a C C₆ alkoxy group or a C C₆ alkoxy-CrC₆ alkyl group; and R² is an alkyl group, optionally, independently substituted one or more times with a halo group or C C₄ alkoxy group; or R² is an alkynyl group optionally, independently substituted one or more times with a C C₄ alkoxy group or a C C₄ alkyl group; or R² is a cyano group.

In another embodiment of Formula (I), R¹ is optionally, independently substituted one or more times with a halo group, a C C₄ alkyl group, or a C C₄ alkoxy group; and R² is an alkyl group, optionally, independently substituted one or more times with a halo group or a C1-C4 alkoxy group; or R² is an alkynyl group, optionally, independently substituted one or more times with a C C₄ alkoxy group or a C C₄ alkyl group; or R² is a cyano group.

Preferably, R¹ is a group represented by the formula (a):

(a)

wherein R^1a and R^{1 b} are each independently selected from the group consisting of a hydrogen atom, a halo group, a hydroxy group, a cyano group, an amino group, a C C₆ alkyl group, C₂-C₆ alkenyl group, a C C₆ alkoxy group and a C C₆ alkoxy-CrC₆ alkyl group.

More preferably, R¹ is a group represented by the formula (b):

(b)

wherein R^1a and R^{1 b} are each independently selected from the group consisting of a hydrogen atom, a halo group, a hydroxy group, a cyano group, an amino group, a C C₆ alkyl group and a C C₆ alkoxy group.

Preferably, in the groups represented by the formulae (a) and/or (b), R^1a is a hydrogen atom, a halo group, a cyano group, a methyl group or a methoxy group; and R^{1 b} is a halo group. More preferably, R^1a is a hydrogen atom, a methyl group or a halo group; and R^{1 b} is a halo group. More preferably, R^1a is a hydrogen atom, a methyl group or a halo group; and R^{1 b} is a chloro group. More preferably, R^1a is a hydrogen atom, a methyl group, a chloro group or a fluoro group; and R^{1 b} is a chloro group. More preferably, R^1a is a methyl group, a chloro group or a fluoro group; and R^{1 b} is a chloro group. Alternatively, preferably, R^1a is a hydrogen atom, a methyl group or a chloro group; and R^{1 b} is a chloro group. More preferably, R^1a is a methyl group or a chloro group; and R^{1 b} is a chloro group. Preferably, R¹ is a 2-chlorophenyl group, a 2-chloro-6-methylphenyl group, a 2-chloro-6- fluorophenyl group or a 2,6-dichlorophenyl group. Most preferably, R¹ is a 2,6- dichlorophenyl group. R² is an optionally substituted alkyl group, an alkynyl group optionally substituted by one or more alkyl groups and/or one or more alkoxy groups, or a cyano group. Preferably, R² is a methyl group, a methyl group substituted by one or more fluoro groups, an alkynyl group optionally substituted by one or more alkyl groups and/or one or more alkoxy groups, or a cyano group. More preferably R² is a methyl group, a difluoromethyl group, an alkynyl group optionally substituted by one or more alkyl groups and/or one or more alkoxy groups, or a cyano group. More preferably still, R² is a methyl group, a difluoromethyl group, an alkynyl group optionally substituted by an alkoxy group, or a cyano group.

In one embodiment, R² is an alkynyl group optionally substituted by one or more alkyl groups and/or one or more alkoxy groups. Preferably, R² is an alkynyl group optionally substituted by one or more methyl groups and/or one or more alkoxy groups. More preferably, R² is an alkynyl group optionally substituted by one or more methyl groups and/or one or more methoxy groups. More preferably, R² is an alkynyl group substituted by one or more methyl groups and/or one or more methoxy groups.

Preferably, R² is an alkynyl group optionally substituted by an alkoxy group. More preferably, R² is an alkynyl group substituted by an alkoxy group. Most preferably, the alkynyl group is substituted by a methoxy group. Preferably, the alkynyl group is a C₂-C₆ alkynyl group, more preferably a C₂-C₅ alkynyl group, more preferably a C₂-C₄ alkynyl group, more preferably a C₂-C₃ alkynyl group, most preferably a C₃ alkynyl group.

More preferably, when R² is an alkynyl group, the alkynyl group is represented by formulc

(c):

(c) In one embodiment, R² is a methyl group or a methyl group substituted by one or more fluoro groups. More preferably, R² is a methyl group or a difluoromethyl group (-CHF₂). Most preferably, R² is an unsubstituted methyl group. Alternatively, preferably, R² is a difluoromethyl group.

In one embodiment, R² is a cyano group.

R³ is an optionally substituted alkyi group, a cycloalkyi group, an alkoxy group or a cycloalkoxy group.

In one embodiment, R³ is an optionally substituted alkyi group. Preferably, the alkyi group is a Ci-C₆ alkyi group, more preferably a C C₅ alkyi group, more preferably a C C₄ alkyi group, more preferably a C C₃ alkyi group, more preferably a C C₂ alkyi group. Most preferably, R³ is an optionally substituted methyl group.

Preferably, R³ is an unsubstituted alkyi group or an alkyi group substituted by a hydroxy group and/or one or more halo groups. More preferably, R³ is an unsubstituted alkyi group or an alkyi group substituted by a hydroxy group and/or one or more fluoro groups. More preferably, R³ is an unsubstituted C C₂ alkyi group or a C C₂ alkyi group substituted by a hydroxy group and/or one or more fluoro groups. Most preferably, R³ is an unsubstituted methyl group or a methyl group substituted by a hydroxy group and/or a CF₃ group.

In one preferable embodiment, R³ is an alkyi group, a cycloalkyi group, an alkoxy group or a cycloalkoxy group.

In one embodiment, R³ is an unsubstituted alkyi group. Preferably, the unsubstituted alkyi group is a C C₆ alkyi group, more preferably a C C₅ alkyi group, more preferably a C C₄ alkyi group, more preferably a C C₃ alkyi group, more preferably a C C₂ alkyi group. Most preferably, R³ is a methyl group.

In one embodiment, R³ is a cycloalkoxy group. Preferably, the cycloalkoxy group is a C₃-C₆ cycloalkoxy group, more preferably a C₃-C₅ cycloalkoxy group, more preferably a C₃-C₄ cycloalkoxy group, more preferably a C₃ cycloalkoxy group. Alternatively, preferably, R³ is a cycloalkyl group. Preferably, the cycloalkyl group is a C₃- C₆ alkyi group, more preferably a C₃-C₅ alkyi group, more preferably a C₃-C₄ alkyi group. Most preferably, R³ is a cyclopropyl group. More preferably, R³ is an alkoxy group. Preferably, the alkoxy group is a C C₆ alkoxy group, more preferably a C C₅ alkoxy group, more preferably a C C₄ alkoxy group, more preferably a C C₃ alkoxy group, more preferably a C C₂ alkoxy group. Most preferably, R³ is a methoxy group. In one preferable embodiment, R³ is an unsubstituted methyl group, a methyl group substituted by a hydroxy group and/or a CF₃ group, or a C₃ cycloalkoxy group.

R⁴ is a hydrogen atom (for example a hydrogen atom or a deuterium atom), an alkyi group or a cycloalkyl group. Preferably, R⁴ is a hydrogen atom (¹ H), a deuterium atom (²H), an alkyi group or a cycloalkyl group.

In one embodiment, R⁴ is an alkyi group. Preferably, the alkyi group is a C C₆ alkyi group, more preferably a C C₅ alkyi group, more preferably a C C₄ alkyi group, more preferably a Ci-C₃ alkyi group, more preferably a C C₂ alkyi group. Most preferably, the alkyi group is a methyl group. Preferably the methyl group is unsubstituted.

In one embodiment, R⁴ is a cycloalkyl group. Preferably, the cycloalkyl group is a C₃-C₆ cycloalkyl group, more preferably a C₃-C₅ cycloalkyl group, more preferably a C₃-C₄ cycloalkyl group. Most preferably, the cycloalkyl group is a cyclopropyl group. Preferably the cycloalkyl group is unsubstituted.

In one embodiment, R⁴ is a hydrogen atom.

In one embodiment, R⁴ is a deuterium atom.

Preferably, R⁴ is a hydrogen atom or an alkyi group. More preferably, R⁴ is a hydrogen atom or a C C₆ alkyi group. More preferably, R⁴ is a hydrogen atom or a C C₄ alkyi group. More preferably, R⁴ is a hydrogen atom or a C C₃ alkyi group. More preferably, R⁴ is a hydrogen atom or a C C₂ alkyi group. More preferably, R⁴ is a hydrogen atom or a methyl group. More preferably, R⁴ is a hydrogen atom. Alternatively, preferably, R⁴ is a methyl group.

X is a nitrogen atom or a CH-group. Preferably, X is a nitrogen atom. Alternatively, preferably, X is a CH-group.

Preferably, when X is a CH-group, R³ is an alkyl group, preferably a methyl group.

More preferably, X is a nitrogen atom and R³ is an alkoxy group. More preferably still, X is a nitrogen atom and R³ is a methoxy group.

Y is a nitrogen atom or a CH-group. Preferably, Y is a CH-group. Alternatively, preferably,

Y is a nitrogen atom. Z is a nitrogen atom or a CH-group. Preferably, Z is a CH-group. Alternatively, preferably, Z is a nitrogen atom.

When X is a nitrogen atom, n is 1. When X is a CH-group, n is 0 or 1. Preferably, when X is a CH-group, n is 1. Alternatively, preferably, when X is a CH-group, n is 0.

More preferably, X is a nitrogen atom or a CH-group and n is 1. Alternatively, preferably, X is a nitrogen atom or a CH-group, and n is 1 when X is a nitrogen atom and 0 when X is a CH-group.

Preferably, in the compound of Formula (I), R¹ is a 2,6-dichlorophenyl group; R² is a methyl group, an alkynyl group substituted by an alkoxy group, or a cyano group; R³ is an alkoxy group; R⁴ is a hydrogen atom or an alkyl group; X is a nitrogen atom; Y is a nitrogen atom or a CH-group; Z is a CH-group; and n is 1.

More preferably, in the compound of Formula (I), R¹ is a 2,6-dichlorophenyl group; R² is a methyl group, an alkynyl group substituted by an alkoxy group, or a cyano group; R³ is a methoxy group; R⁴ is a hydrogen atom or a methyl group; X is a nitrogen atom; Y is a CH- group; Z is a CH-group; and n is 1.

More preferably, in the compound of Formula (I), R¹ is a 2,6-dichlorophenyl group; R² is a methyl group; R³ is a methoxy group; R⁴ is a hydrogen atom or a methyl group; X is a nitrogen atom; Y is a CH-group; Z is a CH-group; and n is 1.

Alternatively, preferably, in the compound of Formula (I), R¹ is a 2,6-dichlorophenyl group; R² is an alkynyl group substituted by an alkoxy group; R³ is a methoxy group; R⁴ is a hydrogen atom or a methyl group; X is a nitrogen atom; Y is a CH-group; Z is a CH-group; and n is 1.

Alternatively, preferably, in the compound of Formula (I), R¹ is a 2,6-dichlorophenyl group; R² is a cyano group; R³ is a methoxy group; R⁴ is a hydrogen atom or a methyl group; X is a nitrogen atom; Y is a CH-group; Z is a CH-group; and n is 1.

Alternatively, preferably, in the compound of Formula (I), R¹ is a 2,6-dichlorophenyl group; R² is a methyl group; R³ is a methoxy group; R⁴ is a hydrogen atom or a methyl group; X is a nitrogen atom; Y is a nitrogen atom; Z is a CH-group; and n is 1.

In a further embodiment, in the compound of Formula (I), R¹ is a 2,6-dichlorophenyl group; R² is a methyl group, an alkynyl group substituted by an alkoxy group, or a cyano group; R³ is an optionally substituted alkyl group, a cycloalkyi group, an alkoxy group or a cycloalkoxy group; R⁴ is a hydrogen atom, a deuterium atom, an alkyl group or a cycloalkyi group; X is a CH-group; Y is a nitrogen atom or a CH-group; Z is a nitrogen atom or a CH-group; and n is 0 or 1.

More preferably, in the compound of Formula (I), R¹ is a 2,6-dichlorophenyl group; R² is a methyl group, an alkynyl group substituted by an alkoxy group, or a cyano group; R³ is an optionally substituted alkyl group; R⁴ is a hydrogen atom or an alkyl group; X is a CH- group; Y is a nitrogen atom or a CH-group; Z is a CH-group; and n is 0 or 1.

More preferably, in the compound of Formula (I), R¹ is a 2,6-dichlorophenyl group; R² is a methyl group, an alkynyl group substituted by an alkoxy group, or a cyano group; R³ is a methyl group or a methyl group substituted by a hydroxy group and/or a -CF₃ group; R⁴ is a hydrogen atom or a methyl group; X is a CH-group; Y is a CH-group; Z is a CH-group; and n is 1.

Alternatively, preferably, in the compound of Formula (I), R¹ is a 2,6-dichlorophenyl group; R² is a methyl group; R³ is a methyl group or a methyl group substituted by a hydroxy group and/or a -CF₃ group; R⁴ is a hydrogen atom or a methyl group; X is a CH-group; Y is a CH- group; Z is a CH-group; and n is 1.

Alternatively, preferably, in the compound of Formula (I), R¹ is a 2,6-dichlorophenyl group; R² is an alkynyl group substituted by an alkoxy group; R³ is a methyl group or a methyl group substituted by a hydroxy group and/or a -CF₃ group; R⁴ is a hydrogen atom or a methyl group; X is a CH-group; Y is a CH-group; Z is a CH-group; and n is 1.

Alternatively, preferably, in the compound of Formula (I), R¹ is a 2,6-dichlorophenyl group; R² is a cyano group; R³ is a methyl group or a methyl group substituted by a hydroxy group and/or a -CF₃ group; R⁴ is a hydrogen atom or a methyl group; X is a CH-group; Y is a CH- group; Z is a CH-group; and n is 1.

Alternatively, preferably, in the compound of Formula (I), R¹ is a 2,6-dichlorophenyl group; R² is a methyl group; R³ is a methyl group or a methoxy group; R⁴ is a hydrogen atom or a methyl group; X is a CH-group or a nitrogen atom; Y is a nitrogen atom; Z is a CH-group; and n is 1.

Preferably, the compound of Formula (I) is selected from the following:

(1) 6-(2,6-Dichlorophenyl)-2-((3-methyl-4-(piperazin-1-yl)phenyl)amino)-5-oxo-5,6- dihydropyrido[4,3-d]pyrimidine-8-carbonitrile;

(2) ( )-6-(2,6-Dichlorophenyl)-2-((3-methyl-4-(3-methylpiperazin-1-yl)phenyl)amino)-5- oxo-5,6-dihydropyrido[4,3-d]pyrimidine-8-carbonitrile;

(3) 6-(2,6-Dichlorophenyl)-2-((3-methoxy-4-(piperazin-1-yl)phenyl)amino)-5-oxo-5,6- dihydropyrido[4,3-d]pyrimidine-8-carbonitrile; (4) ( ?)-6-(2,6-Dichlorophenyl)-2-((3-methoxy-4-(3-methylpiperazin-1-yl)phenyl)amino)- 5-0X0-5, 6-dihydropyrido[4,3-d]pyrimidine-8-carbonitrile;

(5) 6-(2,6-dichlorophenyl)-2-((3-methoxy-4-(piperazin-1-yl)phenyl)amino)-8-(3- methoxyprop-1-yn-1-yl)pyrido[4,3-d]pyrimidin-5(6H)-one;

(6) ( ?)-6-(2,6-dichlorophenyl)-2-((3-methoxy-4-(3-methylpiperazin-1-yl)phenyl)amino)- 8-(3-methoxyprop-1-yn-1-yl)pyrido[4,3-d]pyrimidin-5(6H)-one;

(7) 6-(2,6-dichlorophenyl)- 8-(3-methoxyprop-1-yn-1-yl)-2-((3-methyl-4-(piperazin-1- yl)phenyl)amino)pyrido[4,3-d]pyrimidin-5(6H)-one;

(8) 6-(2,6-Dichlorophenyl)-8-methyl-2-((3-methyl-4-(piperazin-1- yl)phenyl)amino)pyrido[4,3-c]pyrimidin-5(6H)-one; and

(9) 6-(2,6-Dichlorophenyl)-2-((3-methoxy-4-(piperazin-1-yl)phenyl)amino)-8- methylpyrido[4,3-c]pyrimidin-5(6H)-one.

Preferably, the compound of Formula (I) is selected from the following:

(10) 6-(2,6-dichlorophenyl)-8-(3-methoxyprop-1-yn-1-yl)-2-((3-methyl-4-(piperidin-4- yl)phenyl)amino)pyrido[4,3-d]pyrimidin-5(6H)-one;

(1 1) 2-((3-Cyclopropoxy-4-(piperazin-1-yl)phenyl)amino)-6-(2,6-dichlorophenyl)-5-oxo-5,6- dihydropyrido[4,3-d]pyrimidine-8-carbonitrile;

(12) 6-(2-chloro-6-methylphenyl)-8-(difluoromethyl)-2-((3-methoxy-4-(piperazin-1- yl)phenyl)amino)pyrido[4,3-d]pyrimidin-5(6H)-one;

(13) rac-6-(2,6-Dichlorophenyl)-8-(3-methoxyprop-1-yn-1-yl)-2-((3-methyl-4-(pyrrolidin-3- yl)phenyl)amino)pyrido[4,3-d]pyrimidin-5(6H)-one;

(14) rac-6-(2,6-Dichlorophenyl)-2-((3-methyl-4-(pyrrolidin-3-yl)phenyl)amino)-5-oxo-5,6- dihydropyrido[4,3-d]pyrimidine-8-carbonitrile;

(15) 6-(2,6-dichlorophenyl)-2-((3-methoxy-4-(pyrrolidin-3-yl)phenyl)amino)-8-(3- methoxyprop-1-yn-1-yl)pyrido[4,3-d]pyrimidin-5(6H)-one;

(16) rac-6-(2,6-Dichlorophenyl)-2-((3-methoxy-4-(pyrrolidin-3-yl)phenyl)amino)-5-oxo-5,6- dihydropyrido[4,3-d]pyrimidine-8-carbonitrile;

(17) 6-(2,6-Dichlorophenyl)-2-[3-methoxy-4-[(3R)-3-methylpiperazin-1-yl]anilino]-8-methyl- pyrimido[4,5-d]pyridazin-5-one;

(18) 6-(2,6-Dichlorophenyl)-2-(3-methoxy-4-piperazin-1-yl-anilino)-8-methyl-pyrimido[4,5- d]pyridazin-5-one;

(19) 6-(2,6-dichlorophenyl)-5-oxo-2-((4-(piperidin-4-yl)-3-(2,2,2-trifluoro-1- hydroxyethyl)phenyl)amino)-5,6-dihydropyrido[4,3-d]pyrimidine-8-carbonitrile; (20) 6-(2,6-Dichlorophenyl)-5-oxo-2-((4-(piperidin-4-yl)-3-(2,2,2- trifluoroethyl)phenyl)amino)-5,6-dihydropyrido[4,3-d]pyrimidine-8-carbonitrile;

(21) rac-6-(2,6-Dichlorophenyl)-8-(3-methoxyprop-1-yn-1-yl)-2-((4-(piperidin-4-yl)-3-(2,2,2- trifluoro-1-hydroxyethyl)phenyl)amino)pyrido[4,3-d]pyrimidin-5(6H)-one;

(22) 6-(2,6-Dichlorophenyl)-8-(3-methoxyprop-1-yn-1-yl)-2-((4-(piperidin-4-yl)-3-(2,2,2- trifluoroethyl)phenyl)amino)pyrido[4,3-d]pyrimidin-5(6H)-one;

(23) 6-(2-Chloro-6-methylphenyl)-2-((3-methoxy-4-(piperazin-1-yl)phenyl)amino)-5-oxo-5,6- dihydropyrido[4,3-d]pyrimidine-8-carbonitrile;

(24) 6-(2-Chloro-6-fluorophenyl)-2-((3-methoxy-4-(piperazin-1-yl)phenyl)amino)-5-oxo-5,6- dihydropyrido[4,3-d]pyrimidine-8-carbonitrile;

(25) 6-(2-Chlorophenyl)-2-((3-methoxy-4-(piperazin-1-yl)phenyl)amino)-5-oxo-5,6- dihydropyrido[4,3-d]pyrimidine-8-carbonitrile;

(26) 6-(2-Chloro-6-methylphenyl)-2-((3-methyl-4-(piperidin-4-yl)phenyl)amino)-5-oxo-5,6- dihydropyrido[4,3-d]pyrimidine-8-carbonitrile;

(27) 6-(2-Chloro-6-fluorophenyl)-2-((3-methyl-4-(piperidin-4-yl)phenyl)amino)-5-oxo-5,6- dihydropyrido[4,3-d]pyrimidine-8-carbonitrile; and

(28) 6-(2,6-dichlorophenyl)-2-((3-(hydroxymethyl)-4-(piperazin-1-yl)phenyl)amino)-5-oxo- 5,6-dihydropyrido[4,3-d]pyrimidine-8-carbonitrile. Alternativel preferably, the present invention provides a compound of Formula (II):

(II)

or a pharmaceutically acceptable salt or /V-oxide derivative thereof, wherein R¹ , R², R³, are as described above with regard to the compound of Formula (I).

Alternatively, preferably, the present invention provides a compound of Formula (III):

(III)

or a pharmaceutically acceptable salt or /V-oxide derivative thereof, wherein R¹ , R³, R⁴, X, Y and Z are as described above with regard to the compound of Formula (I), and R^2a and R^2b are independently selected from the group consisting of a hydrogen atom and a fluoro group. Preferably, each of R^2a and R^2b is a hydrogen atom or each of R^2a and R^2b is a fluoro group. More preferably, each of R^2a and R^2b is a hydrogen atom.

Alternativ

(IV)

or a pharmaceutically acceptable salt or /V-oxide derivative thereof, wherein m is 1 , 2, or 3, R¹⁰ is C1-C4 alkyl, and R¹ , R³, R⁴, X, Y and Z are as described above with regard to the compound of Formula (I).

Alternatively, preferably, the present invention provides a compound of Formula (IVa):

(IVa)

or a pharmaceutically acceptable salt or /V-oxide derivative thereof, wherein R¹ , R³, R⁴, X, Y and Z are as described above with regard to the compound of Formula (I).

Alternatively, referably, the present invention provides a compound of Formula (V):

Alternatively, preferably, the present invention provides a compound of Formula (VI):

(VI)

or a pharmaceutically acceptable salt or /V-oxide derivative thereof, wherein R¹ , R², R³, R⁴, X, Y and Z are as described above with regard to the compound of Formula (I).

Alternatively, preferably, the present invention provides a compound of Formula (VII):

(VII)

or a pharmaceutically acceptable salt or /V-oxide derivative thereof, wherein R¹ , R², R³, R⁴, Y and Z are as described above with regard to the compound of Formula (I).

Preferably, there is provided the compound of any of Formulae (I), (II), (III), (IV), (IVa), (V), (VI) or (VII), or a pharmaceutically acceptable salt or /V-oxide derivative thereof, and at least one pharmaceutically acceptable excipient.

Suitable pharmaceutically acceptable excipients would be known by the person skilled in the art, for example, fats, water, physiological saline, alcohol (e.g., ethanol), glycerol, polyols, aqueous glucose solution, extending agent, disintegrating agent, binder, lubricant, wetting agent, stabilizer, emulsifier, dispersant, preservative, sweetener, colorant, seasoning agent or aromatizer, concentrating agent, diluent, buffer substance, solvent or solubilizing agent, chemical for achieving storage effect, salt for modifying osmotic pressure, coating agent or antioxidant, saccharides such as lactose or glucose; starch of corn, wheat or rice; fatty acids such as stearic acid; inorganic salts such as magnesium metasilicate aluminate or anhydrous calcium phosphate; synthetic polymers such as polyvinylpyrrolidone or polyalkylene glycol; alcohols such as stearyl alcohol or benzyl alcohol; synthetic cellulose derivatives such as methylcellulose, carboxymethylcellulose, ethylcellulose or hydroxypropylmethylcellulose; and other conventionally used additives such as gelatin, talc, plant oil and gum arabic.

Preferably, there is provided a pharmaceutical composition comprising the compound of any of Formulae (I), (II), (III), (IV), (IVa), (V), (VI) or (VII), or a pharmaceutically acceptable salt or /V-oxide derivative thereof, and at least one pharmaceutically acceptable excipient. In certain embodiments, the pharmaceutical composition further comprises an anti-cancer agent, for example as a combination therapy as described herein. In such embodiments, a suitable anti-cancer agent may be any one or more of a genotoxic agent, a targeted agent and an immune-modulator.

Preferably, there is provided the compound of any of Formulae (I), (II), (III), (IV), (IVa), (V), (VI) or (VII), or a pharmaceutically acceptable salt or /V-oxide derivative thereof, or the pharmaceutical composition as described herein, for use in therapy.

Preferably, there is provided the compound of any of Formulae (I), (II), (III), (IV), (IVa), (V), (VI) or (VII), or a pharmaceutically acceptable salt or /V-oxide derivative thereof, or the pharmaceutical composition as described herein, for use as a medicament. Preferably, there is provided the compound of any of Formulae (I), (II), (III), (IV), (IVa), (V), (VI) or (VII), or a pharmaceutically acceptable salt or /V-oxide derivative thereof, or the pharmaceutical composition as described herein, for use in treating or preventing cancer. Preferably the cancer is selected from colon and rectal (colorectal) cancer, head and neck cancer, lung cancer, oesophagus cancer, ovarian cancer and pancreas cancer. More preferably, the cancer is colon and rectal (colorectal) cancer. Alternatively, preferably, the cancer is lung cancer, more preferably non-small cell lung cancer.

Preferably, there is provided the use of the compound of any of Formulae (I), (II), (III), (IV), (IVa), (V), (VI) or (VII), or a pharmaceutically acceptable salt or /V-oxide derivative thereof, or the pharmaceutical composition as described herein, for the manufacture of a medicament for treating or preventing cancer. Preferably the cancer is selected from colon and rectal (colorectal) cancer, head and neck cancer, lung cancer, oesophagus cancer, ovarian cancer and pancreas cancer. More preferably, the cancer is colon and rectal (colorectal) cancer. Alternatively, preferably, the cancer is lung cancer, more preferably non-small cell lung cancer.

Preferably, there is provided a method of treating or preventing cancer in a human or animal patient comprising administering to a patient in need thereof an effective amount of a compound of any of Formulae (I), (II), (III), (IV), (IVa), (V), (VI) or (VII), or a

pharmaceutically acceptable salt or /V-oxide derivative thereof, or the pharmaceutical composition as described herein. Preferably the cancer is selected from colon and rectal (colorectal) cancer, head and neck cancer, lung cancer, oesophagus cancer, ovarian cancer and pancreas cancer. More preferably, the cancer is colon and rectal (colorectal) cancer. Alternatively, preferably, the cancer is lung cancer, more preferably non-small cell lung cancer.

Preferably, the compounds of the present invention have an IC₅₀ value for Wee-1 kinase of about 0.1 nM to about 1 ,000 nM, more preferably from about 0.1 nM to about 500 nM, or from about 0.1 nM to about 300 nM, or from about 0.1 nM to about 100 nM, or from about 0.1 nM to about 50 nM, or from about 0.1 nM to about 30 nM, or from about 0.1 nM to about 15 nM, or from about 0.1 nM to about 10 nM, or from about 0.1 nM to about 5 nM, or from about 0.1 nM to about 2 nM, or from about 0.1 nM to about 1 nM, or, preferably, less than 10nM, more preferably less than 5 nM, more preferably less than 2 nM, most preferably less than 1 nM. A method for determining the IC₅₀ value of a compound for Wee-1 kinase is described below (see examples).

When introducing elements of the present disclosure or the preferred embodiments(s) thereof, the articles "a", "an", "the" and "said" are intended to mean that there are one or more of the elements. The terms "comprising", "including" and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements.

The foregoing detailed description has been provided by way of explanation and illustration, and is not intended to limit the scope of the appended claims. Many variations in the presently preferred embodiments illustrated herein will be apparent to one of ordinary skill in the art, and remain within the scope of the appended claims and their equivalents. EXPERIMENTAL SECTION

Abbreviations

AcOK: Potassium acetate; aq: aqueous; dba: dibenzylideneacetone; DCM:

dichloromethane; DIPEA: diisopropylethylamine (Hunig's base); DMF: N,N- dimethylformamide; DMF: A/,A/-dimethylformamide dimethyl acetal; dppf: 1 , 1 '- bis(diphenylphosphino)ferrocene; EtOAc: ethyl acetate; ESI: electrospray ionisation; h: hour; HPLC: high pressure liquid chromatography; LC: liquid chromatography; LCMS: liquid chromatography mass spectrometry; M: molar; m/z: mass-to-charge ratio; mCPBA: 3- chloroperbenzoic acid; MeOH: methanol; min: minutes; MS: mass spectrometry; NMR: nuclear magnetic resonance; R_T: retention time; RB: round-bottomed; RT: room

temperature; SM: starting material; TEA*3HF: triethylamine trihydrofluoride; TFA:

trifluoroacetic acid; THF: tetrahydrofuran; TLC: thin layer chromatography. General Experimental Conditions

Solvents and reagents

Common organic solvents that were used in reactions (e.g. THF, DMF, DCM, IPA, and methanol) were purchased anhydrous from Sigma-Aldrich^® in Sure/Seal™ bottles and were handled appropriately under nitrogen. Water was deionised using an Elga PURELAB Option-Q. All other solvents used (i.e. for work-up procedures and purification) were generally HPLC grade and were used as supplied from various commercial sources.

Unless otherwise stated, all starting materials used were purchased from commercial suppliers and used as supplied.

Microwave synthesis

Unless quoted otherwise, microwave experiments were carried out using a CEM

Discover™/Explorer24™ system controlled by Synergy 1.5 software. In other cases a Biotage Initiator™ Eight was used. Both machines give good reproducibility and control at temperature ranges from 60-250°C and pressures of up to maximum of 20 bar.

Flash chromatography

Purification of compounds by flash chromatography was achieved using a Biotage Isolera Four system. Unless otherwise stated, Biotage KP-Sil SNAP cartridge columns (10-340 g) were used along with the stated solvent system and an appropriate solvent gradient depending on compound polarity (determined by TLC analysis). In the case of more polar and basic compounds, Biotage KP-NH SNAP cartridge columns (1 1 g) were used.

NMR spectroscopy

1 H NMR spectra were recorded at ambient temperature using a Bruker (500MHz) spectrometer or a Bruker (400MHz) spectrometer. All chemical shifts (δ) are expressed in ppm. Residual solvent signals were used as an internal standard and the characteristic solvent peaks were corrected to the reference data outlined in J. Org. Chem., 1997, 62, p7512-7515; in other cases, NMR solvents contained tetramethylsilane, which was used as an internal standard.

High Pressure Liquid Chromatography

Liquid Chromatography Mass Spectrometry (LCMS) experiments to determine retention times (RT) and associated mass ions were performed using one of the following methods:

Method A: The system consists of an Agilent Technologies 6130 quadrupole mass spectrometer linked to an Agilent Technologies 1290 Infinity LC system with UV diode array detector and autosampler. The spectrometer consists of an electrospray ionization source operating in positive and negative ion mode. LCMS experiments were performed on each sample submitted using the following conditions: LC Column: Agilent Eclipse Plus C18 RRHD 1.8 micron 50 x 2.1 mm maintained at 40°C. Mobile phases: A) 0.1 % (v/v) formic acid in water; B) 0.1 % (v/v) formic acid in acetonitrile.

Gradient Time (min) Flow (mL/min) %A %B

0.00 0.5 80 20

1.80 0.5 0 100

2.20 0.5 0 100

2.50 0.5 80 20

3.00 0.5 80 20

Method B: The system consists of an Agilent Technologies 6140 single quadrupole mass spectrometer linked to an Agilent Technologies 1290 Infinity LC system with UV diode array detector and autosampler. The spectrometer consists of a multimode ionization source (electrospray and atmospheric pressure chemical ionizations) operating in positive and negative ion mode. LCMS experiments were performed on each sample submitted using the following conditions: LC Column: Zorbax Eclipse Plus C18 RRHD 1.8 micron 50 x 2.1 mm maintained at 40°C. Mobile phases: A) 0.1 % (v/v) formic acid in water; B) 0.1 % (v/v) formic acid in acetonitrile.

Gradient Time (min) Flow (mL/min) %A %B

0.00 1.0 95 5

1.80 1.0 0 100

2.20 1.0 0 100

2.21 1.0 95 5

2.50 1.0 95 5

Preparative High Pressure Liquid Chromatography

The system consisted of an Agilent Technologies 6120 single quadrupole mass

spectrometer linked to an Agilent Technologies 1200 Preparative LC system with Multiple Wavelength detector and autosampler. The mass spectrometer used a multimode ionization source (electrospray and atmospheric pressure chemical ionizations) operating in positive and negative ion mode. Fraction collection was mass-triggered (multimode positive and negative ion). Purification experiments, unless otherwise stated, were performed under basic conditions at an appropriate solvent gradient that was typically determined by the retention time found using HPLC Method A. In cases were the basic conditions were unsuccessful, acidic conditions were employed.

Basic conditions: LC Column: Waters XBridge™ Prep C18 5 μηι OBDTM 19 x 50 mm column at RT. Mobile phase: A) 0.1 % (v/v) ammonium hydroxide in water; B) 0.1 % (v/v) ammonium hydroxide in 95:5, acetonitrile/water. Total experiment time was ca. 10 min and an example method is given:

Gradient Time (min) Flow (mL/min) %A %B

0.00 20.0 50 50

3.00 20.0 12 88

5.00 20.0 12 88

7.00 20.0 0 100

8.0 20.0 0 100

8.20 20.0 50 50 Acidic conditions: LC Column: Waters XBridge™ Prep C18 5μηι OBDTM 19 x 50 mm column at RT. Mobile phase: A) Water 0.1 % (v/v) formic acid in water; B) 0.1 % (v/v) formic acid in 95:5, acetonitrile/water. Total experiment time was ca. 10 min and an example method is given:

Gradient Time (min) Flow (mL/min) %A %B

0.00 20.0 95 5

7.00 20.0 0 100

9.00 20.0 0 100

9.20 20.0 95 5

The pure fractions were combined and concentrated using a Genevac EZ-2 Elite, unless stated otherwise.

Nomenclature

Unless otherwise indicated, the nomenclature of structures was determined using the 'Convert Structure to Name' function of ChemBioDraw Ultra 12.0.2

(CambridgeSoft/PerkinElmer).

Intermediate A: 6-(2,6-Dichlorophenyl)-8-methyl-2-(methylthio)pyrido[4,3-dlpyrimidin-5(6H)- one

6-(2,6-Dichlorophenyl)-8-methyl-2-(methylthio)pyrido[4,3-d]pyrimidin-5(6H)-one was prepared according to the previously reported procedure contained in WO 2014/167347 [Page 54, Example 2, Step 2].

Intermediate B: 8-Bromo-6-(2,6-dichlorophenyl)-2-(methylthio)pyrido[4,3-dlpyrimidin-5(6H)- one

8-bromo-6-(2,6-dichlorophenyl)-2-(methylthio)pyrido[4,3-d]pyrimidin-5(6H)-on was prepared according to the previously reported procedure contained in WO 2014/167347 [Page 54, Example 2, Step 1].

Intermediate C: 6-(2,6-Dichlorophenyl)-2-(methylthio)-5-oxo-5,6-dihydropyrido[4,3- dlpyrimidine-8-carbonitrile

8-bromo-6-(2,6-dichlorophenyl)-2-(methylthio)pyrido[4,3-d]pyrimidin-5(6H)-one

(intermediate B) (0.40 g, 0.959 mmol) was reacted according to General Procedure C to yield the target compound (320 mg; 92 %) after pouring the reaction mixture onto water, filtering off the solid, washing with water and drying on the sinter.

LCMS (Generic): R_T = 1.56 min, m/z =363, 365, 367 [M+H]⁺.

¹ H NMR (500 MHz, DMSO-cfe) δ 9.35 (s, 1 H), 9.12 (s, 1 H), 7.80 (d, 2H), 7.71-7.64 (m, 1 H), 2.69 (s, 3H).

Intermediate D: (6-(2, 6-Dichlorophenyl)-8-(3-methoxyprop- 1-yn- 1-yl)-2- (methylthio)pyrido[ 4, 3-d]pyrimidin- -one:

Copper(l) iodide (2.85 mg, 0.015 mmol) and bis(triphenylphosphie)palladium(ll) chloride (21.03 mg, 0.030 mmol) were added to a pre-degassed, stirring solution of Intermediate B (250 mg, 0.599 mmol), 3-methoxyprop-1-yne (84 mg, 1.199 mmol) and tetrabutylammoium iodide (443 mg, 1.199 mmol) in triethylamine (0.501 ml, 3.60 mmol) / DMF (2.5 ml) using a microwave vial. The reaction vessel was sealed and heated under microwave conditions (CEM Explorer/Discover) at 100 °C (80 W ceiling) for 15 mins. The reaction mixture was partitioned between brine / water (25 ml, 1 : 1) and diethyl ether (20 ml). The aqueous was separated and extracted with diethyl ether (3 x 10 ml). The combined diethyl ether fractions were washed with brine / water (4 x 6 ml, 1 :1), dried (phase separator) and the solvent was removed in vacuo. The resulting residue was purified by flash chromatography (0-25% EtOAc in cyclohexane) to afford the title compound (156.4 mg, 64 %)

LCMS (Method A): R_T = 1.68 min, m/z = 406, 408 [M+H]⁺.

¹ H NMR (500 MHz, DMSO-cfe) δ 9.31 (s, 1 H), 8.46 (s, 1 H), 7.76 (d, 2H), 7.67-7.59 (m, 1 H), 4.39 (s, 2H), 3.38 (s, 3H), 2.68 (s, 3H).

Intermediate E: 6-(2-Chloro-6-methylphenyl)-2-(methylthio)-5-oxo-5, 6-dihydropyrido[4, 3- d]pyrimidine-8-carbonitrile:

8-bromo-6-(2-chloro-6-methyl-phenyl)-2-(methylthio)pyrido[4,3-d]pyrimidin-5(6H)-one

(prepared according to the previously reported procedure contained in WO 2014/167347 [Page 54, Example 2, Step 1], replacing 2,6-dichloroaniline with 2-chloro-6-methylaniline) was reacted according to General Procedure C to yield the target molecule.

LCMS (Method A): R_T = 1.52 min, m/z = 343, 345 [M+H]⁺. ¹ H NMR (500 MHz, DMSO-cfe) δ 9.33 (s, 1 H), 8.98 (s, 1 H), 7.58 (d, 1 H), 7.51 (t, 1 H), 7.47 (d, 1 H), 2.69 (s, 3H), 2.17 (s, 3H).

Intermediate F: 6-(2-Chloro-6-fluorophenyl)-2-(methylthio)-5-oxo-5, 6-dihydropyrido[4, 3- d]pyrimidine-8-carbonitrile

8-bromo-6-(2-chloro-6-fluoro-phenyl)-2-(methylthio)pyrido[4,3-d]pyrimidin-5(6H

(prepared according to the previously reported procedure contained in WO 2014/167347 [Page 54, Example 2, Step 1], replacing 2,6-dichloroaniline with 2-chloro-6-fluoroaniline) was reacted according to General Procedure C to yield the target molecule. LCMS (Method A): R_T = 1.48 min, m/z = 347, 349 [M+H]⁺.

¹ H NMR (500 MHz, DMSO-cfe) δ 9.34 (s, 1 H), 9.12 (s, 1 H), 7.76-7.68 (m, 1 H), 7.66 (d, 1 H), 7.59 (t, 1 H), 2.69 (s, 3H). Intermediate G: 6-(2-Chlorophenyl)-2-(methylthio)-5-oxo-5, 6-dihydropyrido[4, 3- d]pyrimidine-8-carbonitrile

8-bromo-6-(2-chloro-6-methyl-phenyl)-2-(methylthio)pyrido[4,3-d]pyrimidin-5(6H)-one (prepared according to the previously reported procedure contained in WO 2014/167347 [Page 54, Example 2, Step 1], replacing 2,6-dichloroaniline with 2-chloro-aniline) was reacted according to General Procedure C to yield the target molecule. LCMS (Method A): R_T = 1.43 min, m/z =329, 331 [M+H]⁺.

¹ H NMR (500 MHz, DMSO-cfe) δ 9.32 (s, 1 H), 9.03 (s, 1 H), 7.78-7.74 (m, 1 H), 7.69 (dd, 1 H), 7.64-7.56 (m, 2H), 2.69 (s, 3H).

General Procedure A:

mCPBA (<77% pure) (76 mg, 0.341 mmol, 1.2 equiv.) in DCM (0.5 mL) was added to a stirred solution of Intermediate A (100 mg, 0.284 mmol, 1.0 equiv.) in toluene (3.0 mL) at RT under nitrogen. After 15 min, the aniline (0.284 mmol, 1.0 equiv.) and DIPEA (0.149 mL, 0.852 mmol, 3.0 equiv.) were added and the temperature was increased to 60 °C. After 16 h, the reaction mixture was allowed to cool to RT, and was loaded onto a KP-NH column and purified by flash chromatography (0-100%, EtOAc in cyclohexane) to give the A/-Boc protected product. The material was dissolved in DCM (2.0 ml_) and TFA (2.0 ml_, 26.0 mmol) was added. The resultant solution was stirred at RT under nitrogen. After 30 min, the solvents were removed in vacuo and the remaining residue was partitioned between DCM and saturated sodium bicarbonate (aq) solution. The biphasic mixture was separated, extracted (DCM x 2), the combined organic phase was dried (Phase Separator), the solvents were removed in vacuo, and the remaining residue was purified by flash chromatography using a KP-NH column (0-100% EtOAc in cyclohexane; 0-10% MeOH in EtOAc) to give the desired product.

General Procedure B:

Copper (I) Iodide (7.65 mg, 0.040 mmol, 0.025 equiv.) and

bis(triphenylphosphine)palladium(ll) chloride (56.4 mg, 0.080 mmol, 0.05 equiv.) were added to a pre-degassed, stirring solution of Intermediate B (670 mg, 1.606 mmol, 1.0 equiv.), the acetylene (3.21 mmol, 2.0 equiv.) and tetrabutylammonium iodide (1187 mg, 3.21 mmol, 2.0 equiv.) in triethylamine (1.343 ml, 9.64 mmol. 6.0 equiv.) / DMF (6.5 ml). The mixture was heated at 80 °C under a nitrogen atmosphere for 3 h. The reaction mixture was partitioned between brine/water (65 ml, 1 : 1) and diethyl ether (30 ml). The mixture was filtered through a sinter funnel. The aqueous phase was separated and extracted with diethyl ether (2 x 20 ml). The combined diethyl ether fractions were washed with brine/water (4 x 20 ml, 1 : 1), dried (phase separator) and reduced in vacuo. The resulting residue was purified by flash chromatography (0-15% EtOAc in cyclohexane) to afford the title compound.

General Procedure C:

The starting bromide (0.959 mmol), Zinc cyanide (0.113 g; 0.959 mmol), Pd₂dba₃ (8.78 mg, 9.59 μηιοΙ), DPPF (0.013 g; 0.024 mmol) and zinc (3.13 mg; 0.048 mmol) were weighed into a 25ml round-bottomed flask which was then flushed with nitrogen and capped with a septum. DMF (10 ml_ containing 0.03% HOAc) was added via syringe followed by the addition of water (0.1 ml_); nitrogen was bubbled through the mixture for 2 min. and the mixture was subsequently heated under nitrogen at 100°C for 18h.

The mixture was poured onto water (100ml_) and the resulting solid was left settling for 1 h. The solid was filtered; washed with water and dried on the sinter to obtain the desired product which was either used as such or further purified by flash chromatography (0-60% EtOAc in cyclohexane) or recrystallization from EtOAc / cyclohexane mixtures.

General Procedure D:

The Boc-protected amine (0.132 mmol) was dissolved in DCM (3 mL) and TFA (0.8 mL) was added at r.t. whilst stirring. Stirring was continued for 60-90 min (as indicated by HPLC analysis) and the solvent was removed in vacuo. The residue was re-dissolved in DCM (2 mL) and the solution was applied to a 2 g SCX cartridge (prewashed with DCM / MeOH (5: 1)); the compound was left to adsorb for 5 min. and the cartridge was washed with 2 column lengths of DCM / MeOH (5: 1). The desired compound was then eluted using DCM / 7N Ammonia in MeOH (5: 1) and the product containing fractions were combined and the solvent was removed in vacuo. The residue was triturated with diethyl ether (appr. 5 mL) and the desired product was isolated by filtration or further purified by either

recrystallization (EtOAc / cyclohexane) or flash chromatography (Biotage KP-NH cartridge; 0 to 100% EtOAc in cyclohexane).

General Procedure E: Intermediate C or D (1 eq. typically 0.12-0.28 mmol) was suspended in DCM (2-4 mL) and mCPBA 70% (1.1 eq.) was added. The reaction mixture was stirred for 30 min at RT and subsequently diluted to 3-5 mL with DCM and then washed with aqueous sodium thiosulfate solution (2 mL). The organic layer was separated, dried (anh. MgS0₄) and evaporated under reduced pressure. The resulting sulfoxide- / sulfone-mixture was suspended in 2-propanol (2-4 mL) and the aniline analogue was added (1 eq.). The reaction mixture was heated at 80-90 C deg. for 1.5-16h until completion. The volatiles were removed under reduced pressure and the residue was purified by column

chromatography (10-50% EtOAc in cyclohexane) yielding the corresponding A/-Boc protected product, which was dissolved in DCM (2.0 mL) and TFA (1.0 mL, 26.0 mmol) was added. The resultant solution was stirred at RT under nitrogen and checked by HPLC-MS until completion. After approx. 30 min, the volatiles were removed in vacuo and the remaining residue was dissolved in DCM and injected onto a SCX-2 column (2g) prewashed with DCM. The mixture was left to bind for 15 min and then the column was washed with 20% MeOH in DCM. The product was eluted with 20% 7N NH₃ in MeOH in DCM. The product containing fractions were evaporated under reduced pressure yielding the desired compound.

EXAMPLES

The following non-limiting examples further illustrate the present invention.

Example 1 : 6-(2,6-Dichlorophenyl)-2-((3-methyl-4-(piperazin-1-yl)phenyl)amino)-5-oxo-5,6- dihvdropyrido[4,3-dlpyrimidine-8-carbonitrile

Step 1: (6-(2, 6-dichlorophenyl)-2-(methylthio)-5-oxo-5, 6-dihydropyrido[4,3-d]pyrimidin-8- carbonitrile:

8-Bromo-6-(2,6-dichlorophenyl)-2-(methylthio)pyrido[4,3-d]pyrimidin-5(6H)-one

(Intermediate B; 0.4 g; 0.959 mmol) was reacted according to General Procedure C, yielding the title compound (0.32 g, 92%) after filtration which was used as such.

LCMS (Method A): R_T = 1.44 min, m/z = 363, 365 [M+H]⁺.

Step 2: tert-butyl 4-(4-((8-cyano-6-(2,6-dichlorophenyl)-5-oxo-5,6-dihydropyrido[4,3- d]pyrimidin-2-yl)amino)-2-methylphenyl)piperazine-1-carboxylate:

(6-(2,6-dichlorophenyl)-2-(methylthio)-5-oxo-5,6-dihydropyrido[4,3-d]pyrimidin-8-carbonitrile (250 mg; 0.688 mmol) was dissolved in DCM (10 ml_) at r.t. using a round bottomed flask and mCPBA (178 mg, 0.73 mmol, 71 % content) in one portion and the mixture was stirred for 90 min. Another 100 mg of mCPBA was added and stirring was continued for another 15min. HPLC indicated complete consumption of the starting material.

A mixture of aqueous sodium thiosulfate solution (50 ml_) and chloroform (50 ml_) was added and the product was extracted twice with chloroform. The combined organic extracts were washed with 10% aqueous sodium carbonate solution and brine and the solution was dried over sodium sulfate. After filtration the solvent was removed in vacuo to obtain 180 mg of a pale yellow solid which was suspended with tert-butyl 4-(4-amino-2- methylphenyl)piperazine-1-carboxylate (0.152 g, 0.522 mmol) [commercially available] in I PA (4 mL) using a round bottomed flask.

The flask was flushed with nitrogen and the suspension was heated at 90°C for 90 min. The flask was left cooling to r.t. overnight and the solid was filtered off using a phase separation cartridge. The solid was washed with I PA / diethyl ether (1 :1 ; 10 mL) followed by petrol ether (10 mL) and dried on the frit to obtain the target compound (84 mg; 29%) as a bright yellow solid.

LCMS (Method A): R_T = 1.72 min, m/z = 606, 608 [M+H]⁺.

Step 3: 6-(2, 6-Dichlorophenyl)-2-((3-methyl-4-(piperazin- 1-yl)phenyl)amino)-5-oxo-5, 6- dihydropyrido[4,3-d]pyrimidine-8-carbonitrile tert-butyl 4-(4-((8-cyano-6-(2,6-dichlorophenyl)-5-oxo-5,6-dihydropyrido[4,3-d]pyrimidin-2- yl)amino)-2-methylphenyl)piperazine-1-carboxylate (80mg; 0.132 mmol) was reacted according to General Procedure D to yield the target compound (44 mg; 66%) as a bright yellow solid.

LCMS (Method A): R_T = 0.94 min, m/z = 506, 508 [M+H]⁺.

H NMR (400 MHz, CDCI₃) δ 9.20-9.40 (s br, 1 H), 7.30-7.80 (m br., 7H), 7.07 (d, 1 H), 3.04- 3.06 (m, 4H), 2.88-2.91 (m, 4H), 2.38 (s, 3H).

Example 2: ( )-6-(2,6-Dichlorophenyl)-2-((3-methyl-4-(3-methylpiperazin-1- yl)phenyl)amino)-5-oxo-5,6-dihvdropyrido[4,3-dlpyrimidine-8-carbonitrile

Step 1: (R)-tert-butyl 4-(4-((8-cyano-6-(2,6-dichlorophenyl)-5-oxo-5,6-dihydropyrido[4,3- d]pyrimidin-2-yl)amino)-2-methylphenyl)-2-methylpiperazine-1-carboxylate^ 6-(2,6-dichlorophenyl)-2-(methylthio)-5-oxo-5,6-dihydropyrido[4,3-d]pyrimidin

carbonitrile (Intermediate C; 0.30 g; 0.826 mmol) was dissolved in DCM (3 ml_) and Toluene (5 ml_) using a reaction tube. mCPBA (0.214 g; 0.88 mmol) was added in one portion and stirring was continued for 45 min. at r.t..

A solution of ( )-tert-butyl 4-(4-amino-2-methylphenyl)-2-methylpiperazine-1-carboxylate (0.277 g; 0.909 mmol) [prepared according to WO2015/038417] and Hunig's Base (0.43 ml_; 2.48 mmol) dissolved in Toluene (4 ml_) was added via syringe and the reaction tube was capped and heated at 90°C for 15h. The mixture was cooled to r.t., the solvent was removed in vacuo and re-dissolved in DCM / Chloroform (1 : 1 ; 1 ml_) and loaded onto a 28 g Biotage KP-NH cartridge. Flash chromatography (0 to 45 % EtOAc in cyclohexane) yielded the target compound (150 mg; 29 %) as a light yellow solid.

LCMS (Method A): R_T = 1.81 min, m/z = 620, 622 [M+H]⁺.

Step 2: (R)-6-(2, 6-Dichlorophenyl)-2-((3-methyl-4-(3-methylpiperazin- 1-yl)phenyl)amino)-5- oxo-5, 6-dihydropyrido[4, 3-d]pyrimidine-8-carbonitrile

( )-tert-butyl 4-(4-((8-cyano-6-(2,6-dichlorophenyl)-5-oxo-5,6-dihydropyrido[4,3-d]pyrimidin- 2-yl)amino)-2-methylphenyl)-2-methylpiperazine-1-carboxylate (150 mg; 0.242 mmol) was reacted according to General Procedure D to yield the target compound (45 mg; 36%) as a bright yellow solid after recrystallization from EtOAc / Petrol ether.

LCMS (Method A): R_T = 1.1 min, m/z = 520, 522 [M+H]⁺.

1 H NMR (400 MHz, CDCI₃) δ 9.25-9.40 (s br, 1 H), 7.30-7.80 (m br., 7H), 7.06 (d, 1 H), 2.99- 3.09 (m, 5H), 2.66-2.72 (m, 1 H), 2.35-2.40 (m, 4H), 1.1 1 (d, 3H).

Example 3: 6-(2,6-Dichlorophenyl)-2-((3-methoxy-4-(piperazin-1-yl)phenyl)amino)-5-oxo-

5,6-dihvdropyrido[4,3-dlpyrimidine-8-carbonitrile

Step 1: 8-Bromo-6-(2,6-dichlorophenyl)-2-(methylsulfinyl)pyrido[4,3-d]pyrimidin-5(6H)-o 6-(2,6-dichlorophenyl)-2-(methylthio)pyrido[4,3-d]pyrimidin-5(6H)-one (WO 2014/167347 [Page 51 , Example 1 , Step 2].; 3.5 g; 10.35 mmol) was suspended in dry acetonitrile (40 mL) at 85°C. NBS (2.76 g; 15.52 mmol) was added in three portions and the mixture was left stirring for 2.5 hours.

Water (100 mL) was added slowly whilst the flask was still hot and the mixture was cooled slowly to r.t. The resulting solid was filtered and dried on the sinter in air (which resulted in 8-Bromo-6-(2,6-dichlorophenyl)-2-(methylthio)pyrido[4,3-d]pyrimidin-5(6H)-one; 2.55 g, 59%). The solvent of the aqueous filtrate was removed in vacuo to result in a precipitate which was left aging overnight and subsequently filtered and dried on the sinter to yield the target compound (0.88 g; 20%) as an off-white solid.

LCMS (Method A): R_T = 1.03 min, m/z = 434 [M+H]⁺.

Step 2: tert-butyl 4-(4-((8-bromo-6-(2,6-dichlorophenyl)-5-oxo-5,6-dih

d]pyrimidin-2-yl)amino)-2-methoxyphenyl)piperazine-1-carboxylate:

8-Bromo-6-(2,6-dichlorophenyl)-2-(methylsulfinyl)pyrido[4,3-d]pyrimidin-5(6H)-one (0.30 g; 0.693 mmol) was dissolved in DCM (3 mL) and Toluene (5 mL) at r.t. using a reaction tube. A solution of tert-butyl 4-(4-amino-2-methoxyphenyl)piperazine-1-carboxylate (0.234 g; 0.762 mmol) [commercially available] and Hunig's Base (0.36 mL; 2.08 mmol) in DCM (4 mL) was added via syringe and the reaction vial was capped.

The mixture was heated up to 70°C and stirred at that temperature for 15h. The solution was cooled to r.t. and the solvent was removed in vacuo. The residue was re-dissolved in DCM / Chloroform (1 mL; 1 : 1) and loaded onto a 40 g Grace column. Flash

chromatography (0 to 60 % EtOAc / cyclohexane) yielded the target compound (150 mg; 32 %) as a yellow solid.

LCMS (Method A): R_T = 1.66 min, m/z = 677 / 679 [M+H]⁺.

Step 3: tert-butyl 4-(4-((8-cyano-6-(2,6-dichlorophenyl)-5-oxo-5,6-dihydropyrido[4,3- d]pyrimidin-2-yl)amino)-2-methoxyphenyl)piperazine-1-carboxylate: tert-butyl 4-(4-((8-bromo-6-(2,6-dichlorophenyl)-5-oxo-5,6-dihydropyrido[4,3-d]pyrimidin-2- yl)amino)-2-methoxyphenyl)piperazine-1-carboxylate (0.10 g; 0.148 mmol) was reacted according to General Procedure C to yield the target compound (80 mg; 87 %) after flash chromatography (0 to 60 % EtOAc in cyclohexane) using a 40 g Grace cartridge.

LCMS (Method A): R_T = 1.58 min, m/z = 622, 624 [M+H]⁺. Step 4: 6-(2,6-Dichlorophenyl)-2-((3-methoxy-4-(piperazin-1-yl)phenyl)amino)-5-oxo-5,6- dihydropyrido[4,3-d]pyrimidine-8-carbonitrile tert-butyl 4-(4-((8-cyano-6-(2,6-dichlorophenyl)-5-oxo-5,6-dihydropyrido[4,3-d]pyrimidin-2- yl)amino)-2-methoxyphenyl)piperazine-1-carboxylate (0.08 g; 0.129 mmol) was reacted according to General Procedure D to yield the target compound (28 mg; 43 %) as a yellow solid after recrystallization from Chloroform / Petrol ether.

LCMS (Method A): R_T = 0.87 min, m/z = 522, 524 [M+H]⁺.

1 H NMR (400 MHz, d₆-DMSO) δ 10.5-10.7 (s, br. 1 H), 9.19 (s, 1 H), 8.98 (s, 1 H), 7.97 (s, br. 1 H), 7.79-7.63 (m, 3H), 7.24 (m, 1 H), 6.85 (d, 1 H), 3.70-3.90 (s, br., 3H), 2.75-3.05 (m, 8H).

Example 4: (f?)-6-(2,6-Dichlorophenyl)-2-((3-methoxy-4-(3-methylpiperazin-1- yl)phenyl)amino)-5-oxo-5,6-dihvdropyrido[4,3-dlpyrimidine-8-carbonitrile

Step 1: (R)-tert-butyl 4-(4-((8-bromo-6-(2,6-dichlorophenyl)-5-oxo-5,6-dihydropyrido[4,3- d]pyrimidin-2-yl)amino)-2-methoxyphenyl)-2-methylpiperazine-1-carboxylate:

8-Bromo-6-(2,6-dichlorophenyl)-2-(methylsulfinyl)pyrido[4,3-d]pyrimidin-5(6H)-one

(Example 3, step 1 ; 0.30 g; 0.693 mmol) and ( )-tert-butyl 4-(4-amino-2-methoxyphenyl)-2- methylpiperazine-1-carboxylate (0.245 g; 0.762 mmol) [prepared according to

WO2015/038417] were suspended in I PA (5 ml_) at r.t. using a reaction tube.

The tube was capped and the suspension was heated at 90°C for 1.5h. After cooling the suspension to r.t. the solid was filtered, washed with I PA / diethyl ether (1 :1 ; 5 ml_) and dried on the sinter to yield the target compound (343 mg; 72 %) as a bright yellow solid. LCMS (Method A): R_T = 1.75 min, m/z = 690 / 692 [M+H]⁺. Step 2: tert-butyl 4-(4-((8-cyano-6-(2,6-dichlorophenyl)-5-oxo-5,6-dihydropyrido[4,3- d]pyrimidin-2-yl)amino)-2-methoxyphenyl)-2-methylpiperazine-1-carboxylate:

(ft)-tert-butyl 4-(4-((8-bromo-6-(2,6-dichlorophenyl)-5-oxo-5,6-dihydropyrido[4,3- d]pyrimidin-2-yl)amino)-2-methoxyphenyl)-2-methylpiperazine-1-carboxylate (0.172 g; 0.249 mmol) was reacted according to General Procedure C to yield the target compound (80 mg; 50 %) after flash chromatography (0 to 60 % EtOAc in cyclohexane) using a 25 g Biotage silica cartridge followed by trituration with diethyl ether.

LCMS (Method A): R_T = 1.71 min, m/z = 636, 638 [M+H]⁺.

Step 3: (f?)-6-(2,6-Dichlorophenyl)-2-((3-methoxy-4-(3-methylpiperazin-1-yl)phenyl)amino)- 5-0X0-5, 6-dihydropyrido[4,3-d]pyrimidine-8-carbonitrile tert-butyl 4-(4-((8-cyano-6-(2,6-dichlorophenyl)-5-oxo-5,6-dihydropyrido[4,3-d]pyrimidin-2- yl)amino)-2-methoxyphenyl)-2-methylpiperazine-1-carboxylate (0.08 g; 0.126 mmol) was reacted according to General Procedure D to yield the target compound (60 mg; 89 %) as a yellow solid after trituration with diethyl ether.

LCMS (Method A): R_T = 0.95 min, m/z = 536, 538 [M+H]⁺.

H NMR (400 MHz, CDCI₃) δ 9.25-9.40 (s, br. 1 H), 8.08 (s, 0.8H), 7.74-7.78 (m, 2H), 7.43- 7.55 (m, 3H), 6.85-7.24 (m, br. 2H), 3.85-4.10 (s, br., 3H), 3.36-3.41 (m, 2H), 3.07-3.17 (m, 3H), 2.61-2.65 (m, 1 H), 2.27-2.32 (m, 1 H), 1.12 (d, 3H).

Example 5: 6-(2,6-dichlorophenyl)-2-((3-methoxy-4-(piperazin-1-yl)phenyl)amino)-8-(3- methoxyprop-1-vn-1-yl)pyrido[4,3-dlpyrimidin-5(6H)-one

Step 1: (6-(2,6-dichlorophenyl)-8-(3-methoxyprop-1-yn-1-yl)-2-(methylthio)pyrido[4,3- d]pyrimidin-5(6H)-one: Copper(l) iodide (2.85 mg, 0.015 mmol) and bis(triphenylphosphie)palladium(ll) chloride (21.03 mg, 0.030 mmol) were added to a pre-degassed, stirring solution of Intermediate B (250 mg, 0.599 mmol), 3-methoxyprop-1-yne (84 mg, 1.199 mmol) and tetrabutylammoium iodide (443 mg, 1.199 mmol) in triethylamine (0.501 ml, 3.60 mmol) / DMF (2.5 ml) using a microwave vial. The reaction vessel was sealed and heated under microwave conditions (CEM Explorer/Discover) at 100 °C (80 W ceiling) for 15 mins. The reaction mixture was partitioned between brine / water (25 ml, 1 :1) and diethyl ether (20 ml). The aqueous was separated and extracted with diethyl ether (3 x 10 ml). The combined diethyl ether fractions were washed with brine / water (4 x 6 ml, 1 :1), dried (phase separator) and the solvent was removed in vacuo. The resulting residue was purified by flash chromatography (0-25% EtOAc in cyclohexane) to afford the title compound (156.4 mg, 64 %)

LCMS (Method A): R_T = 1.68 min, m/z = 406, 408 [M+H]⁺.

Step 2: tert-butyl 4-(4-((6-(2,6-dichlorophenyl)-8-(3-methoxyprop-1-yn-1-yl)-5-oxo-5,6- dihydropyrido[4,3-d]pyrimidin-2-yl)amino)-2-methoxyph

A solution of mCPBA, 50 % purity (159 mg, 0.462 mmol) in dichloromethane (0.6 ml_) was passed through a phase separator washing through with further dichloromethane (0.3 ml_). This solution was added to a stirring suspension of 6-(2,6-dichlorophenyl)-8-(3- methoxyprop-1-yn-1-yl)-2-(methylthio)pyrido[4,3-d]pyrimidin-5(6H)-one (156.4 mg, 0.385 mmol) in anhydrous toluene (3 ml_) and the mixture was stirred for 5 minutes. DIPEA (0.202 ml_, 1.155 mmol) followed by tert-butyl 4-(4-amino-2-methoxyphenyl)piperazine-1- carboxylate (101 mg, 0.327 mmol) [commercially available] were added and the mixture was heated to 80 °C for 1 h. After cooling the reaction mixture was purified by flash chromatography (0-50%, Ethyl Acetate in Cyclohexane) to afford the title compound (60.8 mg, 24 %).

LCMS (Method A): R_T = 1.87 min, m/z = 665, 667 [M+H]⁺.

Step 3: 6-(2, 6-dichlorophenyl)-2-((3-methoxy-4-(piperazin- 1-yl)phenyl)amino)-8-(3- methoxyprop- 1-yn-1 -yl) pyridof 4, 3-d]pyrimidin-5( 6H) -one:

To a stirring solution of tert-butyl 4-(4-((6-(2,6-dichlorophenyl)-8-(3-methoxyprop-1-yn-1-yl)- 5-0X0-5, 6-dihydropyrido[4,3-d]pyrimidin-2-yl)amino)-2-methoxyphenyl)piperazine-1- carboxylate (60.8 mg, 0.091 mmol) in anhydrous dichloromethane (2 ml) was added TFA (0.5 ml, 6.49 mmol) and the solution was stirred for 60 min. An SCX-2 silica cartridge (5 g) was pretreated with 20% v/v methanol in dichloromethane (50 ml). The reaction mixture was placed evenly on to the SCX-2 column using dichloromethane (3 x 1 ml) to rinse the flask. After 5 mins the column was flushed with 20% v/v methanol in dichloromethane (50 ml) followed by 20% v/v (7M ammonia in methanol) in dichloromethane (25 ml). The ammonia containing fraction was reduced in vacuo. The residue was dissolved in methanol (1 ml) and water (10 ml) and freeze-dried to afford the title compound (45.0 mg, 87 %). LCMS (Method A): R_T = 0.95 min, m/z = 565, 567 [M+H]⁺.

1 H NMR (400 MHz, d4-MeOH) δ 9.22 (s, 1 H), 7.92 (s, 1 H), 7.69-7.87 (m, 1 H), 7.65 (d, 2H), 7.55 (dd, 1 H), 7.53 (s, 1 H), 7.00 (d, 1 H), 4.41 (s, 2H), 3.95 (s, 3H), 3.45 (s, 3H), 2.96-3.08 (m, 8H).

Example 6: (f?)-6-(2,6-dichlorophenyl)-2-((3-methoxy-4-(3-methylpiperazin-1- yl)phenyl)amino)-8-(3-methoxyprop-1-vn-1-yl)pyrido[4,3-dlpyrimidin-5(6H)-one

Step 1: {R)-tert- butyl 4-(4-((6-(2,6-dichlorophenyl)-8-(3-methoxyprop-1-yn-1-yl)-5-oxo-5,6- dihydropyrido[4,3-d]pyrimidin-2-yl)amino)-2-methoxyphenyl)-2-methylpi

carboxylate:

6-(2,6-dichlorophenyl)-8-(3-methoxyprop-1-yn-1-yl)-2-(methylthio)pyrido[4,3-d]pyrimidin- 5(6H)-one (Example 5, step 1 ; 495 mg, 1.22 mmol) was dissolved in DCM (5 ml_) using a reaction tube and mCPBA (315 mg; 1.3 mmol; 71 % content) was added in one portion. Stirring was continued for 1 h., followed by the addition of a solution of ( )-tert-butyl 4-(4- amino-2-methoxyphenyl)-2-methylpiperazine-1 -carboxylate (431 mg, 1.34 mmol) [prepared according to WO2015/038417] and Hunig's base (0.64 ml_; 3.66 mmol) in toluene (5 ml_). The vial was capped and the mixture was heated at 65 °C for 15 h. After cooling to r.t. the reaction mixture was poured onto Ethyl acetate / water and the product was extracted three times with Ethyl acetate. The combined organic extracts were washed with brine and dried over sodium sulfate. After filtration and removal of the solvent in vacuo the residue was purified by flash chromatography (0-45%, Ethyl acetate in Cyclohexane) using a 28 g Biotage KP-NH cartridge to afford the title compound (85 mg, 10.3 %) as a bright yellow solid.

LCMS (Method A): R_T = 1.75 min, m/z = 679, 681 [M+H]⁺. Step 2: (f?)-6-(2,6-dichlorophenyl)-2-((3-methoxy-4-(3-methylpiperazin-1-yl)phenyl)amino)- 8-(3-methoxyprop-1-yn-1-yl)pyrido[4,3-d]pyrimidin-5(6H)-one

To a stirring solution of ( )-tert-butyl 4-(4-((6-(2,6-dichlorophenyl)-8-(3-methoxyprop-1-yn- 1-yl)-5-oxo-5,6-dihydropyrido[4,3-d]pyrimidin-2-yl)amino)-2-methoxyphenyl)-2- methylpiperazine-1-carboxylate (80 mg, 0.118 mmol) was reacted according to General Procedure D to afford the title compound (30 mg, 44 %) after recrystallization from Ethyl acetate / cyclohexane (1 :1 ; 10ml).

LCMS (Method A): R_T = 0.94 min, m/z = 579, 581 [M+H]⁺.

H NMR (400 MHz, d₆-DMSO) δ 10.3-10.45 (s, br. 1 H), 9.16 (s, 1 H), 8.31 (s, 0.9H), 7.45- 7.85 (m, 5H), 6.85 (d, 1 H), 4.38 (s, 2H), 3.80 (s, 3H), 3.35 (s,br., 3H (+residual solvent)), 3.16-3.19 (m, 2H), 2.81-2.90 (m, 3H), 2.10-2.25 (m, 2H), 0.98 (d, 3H).

Example 7: 6-(2,6-dichlorophenyl)- 8-(3-methoxyprop-1-vn-1-yl)-2-((3-methyl-4-(piperazin- 1-yl)phenyl)amino)pyrido[4,3-dlpyrimidin-5(6H)-one

Step 1: tert-butyl 4-(4-((6-(2,6-dichlorophenyl)-8-(3-methoxyprop-1-yn-1-yl)-5-oxo-5,6- dihydropyrido[4,3-d]pyrimidin-2-yl)amino)-2-methylphenyl)^iperazin

6-(2,6-dichlorophenyl)-8-(3-methoxyprop-1-yn-1-yl)-2-(methylthio)pyrido[4,3-d]pyrimidin- 5(6H)-one (Example 5, step 1 ; 156 mg, 0.384 mmol) was dissolved in DCM (2 ml_) and Toluene (3 ml_) using a reaction tube and mCPBA (99 mg; 0.41 mmol; 71 % content) was added in one portion. Stirring was continued for 15 min. followed by the addition of a solution of tert-butyl 4-(4-amino-2-methylphenyl)piperazine-1-carboxylate (123 mg, 0.422 mmol) [commercially available] and Hunig's base (0.201 ml_; 1.15 mmol) in DCM (2 ml_). The vial was capped and the mixture was heated at 65 °C for 15 h. After cooling to r.t. the solvent was removed in vacuo and the residue was re-dissolved in chloroform (1 ml_) and loaded onto a 40 g Grace cartridge. Flash chromatography (0 - 50%, Ethyl acetate in Cyclohexane) afforded the title compound (80 mg, 32 %) as a yellow solid.

LCMS (Method A): R_T = 1.76 min, m/z = 649, 651 [M+H]⁺.

Step 2: 6-(2,6-dichlorophenyl)- 8-(3-methoxyprop-1-yn-1-yl)-2-((3-methyl-4-(piperazin-1- yl)phenyl)amino)pyrido[4,3-d]pyrimidin-5(6H)-one

To a stirring solution of tert-butyl 4-(4-((6-(2,6-dichlorophenyl)-8-(3-methoxyprop-1-yn-1-yl)- 5-0X0-5, 6-dihydropyrido[4,3-d]pyrimidin-2-yl)amino)-2-methylphenyl)-piperazine-1- carboxylate (80 mg, 0.123 mmol) was reacted according to General Procedure D to afford the title compound (35 mg, 52 %) after trituration with diethyl ether as a yellow solid.

LCMS (Method A): R_T = 1.03 min, m/z = 549, 551 [M+H]⁺.

H NMR (400 MHz, CDCI3) δ 9.30 (s, br. 1 H), 7.38-7.85 (m,br., 6H), 7.04 (d, 1 H), 4.42 (s, 2H), 3.49 (s, br., 3H), 3.03-3.05 (m, 4H), 2.87-2.89 (m, 4H), 2.36 (s, 3H).

Example 8: 6-(2,6-Dichlorophenyl)-8-methyl-2-((3-methyl-4-(piperazin-1- yl)phenyl)amino)pyrido[4,3-dlpyrimidin-5(6H)-one

Intermediate A (100 mg, 0.284 mmol) was reacted with te/f-butyl 4-(4-amino-2- methylphenyl)piperazine-1 -carboxylate (83 mg, 0.284 mmol) [commercially available] using General Procedure A to give the title compound (48.5 mg, 33% over 2 steps) as a yellow solid.

LCMS (Method A): R_T = 1.17 min, m/z = 495, 497 [M+H]⁺.

Ή NMR (400 MHz, MeOD): δ 9.20 (s, 1 H), 7.81-7.58 (m, 4H), 7.52 (dd, 1 H), 7.41-7.34 (m, 1 H), 7.07 (d, 1 H), 3.01 (t, 4H), 2.90 (t, 4H), 2.35 (s, 3H), 2.32 (s, 3H). Example 9: 6-(2,6-Dichlorophenyl)-2-((3-methoxy-4-(piperazin-1-yl)phenyl)arriino)-8- methylpyrido[4,3-dlpyrimidin-5(6H)-one

Intermediate A (100 mg, 0.284 mmol) was reacted with te/f-butyl 4-(4-amino-2- methoxyphenyl)piperazine-1-carboxylate (87 mg, 0.284 mmol) [commercially available] using General Procedure A to give the title compound (66.7 mg, 46% over 2 steps) as a yellow solid.

LCMS (Method A): R_T = 1.06 min, m/z = 511 , 513 [M+H]⁺.

Ή NMR (400 MHz, MeOD): δ 9.22 (s, 1 H), 7.85 (br s, 1 H), 7.64 (d, 2H), 7.52 (dd, 1 H), 7.42-7.36 (m, 1 H), 7.31 (dd, 1 H), 6.99 (d, 1 H), 3.95 (s, 3H), 3.02 (s, 8H), 2.35 (s, 3H).

Example 10: 6-(2,6-dichlorophenyl)-8-(3-methoxyprop-1-vn-1-yl)-2-((3-methyl-4-(piperidin- 4-yl)phenyl)amino)pyrido[4,3-dlpyrimidin-5(6H)-one

Step 1: tert-Butyl 4-(2-methyl-4-nitrophenyl)-3,6-dihydropyridine-1(2H)-carboxylate 1-Bromo-2-methyl-4-nitrobenzene (1 g, 4.63 mmol), and te/f-butyl 4-(4,4,5,5-tetramethyl- 1 ,3,2-dioxaborolan-2-yl)-5,6-dihydropyridine-1 (2H)-carboxylate (1.86 g, 6.02 mmol) were suspended in 1 ,4-dioxane (32 ml_) and 2M sodium carbonate solution (5.32 ml_, 10.65 mmol) was added. The mixture was degassed and PdCl₂(dppf)-CH₂Cl₂ adduct (0.378 g, 0.463 mmol) was added. The reaction mixture was stirred intensively overnight at 90 °C. After cooling to RT the reaction mixture was filtered through Celite (washed with EtOAc) and the filtrate was evaporated under reduced pressure. The residue was purified by flash chromatography (10-50% EtOAc in cyclohexane). The product containing fractions were evaporated under reduced pressure, yielding the title compound as a brownish oil that solidified upon storage (1.46 g, 99 %).

LCMS (Method A): R_T = 2.01 min, m/z = 263 [M+H-56]⁺.

¹ H NMR (300 MHz, CDCI₃) δ 8.05 (d, 1 H), 8.00 (dd, 1 H), 7.22 (d, 1 H), 5.63 (s, 1 H), 4.06 (d, 2H), 3.64 (t, 2H), 2.43 - 2.27 (m, 5H), 1.50 (s, 9H).

Step 2: tert-Butyl 4-(4-amino-2-methylphenyl)piperidine-1-carboxylate

A stirring solution of te/f-butyl 4-(2-methyl-4-nitrophenyl)-5,6-dihydropyridine-1 (2H)- carboxylate (1.5 g, 4.71 mmol) in EtOH (60 ml_) was heated to 55 °C . 10 % Pd/C (0.35 g, 0.330 mmol) was added followed by small portions of ammonium formate (3.56 g, 56.6 mmol) to avoid an intensive reaction. The reaction mixture was stirred for approximately 1 h at the same temperature. The suspension was filtered through Celite (washing with fresh ethanol) and the ethanol was removed in vacuo. The resulting residue was purified by flash chromatography (15-80% EtOAc in cyclohexane) to afford the title compound (1.15 g, 3.96 mmol, 84 % yield) as a brownish oil that solidified upon storage.

LCMS (Method A): R_T = 1.16 min, m/z = 235 [M+H-56]⁺.

¹ H NMR (300 MHz, CDCI₃) δ 6.95 (d, 1 H), 6.61-6.41 (m, 2H), 4.38-4.09 (m, 2H), 3.55 (bs, 2H), 2.92-2.63 (m, 3H), 2.26 (s, 3H), 1.79-1.64 (m, 2H), 1.64-1.51 (m, 2H), 1.48 (s, 9H). Step 3: 6-(2, 6-Dichlorophenyl)-8-(3-methoxyprop-1-yn- 1-yl)-2-((3-methyl-4-(piperidin-4- yl)phenyl)amino)pyrido[4, 3-d]pyrimidin-5( 6H)-one

Intermediate D (150 mg, 0.37 mmol) was reacted with te/f-butyl 4-(4-amino-2- methylphenyl)piperidine-1-carboxylate according to General Procedure E, yielding the title compound as a yellow solid (87 mg, 45%).

LCMS (Method A): R_T = 0.93 min, m/z = 548, 550, 552 [M+H]⁺.

¹ H NMR (500 MHz, DMSO-cfe) δ 10.40 (s, 1 H), 9.17 (s, 1 H), 8.31 (s, 1 H), 8.12-7.93 (m, 1 H), 7.75 (d, 3H), 7.66-7.55 (m, 1 H), 7.18 (d, 1 H), 4.41 (s, 2H), 3.37 (s, 3H), 3.09-2.99 (m, 2H), 2.81-2.70 (m, 1 H), 2.65-2.57 (m, 2H), 2.32 (s, 3H), 1.66-1.58 (m, 2H), 1.57-1.43 (m, 2H).

Example 1 1 : 2-((3-Cvclopropoxy-4-(piperazin-1-yl)phenyl)amino)-6-(2,6-dichlorophenyl)-5- oxo-5,6-dihvdropyrido[4,3-dlpyrimidine-8-carbonitrile

Step 1: 1-Bromo-4-nitro-2-vinyloxy-benzene

2-Bromo-5-nitrophenol (1000 mg, 4.59 mmol), vinylacetate (790 mg, 9.17 mmol), and sodium carbonate (292 mg, 2.75 mmol) were suspended in toluene and the flask was flushed with N₂. Bis(1 ,5-cyclooctadiene)diiridium(l) dichloride (31 mg, 0.046 mmol) was added and the reaction mixture was refluxed under N₂ for 4h. The mixture was diluted with EtOAc to 50 mL and washed with sat. Na₂C0₃ (2x 50 mL). The organic layer was dried (MgS0₄) and evaporated under reduced pressure. The product was purified by flash chromatography (10-50% of EtOAc in cyclohexane) and the product containing fractions were evaporated under reduced pressure, yielding a beige solid (578 mg, 52%) which was taken on as such.

LCMS (Method A): R_T = 1.38 min, MS: no ionization.

¹ H NMR (500 MHz, CDCI₃) δ 7.89-7.82 (m, 2H), 7.77 (d, 1 H), 6.65 (dd, 1 H), 4.99 (dd, 1 H), 4.75 (dd, 1 H).

Step 2: 1-Bromo-2-(cyclopropoxy)-4-nitro-benzene

Diethylzinc (1 M in heptane, 9.79 mL, 9.79 mmol) was added to dry DCM (10 mL) under a N₂ atmosphere and chilled in an ice bath. Then TFA (0.75 ml, 9.79 mmol) in DCM (5 mL) was added dropwise and the reaction mixture was stirred for 10 min. Next diiodomethane (0.79 mL, 9.80 mmol) in DCM (5 mL) was added and the reaction mixture was again stirred for 10 - 15 min. Finally 1-bromo-4-nitro-2-vinyloxy-benzene (478.0 mg, 1.96 mmol) in DCM (5 mL) was added and the reaction mixture was removed from the ice bath, warmed to RT and stirred for about 30 min. at RT. After the addition of sat. NH₄CI the resultant mixture was diluted with water and DCM (approx. 25 ml of each) and the organic layer was separated, dried and evaporated under reduced pressure. The product was purified by flash chromatography (5-50% EtOAc in cyclohexane) yielding the target compound as a yellow oil (180 mg, 36 %).

LCMS (Method A): R_T = 1.72 min, MS: no ionization.

¹ H NMR (500 MHz, CDCI₃) δ 8.09 (d, 1 H), 7.74 (dd, 1 H), 7.69 (d, 1 H), 3.96-3.88 (m, 1 H), 0.99-0.88 (m, 4H). Step 3: tert-Butyl 4-[2-(cyclopropoxy)-4-nitro-phenyl]piperazine-1-carboxylate

1-Bromo-2-(cyclopropoxy)-4-nitro-benzene (150.0 mg, 0.58 mmol) was dissolved in 1 ,4- dioxane (3 ml_) and te/f-butylpiperazine-1-carboxylate (162 mg, 0.87 mmol) was added followed by Cesium carbonate (568 mg, 1.74 mmol) and Xantphos (37 mg, 0.064 mmol) The flask was flushed with N₂ and tris[dibenzylideneacetone]dipalladium(0) (27 mg, 0.029 mmol) was added. The reaction mixture was heated at 100 °C overnight. Next the reaction mixture was chilled to RT and filtered through Celite (washed with EtOAc). The product as purified by flash chromatography (10-50 % EtOAc in cyclohexane) and the product containing fractions were concentrated in vacuo to yield the target compound as a yellow oil that solidified upon storage (129 mg, 61 %).

LCMS (Method B): R_T = 1.60 min, m/z = 364 [M+H]⁺.

¹ H NMR (500 MHz, CDCI₃) δ 8.09 (d, 1 H), 7.87 (dd, 1 H), 6.85 (d 1 H), 3.91-3.80 (m, 1 H),

3.66-3.49 (m, 4H), 3.20-3.01 (m, 4H), 1.00-0.76 (m, 4H).

Step 4: tert-Butyl 4-[4-Amino-2-(cyclopropoxy)phenyl]piperazine-1-carboxylate

te/f-Butyl 4-[2-(cyclopropoxy)-4-nitro-phenyl]piperazine-1-carboxylate (129 mg, 0.355 mmol) was dissolved in EtOH (3 ml_) at 60 °C and 10 % Pd/C (26 mg, 0.025 mmol) was added followed by ammonium formate (1 12 mg, 1.77 mmol). The reaction mixture was stirred at the same temperature until completion (intensive gas evolution). The mixture was cooled to RT and filtered through Celite (washed with EtOH). The filtrate was evaporated under reduced pressure and the product was purified by flash chromatography (10-50 % EtOAc in cyclohexane), yielding a reddish oil (1 12 mg, 95 %) that solidified upon storage. LCMS (Method B): R_T = 0.82 min m/z = 334 [M+H]⁺.

¹ H NMR (500 MHz, CDCI₃) δ 8.09 (d, 1 H), 7.87 (dd, 1 H), 6.85 (d, 1 H), 3.91-3.80 (m, 1 H), 3.66-3.49 (m, 4H), 3.20-3.01 (m, 4H), 1.00-0.76 (m, 4H).

Step 5: 2-((3-Cyclopropoxy-4-(piperazin- 1-yl)phenyl)amino)-6-(2, 6-dichlorophenyl)-5-oxo- 5, 6-dihydropyrido[4, 3-d]pyrimidine-8-carbonitrile

Intermediate C (50 mg, 0.138 mmol) was reacted with tert-butyl 4-[4-Amino-2- (cyclopropoxy)phenyl]piperazine-1-carboxylate (37 mg, 0.138 mmol) according to General Procedure E, yielding the title compound as an orange solid (40 mg, 55 %)

LCMS (Method B): R_T = 0.91 min m/z = 548, 550, 552 [M+H]⁺.

¹ H NMR (500 MHz, DMSO-cfe) δ 10.64 (s, 1 H), 9.18 (s, 1 H), 8.95 (s, 1 H), 8.15 (s, 1 H), 7.78 (d, 2H), 7.69-7.59 (m, 1 H), 7.40-7.19 (m, 1 H), 6.83 (d, 1 H), 4.02 (s, 1 H), 2.81 (q, 8H), 2.20 (s, 1 H), 0.85-0.74 (m, 2H), 0.73-0.61 (m, 2H). Example 12: 6-(2-chloro-6-methylphenyl)-8-(difluoromethyl)-2-((3-methoxy-4-(piperazin-1- yl)phenyl)amino)pyrido[4,3-dlpyrimidin-5(6H)-one

Step 1: 6-(2-Chloro-6-methy^henyl)-2-methylsulfanyl-5-oxo^yrido[4,3-d]pyrimidin carbaldehyde

Phosphoryltrichloride (3.73 mL, 39.9 mmol) was added to DMF (18.52 mL, 239 mmol) at 0°C and the mixture was warmed up to RT and stirred for 30 min. The resulting solution was added to a solution of A/-(2-chloro-6-methylphenyl)-4-methyl-2-(methylthio)pyrimidine- 5-carboxamide (1.227 g, 3.99 mmol) in DMF (20 mL) at 0°C and the mixture was warmed to RT and subsequently stirred at 90°C for 15h.

The mixture was cooled to RT and partitioned between MTBE (200 mL) and water / sat. brine (100mL / 100mL) and the mixture was neutralised with sat. sodium

hydrogencarbonate. The organic phase was separated and the aqueous phase was extracted with additional MTBE (2 times 200 mL). The combined organic phases were washed with brine, dried over sodium sulphate, filtered and concentrated in vacuo. The remaining solid was purified by flash chromatography (Hex / EtOAc = 4: 1) to yield the target compound as an off white solid (0.85 g; 62%).

LCMS (Method B): R_T = 1.36 min, m/z = 346, 348 [M+H]⁺.

Step 2: 6-(2-Chloro-6-methyl^henyl)-8-(difluoromethyl)-2-methylsulfan 3- d]pyrimidin-5-one

6-(2-chloro-6-methyl-phenyl)-2-methylsulfanyl-5-oxo-pyrido[4,3-d]pyrimidine-8- carbaldehyde (315 mg, 0.91 mmol) was dissolved in DCM (6 mL) and the flask was flushed with N_2. XtalFluor-E (313 mg, 1.34 mmol) was added followed by TEA*3HF (0.3 ml, 1.82 mmol). The reaction mixture was stirred overnight at RT. Additional 600 mg of XTalFluor-E was added followed by 0.6 ml of TEA*3HF. The reaction mixture was stirred for 5h at RT. 600 mg of XTal Fluor-E was added followed by 0.6 ml of TEA*3HF and the reaction mixture was stirred overnight until completion. Sat. NaHC0₃ solution was added slowly and the organic layer was separated, dried (anh. MgS0₄) and evaporated under reduced pressure. The product was purified by flash chromatography (10-50 % EtOAc in cyclohexane), yielding the target molecule as a clear oil that solidified upon storage.

LCMS (Method B): R_T = 1.45 min, m/z = 368, 370 [M+H]⁺.

1 H NMR (500 MHz, CDCI₃) δ 9.40 (s, 1 H), 7.66 (t, 1 H), 7.44 (dd, 1 H), 7.37 (t, 1 H), 7.32- 7.29 (m, 1 H), 7.20 (t, 1 H), 2.67 (s, 3H), 2.20 (s, 3H).

Step 3: tert-Butyl 4-[4-[[6-(2-chloro-6-methyl^henyl)-8-(difluorome

d]pyrimidin-2-yl]amino]-2-methoxy-phenyl]piperazine-1-carboxylate

6-(2-Chloro-6-methyl-phenyl)-8-(difluoromethyl)-2-methylsulfanyl-pyrido[4,3-d]pyrimidin-5- one (50 mg, 0.136 mmol) was dissolved in DCM (2 mL) and mCPBA (37 mg, 0.150 mmol) was added. The reaction mixture was stirred for 30 min at RT. Then the reaction mixture was diluted to 10 mL with DCM and washed with aqueous sodium thiosulfate solution. The organic layer was separated, dried (anh. MgS0₄) and evaporated under reduced pressure. The residue was suspended in 2-propanol (2 mL) and te/f-butyl 4-(4-amino-2-methoxy- phenyl)piperazine-1-carboxylate (42 mg, 0.136 mmol) was added. The reaction mixture was heated overnight at 90 °C, the volatiles were evaporated under reduced pressure and the residue was purified by flash chromatography (10-50 % EtOAc in cyclohexane), yielding the title compound as a yellow oil (69 mg, 81 %).

LCMS (Method B): R_T = 1.59 min, m/z = 627, 629 [M+H]⁺.

¹ H NMR (500 MHz, CDCI₃) δ 9.33 (s, 1 H), 7.73-7.51 (m, 3H), 7.45-7.40 (m, 1 H), 7.35 (t, 1 H), 7.32-7.27 (m, 1 H), 7.20-7.02 (m, 1 H), 7.02-6.94 (m, 1 H), 6.91 (d, 1 H), 3.95 (s, 3H), 3.71-3.56 (m, 4H), 3.11-2.94 (m, 4H), 2.22 (s, 3H), 1.49 (s, 9H). Step 4: 6-(2-Chloro-6-methyl^henyl)-8-(difluoromethyl)-2-(3-methoxy-4^iperazi anilino)pyrido[4,3-d]pyrimidin-5-one

te/f-Butyl 4-[4-[[6-(2-chloro-6-methyl-phenyl)-8-(difluoromethyl)-5-oxo-pyrido[4,3- d]pyrimidin-2-yl]amino]-2-methoxy-phenyl]piperazine-1-carboxylate (69 mg, 0.1 1 mmol) was dissolved in DCM (4 mL) and TFA (2 mL) were added. The reaction mixture was stirred for 30 min at RT and the volatiles were evaporated under reduced pressure. The residue was dissolved in DCM and injected onto a SCX-2 (2 g, washed with DCM) column. The product was washed with 20% MeOH/DCM and eluted with 20% 7N NH₃ MeOH /DCM. The product containing fractions were evaporated under reduced pressure and lyophilised (ACN/water), yielding the target compound as a yellow solid (41 mg, 71 %).

LCMS (Method B): R_T = 0.89 min, m/z = 527, 529 [M+H]⁺. ¹ H NMR (500 MHz, DMSO-cfe) δ 10.38 (s, 1 H), 9.18 (s, 1 H), 8.12 (s, 1 H), 7.81 (s, 1 H), 7.59- 7.52 (m, 1 H), 7.47 (t, 1 H), 7.45-7.41 (m, 1 H), 7.29-7.03 (m, 2H), 6.85 (d, 1 H), 3.82 (s, 3H), 2.97-2.73 (m, 8H), 2.25 (s, 1 H), 2.14 (s, 3H). Example 13: rac-6-(2,6-Dichlorophenyl)-8-(3-methoxyprop-1-vn-1-yl)-2-((3-methyl-4- (pyrrolidin-3-yl)phenyl)amino)pyrido[4,3-dlpyrimidin-5(6H)-one

Step 1: tert-Butyl 3-(trifluoromethylsulfonyloxy)-2,5-dihydropyrrole-1-carboxylate

i-/V-Boc-3-pyrrolidinone (1000 mg, 5.40 mmol) was dissolved in THF (10 mL) and chilled to -78 °C. 1 M LHMDS in THF (9.99 mmol, 9.99 mL) was added slowly (within approx. 10-15 min). The reaction mixture was stirred for 30 min. Next 1 , 1 , 1-Trifluoro-N-phenyl-N- (trifluoromethyl)sulfonylmethanesulfonamide (2141 mg, 5.99 mmol in THF (20 mL) was added slowly (30 min). The reaction mixture was stirred for an additional 30 min at -78 °C. The acetone bath was replaced with an ice-water bath and the reaction was stirred for an additional 3h. After quenching the reaction by addition of ice cold water (20 mL), the reaction mixture was transfered to a separatory funnel. EtOAc (100 mL) was added and the organic layer was separated. The water layer was extracted with EtOAc (2 x 30 mL). The organic layer was dried (anh. MgS0₄) and evaporated under reduced pressure. The oily residue was dissolved in cyclohexane and injected onto an equilibrated neutral Al₂0₃ column (5% EtOAc in cyclohexane). The product was eluted with EtOAc-cyclohexane gradient (5-15% EtOAc in cyclohexane) and the product containing fraction were concentrated in vacuo to yield the target compound as a yellowish oil (830 mg, 48 %). LCMS (Method A): R_T = 1.81 min, m/z = 262 [M+H-56]⁺.

¹ H NMR (500 MHz, CDCI₃) δ 5.81-5.64 (m, 1 H), 4.38-4.14 (m, 4H), 1.48 (s, 9H).

Step 2: tert-Butyl 3-(2-methyl-4-nitro-phenyl)-2,5-dihydropyrrole-1-carboxylate

te/f-Butyl 3-(trifluoromethylsulfonyloxy)-2,5-dihydropyrrole-1-carboxylate (830 mg, 2.62 mmol) was dissolved in 1 ,4-dioxane (7 mL), AcOK (798 mg, 8.14 mmol). Then

bis(pinacolato)diboron (737 mg, 2.90 mmol), dppf (43 mg, 0.079 mmol) and

Pd(dppf)CI₂DCM (64 mg, 0.079 mmol) were added. The flask was flushed with nitrogen and heated for 6-7h at 80 °C under nitrogen (HPLC-MS tracking of the product: m/z 240 [M+H-56]+). The reaction mixture was cooled to RT and diluted with 10 mL of 1 ,4-dioxane. 1-bromo-2-methyl-4-nitro-benzene (625 mg, 2.90 mmol), 2M Na₂C0₃ solution (3 mL) and Pd(dppf)CI₂ DCM (170 mg, 0.201 mmol) were added and the reaction mixture was intensively stirred at 90 °C overnight under nitrogen. After cooling to RT, the reaction mixture was diluted with EtOAc (50 mL) and water (50 mL). The organic layer was separated and the aqueous layer was extracted with EtOAc (2x 50 mL). The combined organic extracts were dried (anh. MgS0₄) and evaporated under reduced pressure. The product was purified by flash chromatography (10-50 % EtOAc in cyclohexane), yielding the target compound as a yellowish oil (320 mg, 40 %).

LCMS (Method A): R_T = 1.83 min, m/z = 249 [M+H-56]⁺.

¹ H NMR (500 MHz, Chloroform-d) δ 8.02 (s, 1 H), 7.96 (dd, 1 H), 7.26 (d„ 1 H), 5.90 (d„ 1 H), 4.54 -4.15 (m, 4H), 2.43 (s, 3H), 1.44 (s, 9H). Step 3: rac-tert-Butyl 3-(4-amino-2-methyl-phenyl)pyrrolidine- 1-carboxylate

te/f-Butyl 3-(2-methyl-4-nitro-phenyl)-2,5-dihydropyrrole-1-carboxylate (320 mg, 1.05 mmol) was dissolved in EtOH (20 mL) at 70 °C and 10 % Pd/C (78 mg) was added followed by ammonium formate (332 mg, 5.26 mmol). The reaction mixture was stirred for approx. 30 min until the reduction was accomplished (intensive gas evolution). The reaction mixture was cooled to RT, filtered through Celite and the filtrate was evaporated under reduced pressure. The product was purified by flash chromatography (20-60% EtOAc in

cyclohexane) yielding the target compound (268 mg, 92 %) as a clear oil.

LCMS (Method A): R_T = 1.02 min, m/z = 2221 [M+H-56]⁺.

¹ H NMR (500 MHz, CDCI₃) δ 7.05-6.97 (m, 1 H), 6.56 (d, 2H), 4.08-3.80 (m, 2H), 3.79-3.64 (m, 1 H), 3.64-3.47 (m, 1 H), 3.47-3.30 (m, 2H), 3.30-3.13 (m, 1 H), 2.28 (s, 3H), 2.19-2.07 (m, 1 H), 1.98-1.86 (m, 1 H), 1.48 (d, 9H).

Step 4. rac-6-(2, 6-dichlorophenyl)-8-(3-methoxyprop- 1-yn- 1-yl)-2-((3-methyl-4-(pyrrolidin-3- yl)phenyl)amino)pyrido[4, 3-d]pyrimidin-5( 6H)-one

Intermediate D (50 mg, 0.123 mmol) was reacted with rac-tert-butyl 3-(4-amino-2-methyl- phenyl)pyrrolidine-1-carboxylate according to General Procedure E, yielding the title compound as an orange solid (19 mg, 29 %).

LCMS (Method A): R_T = 1.00 min, m/z = 534, 536, 538 [M+H]⁺.

¹ H NMR (500 MHz, DMSO-cfe) δ 10.39 (s, 1 H), 9.16 (s, 1 H), 8.30 (s, 1 H), 7.97 (s, 2H), 7.74 (d, 3H), 7.60 (t, 1 H), 7.23 (d, 1 H), 4.40 (s, 2H), 3.35 (s, 3H), 3.29-3.23 (m, 1 H), 3.19-3.14 (m, 1 H), 3.01-2.88 (m, 2H), 2.63-2.56 (m, 1 H), 2.32 (s, 3H), 2.12-2.04 (m, 1 H), 1.71-1.61 (m, 1 H).

Example 14: rac-6-(2,6-Dichlorophenyl)-2-((3-methyl-4-(pyrrolidin-3-yl)phenyl)arriino)-5- oxo-5,6-dihvdropyrido[4,3-dlpyrimidine-8-carbonitrile

Intermediate C (50 mg, 0.138 mmol) was reacted with rac-tert-butyl 3-(4-amino-2-methyl- phenyl)pyrrolidine-1-carboxylate (obtained as described in Example 13, Step 3) according to General Procedure E, yielding the title compound as an orange solid (41 mg, 60 %) LCMS (Method A): R_T = 0.95 min, m/z = 491 , 493, 495 [M+H]⁺.

¹ H NMR (500 MHz, DMSO-cfe) δ 10.64 (s, 1 H), 9.19 (s, 1 H), 8.96 (s, 1 H), 8.10 (s, 1 H), 7.81- 7.74 (m, 2H), 7.69-7.56 (m, 2H), 7.23 (d, 1 H), 3.28 (d, 1 H), 3.16 (dd, 1 H), 3.03- 2.94 (m, 1 H), 2.94-2.85 (m, 1 H), 2.66- 2.57 (m, 1 H), 2.33 (s, 3H), 2.14-2.02 (m, 1 H), 1.75-1.58 (m, 1 H).

Example 15: 6-(2,6-dichlorophenyl)-2-((3-methoxy-4-(pyrrolidin-3-yl)phenyl)amino)-8-(3- methoxyprop-1-vn-1-yl)pyrido[4,3-dlpyrimidin-5(6H)-one

Step 1. 1-(4-bromo-3-methoxy-phenyl)-2,2,5,5-tetramethyl-1,2,5-azadisilolidine

1-Bromo-2-methoxy-4-nitrobenzene (13 g, 56 mmol) was dissolved in THF (400ml_) and tin(ll) chloride dehydrate (63.2 g, 280 mmol) was added followed by ethanol (80 ml_). The orange solution was left to stir at RT for 18h (a mild exotherm occurs after approx. 30 min). The mixture was poured into EtOAc / 14N aqu. sodium hydroxide solution (400ml_ / 400ml_) and the phases were separated. The organic phase was washed with 14N aqu. sodium hydroxide solution twice followed by water and brine solution. The organic phase was dried over MgS04, the solid was filtered off and the solvent concentrated in vacuo to obtain 8 g (40 mmol, 71 %) of a light brown oil which quickly crystallises and which was taken on as such.

The crude aniline was dissolved in DCM (100ml_) and 1 ,2-bis(chlorodimethylsilyl)ethane (9.65 g, 44.8 mmol) followed by triethylamine (14.84 ml_, 106 mmol) and N,N- dimethylpyridine-4-amine (0.4 g, 3.27 mmol) were added and the mixture was stirred at RT for 3 days.

The orange suspension was poured into aqu. sat. sodium hydrogencarbonate solution / DCM (100ml_ / 200 ml_) and extracted into DCM twice (100 ml_ each). The combined organic phases were washed with sat. sodium hydrogencarbonate solution followed by sat. brine and dried over K₂C0₃.The solid was filtered off and the solvent was removed in vacuo to obtain the target compound as an orange liquid which was taken on as such.

Step 2. tert-Butyl 3-(4-amino-2-methoxy-phenyl)-2,5-dihydropyrrole-1-carboxylate te/f-Butyl 3-(trifluoromethylsulfonyloxy)-2,5-dihydropyrrole-1-carboxylate (1840 mg, 5.80 mmol) (Obtained according to Example 13, Step 1) was dissolved in 1 ,4-dioxane (16 ml_), AcOK (1770 mg, 18.04 mmol), bis(pinacolato)diboron (1635 mg, 6.44 mmol), dppf (96 mg, 0.174 mmol) and Pd(dppf)CI₂DCM (142 mg, 0.174 mmol) were added. The flask was flushed with nitrogen and subsequently heated for 6-7h at 80 °C under nitrogen (MS tracking of the product: m/z 240 [M+H-56]+). The reaction mixture was cooled to RT and diluted with 25 ml_ of 1 ,4-dioxane. 1-(4-bromo-3-methoxy-phenyl)-2,2,5,5-tetramethyl-1 ,2,5- azadisilolidine (2217 mg, 6.44 mmol), 2M Na₂C0₃ solution (6.7 ml_) and Pd(dppf)CI₂ DCM (237 mg, 0.290 mmol) were added. The reaction mixture was intensively stirred at 90 °C overnight under nitrogen and subsequently cooled to RT and diluted with EtOAc (100 mL) and water (100 mL). The organic layer was separated and the aqueous layer was extracted with EtOAc (2x 100 mL). The combined organic extracts were dried (anh. MgS0₄) and evaporated under reduced pressure. The product was purified by flash chromatography (10-50 % EtOAc in cyclohexane), yielding the target compound as a yellowish oil (1660 mg, 98 %).

LCMS (Method A): R_T = 1.38 min, m/z = 291 [M+H]⁺.

¹ H NMR (500 MHz, CDCI₃) δ 6.99 (dd, 1 H), 6.37-6.30 (m, 2H), 6.30-6.18 (m, 1 H), 4.72-4.52 (m, 2H), 4.53-4.39 (m, 2H), 4.34- 4.21 (m, 2H), 3.84 (d„ 3H), 1.50 (d, 9H).

Step 3.rac-tert-Butyl 3-(4-amino-2-methoxy-phenyl)pyrrolidine-1-carboxylate

te/f-Butyl 3-(4-amino-2-methoxy-phenyl)-2,5-dihydropyrrole-1-carboxylate (1000 mg, 3.44 mmol) was dissolved in EtOH (50 mL) and the mixture was heated to 70 °C. Then 10 % Pd/C (256 mg, 0.241 mmol) was added followed by ammonium formate (2170 mg, 34 mmol). The reaction mixture was heated for about 1 h at the same temperature. The reaction mixture was cooled to RT, filtered through Celite (washed with EtOH) and the filtrate was evaporated under reduced pressure. The product was purified by flash chromatography (20-60 % EtOAc in cyclohexane), yielding the target compound as a clear oil (950 mg, 94%).

LCMS (Method A): R_T = 1.10 min, m/z = 237 [M+H-56]⁺.

¹ H NMR (500 MHz, CDCI₃) δ 6.94 (dd, 1 H), 6.32-6.21 (m, 2H), 3.99-3.79 (m, 2H), 3.78 (d, 3H), 3.72-3.63 (m, 1 H), 3.62-3.41 (m, 2H), 3.42-3.26 (m, 1 H), 3.28-3.08 (m, 1 H), 2.16-2.06 (m, 1 H), 2.01-1.89 (m, 1 H), 1.47 (d, 9H). Step 4. rac-tert-butyl 3-[4-[[6-(2,6-dichlorophenyl)-8-(3-methoxyprop-1-ynyl)-5-oxo- pyrido[4,3-d]pyrimidin-2-yl]amino]-2-methoxy-phenyl]pyrrolidine-1-carboxylate:

Intermediate D (50 mg, 0.123 mmol) was reacted with tert-butyl 3-(4-amino-2-methoxy- phenyl)pyrrolidine-1-carboxylate according to General Procedure E, yielding the title compound as an orange solid (14 mg, 21 %).

LCMS (Method A): R_T = 1.02 min, m/z = 550, 552, 554 [M+H]⁺.

¹ H NMR (500 MHz, DMSO-d₆ + TFA) δ 10.51 (s, 1 H), 9.21 (s, 1 H), 9.03-8.66 (m, 2H), 8.32 (s, 1 H), 7.90-7.76 (m, 1 H), 7.77 (s, 1 H), 7.74 (d, 2H), 7.69-7.52 (m, 2H), 7.22 (d, 1 H), 4.38 (s, 2H), 3.85 (s, 3H), 3.70 (s, 2H), 3.66-3.52 (m, 2H), 3.47-3.37 (m, 1 H), 3.35 (s, 3H), 3.31- 3.19 (m, 1 H), 3.10-2.98 (m, 1 H), 2.31-2.20 (m, 1 H), 2.10-1.96 (m, 1 H). Example 16: rac-6-(2,6-Dichlorophenyl)-2-((3-methoxy-4-(pyrrolidin-3-yl)phenyl)arriino)-5-

Intermediate C (50 mg, 0.138 mmol) was reacted with rac-te/f-butyl 3-(4-amino-2-methoxy- phenyl)pyrrolidine-1-carboxylate (obtained as described in Example 15, Step 3) according to General Procedure E, yielding the title compound as an orange solid (34 mg, 74 %). LCMS (Method A): R_T = 0.97 min, m/z = 507, 509, 511 [M+H]⁺.

¹ H NMR (500 MHz, CDCI₃) δ 9.29 (s, 1 H), 8.14 (s, 1 H), 7.79 (s, 2H), 7.55 (d, 2H), 7.52-7.39 (m, 1 H), 7.18 (d, 1 H), 6.84 (d„ 1 H), 4.01 (s, 3H), 3.63-3.46 (m, 1 H), 3.36 (dd, 1 H), 3.31- 3.16 (m, 1 H), 3.09 (dt, 1 H), 2.91 (dd, 1 H), 2.24-2.13 (m, 1 H), 1.97-1.88 (m, 1 H).

Example 17: 6-(2,6-Dichlorophenyl)-2-[3-methoxy-4-[(3R)-3-methylpiperazin-1-yl1anilino1-8- methyl-pyrimido[4,5-dlpyridazin-5-one

Step 1. tert-Butyl (2R)-4-[4-[[6-(2,6-dichlorophenyl)-8-methyl-5-oxo-pyrimido[4,5- d]pyridazin-2-yl]amino]-2-methoxy^henyl]-2-methyl-piperazine-1-carboxylate

In microwave vial 6-(2,6-dichlorophenyl)-8-methyl-2-methylsulfanyl-pyrimido[4,5- d]pyridazin-5-one (Prepared according to WO2013013031 , example 300C, page 216, 70 mg, 0.198 mmol) was suspended in DCM (1.5 ml)/toluene (1.5 ml) and mCPBA (38 mg, 0.218 mmol) was added. The reaction mixture was stirred for 30 min at RT. Then ferf-butyl (2f?)-4-(4-amino-2-methoxy-phenyl)-2-methyl-piperazine-1-carboxylate (64 mg, 0.198 mmol) and DIPEA (104 μΙ, 0.595 mmol) were added and the vial was capped. The mixture was heated at 65 °C overnight. The product was purified by flash chromatography (20-60% EtOAc in cyclohexane). Obtained as a yellow oil (45 mg, 36%). LCMS (Method A): R_T = 2.1 1 min, m/z = 626, 628, 630 [M+H]⁺. ¹ H NMR (500 MHz, CDCI₃) δ 9.42 (s, 1 H), 7.79-7.57 (m, 2H), 7.55-7.43 (m, 2H), 7.41-7.33 (m, 1 H), 7.12-7.03 (m, 1 H), 6.90 (d, 1 H), 4.34-4.27 (m, 1 H), 4.01-3.96 (m, 1 H), 3.94 (s, 3H), 3.39-3.21 (m, 3H), 2.83-2.66 (m, 2H), 2.64 (s, 3H), 1.49 (s, 9H), 1.40 (d, 3H). Step 2. 6-(2,6-Dichlorophenyl)-2-[3-methoxy-4-[(3R)-3-methylpiperazin-1-yl]am^

methyl-pyrimidof 4, 5-d]pyridazin-5-one

ferf-Butyl (2 )-4-[4-[[6-(2,6-dichlorophenyl)-8-methyl-5-oxo-pyrirnido[4,5-d]pyridazin-2- yl]amino]-2-methoxy-phenyl]-2-methyl-piperazine-1-carboxylate (43 mg, 0.0686 mmol) was dissolved in DCM (2 ml_) and TFA (1 ml_) was added. The reaction mixture was stirred for 30 min at RT and then the volatiles were evaporated under reduced pressure. The residue was dissolved in DCM and injected onto a SCX-2 (2g) column (pre-washed with DCM). The mixture was left to bind for 10 min and then the resin was washed with 20% MeOH in DCM. The product was eluted with 20% 7N NH₃ MeOH in DCM. The product containing fractions were evaporated under reduced pressure. The obtained material was lyophilised

(ACN/water), yielding the title compound as an orange solid (31 mg, 85 %).

LCMS (Method B): R_T = 0.88 min, m/z = 526, 528, 530 [M+H]⁺.

¹ H NMR (500 MHz, DMSO-cfe) δ 10.64 (s, 1 H), 9.32 (s, 1 H), 7.92-7.78 (m, 1 H), 7.72 (d, 2H), 7.63-7.56 (m, 1 H), 7.30-7.24 (m, 1 H), 6.88 (d, 1 H), 3.84 (s, 3H), 3.25-3.12 (m, 3H), 2.95-2.80 (m, 3H), 2.55 (s, 3H), 2.19 (t, 1 H), 0.99 (d, 3H).

Example 18: 6-(2,6-Dichlorophenyl)-2-(3-methoxy-4-piperazin-1-yl-anilino)-8-methyl- pyrimido[4,5-dlpyridazin-5-one

Step 1. tert-Butyl 4-[4-[[6-(2, 6-dichlorophenyl)-8-methyl-5-oxo-pyrimido[4, 5-d]pyridazin-2- yl]amino]-2-methoxy-phenyl]piperazine-1-carboxylate

6-(2,6-dichlorophenyl)-8-methyl-2-methylsulfanyl-pyrimido[4,5-d]pyridazin-5-one (Prepared according to WO2013013031 , example 300C, page 216, 1.783 g, 5.05 mmol) was reacted with fe/f-butyl-4-(4-amino-2-methoxy-phenyl)-piperazine-1-carboxylate (1.552 g, 5.05 mmol) according to General procedure E to yield 3.09 g (74%) of the target compound as a yellow solid after filtration of the reaction mixture at RT. LCMS (Method A): R_T = 1.87 min, m/z = 612, 614, 616 [M+H]⁺.

¹ H NMR (500 MHz, CDCI₃) δ 9.43 (s, 1 H), 7.86-7.55 (m, 2H), 7.48 (d, 2H), 7.41-7.32 (m, 1 H), 7.15-7.04 (m, 1 H), 6.93 (d, 1 H), 3.95 (s, 3H), 3.70-3.54 (m, 4H), 3.09-2.88 (m, 4H), 2.63 (s, 3H), 1.49 (s, 9H).

Step 2. 6-(2, 6-Dichlorophenyl)-2-(3-methoxy-4-piperazin- 1-yl-anilino)-8-methyl- pyrimidof 4, 5-d]pyridazin-5-one

te/f-Butyl 4-[4-[[6-(2,6-dichlorophenyl)-8-methyl-5-oxo-pynrnido[4,5-d]pyridazin-2-yl]arnino]- 2-methoxy-phenyl]piperazine-1-carboxylate (150 mg, 0.225 mmol) was dissolved in DCM (6 ml_) and TFA (3 ml_) was added. The reaction mixture was stirred for 30 min at RT and then the volatiles were evaporated under reduced pressure. The residue was dissolved in DCM and injected onto a SCX-2 (2g) column washed with DCM. The mixture was left to bind for 10 min and then the resin was washed with 20% MeOH in DCM. The product was eluted with 20% 7N NH₃ MeOH in DCM. The product containing fractions were evaporated under reduced pressure. The obtained material was lyophilised (ACN/water), yielding the title compound as an orange solid (1 19 mg, 95 %).

LCMS (Method B): R_T = 0.92 min, m/z = 512, 514, 516 [M+H]⁺.

¹ H NMR (500 MHz, DMSO-cfe) δ 10.65 (s, 1 H), 9.32 (s, 1 H), 7.95-7.79 (m, 1 H), 7.72 (d, 2H), 7.59 (t, 1 H), 7.27 (d, 1 H), 6.88 (d, 1 H), 3.84 (s, 3H), 3.00-2.71 (m, 8H), 2.55 (s, 3H), 2.28 (s, 1 H).

Example 19: 6-(2,6-dichlorophenyl)-5-oxo-2-((4-(piperidin-4-yl)-3-(2,2,2-trifluoro-1- hvdroxyethyl)phenyl)amino)-5,6-dihydropyrido[4,3-dlpyrimidine-8-carbonitrile

Step 1. rac-1-(2-Bromo-5-nitrophenyl)-2, 2, 2-trifluoroethan- 1-ol 2-Bromo-5-nitro-benzaldehyde (2.00 mg, 8.69 mmol) was dissolved in THF (25 mL) under nitrogen and the flask was chilled in an ice bath. (Trifluoromethyl)trimethylsilane (1.8 mL, 12.17 mmol) was added followed by 1 M tetrabutylammonium fluoride in THF (0.3 mL, 0.304 mmol). The reaction mixture was stirred for 1 h at 0 °C. Then 1 mL of 1 M

tetrabutylammonium fluoride solution in THF was added and the reaction mixture was stirred for additional 1 h. The volatiles were evaporated under reduced pressure and the product was purified by flash chromatography (20-50% EtOAc in cyclohexane), yielding the target compound as a white solid (2.5 g, 96 %).

LCMS (Method A): R_T = 1.36 min, m/z = 298, 300 [M+H]⁺.

1 H NMR (500 MHz, CDCI₃) δ 8.57 (d, 1 H), 8.13 (dd, 1 H), 7.81 (d, 1 H), 5.68 (p, 1 H), 2.93 (d, 1 H).

Step 2. rac-tert-Butyl 4-(4-nitro-2-(2,2,2-trifluoro-1-hydroxyethyl)phenyl)-3,6- dihydropyridine- 1 ( 2H) -carboxylate

rac- 1-(2-Bromo-5-nitrophenyl)-2,2,2-trifluoroethan-1-ol (2.5 g, 8.33 mmol) and 3,6-dihydro- 2H-pyridine-1-te/f-butoxycarbonyl-4-boronicacid pinacolester (2.83 g, 9.16 mmol) were suspended in 1 ,4-dioxane (30 mL) and 2M disodium carbonate solution (9.58 mL,

19.165mmol) was added. The flask was flushed with N₂ and Pd(dppf)CI₂ DCM was added. The temperature was increased to 90 °C and the reaction mixture was stirred intensively overnight. The reaction mixture was chilled to RT, filtered through Celite and the filtrate was evaporated under reduced pressure. The product was purified by flash chromatography (10-60% EtOAc in cyclohexane), yielding the target compound as a clear oil that solidified upon storage (3.2 g, 95 %).

LCMS (Method B): R_T = 1.47 min, m/z = 303 [M+H-100]⁺.

1 H NMR (500 MHz, CDCI₃) δ 8.58 (d, 1 H), 8.22 (dd, 1 H), 7.34 (d, 1 H), 5.68 (s, 1 H), 5.37 (q, 1 H), 4.12-4.01 (m, 2H), 3.70-3.57 (m, 2H), 3.42-3.27 (m, 1 H), 2.40-2.27 (m, 2H), 1.49 (s, 9H).

Step 3. rac-tert-Butyl 4-(4-amino-2-(2,2,2-trifluoro-1-hydroxyethyl)phenyl)piperidine-1- carboxylate

rac-tert- Butyl 4-[4-nitro-2-(2,2,2-trifluoro-1-hydroxy-ethyl)phenyl]-3,6-dihydro-2H-pyridine-1- carboxylate (500 mg, 1.24 mmol) was heated in EtOH (20 mL) to 70 °C and 10 % Pd/C (53 mg, 0.0497 mmol) was added followed by ammonium formate (392 mg, 6.21 mmol) The reaction was stirred at 70 °C until intensive gas evolution occurred (approx. 15 min). Four additional batches of ammonium formate (392 mg, 6.21 mmol) were added every 10-15 min, until the reduction was accomplished (control by LCMS). The reaction mixture was cooled to RT and filtered through Celite. The Celite was washed with EtOAc. The combined filtrates were evaporated under reduced pressure. The residue was purified by flash chromatography (20-50% EtOAc in cyclohexane), yielding the title compound as a clear oil that solidified upon storage (340 mg. 73 %).

LCMS (Method A): R_T = 1.12 min, m/z = 319 [M+H-56]⁺.

¹ H NMR (500 MHz, CDCI₃) δ 7.06 (d, 1 H), 6.92 (d, 1 H), 6.71 (dd, 1 H), 5.42-5.30 (m, 1 H), 4.36-4.15 (m, 2H), 3.68 (s, 2H), 2.87-2.67 (m, 3H), 2.62-2.47 (m, 1 H), 1.72-1.57 (m, 4H), 1.48 (s, 9H).

Step 4. rac-6-(2, 6-Dichlorophenyl)-5-oxo-2-((4-(piperidin-4-yl)-3-(2, 2, 2-trifluoro- 1- hydroxyethyl)phenyl)amino)-5,6-dihydropyrido[4,3-d]pyrimidi

Intermediate C (100 mg, 0.275 mmol) was reacted with rac-te/f-butyl 4-(4-amino-2-(2,2,2- trifluoro-1-hydroxyethyl)phenyl)piperidine-1-carboxylate according to General Procedure E, yielding the title compound as a yellow solid (1 13 mg, 70 %).

LCMS (Method B): R_T = 0.92 min, m/z = 589, 591 , 593 [M+H]⁺.

¹ H NMR (500 MHz, DMSO-cfe) δ 10.80-10.61 (m, 1 H), 9.20 (s, 1 H), 8.95 (s, 1 H), 8.34 (s, 1 H), 7.85 (s, 1 H), 7.78 (d, 2H), 7.68-7.62 (m, 1 H), 7.31 (d, 1 H), 6.75 (d, 1 H), 5.42 (p, 1 H), 3.09-2.97 (m, 2H), 2.97-2.86 (m, 1 H), 2.70-2.52 (m, 3H), 1.72-1.57 (m, 2H), 1.57-1.42 (m, 2H).

Example 20: 6-(2,6-Dichlorophenyl)-5-oxo-2-((4-(piperidin-4-yl)-3-(2,2,2- trifluoroethyl)phenyl)amino -5,6-dihydropyrido[4,3-dlpyrimidine-8-carbonitrile

Step 1. rac-tert-Butyl 4-(2-( 1-chloro-2,2,2-trifluoroethyl)-4-nitrophenyl)-3, 6-dihydropyridine- 1 (2H)-carboxylate

rac-ferf-Butyl 4-(4-nitro-2-(2,2,2-trifluoro-1-hydroxyethyl)phenyl)-3,6-dihydropyridine-1 (2H)- carboxylate (obtained as described in Example 18, Step 2) (1.6 g, 3.98 mmol) was dissolved in carbon tetrachloride (80 mL) and triphenylphosphine (3.13 g, 1 1.93 mmol) was added. The resultant mixture was refluxed under nitrogen overnight. Next the reaction mixture was cooled and injected directly onto a 220g silica column. The product was purified by flash chromatography (10-40% EtOAc in cyclohexane) and the product containing fractions were concentrated in vacuo, yielding the title compound as a clear oil (1.33 g, 79 %).

LCMS (Method B): R_T = 1.70 min, m/z = 365 [M+H-56]⁺, 321 [M+H-100]⁺.

¹ H NMR (500 MHz, Chloroform-d) δ 8.60 (d, 1 H), 8.24 (dd, 1 H), 7.37 (d, 1 H), 5.73 (s, 1 H),

5.49 (q, 1 H), 4.18-4.03 (m, 2H), 3.75-3.62 (m, 2H), 2.46-2.28 (m, 2H), 1.52 (s, 9H). Step 2. rac-tert-butyl 4-(4-amino-2-(2, 2, 2-trifluoroethyl)phenyl)piperidine-1 -carboxylate rac-ferf-Butyl 4-(2-(1-chloro-2,2,2-trifluoroethyl)-4-nitrophenyl)-3,6-dihydropyridine-1 (2H)- carboxylate (1.33 g, 3.16 mmol) was heated in EtOH (40 mL) to 70 °C. 10 % Pd/C (135 mg, 0.126 mmol) was added followed by ammonium formate (997 mg, 15.80 mmol). The reaction was stirred at 70 °C until intensive gas evolution occurred (15 min). The reaction was continued to stir at the same temperature for an additional 1 h, whilst fresh batches of ammonium formate (997 mg, 15.80 mmol) were added every 15 min. until the reduction was accomplished. The reaction mixture was cooled to RT and filtered through Celite. The Celite was washed with EtOH and the combined filtrate was evaporated under reduced pressure. The residue was purified by flash chromatography (10-50% EtOAc in

cyclohexane), yielding the title compound as a clear oil that solidified upon storage (957 mg, 84 %).

LCMS (Method A): R_T = 1.39 min, m/z = 303 [M+H-56]⁺.

¹ H NMR (500 MHz, CDCI₃-c) δ 7.12 (d, 1 H), 6.86 (dd, 1 H), 6.77 (d, 1 H), 4.32-4.17 (m, 2H), 3.40 (q, 2H), 2.86-2.70 (m, 3H), 1.68-1.55 (m, 4H), 1.48 (s, 9H).

Step 3.6-(2, 6-Dichlorophenyl)-5-oxo-2-((4-(piperidin-4-yl)-3-(2, 2, 2- trifluoroethyl)phenyl)amino)-5,6-dihydropyrido[4,3-d]pyrim

Intermediate C (100 mg, 0.275 mmol) was reacted with rac-te/f-butyl 4-(4-amino-2-(2,2,2- trifluoroethyl)phenyl)piperidine-1 -carboxylate according to General Procedure E, yielding the title compound as a yellow solid (101 mg, 64 %).

LCMS (Method B): R_T = 1.00 min, m/z = 573. 575. 577 [M+H]⁺.

¹ H NMR (500 MHz, DMSO-cfe) δ 10.84-10.59 (m, 1 H), 9.21 (s, 1 H), 8.96 (s, 1 H), 8.34 (d, 1 H), 7.78 (d, 3H), 7.72-7.57 (m, 1 H), 7.32 (d, 1 H), 3.69 (q, 2H), 3.09-2.95 (m, 2H), 2.87- 2.76 (m, 1 H), 2.68-2.57 (m, 2H), 1.67-1.46 (m, 4H). Example 21 : rac-6-(2,6-Dichlorophenyl)-8-(3-methoxyprop-1-vn-1-yl)-2-((4-(piperidin-4-yl)- 3-(2,2,2-trifluoro-1-hvdroxyethyl)phenyl)amino)pyrido[4,3-dlpyrimidin-5(6H)-one

Intermediate D (100 mg, 0.246 mmol) was reacted with rac-te/f-butyl 4-(4-amino-2-(2,2,2- trifluoro-1-hydroxyethyl)phenyl)piperidine-1-carboxylate (obtained as described in Example 18, Step 3) according to General Procedure E, yielding the title compound as an off-white solid (67 mg, 43 %).

LCMS (Method B): R_T = 0.97 min, m/z = 632, 634, 636 [M+H]⁺.

1 H NMR (500 MHz, DMSO-cfe) δ 10.52 (s, 1 H), 9.17 (s, 1 H), 8.59 (s, 1 H), 8.29 (s, 1 H), 7.80 (d, 1 H), 7.74 (d, 2H), 7.63-7.57 (m, 1 H), 7.31 (d, 1 H), 6.74 (d, 1 H), 5.42 (p, 1 H), 4.42 (s, 2H), 3.38 (s, 3H), 3.09-2.96 (m, 2H), 2.92-2.82 (m, 1 H), 2.70-2.51 (m, 3H), 1.71-1.58 (m, 2H), 1.58-1.42 (m, 2H). Example 22: 6-(2,6-Dichlorophenyl)-8-(3-methoxyprop-1-vn-1-yl)-2-((4-(piperidin-4-yl)-3- (2,2,2-trifluoroethyl)phenyl)amino)pyrido[4,3-dlpyrimidin-5(6H)-one

Intermediate D (100 mg, 0.246 mmol) was reacted with rac-te/f-butyl 4-(4-amino-2-(2,2,2- trifluoro-1-hydroxyethyl)phenyl)piperidine-1-carboxylate (obtained as described in Example 19, Step 2) according to General Procedure E, yielding the title compound as an off-white solid (66 mg, 43 %).

LCMS (Method B): R_T = 1.05 min, m/z = 616, 618, 620 [M+H]⁺. ¹H NMR (500 MHz, DMSO-cfe) δ 10.52 (s, 1H), 9.17 (s, 1H), 8.59 (s, 1H), 8.29 (s, 1H), 7.80 (d, 1H), 7.74 (d, 2H), 7.63-7.57 (m, 1H), 7.31 (d, 1H), 6.74 (d, 1H), 5.42 (p, 1H), 4.42 (s, 2H), 3.38 (s, 3H), 3.09-2.96 (m, 2H), 2.92-2.82 (m, 1H), 2.70-2.51 (m, 3H), 1.71-1.58 (m, 2H), 1.58-1.42 (m, 2H).

Example 23: 6-(2-Chloro-6-methylphenyl)-2-((3-methoxy-4-(piperazin-1-yl)phenyl)arriino)-5- oxo-5,6-dihvdropyrido[4,3-dlpyrimidine-8-carbonitrile

Intermediate E was reacted with tert-butyl 4-(4-amino-2-methoxyphenyl)piperazine-1- carboxylate according to General Procedure E yielding the title compound as a yellow solid.

LCMS (Method Enamine): R_T = 1.08 min, m/z = 502, 504 [M+H]⁺.

¹H NMR (400 MHz, CDCI₃) δ 9.2- 9.3 (s, br, 1H), 8.05-8.15 (s, br, 1H), 7.75 (d, 2H), 7.25- 7.45 (m, 3H), 6.8 - 6.95 (m, 2H), 3.9 - 4.1 (s, br, 3H), 3.0 - 3.2 (m, br, 8H), 2.2 (s, 3H).

Example 24: 6-(2-Chloro-6-fluorophenyl)-2-((3-methoxy-4-(piperazin-1-yl)phenyl)amino)-5- oxo-5,6-dihvdropyrido[4,3-dlpyrimidine-8-carbonitrile

Intermediate F was reacted with tert-butyl 4-(4-amino-2-methoxyphenyl)piperazine-1- carboxylate according to General Procedure E, yielding the title compound as an off-white solid.

LCMS (Method Enamine): R_T = 1.05 min, m/z = 506, 508 [M+H]⁺.

¹H NMR (400 MHz, CDCI₃) δ 10.5-10.7 (s, br, 1H), 9.2 (s, br, 1H), 8.95 (s, br, 1H), 7.9- 8.0 (s, br, 1H), 7.5-7.8 (m, br, 4H), 7.2-7.3 (m, br, 1H), 6.8-6.9 (m, br, 1H), 3.7-3.9 (s, br, 3H), 2.7-2.9 (m, br, 8H). Example 25: 6-(2-Chlorophenyl)-2-((3-methoxy-4-(piperazin-1-yl)phenyl)arriino)-5-oxo-5,6- dihvdropyrido[4,3-dlpyrimidine-8-carbonitrile

Intermediate G was reacted with tert-butyl 4-(4-amino-2-methoxyphenyl)piperazine-1- carboxylate according to General Procedure E, yielding the title compound as an off-white solid.

LCMS (Method Enamine): R_T = 1.04 min, m/z = 488, 490 [M+H]⁺.

1H NMR (400 MHz, CDCI₃) δ 10.4-10.7 (s, br, 1H), 9.1 - 9.2 (s, br, 1H), 8.6-8.8 (s, br, 1H), 7.7-8.1 (s, br, 1H), 7.5-7.9 (m, br, 5H), 7.2-7.3 (m, br, 1H), 6.8-6.9 (m, br, 1H), 3.8 - 4.0 (s, br, 3H), 2.7 - 3.0 (m, br, 8H).

Example 26: 6-(2-Chloro-6-methylphenyl)-2-((3-methyl-4-(piperidin-4-yl)phenyl)amino)-5- oxo-5,6-dihvdropyrido[4,3-dlpyrimidine-8-carbonitrile

Intermediate E was reacted with tert-butyl 4-(4-amino-2-methylphenyl)piperidine-1- carboxylate (Example 10, step 2) according to General Procedure E, yielding the title compound as an off-white solid.

LCMS (Method Enamine): R_T = 1.12 min, m/z = 485, 487 [M+H]⁺.

¹H NMR (400 MHz, CDCI₃) δ 10.5-10.7 (s, br, 1H), 9.2 (s, 1H), 8.85 (2, 1H), 8.05-8.2 (s, br, 1H), 7.4-7.75 (m, 4H), 7.1 -7.2 (m, 1H), 2.9-3.1 (m, 2H), 2.55-2.65 (m, br, 3H), 2.3 (s, br, 3H), 2.15 (s, br, 3H), 1.4-1.7 (m, 4H).

Example 27: 6-(2-Chloro-6-fluorophenyl)-2-((3-methyl-4-(piperidin-4-yl)phenyl)amino)-5- oxo-5,6-dihvdropyrido[4,3-dlpyrimidine-8-carbonitrile

Intermediate F was reacted with tert-Butyl 4-(4-amino-2-methylphenyl)piperidine-1- carboxylate (Example 10, step 2) according to General Procedure E, yielding the title compound as an off-white solid.

LCMS (Method Enamine): R_T = 1.09 min, m/z = 489, 491 [M+H]⁺.

¹ H NMR (400 MHz, CDCI₃) δ 10.5 - 10.8 (s, br, 1 H), 9.15 (s, 1 H), 8.95 (s, 1 H), 8.0 - 8.2 (s, br, 1 H), 7.5 - 7.7 (m, 4H), 7.1 - 7.2 (m, 1 H), 3.0 - 3.1 (m, 2H), 2.55 - 2.8 (m, br, 3H), 2.25 - 2.4 (s, br, 3H), 1.4 - 1.7 (m, 4H). Example 28: 6-(2,6-dichlorophenyl)-2-((3-(hvdroxymethyl)-4-(piperazin-1-yl)phenyl)amino)-

5-oxo-5,6-dihvdropyrido[4,3-dlpyrimidine-8-carbonitrile:

Step 1: tert-butyl 4-(4-((8-cyano-6-(2, 6-dichlorophenyl)-5-oxo-5, 6-dihydropyrido[4,3- d]pyrimidin-2-yl)amino)-2-(hydroxymethyl)phenyl)piperazine-1 -carboxylate:

Intermediate C (300 mg, 0.83 mmol) was suspended in DCM (15 mL) and mCPBA 77% (224 mg, 0.91 mmol) was added. The reaction mixture was stirred for 1 hr at RT. The reaction was washed with aqueous sodium thiosulfate solution (5 mL). The organic layer was separated through a Biotage phase separator and concentrated under reduced pressure. I PA (20 ml) and te/f-butyl 4-(4-amino-2-(hydroxymethyl)phenyl)piperazine-1- carboxylate (254 mg, 0.83 mmol) (prepared as described in WO2015092431 , example 10 step 1) was added to the sulfoxide- / sulfone mixture and the reaction mixture heated at 90°C overnight. The reaction mixture was concentrated and the residue purified by flash chromatography (Si0₂ gradient 20-60% ethyl acetate in cyclohexane) to afford the title compound (352 mg, 68 %).

LCMS (Method A): RT = 1.58 min, m/z = 622 / 624 [M+H]+. Step 2: 6-(2, 6-dichlorophenyl)-2-((3-(hydroxymethyl)-4-(piperazin- 1 -yl)phenyl)amino)-5-oxo- 5, 6-dihydropyrido[4, 3-d]pyrimidine-8-carbonitrile:

To a solution of te/f-butyl 4-[4-[[8-cyano-6-(2,6-dichlorophenyl)-5-oxo-pyrido[4,3- d]pyrirnidin-2-yl]arnino]-2-(hydroxymethyl)phenyl]piperazine-1-carboxylate (350 mg, 0.56 mmol) in dichloromethane (12ml_) was charged 4M HCI in 1 ,4-dioxane (1.7 ml_, 6.7 mmol) and the reaction was stirred at RT overnight. The precipitated solid was collected by filtration and washed with DCM. This was then loaded onto a pre-washed (25ml, 20% MeOH in DCM) SCX-2 cartridge and the column washed through with 20% MeOH in DCM (50 ml), the product was then eluted with 20% 7N NH3 in MeOH in DCM, affording the title compound (250mg, 85 %).

LCMS (Method A): R_T = 0.74 min, m/z = 522, 524 [M+H]+.

1 H NMR (500 MHz, d₆-DMSO) δ 10.46-10.79 (s, br. 1 H), 9.18 (s, 1 H), 8.95 (s, 1 H), 8.01- 8.23 (s, br. 1 H), 7.87-7.71 (m, 3H), 7.61-7.68 (m, 1 H), 7.03 (d, 1 H), 5.00-5.15 (s, br., 1 H), 4.57 (d, 2H), 2.81-2.92 (m, 4H), 2.70-2.81 (m, 4H).

Comparison of compounds of the present invention with those of the prior art and other compounds:

Table 1 : Comparison of Examples 13 and 24 of WO2014/167347 with

compounds of the present invention

Table 1 shows that compounds of the present invention show improved or comparable activity, comparable solubility and stability compared to those taught in WO 2014/167347. In particular, Example 9 shows that in the presence of the methyl-group on the pyridone- core the methoxy-group on the benzene results in an improved kinetic solubility compared to the methyl-analogue (example 8), whereas in the absence of the methyl-group on the pyridone, the kinetic solubility is similar (examples 13 and 14 of WO2014/167347

(comparative examples 1 and 2). Comparison of Example 13 of WO2014/167347 with compounds of the

Table 2 shows that exemplary compounds of the present invention display an enhanced Wee-1 kinase inhibitory effect (Wee-1 IC₅₀ value), an enhanced Wee-1 potency in cells (pCDC2 value), similar kinetic solubility (KSol value), and a similar stability in human microsomes (HLM), compared to Example 13 of WO 2014/167347. Table 3: Comparison of alkynyl analogues

Table 3 shows the importance of an alkoxy group as R³, a nitrogen atom as X, and a methoxymethylalkynyl group as R² in order for the compound to exhibit both good activity and good solubility. Table 4: Comparison of cyano-analogues

Table 4 shows the importance of an alkoxy group as R³, a nitrogen atom as X, and a cyano group as R² in order for the compound to exhibit both good activity and good solubility. Table 5: Examples 10 to 28

- 81 -

Table 5 shows the Wee-1 kinase inhibitory effect and Wee-1 potency in cells of Examples 10 to 28.

Claims

CLAIMS:

1.

(I)

or a pharmaceutically acceptable salt or /V-oxide derivative thereof, wherein:

R¹ is an optionally substituted aryl or heteroaryl group;

R² is an optionally substituted alkyi group, an alkynyl group optionally substituted by one or more alkyi groups and/or one or more alkoxy groups, or a cyano group; R³ is an optionally substituted alkyi group, a cycloalkyl group, an alkoxy group or a cycloalkoxy group;

R⁴ is a hydrogen atom, an alkyi group or a cycloalkyl group;

X is a nitrogen atom or a CH-group;

Y is a nitrogen atom or a CH-group;

Z is a nitrogen atom or a CH-group; and

n is 1 when X is a nitrogen atom and n is 0 or 1 when X is a CH-group.

2. The compound of claim 1 , or a pharmaceutically acceptable salt or /V-oxide derivati in R¹ is a group represented by the formula (b):

(b)

wherein R^1a and R^{1 b} are each independently selected from the group consisting of a hydrogen atom, a halo group, a hydroxyl group, a cyano group, an amino group, a C C₆ alkyi group, C₂-C₆ alkenyl group, a C C₆ alkoxy group and a C C₆ alkoxy-CrC₆ alkyi group.

3. The compound of any of the preceding claims, or a pharmaceutically acceptable salt or /V-oxide derivative thereof, wherein R¹ is a 2,6-dichlorophenyl group.

4. The compound of any of the preceding claims, or a pharmaceutically acceptable salt or /V-oxide derivative thereof, wherein R² is a methyl group, a methyl group substituted by one or more fluoro groups, an alkynyl group optionally substituted by one or more alkyl groups and/or one or more alkoxy groups, or a cyano group.

5. The compound of any of the preceding claims, or a pharmaceutically acceptable salt or /V-oxide derivative thereof, wherein R² is an alkynyl group optionally substituted by an alkoxy group.

6. The compound of any of the preceding claims, or a pharmaceutically acceptable salt or /V-oxide derivative thereof, wherein the alkynyl group is substituted by an alkoxy group.

7. The compound of any of the preceding claims, or a pharmaceutically acceptable salt or /V-oxide derivative thereof, wherein the alkynyl group is a C₂-C₃ alkynyl group.

8. The compound of claims 1 to 4, or a pharmaceutically acceptable salt or /V-oxide derivative thereof, wherein R² is a methyl group or a difluoromethyl group.

9. The compound of claims 1 to 4, or a pharmaceutically acceptable salt or /V-oxide derivative thereof, wherein R² is a methyl group.

10. The compound of claims 1 to 4, or a pharmaceutically acceptable salt or /V-oxide derivative thereof, wherein R² is a cyano group.

1 1. The compound of any of the preceding claims, or a pharmaceutically acceptable salt or /V-oxide derivative thereof, wherein R³ is an alkyl group, a cycloalkyl group, an alkoxy group or a cycloalkoxy group.

12. The compound of any of the preceding claims, or a pharmaceutically acceptable salt or /V-oxide derivative thereof, wherein R³ is an alkoxy group or a cycloalkoxy group.

13. The compound of any of the preceding claims, or a pharmaceutically acceptable salt or /V-oxide derivative thereof, wherein R³ is an alkoxy group.

14. The compound of any of the preceding claims, or a pharmaceutically acceptable salt or /V-oxide derivative thereof, wherein R³ is a methoxy group.

15. The compound of any of claims 1 to 10, or a pharmaceutically acceptable salt or N- oxide derivative thereof, wherein R³ is an optionally substituted alkyl group.

16. The compound of claim 15, wherein R³ is an unsubstituted alkyl group or an alkyl group substituted by a hydroxy group and/or one or more fluoro groups.

17. The compound of claim 15 or claim 16, wherein R³ is an unsubstituted methyl group or a methyl group substituted by a hydroxy group and/or a CF₃ group.

18. The compound of any of the preceding claims, or a pharmaceutically acceptable salt or /V-oxide derivative thereof, wherein R⁴ is a hydrogen atom or a methyl group.

19. The compound of any of the preceding claims, or a pharmaceutically acceptable salt or /V-oxide derivative thereof, wherein X is a nitrogen atom.

20. The compound of any of claims 1 to 18, or a pharmaceutically acceptable salt or N- oxide derivative thereof, wherein X is a CH-group.

21. The compound of any of the preceding claims, or a pharmaceutically acceptable salt or /V-oxide derivative thereof, wherein Y is a CH-group.

22. The compound of any of the preceding claims, or a pharmaceutically acceptable salt or /V-oxide derivative thereof, wherein Z is a CH-group.

23. The compound of any of the preceding claims, or a pharmaceutically acceptable salt or /V-oxide derivative thereof, wherein n is 1.

24. The compound of claim 20, or a pharmaceutically acceptable salt or /V-oxide derivative thereof, wherein n is 0.

25. The compound of claim 1 , or a pharmaceutically acceptable salt or /V-oxide derivative thereof, wherein the compound is selected from the following:

(3) 6-(2,6-Dichlorophenyl)-2-((3-methoxy-4-(piperazin-1-yl)phenyl)amino)-5-oxo-5,6- dihydropyrido[4,3-d]pyrimidine-8-carbonitrile;

(4) (f?)-6-(2,6-Dichlorophenyl)-2-((3-methoxy-4-(3-methylpiperazin-1-yl)phenyl)amino)- 5-0X0-5, 6-dihydropyrido[4,3-d]pyrimidine-8-carbonitrile;

(6) (f?)-6-(2,6-dichlorophenyl)-2-((3-methoxy-4-(3-methylpiperazin-1-yl)phenyl)amino)- 8-(3-methoxyprop-1-yn-1-yl)pyrido[4,3-d]pyrimidin-5(6H)-one;

26. The compound of claim 1 , or a pharmaceutically acceptable salt or /V-oxide derivative thereof, wherein the compound is selected from the following:

(13) rac-6-(2,6-Dichlorophenyl)-8-(3-methoxyprop-1-yn-1-yl)-2-((3-methyl-4-(pyrrolidin-3- yl)phenyl)amino)pyrido[4,3-d]pyrimidin-5(6H)-one; (14) rac-6-(2,6-Dichlorophenyl)-2-((3-methyl-4-(pyrrolidin-3-yl)phenyl)amino)-5-oxo-5,6- dihydropyrido[4,3-d]pyrimidine-8-carbonitrile;

(19) 6-(2,6-dichlorophenyl)-5-oxo-2-((4-(piperidin-4-yl)-3-(2,2,2-trifluoro-1- hydroxyethyl)phenyl)amino)-5,6-dihydropyrido[4,3-d]pyrimidine-8-carbonitrile;

(20) 6-(2,6-Dichlorophenyl)-5-oxo-2-((4-(piperidin-4-yl)-3-(2,2,2- trifluoroethyl)phenyl)amino)-5,6-dihydropyrido[4,3-d]pyrimidine-8-carbonitrile;

(28) 6-(2,6-dichlorophenyl)-2-((3-(hydroxymethyl)-4-(piperazin-1-yl)phenyl)amino)-5-oxo- 5,6-dihydropyrido[4,3-d]pyrimidine-8-carbonitrile.

27. The compound of any of claims 1 to 26, or a pharmaceutically acceptable salt or N- oxide derivative thereof, and at least one pharmaceutically acceptable excipient.

28. A pharmaceutical composition comprising the compound of any of claims 1 to 26, or a pharmaceutically acceptable salt or /V-oxide derivative thereof, and at least one pharmaceutically acceptable excipient.

29. The pharmaceutical composition of claim 28 comprising one or more further pharmaceutically active agents.

30. The compound of any of claims 1 to 26, or a pharmaceutically acceptable salt or N- oxide derivative thereof, or the pharmaceutical composition of claim 28 or claim 29, for use in therapy.

31. The compound of any of claims 1 to 26, or a pharmaceutically acceptable salt or N- oxide derivative thereof, or the pharmaceutical composition of claim 28 or claim 29, for use as a medicament.

32. The compound of any of claims 1 to 26, or a pharmaceutically acceptable salt or N- oxide derivative thereof, or the pharmaceutical composition of claim 28 or claim 29, for use in treating or preventing cancer.

33. Use of the compound as defined any of claims 1 to 26, or a pharmaceutically acceptable salt or /V-oxide derivative thereof, or the pharmaceutical composition of claim 28 or claim 29, for the manufacture of a medicament for treating or preventing cancer.

34. A method of treating or preventing cancer in a human or animal patient comprising administering to a patient in need thereof an effective amount of a compound according to any one of claims 1 to 26, or a pharmaceutically acceptable salt or /V-oxide derivative thereof, or the pharmaceutical composition of claim 28 or claim 29.