WO2025172707A1

WO2025172707A1 - Heterocyclic compounds modulating exonuclease 1 (exo1)

Info

Publication number: WO2025172707A1
Application number: PCT/GB2025/050273
Authority: WO
Inventors: Lars Burgdorf; Bernd Neff; Bruce Follows; Catherine Jorand-Lebrun; Christin RAKERS; Julien LEFRANC; Christoph GÖLDNER; Lizbeth Deselm; Roch Boivin; Xiaoling Chen; Owen Davis; Robert Heald; Samuel Mann
Original assignee: Merck Patent GmbH; Artios Pharma Ltd
Current assignee: Merck Patent GmbH; Artios Pharma Ltd
Priority date: 2024-02-13
Filing date: 2025-02-13
Publication date: 2025-08-21
Anticipated expiration: 2026-08-13

Abstract

The present invention relates to compounds of formula (I) and stereoisomers, tautomers, N-ox- ides, and pharmaceutically acceptable salts thereof that are useful for modulating exonuclease 1 (EXO1). The present invention further relates to the compounds of formula (I) for use as a medicament and to a pharmaceutical composition comprising said compounds.

Description

HETEROCYCLIC COMPOUNDS MODULATING EXONUCLEASE 1 (EXO1 )

FIELD OF THE INVENTION

The present invention relates to compounds of formula (I), and stereoisomers, tautomers, N-ox- ides, or pharmaceutically acceptable salts thereof that are useful for modulating exonuclease 1 (EXO1). The present invention further relates to compounds of the formula (I) for use as a medicament and to pharmaceutical compositions comprising said compounds. Further, the present invention relates to compounds of formula (I) and pharmaceutical compositions comprising said compounds for use in the treatment of cancer, preferably a cancer selected from the group consisting of hepatocellular carcinoma (HCC), glioma, colon cancer/colorectal cancer, in particular nonpolyposis colorectal cancer (HNPCC), breast cancer, ovarian cancer, lung cancer, pancreatic cancer, gastric tract cancer, cancer of the small intestine, oral cancer, and cervical cancer.

BACKGROUND OF THE INVENTION

EXO1 participates in DNA replication and post-replication processes and DNA repair pathways, for example mismatch repair (MMR), translesion DNA synthesis (TLS), nucleotide excision repair (NER), double-strand break repair (DSBR), and checkpoint activation. Dysfunction of EXO1 could therefore lead to alterations in DNA repair processes, which in turn can lead to replication stress, genomic instability and consequently to the development of cancer.

The prognostic value and therapeutic potential of EXO1 in HCC has been confirmed and a correlation between overexpression of EXO1 and larger tumour size as well as a lower survival rate has been shown (Dai, Y., Tang, Z., Yang, Z., Zhang, L., Deng, Q., Zhang, X., Yu, Y., Liu, X., Zhu, J. (2018), EXO1 overexpression is associated with poor prognosis of hepatocellular carcinoma patients, Cell Cycle, 17(19-20), 2386-2397). Furthermore, EXO1 has been investigated as a biomarker for the treatment of breast cancer. It was shown that increased EXO1 expression is associated with carcinogenesis and poor prognosis in breast cancer. In addition, the study showed that breast cancer samples with high EXO1 expression were associated with cell cycle activation and inhibition of the myocardial contraction pathway (Liu, J., Zhang, J. (2021), Elevated EXO1 expression is associated with breast carcinogenesis and poor prognosis, Annals of Translational Medicine, 9(2)). Insufficient expression of EXO1 , FEN1 or DNA2 is shown to lead to deficiencies in 5'-flap processing capacity, which prevents Okazaki fragment ligation leading to potential deleterious effects. In most cases, short 5'-flaps are mainly cleaved by FEN1 , resulting in a DNA nick for ligation. As a backup for FEN1 , EXO1 also degrades a small percentage of such short 5'-flaps (Sun, H., Ma, L., Tsai, Y. F., Abeywardana, T., Shen, B., Zheng, L. (2023), Okazaki fragment maturation: DNA flap dynamics for cell proliferation and survival, Trends in Cell Biology, 33(3), 221-234). EXO1 has proven to be an important protein in cancer research and is being investigated as a candidate gene for cancer therapies due to its increased expression in various tumours (Keijzers, G., Bakula, D., Petr, M. A., Madsen, N. G.

K., Teklu, A., Mkrtchyan, G., Osborne, B., Scheibye-Knudsen, M. (2018), Human exonuclease 1 (EXO1) regulatory functions in DNA replication with putative roles in cancer, International journal of molecular sciences, 20(1), 74).

Therefore, EXO1 is considered to be an important therapeutic target for cancer treatment I oncology drug discovery. In other words, compounds modulating EXO1 may be useful for treating cancer, preferably a cancer selected from hepatocellular carcinoma (HCC), glioma, colon cancer/colorectal cancer, in particular nonpolyposis colorectal cancer (HNPCC), breast cancer, ovarian cancer, lung cancer, pancreatic cancer, gastric tract cancer, cancer of the small intestine, oral cancer, and cervical cancer.

OBJECTS AND SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide compounds that modulate EXO1 , in particular inhibit EXO1. In particular, it is an object to provide compounds that inhibit EXO1 with high activity. It is another object of the present invention to provide compounds, which are suitable for use in the treatment of one or more diseases, in which the modulation, in particular the inhibition, of EX01 is beneficial. It is another object of the present invention to provide compounds, which are suitable for use as a medicament. It is yet another object to provide compounds, which are suitable for the use in the treatment of cancer.

The above objects can be achieved by the compounds of formula (I) as defined herein (including stereoisomers, tautomers, /V-oxides, or pharmaceutically acceptable salts thereof) as well as pharmaceutical compositions comprising the same, and by the medical uses thereof. The inventors of the present invention inter alia surprisingly found that the compounds of formula (I) as defined herein act as modulators of EX01 , in particular that they inhibit EX01 .

Accordingly, the compounds of formula (I) (including stereoisomers, tautomers, /V-oxides, or pharmaceutically acceptable salts thereof) as well as the pharmaceutical compositions comprising the same can be used as a medicament, in particular for the treatment of cancer, wherein the treatment preferably involves the administration of the compound of formula (I) as modulators of EX01 in an effective amount to individuals in need of such treatment.

Various aspects of the invention are detailed in this document, including compounds represented by formula (I) as well as stereoisomers, tautomers, /V-oxides, and pharmaceutically acceptable salts thereof.

In a first aspect, the present invention therefore relates to a compound of formula (I) or a stereoisomer, tautomer, N-oxide, or pharmaceutically acceptable salt thereof, wherein

R¹ is phenyl, a 5- or 6-membered aromatic heterocyclyl, or an 8- to 10-membered aromatic carbobicyclyl or heterobicyclyl, wherein the aforementioned heterocyclic and heterobicy- clic rings comprise one or more, same or different heteroatoms selected from O, N, or S, wherein said N- and/or S-atoms are independently oxidized or non-oxidized, and wherein each of the aforementioned aromatic rings is independently unsubstituted or substituted with one or more, same or different, substituents R^x;

R² is Ci-C4-alkyl, phenyl, or a 5- or 6-membered aromatic heterocyclyl, wherein the aforementioned heterocyclic ring comprises one or more, same or different heteroatoms selected from O, N, or S, wherein said N- and/or S-atoms are independently oxidized or non-oxidized, and wherein each of the aforementioned aromatic rings is independently unsubstituted or substituted with one or more, same or different, substituents R^Y1; or R² and R^x, if present, together with the atoms by which they are connected form a fused 5- to 7-membered partially unsaturated carbocyclyl or heterocyclyl, wherein the aforementioned heterocyclic ring comprises one or more, same or different heteroatoms selected from O, N, or S, wherein said N- and/or S-atoms are independently oxidized or non-oxidized, and wherein each substitutable atom in the aforementioned partially unsaturated rings is independently unsubstituted or substituted with one or more, same or different substituents R^Y2;

R³ is a 5- or 6-membered aromatic carbocyclyl, carbocyclyl-Ci-C2-alkyl, heterocyclyl, or het- erocyclyl-Ci-C2-alkyl, or an 8- to 10-membered aromatic carbobicyclyl, carbobicyclyl-Ci- C2-alkyl, heterobicyclyl, or heterobicyclyl-Ci-C2-alkyl, wherein the aforementioned heterocyclic and heterobicyclic rings independently comprise one or more, same or different heteroatoms selected from O, N, or S, wherein said N- and/or S-atoms are independently oxidized or non-oxidized, and wherein each of the aforementioned aromatic rings is independently unsubstituted or substituted with one or more, same or different, substituents R^z;

R⁴ is H or Ci-C4-alkyl; and

R⁵ is H, Ci-C₄-alkyl, Ci-C₄-alkoxy, or C(=O)NR^N1R^N2; and wherein

R^x is halogen or Ci-C₄-alkyl;

R^Y1 is halogen or Ci-C₄-alkyl;

R^Y2 is halogen or Ci-C₄-alkyl;

R^z is halogen, Ci-C₄-alkyl, or Ci-C₄-haloalkyl;

R^N1 is H or Ci-C₄-alkyl; and

R^N2 is H or Ci-C₄-alkyl.

In one preferred embodiment, the compound is a compound of formula (IA):

In another preferred embodiment,

R¹ is phenyl, or a 9- or 10-membered aromatic carbobicyclyl or heterobicyclyl, wherein the aforementioned heterocyclic and heterobicyclic rings comprise one or more, same or different heteroatoms selected from O, N, or S, wherein said N- and/or S-atoms are independently oxidized or non-oxidized, and wherein each of the aforementioned aromatic rings is independently unsubstituted or substituted with one or more, same or different, substituents R^x.

In a more preferred embodiment,

R¹ is phenyl, or a 9- or 10-membered aromatic carbobicyclyl or heterobicyclyl, wherein the aforementioned heterocyclic and heterobicyclic rings comprise one or more, same or different heteroatoms selected from O, N, or S, wherein said N- and/or S-atoms are independently oxidized or non-oxidized, and wherein each of the aforementioned aromatic rings is independently unsubstituted or substituted with one or more, same or different, substituents R^x; and

R^x is halogen or Ci-C2-alkyl.

In an even more preferred embodiment,

R¹ is phenyl, wherein said phenyl is unsubstituted or substituted with one or more, same or different substituents R^x.

In an especially preferred embodiment,

R¹ is phenyl, wherein said phenyl is unsubstituted or substituted with one or more, same or different substituents R^x; and

R^x is Cl or F.

In another preferred embodiment,

R² is methyl, ethyl, or phenyl; or R² and R^x, if present, together with the atoms by which they are connected form a fused 6- membered partially unsaturated carbocyclyl.

In a more preferred embodiment,

R² is methyl; or R² and R^x, if present, together with the atoms by which they are connected form a fused 6- membered partially unsaturated carbocyclyl.

In an even more preferred embodiment,

R² is methyl.

In another preferred embodiment,

R³ is a 6-membered aromatic carbocyclyl, carbocyclyl-Ci-alkyl, heterocyclyl, heterocyclyl- Ci-alkyl, or an 9- or 10-membered aromatic carbobicyclyl or heterobicyclyl, wherein the aforementioned heterocyclic and heterobicyclic rings independently comprise one or more, same or different heteroatoms selected from O, N, or S, wherein said N- and/or S- atoms are independently oxidized or non-oxidized, and wherein each of the aforementioned aromatic rings is independently unsubstituted or substituted with one or more, same or different, substituents R^z; wherein preferably

R^z is halogen, Ci-C2-alkyl, or Ci-C2-haloalkyl.

In another preferred embodiment,

R^z is F, CH₃, or CF₃.

In another preferred embodiment,

R⁴ is H or CH₃.

In a more preferred embodiment,

R⁴ is H.

In another preferred embodiment,

R⁵ is H or CH₃.

In a more preferred embodiment,

R⁵ is H.

In another preferred embodiment, the compound is a compound of formula (IA-1):

In yet another preferred embodiment, the compound is a compound of formula (IA-2):

In another preferred embodiment, the compound according to formula (I) is selected from the group consisting of:

4-hydroxy-8-phenyl-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine-3,5-di- one;

(8R)-4-hydroxy-8-phenyl-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine-3,5- dione;

(8S)-4-hydroxy-8-phenyl-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine-3,5- dione;

8-benzyl-4-hydroxy-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine-3,5-di- one;

(8S)-8-benzyl-4-hydroxy-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine-3,5- dione;

(8R)-8-benzyl-4-hydroxy-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine-3,5- dione;

4-hydroxy-6-[(1S)-1-phenylethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine-3,5- dione;

(8R)-4-hydroxy-6-[(1S)-1-phenylethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyridazino[1,6-a]pyra- zine-3, 5-dione;

(8S)-4-hydroxy-6-[(1S)-1-phenylethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyridazino[1,6-a]pyra- zine-3, 5-dione;

4-hydroxy-6-[(1S)-1-phenylethyl]-8-[6-(trifluoromethyl)pyridin-3-yl]-3H,5H,6H,7H,8H-pyri- dazino[1,6-a]pyrazine-3, 5-dione;

(8S)-4-hydroxy-6-[(1S)-1-phenylethyl]-8-[6-(trifluoromethyl)pyridin-3-yl]-3H,5H,6H,7H,8H-pyri- dazino[1,6-a]pyrazine-3, 5-dione;

(8R)-4-hydroxy-6-[(1S)-1-phenylethyl]-8-[6-(trifluoromethyl)pyridin-3-yl]-3H,5H,6H,7H,8H-pyri- dazino[1,6-a]pyrazine-3, 5-dione;

4-hydroxy-8-(isoquinolin-8-yl)-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1,6-a]pyra- zine-3, 5-dione;

(8S)-4-hydroxy-8-(isoquinolin-8-yl)-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1,6-a]py- razine-3, 5-dione;

(8R)-4-hydroxy-8-(isoquinolin-8-yl)-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1,6-a]py- razine-3, 5-dione;

6-[(1S)-1-(3-chlorophenyl)ethyl]-4-hydroxy-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyridazino[1,6-a]py- razine-3, 5-dione;

(8R)-6-[(1S)-1-(3-chlorophenyl)ethyl]-4-hydroxy-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyridazino[1,6- a]pyrazine-3, 5-dione;

(8S)-6-[(1S)-1-(3-chlorophenyl)ethyl]-4-hydroxy-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyridazino[1,6- a]pyrazine-3, 5-dione;

4-hydroxy-6-[(1S)-1-phenylethyl]-8-[(pyridin-3-yl)methyl]-3H,5H,6H,7H,8H-pyridazino[1,6-a]pyra- zine-3, 5-dione;

4-hydroxy-8-(1-methyl-1 H-indazol-4-yl)-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1,6- a]pyrazine-3, 5-dione;

(8S)-4-hydroxy-8-(1-methyl-1 H-indazol-4-yl)-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyri- dazino[1,6-a]pyrazine-3, 5-dione;

(8R)-4-hydroxy-8-(1-methyl-1 H-indazol-4-yl)-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyri- dazino[1,6-a]pyrazine-3, 5-dione;

8-(4-fluorophenyl)-4-hydroxy-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine- 3, 5-dione; (8S)-8-(4-fluorophenyl)-4-hydroxy-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1,6-a]py- razine-3, 5-dione;

(8R)-8-(4-fluorophenyl)-4-hydroxy-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1,6-a]py- razine-3, 5-dione;

4-hydroxy-8-methyl-6-[(1S)-1-phenylethyl]-8-[5-(trifluoromethyl)pyridin-2-yl]-3H,5H,6H,7H,8H- pyridazino[1,6-a]pyrazine-3, 5-dione;

(8R)-4-hydroxy-8-methyl-6-[(1S)-1-phenylethyl]-8-[5-(trifluoromethyl)pyridin-2-yl]-

3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine-3, 5-dione;

(8S)-4-hydroxy-8-methyl-6-[(1S)-1-phenylethyl]-8-[5-(trifluoromethyl)pyridin-2-yl]-

3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine-3, 5-dione;

6-[(1S)-1-(3-chlorophenyl)ethyl]-4-hydroxy-8-[6-(trifluoromethyl)pyridin-3-yl]-3H,5H,6H,7H,8H- pyridazino[1,6-a]pyrazine-3, 5-dione;

(8S)-6-[(1S)-1-(3-chlorophenyl)ethyl]-4-hydroxy-8-[6-(trifluoromethyl)pyridin-3-yl]-

3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine-3, 5-dione;

(8R)-6-[(1S)-1-(3-chlorophenyl)ethyl]-4-hydroxy-8-[6-(trifluoromethyl)pyridin-3-yl]-

3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine-3, 5-dione;

4-hydroxy-6-[(1S)-1 ,2,3,4-tetrahydronaphthalen-1-yl]-8-[6-(trifluoromethyl)pyridin-3-yl]-

3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine-3, 5-dione;

(8S)-4-hydroxy-6-[(1S)-1 ,2,3,4-tetrahydronaphthalen-1-yl]-8-[6-(trifluoromethyl)pyridin-3-yl]-

3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine-3, 5-dione;

(8R)-4-hydroxy-6-[(1S)-1,2,3,4-tetrahydronaphthalen-1-yl]-8-[6-(trifluoromethyl)pyridin-3-yl]-

3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine-3, 5-dione;

4-hydroxy-6-[(1S)-1-(naphthalen-1-yl)ethyl]-8-[6-(trifluoromethyl)pyridin-3-yl]-3H,5H,6H,7H,8H- pyridazino[1,6-a]pyrazine-3, 5-dione;

4-hydroxy-6-[(1S)-1-(naphthalen-2-yl)ethyl]-8-[6-(trifluoromethyl)pyridin-3-yl]-3H,5H,6H,7H,8H- pyridazino[1,6-a]pyrazine-3, 5-dione;

(8S)-4-hydroxy-6-[(1S)-1-(naphthalen-2-yl)ethyl]-8-[6-(trifluoromethyl)pyridin-3-yl]-

3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine-3, 5-dione;

(8R)-4-hydroxy-6-[(1S)-1-(naphthalen-2-yl)ethyl]-8-[6-(trifluoromethyl)pyridin-3-yl]-

3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine-3, 5-dione;

4-hydroxy-6-[(1S)-1-(1-methyl-1 H-indazol-6-yl)ethyl]-8-[6-(trifluoromethyl)pyridin-3-yl]-

3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine-3, 5-dione;

(8S)-4-hydroxy-6-[(1S)-1-(1-methyl-1 H-indazol-6-yl)ethyl]-8-[6-(trifluoromethyl)pyridin-3-yl]-

3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine-3, 5-dione;

(8R)-4-hydroxy-6-[(1S)-1-(1-methyl-1 H-indazol-6-yl)ethyl]-8-[6-(trifluoromethyl)pyridin-3-yl]-

3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine-3, 5-dione;

4-hydroxy-8-(1-methyl-1 H-indazol-4-yl)-6-[(1S)-1,2,3,4-tetrahydronaphthalen-1-yl]-

3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine-3, 5-dione;

(8S)-4-hydroxy-8-(1-methyl-1 H-indazol-4-yl)-6-[(1S)-1 ,2,3,4-tetrahydronaphthalen-1-yl]-

3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine-3, 5-dione;

4-hydroxy-8-(1-methyl-1 H-indazol-3-yl)-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1,6- a]pyrazine-3, 5-dione;

(8R)-4-hydroxy-8-(1-methyl-1 H-indazol-3-yl)-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyri- dazino[1,6-a]pyrazine-3, 5-dione;

(8S)-4-hydroxy-8-(1-methyl-1 H-indazol-3-yl)-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyri- dazino[1,6-a]pyrazine-3, 5-dione;

6-[(1S)-1-(4-fluorophenyl)ethyl]-4-hydroxy-8-(1-methyl-1 H-indazol-4-yl)-3H,5H,6H,7H,8H-pyri- dazino[1,6-a]pyrazine-3, 5-dione;

(8R)-6-[(1S)-1-(4-fluorophenyl)ethyl]-4-hydroxy-8-(1-methyl-1 H-indazol-4-yl)-3H,5H,6H,7H,8H- pyridazino[1,6-a]pyrazine-3, 5-dione;

(8S)-6-[(1S)-1-(4-fluorophenyl)ethyl]-4-hydroxy-8-(1-methyl-1 H-indazol-4-yl)-3H,5H,6H,7H,8H- pyridazino[1,6-a]pyrazine-3, 5-dione;

4-hydroxy-6-[(1S)-1-(1-methyl-1 H-indazol-5-yl)ethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyri- dazino[1,6-a]pyrazine-3,5-dione;(8R)-4-hydroxy-6-[(1S)-1-(1-methyl-1 H-indazol-5-yl)ethyl]-8- (pyridin-2-yl)-3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine-3, 5-dione; (8S)-4-hydroxy-6-[(1S)-1-(1-methyl-1 H-indazol-5-yl)ethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyri- dazino[1 ,6-a]pyrazine-3, 5-dione;

4-hydroxy-8-(1-methyl-1 H-indazol-4-yl)-6-[(1S)-1-phenylpropyl]-3H,5H,6H,7H,8H-pyridazino[1 ,6- a]pyrazine-3, 5-dione;

(8S)-4-hydroxy-8-(1-methyl-1 H-indazol-4-yl)-6-[(1S)-1-phenylpropyl]-3H,5H,6H,7H,8H-pyri- dazino[1 ,6-a]pyrazine-3, 5-dione;

(8R)-4-hydroxy-8-(1-methyl-1 H-indazol-4-yl)-6-[(1S)-1-phenylpropyl]-3H,5H,6H,7H,8H-pyri- dazino[1 ,6-a]pyrazine-3, 5-dione;

4-hydroxy-2-methyl-6-[(1S)-1-phenylethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyridazino[1 ,6-a]py- razine-3, 5-dione;

(8R)-4-hydroxy-2-methyl-6-[(1S)-1-phenylethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyridazino[1 ,6- a]pyrazine-3, 5-dione;

(8S)-4-hydroxy-2-methyl-6-[(1S)-1-phenylethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyridazino[1 ,6- a]pyrazine-3, 5-dione;

6-(diphenylmethyl)-4-hydroxy-8-(1-methyl-1 H-indazol-4-yl)-3H,5H,6H,7H,8H-pyridazino[1 ,6- a]pyrazine-3, 5-dione; and (8R)-4-hydroxy-8-(1-methyl-1 H-indazol-4-yl)-6-[(1S)-1 ,2,3,4-tetrahydronaphthalen-1-yl]- 3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3, 5-dione.

In a further aspect, the present invention relates to a pharmaceutical composition comprising a pharmaceutically effective amount of the compound of formula (I) as defined herein, and optionally a pharmaceutically acceptable carrier, diluent or excipient.

In yet another aspect, the present invention relates to a compound of formula (I) as defined herein or a pharmaceutical composition as defined herein for use in medicine.

In yet another aspect, the present invention relates to a compound of formula (I) as defined herein or a pharmaceutical composition as defined herein for use in the treatment of cancer, preferably for use in the treatment of a cancer selected from hepatocellular carcinoma (HCC), glioma, colon cancer/colorectal cancer, in particular nonpolyposis colorectal cancer (HNPCC), breast cancer, ovarian cancer, lung cancer, pancreatic cancer, gastric tract cancer, cancer of the small intestine, oral cancer, and cervical cancer.

DETAILED DESCRIPTION OF THE INVENTION

In the following disclosure, preferred embodiments of the substituents in the above formula (I) are described in further detail. It is to be understood that each preferred embodiment is relevant on its own as well as in combination with other preferred embodiments. Furthermore, it is to be understood that the preferred embodiments in each case also apply to the stereoisomers, tautomers, /V-oxides, or pharmaceutically acceptable salts of the compounds of the invention.

As indicated above, the present invention relates to a compound of formula (I) or a stereoisomer, tautomer, N-oxide, or pharmaceutically acceptable salt thereof, wherein

R² is Ci-C4-alkyl, phenyl, or a 5- or 6-membered aromatic heterocyclyl, wherein the aforementioned heterocyclic ring comprises one or more, same or different heteroatoms selected from O, N, or S, wherein said N- and/or S-atoms are independently oxidized or non-oxidized, and wherein each of the aforementioned aromatic rings is independently unsubstituted or substituted with one or more, same or different, substituents R^Y1; or R² and R^x, if present, together with the atoms by which they are connected form a fused 5- to 7-membered partially unsaturated carbocyclyl or heterocyclyl, wherein the aforementioned heterocyclic ring comprises one or more, same or different heteroatoms selected from O, N, or S, wherein said N- and/or S-atoms are independently oxidized or non-oxi- dized, and wherein each substitutable atom in the aforementioned partially unsaturated rings is independently unsubstituted or substituted with one or more, same or different substituents R^Y2;

R⁴ is H or Ci-C4-alkyl; and

R⁵ is H, Ci-C₄-alkyl, Ci-C₄-alkoxy, or C(=O)NR^N1R^N2; and wherein

R^x is halogen or Ci-C4-alkyl;

R^Y1 is halogen or Ci-C4-alkyl;

R^Y2 is halogen or Ci-C4-alkyl;

R^z is halogen, Ci-C4-alkyl, or Ci-C4-haloalkyl;

R^N1 is H or Ci-C4-alkyl; and

R^N2 is H or Ci-C4-alkyl.

In one preferred embodiment, the compound is a compound of formula (IA):

Depending on the configuration of the chiral carbon atom of the 6-membered ring, the compound of formula (IA) may be a compound of formula (IA-1) or (IA-2):

In one preferred embodiment, the compound of formula (I) is a compound of formula (IA-1). In another preferred embodiment, the compound of formula (I) is a compound of formula (IA-2).

In connection with the compounds of formula (I) and in particular in connection with the compounds of formula (IA), (IA-1) or (IA-2), the substituents R¹, R², R³, R⁴, and R⁵ as well as R^x, R^Y1, R^Y2, R^z, R^N1, and R^N2 are defined as follows: In one embodiment,

R¹ is phenyl, a 5- or 6-membered aromatic heterocyclyl, or an 8- to 10-membered aromatic carbobicyclyl or heterobicyclyl, wherein the aforementioned heterocyclic and heterobicy- clic rings comprise one or more, same or different heteroatoms selected from O, N, or S, wherein said N- and/or S-atoms are independently oxidized or non-oxidized, and wherein each of the aforementioned aromatic rings is independently unsubstituted or substituted with one or more, same or different, substituents R^x.

In a more preferred embodiment,

R¹ is phenyl, or a 9- or 10-membered aromatic carbobicyclyl or heterobicyclyl, wherein the aforementioned heterocyclic and heterobicyclic rings comprise one or more, same or different heteroatoms selected from O, N, or S, wherein said N- and/or S-atoms are independently oxidized or non-oxidized, and wherein each of the aforementioned aromatic rings is independently unsubstituted or substituted with one or more, same or different, substituents R^x; wherein

R^x is halogen or Ci-C2-alkyl.

In an even more preferred embodiment,

R^x is Cl, F, or CH₃.

In an even more preferred embodiment,

R¹ is selected from the group consisting of wherein the wavy line in each case marks the connection to the remainder of the molecule.

In an even more preferred embodiment,

R¹ is phenyl, wherein said phenyl is unsubstituted or substituted with one or more, same or different substituents R^x; and wherein preferably

R^x is Cl or F.

In one particularly preferred embodiment,

R¹ is phenyl, wherein said phenyl is substituted with one substituent R^x wherein the wavy line marks the connection to the remainder of the molecule.

In another particularly preferred embodiment,

R¹ is unsubstituted phenyl.

Thus, in one particularly preferred embodiment of the compounds of formula (I) and in particular of the compounds of formula (IA), (IA-1) or (IA-2),

R¹ is phenyl, wherein said phenyl is unsubstituted or substituted with one substituent R^x.

In this connection, it is preferred that R^x is Cl or F.

In one embodiment,

R² is Ci-C4-alkyl, phenyl, or a 5- or 6-membered aromatic heterocyclyl, wherein the aforementioned heterocyclic ring comprises one or more, same or different heteroatoms selected from O, N, or S, wherein said N- and/or S-atoms are independently oxidized or non-oxidized, and wherein each of the aforementioned aromatic rings is independently unsubstituted or substituted with one or more, same or different, substituents R^Y1; or R² and R^x, if present, together with the atoms by which they are connected form a fused 5- to 7-membered partially unsaturated carbocyclyl or heterocyclyl, wherein the aforementioned heterocyclic ring comprises one or more, same or different heteroatoms selected from O, N, or S, wherein said N- and/or S-atoms are independently oxidized or non-oxi- dized, and wherein each substitutable atom in the aforementioned partially unsaturated rings is independently unsubstituted or substituted with one or more, same or different substituents R^Y2.

In this connection, the following definitions of R^Y1 and R^Y2 apply:

In one embodiment,

R^Y1 is halogen or Ci-C4-alkyl; and

R^Y2 is halogen or Ci-C4-alkyl.

In a preferred embodiment,

R^Y1 is Cl, F, or CH₃; and

R^Y2 is Cl, F, or CH₃;.

In a preferred embodiment,

The embodiment that R² and R^x together with the atoms by which they are connected form a fused 6-membered partially unsaturated carbocyclyl is preferred in connection with the embodiment that R¹ is phenyl substituted with one substituent R^x. Said R^x then together with R² and together with the atoms by which R² and R^x are connected then forms the 6-membered partially unsaturated carbocylclyl. The resulting moiety -CHR¹R² thus preferably has the following structure:

The partial unsaturation of the 6-membered carbocyclyl that is formed by R² and R^x together with the atoms by which they are connected thus stems from the phenyl ring representing R¹.

In an even more preferred embodiment,

R² is methyl; or R² and R^x, if present, together with the atoms by which they are connected form a fused 6- membered partially unsaturated carbocyclyl;

In a particularly preferred embodiment,

R² is methyl.

Thus, in one particularly preferred embodiment of the compounds of formula (I) and in particular of the compounds of formula (IA), (IA-1) or (IA-2), R² is methyl.

In one embodiment,

R³ is a 5- or 6-membered aromatic carbocyclyl, carbocyclyl-Ci-C2-alkyl, heterocyclyl, or het- erocyclyl-Ci-C2-alkyl, or an 8- to 10-membered aromatic carbobicyclyl, carbobicyclyl-Ci- C2-alkyl, heterobicyclyl, or heterobicyclyl-Ci-C2-alkyl, wherein the aforementioned heterocyclic and heterobicyclic rings independently comprise one or more, same or different heteroatoms selected from O, N, or S, wherein said N- and/or S-atoms are independently oxidized or non-oxidized, and wherein each of the aforementioned aromatic rings is independently unsubstituted or substituted with one or more, same or different, substituents R^z.

In a preferred embodiment,

R³ is a 6-membered aromatic carbocyclyl, carbocyclyl-Ci-alkyl, heterocyclyl, heterocyclyl- Ci-alkyl, or an 9- or 10-membered aromatic carbobicyclyl or heterobicyclyl, wherein the aforementioned heterocyclic and heterobicyclic rings independently comprise one or more, same or different heteroatoms selected from O, N, or S, wherein said N- and/or S- atoms are independently oxidized or non-oxidized, and wherein each of the aforementioned aromatic rings is independently unsubstituted or substituted with one or more, same or different, substituents R^z.

In this connection, the following definitions of R^z apply:

In one embodiment,

R^z is halogen, Ci-C4-alkyl, or Ci-C4-haloalkyl.

In a preferred embodiment,

R^z is halogen, Ci-C2-alkyl, or Ci-C2-haloalkyl.

In a more preferred embodiment,

R^z is F, CH₃, or CF₃.

R³ is a 6-membered aromatic carbocyclyl, carbocyclyl-Ci-alkyl, heterocyclyl, heterocyclyl-Ci- alkyl, or an 9- or 10-membered aromatic carbobicyclyl or heterobicyclyl, wherein the aforementioned heterocyclic and heterobicyclic rings independently comprise one or more, same or different heteroatoms selected from O, N, or S, wherein said N- and/or S-atoms are independently oxidized or non-oxidized, and wherein each of the aforementioned aromatic rings is independently unsubstituted or substituted with one or more, same or different, substituents R^z; wherein preferably

R^z is F, CH₃, or CF₃.

In one embodiment,

R⁴ is H or Ci-C4-alkyl.

In a preferred embodiment,

R⁴ is H or CH₃.

In a more preferred embodiment,

R⁴ is H.

Thus, in one particularly preferred embodiment of the compounds of formula (I) and in particular of the compounds of formula (IA), (IA-1) or (IA-2), R⁴ is H.

In one embodiment,

R⁵ is H, Ci-C4-alkyl, Ci-C4-alkoxy, or C(=O)NR^N1R^N2; wherein

R^N1 is H or Ci-C4-alkyl; and

R^N2 is H or Ci-C4-alkyl.

In a preferred embodiment,

R⁵ is H or CH₃.

In a more preferred embodiment,

R⁵ is H.

Thus, in one particularly preferred embodiment of the compounds of formula (I) and in particular of the compounds of formula (IA), (IA-1) or (IA-2), R⁵ is H.

In one embodiment, the compound according to formula (I) is selected from the group consisting of: 4-hydroxy-8-phenyl-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3,5-di- one; (8R)-4-hydroxy-8-phenyl-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine-3,5- dione;

8-(4-fluorophenyl)-4-hydroxy-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine-

3,5-dione;

(8S)-8-(4-fluorophenyl)-4-hydroxy-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1,6-a]py- razine-3, 5-dione;

3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine-3, 5-dione;

6-[(1S)-1-(3-chlorophenyl)ethyl]-4-hydroxy-8-[6-(trifluoromethyl)pyridin-3-yl]-3H,5H,6H,7H,8H- pyridazino[1,6-a]pyrazine-3, 5-dione; (8S)-6-[(1S)-1-(3-chlorophenyl)ethyl]-4-hydroxy-8-[6-(trifluoromethyl)pyridin-3-yl]-

3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine-3, 5-dione;

4-hydroxy-6-[(1S)-1-(1-methyl-1 H-indazol-5-yl)ethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyri- dazino[1,6-a]pyrazine-3,5-dione;(8R)-4-hydroxy-6-[(1S)-1-(1-methyl-1 H-indazol-5-yl)ethyl]-8- (pyridin-2-yl)-3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine-3, 5-dione;

(8S)-4-hydroxy-6-[(1S)-1-(1-methyl-1 H-indazol-5-yl)ethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyri- dazino[1,6-a]pyrazine-3, 5-dione;

4-hydroxy-8-(1-methyl-1 H-indazol-4-yl)-6-[(1S)-1-phenylpropyl]-3H,5H,6H,7H,8H-pyridazino[1,6- a]pyrazine-3, 5-dione;

(8S)-4-hydroxy-8-(1-methyl-1 H-indazol-4-yl)-6-[(1S)-1-phenylpropyl]-3H,5H,6H,7H,8H-pyri- dazino[1,6-a]pyrazine-3, 5-dione;

(8R)-4-hydroxy-8-(1-methyl-1 H-indazol-4-yl)-6-[(1S)-1-phenylpropyl]-3H,5H,6H,7H,8H-pyri- dazino[1,6-a]pyrazine-3, 5-dione;

4-hydroxy-2-methyl-6-[(1S)-1-phenylethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyridazino[1,6-a]py- razine-3, 5-dione;

(8R)-4-hydroxy-2-methyl-6-[(1S)-1-phenylethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyridazino[1,6- a]pyrazine-3, 5-dione; (8S)-4-hydroxy-2-methyl-6-[(1 S)-1 -phenylethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyridazino[1 ,6- a]pyrazine-3, 5-dione;

In one preferred embodiment, the compound according to formula (I) is selected from the group consisting of:

(8R)-4-hydroxy-8-phenyl-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3,5- dione;

(8R)-8-benzyl-4-hydroxy-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3,5- dione;

(8R)-4-hydroxy-6-[(1S)-1-phenylethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyra- zine-3, 5-dione;

(8R)-4-hydroxy-6-[(1S)-1-phenylethyl]-8-[6-(trifluoromethyl)pyridin-3-yl]-3H,5H,6H,7H,8H-pyri- dazino[1 ,6-a]pyrazine-3, 5-dione;

(8R)-4-hydroxy-8-(isoquinolin-8-yl)-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1 ,6-a]py- razine-3, 5-dione;

(8R)-6-[(1S)-1-(3-chlorophenyl)ethyl]-4-hydroxy-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyridazino[1 ,6- a]pyrazine-3, 5-dione;

(8R)-4-hydroxy-8-(1-methyl-1 H-indazol-4-yl)-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyri- dazino[1 ,6-a]pyrazine-3, 5-dione;

(8R)-8-(4-fluorophenyl)-4-hydroxy-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1 ,6-a]py- razine-3, 5-dione;

(8R)-4-hydroxy-8-methyl-6-[(1S)-1-phenylethyl]-8-[5-(trifluoromethyl)pyridin-2-yl]- 3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3, 5-dione;

3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3, 5-dione;

(8R)-4-hydroxy-6-[(1S)-1 ,2,3,4-tetrahydronaphthalen-1-yl]-8-[6-(trifluoromethyl)pyridin-3-yl]- 3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3, 5-dione;

3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3, 5-dione;

(8R)-4-hydroxy-6-[(1S)-1-(1-methyl-1 H-indazol-6-yl)ethyl]-8-[6-(trifluoromethyl)pyridin-3-yl]- 3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3, 5-dione;

(8R)-4-hydroxy-8-(1-methyl-1 H-indazol-3-yl)-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyri- dazino[1 ,6-a]pyrazine-3, 5-dione;

(8R)-6-[(1S)-1-(4-fluorophenyl)ethyl]-4-hydroxy-8-(1-methyl-1 H-indazol-4-yl)-3H,5H,6H,7H,8H- pyridazino[1 ,6-a]pyrazine-3, 5-dione;

(8R)-4-hydroxy-2-methyl-6-[(1S)-1-phenylethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyridazino[1 ,6- a]pyrazine-3, 5-dione; and

(8R)-4-hydroxy-8-(1-methyl-1 H-indazol-4-yl)-6-[(1S)-1 ,2,3,4-tetrahydronaphthalen-1-yl]- 3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3, 5-dione.

In another preferred embodiment, the compound according to formula (I) is selected from the group consisting of (8S)-4-hydroxy-8-phenyl-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3,5- dione;

(8S)-8-benzyl-4-hydroxy-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3,5- dione;

(8S)-4-hydroxy-6-[(1S)-1-phenylethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyra- zine-3, 5-dione;

(8S)-4-hydroxy-6-[(1S)-1-phenylethyl]-8-[6-(trifluoromethyl)pyridin-3-yl]-3H,5H,6H,7H,8H-pyri- dazino[1 ,6-a]pyrazine-3, 5-dione; (8S)-4-hydroxy-8-(isoquinolin-8-yl)-6-[(1 S)-1 -phenylethyl]-3H,5H,6H,7H ,8H-pyridazino[1 ,6-a]py- razine-3, 5-dione;

(8S)-6-[(1S)-1-(3-chlorophenyl)ethyl]-4-hydroxy-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyridazino[1 ,6- a]pyrazine-3, 5-dione;

(8S)-4-hydroxy-8-(1-methyl-1 H-indazol-4-yl)-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyri- dazino[1 ,6-a]pyrazine-3, 5-dione;

(8S)-8-(4-fluorophenyl)-4-hydroxy-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1 ,6-a]py- razine-3, 5-dione;

(8S)-4-hydroxy-8-methyl-6-[(1S)-1-phenylethyl]-8-[5-(trifluoromethyl)pyridin-2-yl]- 3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3, 5-dione;

(8S)-6-[(1S)-1-(3-chlorophenyl)ethyl]-4-hydroxy-8-[6-(trifluoromethyl)pyridin-3-yl]- 3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3, 5-dione;

(8S)-4-hydroxy-6-[(1S)-1 ,2,3,4-tetrahydronaphthalen-1-yl]-8-[6-(trifluoromethyl)pyridin-3-yl]- 3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3, 5-dione;

(8S)-4-hydroxy-6-[(1S)-1-(naphthalen-2-yl)ethyl]-8-[6-(trifluoromethyl)pyridin-3-yl]- 3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3, 5-dione;

(8S)-4-hydroxy-6-[(1S)-1-(1-methyl-1 H-indazol-6-yl)ethyl]-8-[6-(trifluoromethyl)pyridin-3-yl]- 3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3, 5-dione;

(8S)-4-hydroxy-8-(1-methyl-1 H-indazol-4-yl)-6-[(1S)-1 ,2,3,4-tetrahydronaphthalen-1-yl]- 3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3, 5-dione;

(8S)-4-hydroxy-8-(1-methyl-1 H-indazol-3-yl)-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyri- dazino[1 ,6-a]pyrazine-3, 5-dione;

(8S)-6-[(1S)-1-(4-fluorophenyl)ethyl]-4-hydroxy-8-(1-methyl-1 H-indazol-4-yl)-3H,5H,6H,7H,8H- pyridazino[1 ,6-a]pyrazine-3, 5-dione;

(8S)-4-hydroxy-6-[(1S)-1-(1-methyl-1 H-indazol-5-yl)ethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyri- dazino[1 ,6-a]pyrazine-3, 5-dione;

(8S)-4-hydroxy-8-(1-methyl-1 H-indazol-4-yl)-6-[(1S)-1-phenylpropyl]-3H,5H,6H,7H,8H-pyri- dazino[1 ,6-a]pyrazine-3, 5-dione; and

(8S)-4-hydroxy-2-methyl-6-[(1S)-1-phenylethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyridazino[1 ,6- a]pyrazine-3, 5-dione.

DEFINITIONS

The term “compound(s) of the present invention” is to be understood as equivalent to the term "compound(s) according to the invention" and relates to the compounds of formula (I) as well as to compounds of formula (IA), (IA-1) or (IA-2), and also covers a stereoisomer, tautomer, N-ox- ide, or pharmaceutically acceptable salt thereof.

The compounds according to the invention may be amorphous or may exist in one or more different crystalline states (polymorphs), which may have different macroscopic properties such as stability or show different biological properties such as activities. The present invention relates to amorphous and crystalline forms of compounds of formula (I), mixtures of different crystalline states of the compounds of formula (I), as well as amorphous or crystalline salts thereof.

The compounds according to the invention also include solvates, in particular hydrates of the compounds of formula (I). The term “hydrate” in connection with the compounds of formula (I) refers to a compound of formula (I), which contains water or its constituent elements (i.e. H and OH). Preferably, a hydrate of the compounds of formula (I) is a compound of formula (I), which incorporates water molecules in the crystalline structure but does not alter the chemical structure of formula (I). It is to be understood that such hydrates of the compounds provided herein, particularly the compounds of the present invention, also include hydrates of pharmaceutically acceptable salts of the corresponding compounds.

Salts of the compounds according to the invention are preferably pharmaceutically acceptable salts, such as those containing counterions present in drug products listed in the US FDA Or- ange Book database. They can be formed in a customary manner, e.g., by reacting the compound with an acid of the anion in question, if the compounds according to the invention have a basic functionality, or by reacting acidic compounds according to the invention with a suitable base.

Suitable cationic counterions are in particular the ions of the alkali metals, preferably lithium, sodium and potassium, of the alkaline earth metals, preferably calcium, magnesium and barium, and of the transition metals, preferably manganese, copper, silver, zinc and iron, and also ammonium (NH₄ ⁺) and substituted ammonium in which one to four of the hydrogen atoms are replaced by Ci-C4-alkyl, Ci-C4-hydroxyalkyl, Ci-C4-alkoxy, Ci-C4-alkoxy-Ci-C4-alkyl, hydroxy-Ci- C4-alkoxy-Ci-C4-alkyl, phenyl or benzyl. Examples of substituted ammonium ions comprise methylammonium, isopropylammonium, dimethylammonium, diisopropylammonium, trimethylammonium, tetramethylammonium, tetraethylammonium, tetrabutylammonium, 2-hydroxy- ethylammonium, 2-(2-hydroxyethoxy)ethyl-ammonium, bis(2-hydroxyethyl)ammonium, benzyltrimethylammonium and benzyltriethylammonium, furthermore the cations of 1 ,4-piperazine, meglumine, benzathine and lysine.

Suitable anionic counterions are in particular chloride, bromide, hydrogensulfate, sulfate, dihydrogenphosphate, hydrogenphosphate, phosphate, nitrate, bicarbonate, carbonate, hexafluorosilicate, hexafluorophosphate, benzoate, and the anions of Ci-C4-alkanoic acids, preferably formate, acetate, propionate and butyrate, furthermore lactate, gluconate, and the anions of poly acids such as succinate, oxalate, maleate, fumarate, malate, tartrate and citrate, furthermore sulfonate anions such as besylate (benzenesulfonate), tosylate (p-toluenesulfonate), napsylate (naphthalene-2-sulfonate), mesylate (methanesulfonate), esylate (ethanesulfonate), and ethanedisulfonate. They can be formed by reacting compounds according to the invention that have a basic functionality with an acid of the corresponding anion.

Tautomers may be formed, if a substituent is present at the compound of formula (I), which allows for the formation of tautomers such as keto-enol tautomers, imine-enamine tautomers, am- ide-imidic acid tautomers or the like.

The term "/V-oxide" includes any compound of the present invention which has at least one tertiary nitrogen atom that is oxidized to an /V-oxide moiety.

Depending on the substitution pattern, the compounds according to the invention may have one or more centres of chirality, including axial chirality providing different stereoisomers. The invention provides both, pure enantiomers or pure diastereomers, of the compounds according to the invention, and their mixtures, including racemic mixtures. Suitable compounds according to the invention also include all possible geometrical stereoisomers (cis/trans isomers or E/Z isomers) and mixtures thereof. E/Z- isomers may be present with respect to, e.g., an alkene, carbon-ni- trogen double-bond or amide group.

Any formula or structure given herein, including compounds of formula (I), is also intended to represent unlabeled forms as well as isotopically labeled forms of the compounds. Isotopically labeled compounds have structures depicted by the formulas given herein except that one or more atoms are replaced by an atom having a selected atomic mass or mass number. Examples of isotopes that can be incorporated into compounds of the disclosure include isotopes of hydrogen, carbon, nitrogen, oxygen, phosphorous, fluorine and chlorine, such as, but not limited to ²H (deuterium, D), ³H (tritium), ¹¹C, ¹³C, ¹⁴C, ¹⁵N, ¹⁸F, ³¹P, ³²P, ³⁵S, ³⁶CI and ¹²⁵l. For example, radioactive isotopes such as ³H, ¹³C and ¹⁴C provide isotopically labelled compounds useful in metabolic studies, reaction kinetic studies, detection or imaging techniques, such as positron emission tomography (PET) or single-photon emission computed tomography (SPECT) including drug or substrate tissue distribution assays or in radioactive treatment of patients. Further, the disclosure includes compounds of formula (I) in which from 1 to n hydrogens attached to a carbon atom is/are replaced by deuterium, in which n is the number of hydrogens in the mole- cule. Deuterium labeled or substituted therapeutic compounds of the disclosure may have improved DMPK (drug metabolism and pharmacokinetics) properties, relating to distribution, metabolism and excretion (ADME). Substitution with heavier isotopes such as deuterium may afford certain therapeutic advantages resulting from greater metabolic stability, for example increased in vivo half-life, reduced dosage requirements and/or an improvement in therapeutic index. See, for example, Poster, "Deuterium Isotope Effects in Studies of Drug Metabolism", Trends Pharmacol. Sei. 5(12):524- 527 (1984). Such compounds are synthesized by means well known in the art, for example by employing starting materials in which one or more hydrogens have been replaced by deuterium. The concentration of such a heavier isotope, specifically deuterium, may be defined by an isotopic enrichment factor. Unless otherwise stated, when a position is designated specifically as "H" or "hydrogen", the position is understood to have hydrogen at its natural abundance isotopic composition. Accordingly, in the compounds of this disclosure any atom specifically designated as a deuterium (D) is meant to represent deuterium.

The term "substituted", as used herein, means that a hydrogen atom bonded to a designated atom is replaced with a specified substituent, provided that the substitution results in a stable or chemically feasible compound. Unless otherwise indicated, a substituted atom may have one or more substituents and each substituent is independently selected. The term "substitutable atom" means that attached to the atom is a hydrogen, which can be replaced with a suitable substituent. The term "substitutable", when used in reference to a designated atom, means that attached to the atom is a hydrogen, which can be replaced with a suitable substituent. When it is referred to certain atoms or moieties being substituted with “one or more” substituents, the term “one or more” is intended to cover at least one substituent, e.g., 1 to 10 substituents, preferably 1 , 2, 3, 4, or 5 substituents, more preferably 1 , 2, or 3 substituents, most preferably 1 , or 2 substituents. When neither the term “unsubstituted” nor “substituted” is explicitly mentioned concerning a moiety, said moiety is to be considered as unsubstituted.

The organic moieties mentioned in the above definitions of the variables are - like the term halogen - collective terms for individual listings of the individual group members. The prefix C_n-C_m indicates in each case the possible number of carbon atoms in the group.

The term “halo” refers to fluoro, chloro, or bromo, particularly fluoro or chloro. The term “halogen” denotes in each case fluorine, bromine, chlorine or iodine, in particular fluorine, chlorine, or bromine.

The term "alkyl" as used herein denotes in each case a straight-chain or branched alkyl group having usually from 1 to 6 carbon atoms, preferably 1 to 5 or 1 to 4 carbon atoms, more preferably 1 to 3 or 1 or 2 carbon atoms. Examples of an alkyl group are methyl, ethyl, n-propyl, isopropyl, n-butyl, 2-butyl, /so-butyl, terf-butyl, n-pentyl, 1 -methylbutyl, 2- methylbutyl, 3-methyl- butyl, 2,2-dimethylpropyl, 1 -ethylpropyl, n-hexyl, 1 ,1 -di methyl propyl, 1 ,2-dimethylpropyl, 1- methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1 ,1 -di methyl butyl, 1 ,2-dimethyl- butyl, 1 ,3-di methyl butyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 3,3-dimethylbutyl, 1-ethylbutyl, 2- ethylbutyl, 1 , 1 ,2-trimethylpropyl, 1 ,2,2- trimethylpropyl, 1-ethyl1-methylpropyl, and 1-ethyl-2- methyl propyl.

The term "haloalkyl" as used herein denotes in each case a straight-chain or branched alkyl group having usually from 1 to 4 carbon atoms, preferably 1 to 3 or 1 or 2 carbon atoms, wherein the hydrogen atoms of this group are partially or totally replaced with halogen atoms. Preferred haloalkyl moieties are selected from Ci-C4-haloalkyl, more preferably from C1-C3- haloalkyl or Ci-C2-haloalkyl, in particular from Ci-C2-fluoroalkyl such as fluoromethyl, difluoromethyl, trifluoromethyl, 1 -fluoroethyl, 2-fluoroethyl, 2,2-difluoroethyl, 2,2,2-trifluoroethyl, pentafluoroethyl, and the like.

The term "alkoxy" as used herein denotes in each case a straight-chain or branched alkyl group which is bonded via an oxygen atom to the remainder of the molecule and has usually from 1 to 4 carbon atoms, preferably 1 to 2 carbon atoms, more preferably 1 carbon atom. Examples of an alkoxy group are methoxy, ethoxy, n-propoxy, /so-propoxy, n-butyloxy, 2-butyloxy, /so-bu- tyloxy, terf-butyloxy, and the like.

The term “alkoxyalkyl” as used herein refers to an alkoxy group as defined herein having usually from 1 to 4 carbon atoms, preferably 1 to 2 carbon atoms, more preferably 1 carbon atom, which is bonded via an alkyl group as defined herein having usually from 1 to 4 carbon atoms, preferably 1 to 2 carbon atoms, more preferably 1 carbon atom, to the remainder of the molecule. Thus, it refers to an alkyl group, which is bonded via oxygen to a further alkyl group, which is then bonded to the remainder of the molecule. Examples of alkoxyalkyl groups are methoxymethyl, methoxyethyl, ethoxymethyl, ethoxyethyl, and the like. Alkyl and alkoxy groups can be unbranched or branched, and examples of alkyl include but are not limited to methyl, ethyl, n- propyl, iso -propyl, n-butyl, iso -butyl, sec-butyl, and terf-butyl. Examples of alkoxy include methoxy, ethoxy, n-propoxy, iso -propoxy, n-butoxy, iso -butoxy, sec-butoxy, and terf-butoxy.

The term "haloalkoxy" as used herein denotes in each case a straight-chain or branched alkoxy group having from 1 to 4 carbon atoms, preferably 1 to 2 carbon atoms, more preferably 1 carbon atom, wherein the hydrogen atoms of this group are partially or totally replaced with halogen atoms, in particular fluorine atoms. Preferred haloalkoxy moieties include Ci-haloalkoxy, in particular Ci-fluoroalkoxy, such as trifluoromethoxy and the like.

The term “hydroxyalkyl” as used herein denotes in each case a straight-chain or branched alkyl group having usually from 1 to 6 carbon atoms, preferably from 1 to 4 carbon atoms, more preferably 1 to 2 carbon atoms, and being further substituted with 1 to 5, preferably with 1 to 2 hydroxy groups, in particular with 1 hydroxy group, wherein a hydroxy group is a OH group. Preferably, the one hydroxy group is terminating the straight-chain or branched alkyl group so that the hydroxy group is bonded to an alkyl bridge, which is bonded to the remainder of the molecule. Examples of an hydroxyalkyl group are hydroxymethyl, hydroxyethyl, n-hydroxypropyl, 2- hydroxypropyl, n-hydroxybutyl, 2-hydroxy butyl, 2-hydroxy-2-methylpropyl, and n-hydroxypentyl. Hydroxymethyl, hydroxyethyl, hydroxypropyl, and hydroxybutyl, are preferred, in particular hydroxymethyl and hydroxyethyl.

“=O” represents an oxo substituent.

The term “carbocyclic”, “carbocyclyl”, or “carbocycle” includes, unless otherwise indicated, in general a 3- to 10- membered monocyclic or bicyclic ring, preferably a 4- to 8-membered or a 3- to 6-membered or a 5- to 7-membered monocyclic or bicyclic ring, more preferably a 3-, 4-, 5- or 6-membered monocyclic ring, comprising 3 to 10, preferably 4 to 8 or 3 to 6 or 5 to 7, more preferably 3, 4, 5 or 6 carbon atoms. The carbocycle may be saturated, partially or fully unsaturated, or aromatic, wherein saturated means that only single bonds are present, and partially or fully unsaturated means that one or more double bonds may be present in suitable positions, while the Huckel rule for aromaticity is not fulfilled, whereas aromatic means that the Huckel (4n + 2) rule is fulfilled. Also “aryls” are covered by the term “carbocycles”.

The term “aryl” or “aromatic carbocycle” refers to aromatic carbocyclic rings based on carbon atoms as ring members, preferably 6-membered aromatic carbocyclic rings based on carbon atoms as ring members. A preferred example is phenyl. Unless otherwise indicated, the term “aryl” further covers “aromatic carbobicycles” as defined herein. The term “carbocyclic” or “carbocyclyl”, unless otherwise indicated, may therefore cover inter alia cycloalkyl, cycloalkenyl, as well as phenyl. Preferably, the term “carbocyclic” or “carbocyclyl” covers phenyl and cycloalkyl, for example phenyl, cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl. The term “cycloalkyl” as used herein denotes in each case a monocyclic cycloaliphatic radical having usually from 3 to 10 or from 3 to 6 carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl and cyclodecyl or cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl. Cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl are preferred. The term "carbobicyclic" or “carbobicyclyl” includes in general 6 to 14-membered, preferably 7- to 12-membered or 8- to 10-membered, more preferably 9- or 10-membered bicyclic rings comprising 6 to 14, preferably 7 to 12 or 8 to 10, more preferably 9 or 10 carbon atoms. The carbobicycle may be saturated, partially or fully unsaturated, or aromatic, wherein saturated means that only single bonds are present, and partially or fully unsaturated means that one or more double bonds may be present in suitable positions, while the Huckel rule for aromaticity is not fulfilled, whereas aromatic means that the Huckel (4n + 2) rule is fulfilled. Preferably, the term “aromatic” in connection with the carbobicyclic ring means that both rings of the bicylic moiety are aromatic, so that, e.g., 8 TT electrons are present in case of a 10-membered aromatic carbobicyclic ring. The term “carbobicylce” or “carbobicyclyl”, unless otherwise indicated, may therefore cover inter alia bicycloalkyl, bicycloalkenyl, as well as bicyclic aromatic groups, for example bicyclohexane (decalin), bicycloheptane (such as norbornane), bicyclooctane (such as bicyclo[2.2.2]octane, bicyclo[3.2.1]octane or bicyclo[4.2.0]octane), bicyclononane (such as bicy- clo[3.3.1]nonane or bicyclo[4.3.0]nonane ), bicyclodecane (such as bicyclo[4.4.0]decane), bicycloundecane (such as bicyclo[3.3.3]undecane), norbornene, naphthalene and the like. Preferably, the carbobicycle is a fused carbobicycle, which is preferably aromatic, for example naphthalene. The term “carbocyclylalkyl” as used herein, refers to carbocyclyl as defined herein, which is bonded to the remainder of the molecule via an alkyl group having usually from 1 to 2 carbon atoms, preferably 1 carbon atom. Preferably, the term “carbocyclylalkyl” refers to phenylalkyl or cycloalkylalkyl, which refers to the corresponding groups being bonded to the remainder of the molecule via an alkyl group. Preferred examples of carbocyclylalkyl include benzyl (i.e., phenylmethyl), phenylethyl, cyclopropyl methyl, cyclopropylethyl, cyclobutylmethyl, cyclobutylethyl, cyclopentylmethyl, cyclopentylethyl, cyclohexylmethyl, cyclohexylethyl. The term “carbocyclyloxy” as used herein denotes in each case a carbocyclyl as defined herein, which is bonded via an oxygen atom to the remainder of the molecule. Examples of carbocyclyloxy include phenyloxy or cyclopropyloxy. The same applies to the terms “aryloxy” and “benzyloxy” referring to the corresponding groups, which are bonded to the remainder of the molecule via an oxygen atom.

The term “heterocyclic” or “heterocyclyl” includes, unless otherwise indicated, in general a 3- to 10-membered, preferably a 4- to 8-membered or 5- to 7-membered, more preferably 5- or 6- membered, in particular 6-membered monocyclic ring. The heterocycle may be saturated, partially or fully unsaturated, or aromatic, wherein saturated means that only single bonds are present, and partially or fully unsaturated means that one or more double bonds may be present in suitable positions, while the Huckel rule for aromaticity is not fulfilled, whereas aromatic means that the Huckel (4n + 2) rule is fulfilled. The heterocycle typically comprises one or more, e.g. 1 , 2, 3, or 4, preferably 1 , 2, or 3 heteroatoms selected from N, O and S as ring members, where S-atoms as ring members may be present as S, SO or SO2. The remaining ring members are carbon atoms. In a preferred embodiment, the heterocycle is an aromatic heterocycle, preferably a 5- or 6-membered aromatic heterocycle comprising one or more, e.g. 1 , 2, 3, or 4, preferably 1 , 2, or 3 heteroatoms selected from N, O and S as ring members, where S-atoms as ring members may be present as S, SO or SO2. Examples of aromatic heterocycles are provided below in connection with the definition of “hetaryl”. “Hetaryls” or “heteroaryls” are covered by the term “heterocycles”. The saturated or partially or fully unsaturated heterocycles usually comprise 1 , 2, 3, 4 or 5, preferably 1 , 2 or 3 heteroatoms selected from N, O and S as ring members, where S-atoms as ring members may be present as S, SO or SO2.

The skilled person is aware that S, SO or SO2 is to be understood as follows:

Further, a skilled person is aware that resonance structures of the oxidized forms may be possible. Saturated heterocycles include, unless otherwise indicated, in general 3- to 10-membered, preferably 4- to 8-membered or 5- to 7-membered, more preferably 5- or 6-membered monocyclic rings comprising 3 to 10, preferably 4 to 8 or 5 to 7, more preferably 5 or 6 atoms comprising at least one heteroatom, such as pyrrolidine, tetrahydrothiophene, tetrahydrofuran, piperidine, tetrahydropyran, dioxane, morpholine or piperazine. The term “heterobicyclic” or “heterobicyclyl” includes, unless otherwise indicated, in general 6 to 14-membered, preferably 7- to 12-membered or 8- to 10-membered, more preferably 8- or 9- membered bicyclic rings. The heterobicycle may be saturated, partially or fully unsaturated, or aromatic, wherein saturated means that only single bonds are present, and 5 partially or fully unsaturated means that one or more double bonds may be present in suitable positions, while the Huckel rule for aromaticity is not fulfilled, whereas aromatic means that the Huckel (4n + 2) rule is fulfilled. For being “aromatic”, it is sufficient if one of the two rings of the bicyclic moieties is aromatic, while the other is non-aromatic. The heterobicycle typically comprises one or more, e.g., 1 , 2, 3, or 4, preferably 1 , 2, or 3 heteroatoms selected from N, O and S as ring members, where S-atoms as ring members may be present as S, SO or SO2. The remaining ring members are carbon atoms. Examples of heterobicycles include but are not limited to: benzofuranyl, benzothienyl, indolyl, indazolyl, benzimidazolyl, benzoxathiazolyl, benzoxadiazolyl, benzothiadia- zolyl, benzoxazinyl, quinolinyl, isoquinolinyl, purinyl, 1 ,8-naphthyridyl, pteridyl, pyrido[3,2-d]py- rimidyl, pyridoimidazolyl, triethylenediamine or quinuclidine and the like.

The term “heteroaryl” or “aromatic heterocycle” or “aromatic heterocyclic ring” or "hetaryl" or “heterocyclyl” includes monocyclic 5- or 6-membered aromatic heterocycles comprising as ring members 1 , 2, 3 or 4 heteroatoms selected from N, O and S, where S-atoms as ring members may be present as S, SO or SO2. Examples of 5- or 6-membered aromatic heterocycles include pyridyl (also referred to as pyridinyl), i.e. 2-, 3-, or 4-pyridyl, pyrimidinyl, i.e. 2-, 4- or 5- pyrimidi- nyl, pyrazinyl, pyridazinyl, i.e. 3- or 4-pyridazinyl, thienyl, i.e. 2- or 3-thienyl, furyl, i.e. 2-or 3-fu- ryl, pyrrolyl, i.e. 2- or 3-pyrrolyl, oxazolyl, i.e. 2-, 3- or 5-oxazolyl, isoxazolyl, i.e. 3-, 4- or 5-isoxa- zolyl, thiazolyl, i.e. 2-, 3- or 5- thiazolyl, isothiazolyl, i.e. 3-, 4- or 5-isothiazolyl, pyrazolyl, i.e. 1-, 3-, 4- or 5-pyrazolyl, i.e. 1-, 2-, 4- or 5-imidazolyl, oxadiazolyl, e.g. 2- or 5-[1 ,3,4]oxadiazolyl, 4- or 5-(1 ,2,3-oxadiazol)yl, 3- or 5-(1 ,2,4-oxadiazol)yl, 2- or 5-(1 ,3,4- thiadiazol)yl, thiadiazolyl, e.g. 2- or 5-(1 ,3,4-thiadiazol)yl, 4- or 5-(1 ,2,3-thiadiazol)yl, 3- or 5- (1 ,2,4-thiadiazol)yl, triazolyl, e.g. 1 H-, 2H- or 3H-1 ,2,3-triazol-4-yl, 2H-triazol-3-yl, 1 H-, 2H-, or 4H-1 ,2,4-triazolyl and tetrazolyl, i.e. 1 H- or 2H-tetrazolyl. Unless otherwise indicated, the term “hetaryl” further covers “aromatic heterobicycles” as defined above.

As used herein, the terms “carbocyclylalkyl” as well as the term “cycloalkylalkyl”, and the like refer to the corresponding groups, which are bonded to the remainder of the molecule via an alkyl, preferably via a Ci-C2-alkyl group. Preferred examples include benzyl (i.e. phenylmethyl), cyclohexylmethyl.

As used herein, the terms “aryloxy” and “benzyloxy” refer to the corresponding groups, which are bonded to the remainder of the molecule via an oxygen atom. Preferred examples include phenyloxy and phenylmethyloxy (i.e. benzyloxy).

The term "cancer" pertains to a disease characterized by the rapid and uncontrolled growth of abnormal cells that can spread locally or through the bloodstream and lymphatic system. Various cancers, including colorectal, gastric, endometrial, prostate, adrenocortical, uterine, cervical, oesophageal, breast, kidney, and ovarian cancer, among others, are described herein. The terms "tumour", “tumor” and "cancer" are used interchangeably and encompass both solid and liquid tumours, including diffuse or circulating tumours. As used herein, the terms "tumour" and "cancer" include premalignant, as well as malignant cancers and tumours.

An “EXO1 modulator” or "EXO1 inhibitor" refers to a compound that modulates or inhibits exonuclease 1 (EXO1).

The term "medicine" as used herein is intended to be a generic term inclusive of prescription and non-prescription medications. The compound for use in medicine should be understood as being useful in maintaining health or promoting recovery from a disease, preferably cancer. Further, the term "medicine" includes medicine in any form, including, without limitation, e.g., pills, salves, creams, powders, ointments, capsules, injectable medications, drops, vitamins and suppositories. The scope of this invention is not limited by the type, form or dosage of the medicine.

A "pharmaceutical composition" is a compound of the invention or a pharmaceutically acceptable salt thereof, along with at least one pharmaceutically acceptable carrier, prepared for oral or parenteral administration. A "pharmaceutically acceptable carrier" includes substances used in the preparation or use of pharmaceutical compositions, such as diluents, solvents, dispersion media, surfactants, antioxidants, preservatives, isotonic agents, buffering agents, emulsifiers, and more. The term “pharmaceutically acceptable excipient” as used herein refers to compounds commonly comprised in pharmaceutical compositions, which are known to the skilled person. Typically, a pharmaceutically acceptable excipient can be defined as being pharmaceutically inactive.

A "therapeutically effective amount" of a compound refers to an amount that, when administered to a subject, achieves a biological or medical response, such as the reduction of enzyme or protein activity or the alleviation, mitigation, or prevention of symptoms, disease progression, or the disease itself.

A "subject" can be a human, primate, dog, rabbit, guinea pig, pig, rat, or mouse, depending on the context.

"Treat," "treating," or "treatment" refers to alleviating or mitigating a disease or disorder or reducing symptoms. The term “treatment” is to be understood as also including the option of “prophylaxis”. Thus, whenever reference is made herein to a “treatment” or “treating”, this is to be understood as “treatment and/or prophylaxis” or “treating and/or preventing”. "Prevent," "preventing," or "prevention" involves prophylactic treatment or delaying the onset or progression of a disease. A subject is "in need of" treatment if they would benefit from it biologically, medically, or in terms of quality of life.

It needs to be understood that the term “comprising” is not limiting. For the purposes of the present invention, the term “consisting of’ is considered to be a preferred embodiment of the term “comprising of”. If hereinafter a group is defined to comprise at least a certain number of embodiments, this is also meant to encompass a group which preferably consists of these embodiments only.

The terms “about” and “approximately” in the context of the present invention denotes an interval of accuracy that a person skilled in the art will understand to still ensure the technical effect of the feature in question. The term typically indicates a deviation from the indicated numerical value of ±10% and preferably ±5%.

Finally, terms such as “a”, “an”, “the”, and similar terms encompass both singular and plural forms unless otherwise indicated or contradicted by the context. The use of examples or exemplary language serves to clarify the invention but does not limit the scope of the claimed invention.

ROUTES OF ADMINISTRATION AND FORMULATIONS

A pharmaceutical composition according to the present invention may be formulated for oral, buccal, nasal, rectal, topical, transdermal or parenteral application. Preferred non-parenteral routes include mucosal (e.g., oral, vaginal, nasal, cervical, etc.) routes, of which the oral application may be preferred. Preferred parenteral routes include but, are not limited to, one or more of subcutaneous, intravenous, intra-muscular, intraarterial, intradermal, intrathecal and epidural administrations. Preferably administration is by subcutaneous, intra-tumoral or peri-tumoral routes. Particularly preferred is intratumoral administration. The compound according to formula (I) should be applied in pharmaceutically effective amounts, for example in the amounts as set out herein below. A pharmaceutical composition of the present invention may also be designated as formulation or dosage form. A compound of formula (I) may also be designated in the following as (pharmaceutically) active agent or active compound.

Pharmaceutical compositions may be solid or liquid dosage forms or may have an intermediate, e.g. gel-like character depending inter alia on the route of administration.

In general, the inventive dosage forms can comprise various pharmaceutically acceptable excipients which will be selected depending on which functionality is to be achieved for the dosage form. A “pharmaceutically acceptable excipient” in the meaning of the present invention can be any substance used for the preparation of pharmaceutical dosage forms, including coating materials, film-forming materials, fillers, disintegrating agents, release-modifying materials, carrier materials, diluents, binding agents and other adjuvants. Typical pharmaceutically acceptable excipients include substances like sucrose, mannitol, sorbitol, starch and starch derivatives, lactose, and lubricating agents such as magnesium stearate, disintegrants and buffering agents. The term “carrier” denotes pharmaceutically acceptable organic or inorganic carrier substances with which the active ingredient is combined to facilitate the application. Suitable pharmaceutically acceptable carriers include, for instance, water, aqueous salt solutions, alcohols, oils, preferably vegetable oils, propylene glycol, polyoxyethelene sorbitans, polyethylene-polypropylene block co-polymers such as poloxamer 188 or poloxamer 407, polyethylene glycols such as polyethylene glycol 200, 300, 400, 600, etc., gelatin, lactose, amylose, magnesium stearate, surfactants, perfume oil, fatty acid monoglycerides, diglycerides and triglycerides, polyoxyethylated medium or long chain fatty acids such as ricinoleic acid, and polyoxyethylated fatty acid mono-, di, and triglycerides such as capric or caprilic acids, petroethral fatty acid esters, hydroxymethyl celluloses such as hydroxymethyl, hydroxyethyl, hydroxypropyl, hydroxypropyl acetate succinate, polyvinylpyrrolidone, crosspovidone and the like. Preferably, the compounds of the present invention are administered in a pharmaceutical composition comprising of lipids, interbilayer crosslinked multilamellar vesicles, biodegradeable poly(D,L-lactic-co-glycolic acid) [PLGA]- based or poly anhydride-based nanoparticles or microparticles, nanoporous particle-supported lipid bilayers and as a conjugate with an antibody.

The pharmaceutical compositions can be sterile and, if desired, mixed with auxiliary agents, like lubricants, preservatives, stabilizers, wetting agents, emulsifiers, salts for influencing osmotic pressure, buffers, colorings, flavoring and/or aromatic substances and the like which do not del- eteriously react with the active compound. It is to be understood that the term “carrier” also covers an antibody that delivers the compound of formula (I).

If liquid dosage forms are considered for the present invention, these can include pharmaceutically acceptable emulsions, solutions, suspensions and syrups containing inert diluents commonly used in the art such as water. These dosage forms may contain e.g. microcrystalline cellulose for imparting bulk, alginic acid or sodium alginate as a suspending agent, methylcellulose as a viscosity enhancer and sweeteners/flavoring agents.

For parenteral application, particularly suitable vehicles consist of solutions, preferably oily or aqueous solutions, as well as suspensions, emulsions, or implants. Pharmaceutical formulations for parenteral administration are particularly preferred and include aqueous solutions of the compounds of formula (I) in water-soluble form. Additionally, suspensions of the compounds of formula (I) may be prepared as appropriate oily injection suspensions. Suitable lipophilic solvents or vehicles include fatty oils such as sesame oil, or synthetic fatty acid esters, such as ethyl oleate or triglycerides, or liposomes. Aqueous injection suspensions may contain substances, which increase the viscosity of the suspension, such as sodium carboxymethyl cellulose, sorbitol, or dextran. Particularly preferred dosage forms are injectable preparations of a compound of formula (I). Thus, sterile injectable aqueous or oleaginous suspensions can for example be formulated according to the known art using suitable dispersing agents, wetting agents and/or suspending agents. A sterile injectable preparation can also be a sterile injectable solution or suspension in a non-toxic parenterally acceptable diluent or solvent. Among the acceptable vehicles and solvents that can be used are water and isotonic sodium chloride solution. Sterile oils are also conventionally used as solvent or suspending medium. Preferred applications for injectable preparations comprising the compounds of the present invention are intravenous, intratumoral and peritumoral administration.

Suppositories for rectal administration of a compound of formula (I) can be prepared by e.g. mixing the compound with a suitable non-irritating excipient such as cocoa butter, synthetic triglycerides and polyethylene glycols which are solid at room temperature but liquid at rectal temperature such that they will melt in the rectum and release the compound according to formula (I) from said suppositories.

For administration by inhalation, the compounds according to the present invention may be conveniently delivered in the form of an aerosol spray from pressurized packs or a nebulizer, with the use of a suitable propellant, e.g., dichlorodifluoromethane, trichlorofluoromethane, dichloro- tetrafluoroethane, carbon dioxide or other suitable gas. In the case of a pressurized aerosol the dosage unit may be determined by providing a valve to deliver a metered amount. Capsules and cartridges of e.g. gelatin for use in an inhaler or insufflator may be formulated containing a powder mix of the compound and a suitable powder base such as lactose or starch.

Oral dosage forms may be liquid or solid and include e.g. tablets, troches, pills, capsules, powders, effervescent formulations, dragees and granules. Pharmaceutical preparations for oral use can be obtained as solid excipient, optionally grinding a resulting mixture, and processing the mixture of granules, after adding suitable auxiliaries, if desired, to obtain tablets or dragee cores. Suitable excipients are, in particular, fillers such as sugars, including lactose, sucrose, mannitol, or sorbitol; cellulose preparations such as, for example, maize starch, wheat starch, rice starch, potato starch, gelatin, gum tragacanth, methyl cellulose, hydroxypropylmethyl-cellu- lose, sodium carboxymethylcellulose, and/or polyvinylpyrrolidone (PVP). If desired, disintegrating agents may be added, such as the cross-linked polyvinyl pyrrolidone, agar, or alginic acid or a salt thereof such as sodium alginate. The oral dosage forms may be formulated to ensure an immediate release of the compound of formula (I) or a sustained release of the compound of formula (I).

A solid dosage form may comprise a film coating. For example, the inventive dosage form may be in the form of a so-called film tablet. A capsule of the invention may be a two-piece hard gelatin capsule, a two-piece hydroxypropylmethylcellulose capsule, a two-piece capsule made of vegetable or plant-based cellulose, or a two-piece capsule made of polysaccharide.

The dosage form according to the invention may be formulated for topical application. Suitable pharmaceutical application forms for such an application may be a topical nasal spray, sublingual administration forms and controlled and/or sustained release skin patches. For buccal administration, the compositions may take the form of tablets or lozenges formulated in conventional manner.

The compositions may conveniently be presented in unit dosage forms and may be prepared by any of the methods well known in the art of pharmacy. The methods can include the step of bringing the compounds into association with a carrier, which constitutes one or more accessory ingredients. In general, the compositions are prepared by uniformly and intimately bringing the compounds into association with a liquid carrier, a finely divided solid carrier, or both, and then, if necessary, shaping the product. Liquid dose units are vials or ampoules. Solid dose units are tablets, capsules and suppositories. As regards human patients, the compound of formula (I) may be administered to a patient in an amount of about 0.001 mg to about 5000 mg per day, preferably of about 0.01 mg to about 1000 mg per day, more preferably of about 0.05 mg to about 250 mg per day, which is the effective amount. The phrase “effective amount” means an amount of compound that, when administered to a mammal in need of such treatment, is sufficient to treat or prevent a particular disease or condition.

MEDICAL INDICATIONS

The compounds according to the present invention are suitable for use in medicine. The compounds of the present invention are useful for (partially) modulating EXO1. Thus, the compounds according to the present invention are particularly suitable for use in the treatment of a disease associated with modulating EXO1 , in particular a proliferative disorder such as cancer or pre- cancerous syndromes.

Thus, in one embodiment, the present invention relates to a compound of formula (I) as defined herein or a pharmaceutical composition as defined herein for use in medicine. In particular, the compound of the present invention or a pharmaceutical composition comprising the same is for use in the treatment of a disease selected from the group consisting of cancer or pre-cancerous syndromes. Preferably, said cancer is selected from the group consisting of hepatocellular carcinoma (HCC), glioma, colon cancer/colorectal cancer, in particular nonpolyposis colorectal cancer (HNPCC), breast, ovarian, lung, pancreatic, gastric tract cancer, cancer of the small intestine, oral cancer, cervical cancer.

In further aspects, the present invention relates to methods of treatment comprising the administration of a compound of formula (I) as defined herein or a pharmaceutical composition comprising the same as defined herein to a human or animal body. In particular, the present invention relates to methods of treating diseases that can be addressed by EXO1 modulation, with a particular emphasis on cancers such as hepatocellular carcinoma (HCC), glioma, colon cancer/colorectal cancer, in particular nonpolyposis colorectal cancer (HNPCC), breast, ovarian, lung, pancreatic, gastric tract cancer, cancer of the small intestine, oral cancer, and cervical cancer.

Moreover, the invention further relates to the manufacture of a medicament for the treatment of diseases that can be addressed by EXO1 modulation, with a particular emphasis on cancers such as hepatocellular carcinoma (HCC), glioma, colon cancer/colorectal cancer, in particular nonpolyposis colorectal cancer (HNPCC), breast, ovarian, lung, pancreatic, gastric tract cancer, cancer of the small intestine, oral cancer, and cervical cancer.

It is to be understood that in connection with the medical uses of the invention it can be preferred that the compounds according to the present invention are administered in combination with antibodies, radiotherapy, surgical therapy, immunotherapy, chemotherapy, toxin therapy, gene therapy, or any other therapy known to those of ordinary skill in the art for treatment of a particular disease. This is particularly relevant in connection with the treatment of cancer.

The present invention is further illustrated by the following examples.

EXAMPLES

The compounds described herein may be prepared using the following methods and schemes. The sequence of reactions is an illustrative example. Swapping steps is possible and reaction conditions can be easily adapted. Unless specified otherwise, all starting materials used are commercially available or can be synthesised analogously to the described intermediates or routes described in the literature.

The following abbreviations are used herein: aq (aqueous), h or hrs (hour(s)), g (gram), L (liter), mg (milligram), MHz (Megahertz), min. (minute), mm (millimeter), mmol (millimole), mM (millimolar), m.p. (melting point), eq ( equivalent), mL (milliliter), pL (microliter), ACN (acetonitrile), AcOH (acetic acid), CDC (deuterated chloroform), CD3OD (deuterated methanol), CH3CN (acetonitrile), c-hex (cyclohexane), DCC (dicyclohexyl carbodiimide), DCM (dichloromethane), DIC (diisopropyl carbodiimide), DIEA (diisopropylethyl-amine), DMF (dimethylformamide), DMSO (dimethylsulfoxide), DMSO-de (deuterated dimethylsulfoxide), EDC (1-(3-dimethyl-amino-propyl)-3-ethylcarbodiimide), ESI (Electrospray ionization), EtOAc or EA (ethyl acetate), Et20 (diethyl ether), EtOH (ethanol), FA (formic acid), PG (protecting group), HATLI (dimethylamino-([1 ,2,3]triazolo[4,5-b]pyridin-3-yloxy)-meth- ylene]-dimethyl-ammonium hexafluorophosphate), HPLC (High Performance Liquid Chromatography), i-PrOH (2-propanol), K2CO3 (potassium carbonate), LC (Liquid Chromatography), LCMS, LC MS, LC-MS, or LC/MS (High-Performance Liquid Chromatography coupled to Mass Spectrometry), MeOH (methanol), MgSCU (magnesium sulfate), MS (mass spectrometry), MTBE (Methyl tert-butyl ether), NaHCCh (sodium bicarbonate), NaBH4 (sodium borohydride), NMM (N-methyl morpholine), NMR (Nuclear Magnetic Resonance), PyBOP (benzotriazole-1-yl- oxy-tris-pyrrolidino-phosphonium hexafluorophosphate), RT (room temperature), Rt (retention time), SPE (solid phase extraction), T or temp (temperature); TBTU (2-(1-H-benzotriazole-1-yl)- 1 ,1 ,3,3-tetramethyluromium tetrafluoro borate), TEA (triethylamine), TFA (trifluoroacetic acid), THF (tetra hydrofuran), TLC (Thin Layer Chromatography), UPLCMS, UPLC MS, UPLC-MS, or UPLC/MS (Ultra-Performance Liquid Chromatography coupled to Mass Spectrometry), UV (Ultraviolet).

Instrument specifications:

The microwave chemistry is performed on a single mode microwave reactor EmrysTM Opti- miser from Personal Chemistry.

Preparative column chromatography was performed with a Teledyne-lsco CombiFlash EZ Prep (column: Redi Sep Rf C-18, 360 g, eluent: gradient Water+0,1 % HCOOH --> ACN+0,1% HCOOH, flow-rate: 150 ml/min, detection: UV 214nm) or Biotage Isolera Prime or preparative HPLC. Preparative HPLC was performed on an Agilent 1200. Column: Chromolith prep RP 18e Merck KGaA; C18 silica gel; mobile phase: 0.1 % formic acid in water / 0.1 % formic acid in acetonitrile; 10% to 50% gradient in 10 min; detector UV 254 nm.

Mass spectrum: LC/MS Waters ZMD (ESI) or Hewlett Packard System of the HP 1100 series (Ion source: Electrospray (positive mode) or Waters Acquity H Class SQD; Scan: 100-1000 m/z; Fragmentation-voltage: 60 V; Gas-temperature: 300°C, DAD: 220 nm. Flow rate: 2.4 ml/Min. The used splitter reduced the flow rate after the DAD for the MS to 0,75ml/Min; Column: Chromolith Speed ROD RP-18e 50-4.6; Solvent: LiChrosolv-quality from the company Merck KGaA or as mentioned in the method. LCMS data provided in the examples are given with retention time, purity and/or mass in m/z.

LCMS method 0: Column: HALO C18, 2 pm, 3.0 x 30 mm, Column Oven: 40C; Mobile Phase A: Water/0.05% TFA, Mobile Phase B: ACN/0.05% TFA; Flow rate: 1.5 mL/min; Gradient: 5%B to 100%B in 2.0 min, hold 0.5 min; 254nm.

LCMS method 1 :

Column: HALO C18, 2 pm, 3.0 x 30 mm, Column Oven: 40C; Mobile phase A: Water/0.1% FA; Mobile phase B: Acetonitrile/0.1 % FA; Flow rate: 1.5 mL/min; Gradient: 5%B to 100%B in 1.2 min, hold 0.5 min; 254nm LCMS method 2:

Column: HALO C18, 2 pm, 3.0 x 30 mm, Column Oven 40 C; Mobile phase A: water/0.1 %FA, Mobile phase B: ACN/0.1%FA, Flow rate: 1.5 ml/min;

LCMS method 3

HALO C18; Mobile Phase A: Water+0.05%TFA; Mobile Phase B: ACN+0.05%TFA

LCMS method 4

HALO C18; Mobile Phase A: Water/0.05% TFA, Mobile Phase B: Acetonitrile/0.05% TFA LCMS method 5

HALO C18; Mobile phase A: Water/0.1% FA; Mobile phase B: Acetonitrile/0.1% FA LCMS method 6

LC-MS, Agilent 1200 Series, Column: Chromolith HR RP-18e 50-4,6; 3.3ml/min; solvent A: Water + 0.1% TFA; solvent B: Acetonitrile + 0.1 % TFA; 220 nm; 0 to 2,0 min: 1%B to 99%B; 2,0 to 2,5 min. 99%B

LCMS method 9

Column: Xbridge C18, 3.5pm, 4.6*50mm; Flow Rate:1.5 mL/min; Analysis Time: 5.0 min; MS scan range: 100-1000; Mobile Phase A: o . 05%TFAin water; Mobile Phase B: acetonitrile; Gradient: 0.0 min: 5 % B, 4.5 min: 95 % B,

1 H NMR was recorded on Bruker DPX-300, DRX-400 or AVII-400 spectrometer, using residual signal of deuterated solvent as internal reference. Chemical shifts (5) are reported in ppm relative to the residual solvent signal (5 = 2.49 ppm for 1 H NMR in DMSO-d6). 1 H NMR data are reported as follows: chemical shift (multiplicity, coupling constants, and number of hydrogens). Multiplicity is abbreviated as follows: s (singlet), d (doublet), t (triplet), q (quartet), m (multiplet), br (broad).

General Synthetic Schemes:

Scheme A: Synthesis route and typical conditions to key intermediate ethyl 5-(benzyloxy)-4-oxo- 1 ,4-dihydropyridazine-3-carboxylate hydrochloride.

Di-tert-butyl dicarbonate,

NaHCO3, THF, RT, 16 h tert-Butoxy

Scheme B: Synthesis routes and typical conditions to key aminoethanol intermediate ; Route B1 : a) Alcohol oxidation to an aldehyde with e.g. MnO2 in DCM at RT over night; b) Oxirane introduction with iodotrimethyl-h-sulfanone and NaH in THF at RT for 2 hours; c) Epoxide opening with NaCIO4 in ACN at 60 °C for 48 hours; Route B2: d) Heck coupling conditions, for example a vinyl ether with 1 ,1'-Bis(diphenylphosphino)ferrocene, Pd(ll) acetate, triethylamine, ethylene glycol; Hal is halogen; e) Bromination with e.g. HBr and Br2 in acetic acid; f) alkyl amination conditions under basic conditions with e.g. potassium carbonate; g) reduction conditions with e.g. lithium aluminum hydride (1 M in tetrahydrofuran). H₂N R¹

^{1 l u}\ _ )=n a? i ^L ^RJ R^

Scheme C: Synthesis route and typical conditions to 4-hydroxy-6,8-substituted-7,8-dihydro-3H- pyrazino[1 ,2-b]pyridazine-3,5(6H)-dione a) Protecting group introduction, e.g. N,O-Bis(trimethylsilyl)-acetamide and 2-(trimethylsilyl)eth- oxymethyl chloride in tert-butyl methyl ether at RT for 4 hours; b) amide coupling with typical acid activation conditions like HATLI, thion coyl chloride, BOP; c) Chlorination with e.g. thionyl chloride in DCM at RT for 45 min; d) Cyclisa stion with e.g. LiBr in dioxane at 130 °C for 1.5 hours.

I co a - o

Synthesis of key intermediate (Scheme A)

Synthesis of key intermediate ethyl 5-(benzyloxy)-4-oxo-1 ,4-dihydropyridazine-3-carboxylate hydrochloride following Scheme A. Intermediate ethyl (2E)-4-(benzyloxy)-2-hydrazinylidene-3-oxobutanoate

Synthesis of ethyl (2E)-4-(benzyloxy)-2-hydrazinylidene-3-oxobutanoate was done in flow chemistry with a Vapourtec R-series Flow-Reactor, equipped with R2plus and R2Splus Pump modules, and four 10 ml standard PFA tube reactors. System Solvent: ACN

BPR=6 bar

Flow rate A: 0.50 ml/min

Flow rate B: 0.50 ml/min

Flow rate D: 0,50 ml/min

Reactor temp 1 = 25°C

Reactor temp 2 = 25°C

Reactor temp 3 = 30°C

Reactor temp 4 = 30°C

Channel A: Solution of ethyl 4-(benzyloxy)-3-oxobutanoate (11.8 g; 50 mmol; 1 eq.) and triethylamine (10.4 ml; 75 mmol; 1.5 eq.) in acetonitrile filled up to 100 ml (to give a 0.5 M solution of ethyl 4-(benzyloxy)-3-oxobutanoate)

Channel B: p-Toluenesulfonyl azide solution, 11-15 % (w/w) in toluene (99.7 ml; 50 mmol; 1 eq.) Channel D: Trimethylphosphine solution, 1.0 M in THF (100 ml; 100 mmol; 2 eq.)

The streams of A and B were mixed in a T-mixer and pumped through reactor 1 and 2 (in series, total flow: 1 ,0 ml/min, T=25°C). The product stream of reactor 1 and 2 was mixed with the stream D via T-mixer and pumped through the reactors 2 and 3 (in series) at T=35°C. The final product stream was collected in a flask that contains 100 ml of water equipped with a stir bar. The mixture was stirred for 1h at RT to quench the trimethylphospine, diluted with EtOAc and washed with water and brine. The separated organic layer was dried over Na2SO4 and the solvent was removed in vacuo to give crude ethyl (2E)-4-(benzyloxy)-2-hydrazinylidene-3-oxobuta- noate (22,30 g; 36,706 mmol) as an orange oil (22.3 g).

LCMS (LC-MS, Agilent 1200 Series, Chromolith HR RP-18e 50-4,6; 3.3ml/min; solvent A: Water + 0.1% TFA; solvent B: Acetonitrile + 0.1% TFA; 220 nm; 0 to 2,0 min: 1%B to 99%B; 2,0 to 2,5 min. 99%B): purity 43.5 %, Rt 1.39 and 1.437 min (E/Z mixture), [M+Na]⁺ 287.0 m/z.

Intermediate ethyl (2E)-4-(benzyloxy)-2-({[(tert-butoxy)carbonyl]amino}imino)-3-oxobutanoate

Di-tert-butyl dicarbonate for synthesis (11.8 ml; 55 mmol; 1.5 eq.) and sodium hydrogen carbonate (9.25 g; 3 eq.) were added to a solution of ethyl (2E)-4-(benzyloxy)-2-hydrazinylidene-3- oxobutanoate (22.3 g; 36.7 mmol; 1 eq.) in tetrahydrofuran (250 ml) and the resulting mixture was stirred at RT for 16h. The reaction mixture was diluted with EtOAc and washed with water and brine. The separated organic layer was dried over Na2SO4 and the solvent was removed in vacuo. The residue was purified by flash chromatography (n-Heptane/EtOAc) to yield ethyl (2E)- 4-(benzyloxy)-2-({[(tert-butoxy)carbonyl]amino}imino)-3-oxobutanoate (9.4 g) as an off-white solid.

LCMS (LC-MS, Agilent 1200 Series, Chromolith HR RP-18e 50-4,6; 3.3ml/min; solvent A: Water + 0.1% TFA; solvent B: Acetonitrile + 0.1% TFA; 220 nm; 0 to 2,0 min: 1%B to 99%B; 2,0 to 2,5 min. 99%B): purity 100 %, Rt 1.82 min, [M+Na]⁺ 381.1 m/z.

Key intermediate ethyl 5-(benzyloxy)-4-oxo-1,4-dihydropyridazine-3-carboxylate hydrochloride

Synthesis of key intermediate ethyl 5-(benzyloxy)-4-oxo-1 ,4-dihydropyridazine-3-carboxylate hydrochloride was done in flow chemistry with a Vapourtec R-series Flow-Reactor equipped with R2plus and R2Splus Pump modules, and four 10 ml standard PFA tube reactors.

System Solvent: THF

BPR=6 bar

Flow rate A: 0.50 ml/min

Flow rate B: 0.50 ml/min

Reactor temp 1 = 60°C

Reactor temp 2 = 60°C

Reactor temp 3 = 60°C

Reactor temp 4 = 60°C

Channel A: Solution of tert-butoxy bis(dimethylamino)methane (13.5 g; 77.4 mmol; 3 eq.) in 10 ml tetra hydrofuran, filled up with tetrahydrofuran to 50 ml (about 1.5 M tert-butoxy bis(dimethyla- mino)methane).

Channel B: Solution of ethyl (2E)-4-(benzyloxy)-2-({[(tert-butoxy)carbonyl]amino}imino)-3-oxobu- tanoate (9.4 g; 25.8 mmol; 1 eq.) in 30 ml tetrahydrofuran, filled up with tetra hydrofuran to 50 ml (about 0.5 M of ethyl (2E)-4-(benzyloxy)-2-({[(tert-butoxy)carbonyl]amino}imino)-3-oxobuta- noate).

The stream of A was pumped through reactor 1 (2ml volume) at 60°C for pre-heating the reagent. The output of reactor 1 and stream B were mixed in a T-mixer and pumped at 60°C through the reactors 2-4 (in series, 30 ml total volume). Total flow: 1.0 ml/min. The final product stream was manually collected in a flask. The collected product solution was cooled in an ice bath and acidified to pH 2 by adding hydrogen chloride solution (4 M in dioxane). The precipitated product was isolated by filtration, washed with acetone/water 1 :1 and dried in vacuo to give ethyl 5-(benzyloxy)-4-oxo-1 ,4-dihydropyridazine-3-carboxylate hydrochloride (5.07 g) as a colorless solid.

LCMS (LC-MS, Agilent 1200 Series, Chromolith HR RP-18e 50-4,6; 3.3ml/min; solvent A: Water + 0.1% TFA; solvent B: Acetonitrile + 0.1% TFA; 220 nm; 0 to 2,0 min: 1 %B to 99%B; 2,0 to 2,5 min. 99%B): purity 96.4 %, Rt 1.12 min., [M+Na]⁺ 297.0 m/z.

Synthesis of amino alcohol intermediates (Scheme B)

Amino alcohol intermediates were synthesised according to route B1 or route B2 of scheme B, as described for 1-(1-methyl-1 H-indazol-4-yl)-2-{[(1S)-1-phenylethyl]amino}ethan-1-ol in the following.

Route B1

Intermediate 1-methyl-1 H-indazole-4-carbaldehyde

To a solution of (1-methyl-1 H-indazol-4-yl)methanol (5.00 g; 29.29 mmol; 1.00 eq.) in DCM (200.00 ml) was added MnC>2 (40.20 g; 439.30 mmol; 15.00 eq.) at room temperature. The resulting mixture was stirred for 24 h at room temperature. The resulting mixture was filtered, and the solvent of the filtrate was removed under reduced pressure. The residue was purified by silica gel column chromatography (PE:EA (4:1)) to afford 1-methyl-1 H-indazole-4-carbaldehyde as colorless solid (4.40 g; 90.4 %).

LCMS (HALO C18; Mobile Phase A:Water/0.1 % FA, Mobile Phase B: ACN/0.1 % FA): Purity 96.4%, Rt 0.66 min., [M+H]⁺ calc.: 160.06, found: 161.1 m/z.

Intermediate 1-methyl-4-(oxiran-2-yl)-1 H-indazole

To a solution of iodotrimethyl-h-sulfanone (9.19 g; 39.68 mmol; 1.50 eq.) in DMSO (60.00 ml) was added NaH (1.59 g; 39.68 mmol; 1.50 eq.) at O°C. The resulting mixture was stirred for 1 h at room temperature. To the above mixture was added a solution of 1-methyl-1 H-indazole-4- carbaldehyde (4.40 g; 26.45 mmol; 1.00 eq.) in THF (60.00 ml) at room temperature. The resulting mixture was stirred for 2 h at room temperature and the mixture was poured into ice water, and extracted with EA. The combined organic layers were washed with brine and dried over anhydrous Na2SC>4. After filtration, the solvent of the filtrate was removed under reduced pressure and purified by silica gel column chromatography (PE:EA (4:1)) to afford 1-methyl-4-(oxiran-2- yl)-1 H-indazole as colorless liquid (1.58 g; 28.8 %).

LC/MS (HALO C18;Mobile Phase A:Water/0.1 % FA, Mobile Phase B: ACN/0.1% FA): Purity 84.1%, Rt 0.64 min., [M+H]⁺ calc.: 174.08, found: 175.15 m/z.

Amino alcohol intermediate 1-(1-methyl-1 H-indazol-4-yl)-2-{[(1S)-1-phenylethyl]amino}ethan-1-

To a mixture of 1-methyl-4-(oxiran-2-yl)-1 H-indazole (1.50 g; 7.23 mmol; 1.00 eq.) and (1S)-1- phenylethan-1-amine (1.85 g; 14.47 mmol; 2.00 eq.) in ACN (30.00 ml) was added NaCIO4 (2.80 g; 21.70 mmol; 3.00 eq.) at room temperature. The resulting mixture was stirred for 48 h at 60°C. The mixture was allowed to cool down to room temperature and was poured into water and extracted with EA. The combined organic layers were washed with brine and dried over anhydrous Na2SC>4. After filtration, the filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography CH2Cl2:MeOH (10:1) and reverse phase chromatography (column, C18(48 g); mobile phase: MeCN in water, 0% to 42% gradient in 26 min; detector: UV 254 nm) to afford 1-(1-methyl-1 H-indazol-4-yl)-2-{[(1S)-1-phe- nylethyl]amino}ethan-1-ol as colorless gum (1.69 g; 76.1 % yield)

LCMS (LC-MS, Agilent 1200 Series, Chromolith HR RP-18e 50-4,6; 3.3ml/min; solvent A: Water + 0.1% TFA; solvent B: Acetonitrile + 0.1% TFA; 220 nm; 0 to 2,0 min: 1 %B to 99%B; 2,0 to 2,5 min. 99%B): Purity 96.2%, Rt 0.43 min., [M+H]⁺ calc.: 295.17, found: 295.95m/z.

Route B2

Intermediate: 1-(1-methyl-1 H-indazol-4-yl)ethan-1-one

A stirred solution of 4-bromo-1 -methylindazole (10.0 g; 47.4 mmol; 1.00 eq.), 1 ,1'-bis(diphe- nylphosphino)ferrocene (2.63 g; 4.74 mmol; 0.10 eq.), palladium^ I) acetate (532 mg; 2.4 mmol; 0.05 eq.) and triethylamine (16.5 ml; 118.5 mmol; 2.5 eq.) in ethylene glycol (150 ml) was degassed by evacuation and refilling with N2 (3 times). Then, butyl vinyl ether (24.52 ml; 189.52 mmol; 4.00 eq.) was added and the resulting mixture was stirred overnight at 100°C under N2 atmosphere. Reaction mixture was cooled to room temperature and aqueous hydrochloric acid (4.0 M) (35.5 ml; 142.1 mmol; 3.0 eq.) was added slowly and stirred at 25°C for 4 hrs. A saturated solution of NaHCOs (~ 40mL for 5g scale) was added to basify the mixture to a pH of about 8. The mixture was extracted with EtOAc. The combined EtOAc phases were washed with brine and the combined organic layers were dried over Na2SO4 and filtered. The solvent was removed under vacuo. The residue was purified by column chromatography (Biotage Instrument. Column Interchim 200g Si-Gel. 5-60% EtOAc / Hexanes; product eluted around 50% EtOAc / Hexanes) to give 1-(1-methyl-1 H-indazol-4-yl)ethan-1-one as a colorless solid (7.20 g; 87.2 %). 1 H NMR (Bruker 400 MHz, DMSO) 5 8.45 (s, 1 H), 7.99 (d, J = 8.4 Hz, 1 H), 7.90 (d, J = 7.1 Hz, 1 H), 7.55 (td, J = 8.0, 1.7 Hz, 1 H), 4.10 (s, 3H), 2.68 (s, 3H). LC/MS (Waters UPLC/MS (COLUMN: ACQUITY UPLC@BEH C18 1.7 MICRON:ACQUITY UPLC® BEH C18 1.7pm; 5- 95% ACN I Water (0.1 % formic acid in both mobile phases), 1.5 min gradient): [M+H]⁺ 175 m/z, Rt 0.85 min.

Intermediate 2-bromo-1-(1-methyl-1 H-indazol-4-yl)ethan-1-one hydrobromide

To a mixture of 1-(1-methyl-1 H-indazol-4-yl)ethan-1-one (7000 mg; 40.2 mmol; 1.00 eq.) and hydrogen bromide solution (33 wt. % in acetic acid) (109.15 ml; 602.76 mmol; 15.00 eq.) in acetic acid (14.00 ml) was added bromine (2.26 ml; 44.20 mmol; 1.10 eq.) at 0°C and the mixture was stirred at room temperature for 2 h. 350 mL MTBE (50 mL for 1 g scale) was added and the precipitate was collected by filtration and rinsed with 350 mL MTBE (50 mL for 1g scale) to give 2-bromo-1-(1-methyl-1 H-indazol-4-yl)ethan-1-one hydrobromide as colorless solid (14.9 g).

1 H NMR (Bruker 400 MHz, DMSO) 5 8.45 (s, 1 H), 8.08 - 7.98 (m, 3H), 7.98 (s, 1 H), 7.63 - 7.51 (m, 2H), 5.03 (s, 2H). LC/MS (Waters UPLC/MS (COLUMN: ACQUITY UPLC@BEH C18 1.7 MICRON:ACQUITY UPLC® BEH C18 1.7pm; 5-95% ACN I Water (0.1% formic acid in both mobile phases), 1.5 min gradient)): [M+H]⁺ 253 and 255 m/z, Rt 0.97 min.

To a suspension of 2-bromo-1-(1-methyl-1 H-indazol-4-yl)ethan-1-one hydrobromide (14.90 g; 40.15 mmol; 1.00 eq.) in tetra hydrofuran (298 ml) at -78°C was added slowly (S)-(-)-1 -phenylethylamine (15.53 ml; 120.45 mmol; 3.00 eq.) followed by potassium carbonate (12.21 g; 88.33 mmol; 2.20 eq.). The mixture was stirred at -78°C for 5 minutes before warming to 0°C and stirring for 5 hrs.

The mixture was cooled to -78°C and lithium aluminum hydride (1M in tetrahydrofuran) (60.22 ml; 60.22 mmol; 1.50 eq.) was added slowly over 30 minutes and the mixture was stirred at - 78°C for 1 hr. Water was added, and the mixture was extracted with ethyl acetate. The combined organic layers were washed with brine and dried over Na2SO4. The solvent was removed in vacuo. The residue was purified by column chromatography (Biotage, Column Interchim 200g Si-Gel. 20-100% EtOAc / Hexanes) and the product was azeotroped 3 times with toluene to obtain 1-(1-methyl-1 H-indazol-4-yl)-2-{[(1S)-1-phenylethyl]amino}ethan-1-ol (10.10 g) as light yellow gum.

LC/MS (Waters UPLC/MS (COLUMN: ACQUITY UPLC@BEH C18 1.7 MICRON:ACQUITY UPLC® BEH C18 1.7pm; 5-95% ACN I Water (0.1% formic acid in both mobile phases), 1.5 min gradient)): [M+H]⁺ 296 m/z, Rt 1.49 min.

Synthesis of compounds of formula (I)

Examples were synthesised following general scheme C as described for Examples 14 and Example 15 in the following.

Intermediate 5-(benzyloxy)-4-oxo-1-{[2-(trimethylsilyl)ethoxy]methyl}-1 ,4-dihydropyridazine-3- carboxylic acid

At RT, N,O-bis(trimethylsilyl)-acetamide (52.1 ml; 212.4 mmol; 2.2 eq.) was added to a suspension of ethyl 5-(benzyloxy)-4-oxo-1 ,4-dihydropyridazine-3-carboxylate hydrochloride (30 g; 96 mmol; 1 eq.) in tert-butyl methyl ether (500 ml) and the mixture was stirred for 30 min. at RT. To the resulting solution, 2-(trimethylsilyl)ethoxymethyl chloride (25.6 ml; 144.8 mmol; 1.5 eq.) was added and the mixture was stirred for 4h at RT. The reaction mixture was quenched with saturated NaHCOs-solution to pH 4-5 and the phases were separated. To the separated organic layer was added aqueous sodium hydroxide solution (1 M) (193 ml; 193 mmol; 2 eq.) and the mixture was stirred at RT. The phases were separated. The aqueous layer was acidified to pH 2-3 by adding aqueous HCI (2 M). The resulting white solid was isolated by filtration, washed with water and dried at 50°C in vacuo to give 5-(benzyloxy)-4-oxo-1-{[2-(trimethylsilyl)eth- oxy]methyl}-1 ,4-dihydropyridazine-3-carboxylic acid (33,30 g; 88,451 mmol) as a colorless solid 33.3 g (92%)

LC/MS (Agilent 1200 Series, Chromolith HR RP-18e 50-4,6; 3.3ml/min; solvent A: Water + 0.1% TFA; solvent B: Acetonitrile + 0.1 % TFA; 220 nm; 0 to 2,0 min: 1 %B to 99%B; 2,0 to 2,5 min. 99%B): [M+H]⁺ 377.1 ; [M+Na]⁺ 399.1 ; purity 100 %, Rt 1.752 min.

Intermediate 5-(benzyloxy)-N-[2-hydroxy-2-(1-methyl-1 H-indazol-4-yl)ethyl]-4-oxo-N-[(1S)-1- phenylethyl]-1-{[2-(trimethylsilyl)ethoxy]methyl}-1 ,4-dihydropyridazine-3-carboxamide

HATLI (38 g; 100 mmol; 1.15 eq.) and N-ethyl di-isopropyl amine (44.7 ml; 3 eq.) was added to a suspension of 5-(benzyloxy)-4-oxo-1-{[2-(trimethylsilyl)ethoxy]methyl}-1 ,4-dihydropyridazine- 3-carboxylic acid (33 g; 1 eq.) in dichloromethane (600 ml) and the mixture was stirred for 1h at RT. 1-(1-Methyl-1 H-indazol-4-yl)-2-{[(1S)-1-phenylethyl]amino}ethan-1-ol (26.18 g; 1 eq.) was added and stirred for 1.5h. The reaction mixture was diluted with DCM and washed with water, aqueous HCI (1 M), saturated NaHCCh, and water. The separated organic layer was dried over Na2SC>4 and the solvent was removed in vacuo to afford 5-(benzyloxy)-N-[2-hydroxy-2-(1-me- thyl-1 H-indazol-4-yl)ethyl]-4-oxo-N-[(1S)-1-phenylethyl]-1-{[2-(trimethylsilyl)ethoxy]methyl}-1,4- dihydropyridazine-3-carboxamide as brown gum (79 g; quant).

LC/MS (LC-MS, Agilent 1200 Series, Chromolith HR RP-18e 50-4,6; 3.3ml/min; solvent A: Water + 0.1% TFA; solvent B: Acetonitrile + 0.1% TFA; 220 nm; 0 to 2,0 min: 1%B to 99%B; 2,0 to 2,5 min. 99%B): [M+H]⁺ 654.2; purity 80 %, (diastereomeric mixture 35% + 44.9% = 80%); Rt 1.926-1.962 min.

Intermediate 5-(benzyloxy)-N-[2-chloro-2-(1-methyl-1 H-indazol-4-yl)ethyl]-4-oxo-N-[(1S)-1-phe- nylethyl]-1-{[2-(trimethylsilyl)ethoxy]methyl}-1 ,4-dihydropyridazine-3-carboxamide

A solution of 5-(benzyloxy)-N-[2-hydroxy-2-(1-methyl-1 H-indazol-4-yl)ethyl]-4-oxo-N-[(1S)-1- phenylethyl]-1-{[2-(trimethylsilyl)ethoxy]methyl}-1,4-dihydropyridazine-3-carboxamide (79 g;

87.6 mmol; 1 eq.) in dichloromethane (500 ml) was cooled in ice/water and thionyl chloride (12.7 ml; 175.2 mmol; 2 eq.) was added dropwise and stirred for 45 minutes. The solvent and excess of thionyl chloride was removed in vacuo, the residue was redissolved in DCM and the solvent was removed in vacuo again to give crude 5-(benzyloxy)-N-[2-chloro-2-(1-methyl-1 H- indazol-4-yl)ethyl]-4-oxo-N-[(1S)-1-phenylethyl]-1-{[2-(trimethylsilyl)ethoxy]methyl}-1 ,4-dihydro- pyridazine-3-carboxamide as an orange foam (95 g; 100 %).

LCMS (Agilent 1200 Series, Chromolith HR RP-18e 50-4,6; 3.3ml/min; solvent A: Water + 0.1% TFA; solvent B: Acetonitrile + 0.1 % TFA; 220 nm; 0 to 2,0 min: 1 %B to 99%B; 2,0 to 2,5 min. 99%B): [M+H]⁺ 672.2 ; Rt 2.053 min.

Example 14 (8S)-4-hydroxy-8-(1-methyl-1 H-indazol-4-yl)-6-[(1S)-1-phenylethyl]-

3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3, 5-dione and Example 15 (8R)-4-hydroxy-8-(1-me- thyl-1 H-indazol-4-yl)-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3,5-di- one

Lithium bromide (3.3 ml; 131 mmol; 1.5 eq.) was added to a solution of 5-(benzyloxy)-N-[2- chloro-2-(1-methyl-1 H-indazol-4-yl)ethyl]-4-oxo-N-[(1S)-1-phenylethyl]-1-{[2-(trimethylsilyl)eth- oxy]methyl}-1 ,4-dihydropyridazine-3-carboxamide (95 g; 87.6; 1 eq.) in 1 ,4-dioxane (600 ml) and the mixture was heated to 130°C for 1.5h. After cooling to RT, the solvent was removed in vacuo. The residue was dissolved in DCM and was washed with water and brine. The separated organic layer was dried over Na2SO4 and concentrated in vacuo. The resulting solid residue was triturated with MTBE, filtered, and dried in vacuo to give 44 g of crude 4-hydroxy-8-(1- methyl-1 H-indazol-4-yl)-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3,5- dione. The crude product of this reaction was purified by column chromatography (C-18 Flash, EZ-prep in 8 runs, Teledyne-lsco CombiFlash EZ Prep, column: Redi Sep Rf C-18, 360 g, eluent: gradient Water+0,1 % HCOOH --> ACN+0,1 % HCOOH, flow-rate: 150 ml/min, detection: UV 214nm) and two diastereomers were separated.

The fractions containing Example 14 were combined and the ACN was evaporated in vacuo. To the aqueous residue was added saturated NaHCOs solution and the product was extracted with DCM. The separated organic layer was dried over Na2SO4 and concentrated in vacuo. The solid residue was triturated with ether, filtered and dried in vacuo at 50°C to give (8S)-4-hy- droxy-8-(1-methyl-1 H-indazol-4-yl)-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1 ,6-a]py- razine-3, 5-dione as beige solid (8.96 g).

LCMS (LC-MS, Agilent 1200 Series, Chromolith HR RP-18e 50-4,6; 3.3ml/min; solvent A: Water + 0.1% TFA; solvent B: Acetonitrile + 0.1% TFA; 220 nm; 0 to 2.0 min: 1 %B to 99%B; 2.0 to 2.5 min. 99%B): [M+H]⁺ 416.1 ; purity 100 %, Rt 1.365 min.

The fractions containing Example 15 were combined and the ACN was removed in vacuo. To the aqueous residue was added saturated NaHCCh solution and the product was extracted with DCM. The separated organic layer was dried over Na2SC>4 and concentrated in vacuo. The residue was triturated with ether, filtered and dried in vacuo at 50°C to give (8R)-4-hydroxy-8-(1- methyl-1 H-indazol-4-yl)-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3,5- dione as a beige solid (6.37 g).

LC/MS (Agilent 1200 Series, Chromolith HR RP-18e 50-4,6; 3.3ml/min; solvent A: Water + 0.1% TFA; solvent B: Acetonitrile + 0.1 % TFA; 220 nm; 0 to 2,0 min: 1 %B to 99%B; 2,0 to 2,5 min. 99%B): [M+H]⁺ 416.1 ; purity 98.1 %, Rt 1.462 min.

Alternative route to Scheme C for the synthesis of Examples 14 and 15 without protecting group: Intermediate 5-(benzyloxy)-N-[2-hydroxy-2-(1-methyl-1 H-indazol-4-yl)ethyl]-4-oxo-N-[(1S)-1- phenylethyl]-1 ,4-dihydropyridazine-3-carboxamide

To a mixture of 1-(1-methyl-1 H-indazol-4-yl)-2-{[(1S)-1-phenylethyl]amino}ethan-1-ol (1.50 g; 4.88 mmol; 1.00 eq.) and 5-(benzyloxy)-4-oxo-1 ,4-dihydropyridazine-3-carboxylic acid (1.81 g; 7.32 mmol; 1.50 eq.) in DMF (15.00 ml) was added DIEA (2.65 g; 19.52 mmol; 4.00 eq.) and BOP (3.41 g; 7.32 mmol; 1.50 eq.) at room temperature. The resulting mixture was stirred for 12 h at room temperature. The resulting mixture was poured into water and extracted with EA. The combined organic layers were washed with brine and dried over anhydrous Na2SO4. After filtration, the solvent was removed in vacuo. The residue was purified by column chromatography (CH2Cl2:MeOH (10:1)) to afford 5-(benzyloxy)-N-[2-hydroxy-2-(1-methyl-1 H-indazol-4-yl)ethyl]-4- oxo-N-[(1S)-1-phenylethyl]-1 ,4-dihydropyridazine-3-carboxamide as light yellow solid (2.20 g). LC/MS (HALO C18; Mobile Phase A:Water/0.1 % FA, Mobile Phase B: ACN/0.1% FA): purity 83.09 %, Rt 0.866 min; [M+H]⁺ 524.25.

Intermediate 5-(benzyloxy)-N-[2-chloro-2-(1-methyl-1 H-indazol-4-yl)ethyl]-4-oxo-N-[(1S)-1-phe- nylethyl]-1 ,4-dihydropyridazine-3-carboxamide

To a solution of 5-(benzyloxy)-N-[2-hydroxy-2-(1-methyl-1 H-indazol-4-yl)ethyl]-4-oxo-N-[(1S)-1- phenylethyl]-1 ,4-dihydropyridazine-3-carboxamide (1.00 g; 1.59 mmol; 1.00 eq.) in DCM (20.00 ml) was added SOCh (3.97 g; 31.70 mmol; 20.00 eq.) at room temperature. The resulting mixture was stirred for 2 h at room temperature. The solvent was removed in vacuo to afford 5- (benzyloxy)-N-[2-chloro-2-(1-methyl-1 H-indazol-4-yl)ethyl]-4-oxo-N-[(1S)-1-phenylethyl]-1 ,4-di- hydropyridazine-3-carboxamide as light yellow solid (2.60 g). LC/MS (HALO C18;Mobile Phase A:Water/0.1% FA, Mobile Phase B: ACN/0.1% FA): Purity 11.74%, Rt 0.939 min, [M-H]’ 540.1.

4-hydroxy-8-(1-methyl-1 H-indazol-4-yl)-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1,6- a]pyrazine-3, 5-dione

A solution of 5-(benzyloxy)-N-[2-chloro-2-(1-methyl-1 H-indazol-4-yl)ethyl]-4-oxo-N-[(1S)-1-phe- nylethyl]-1,4-dihydropyridazine-3-carboxamide (2.50 g; 0.54 mmol; 1.00 eq.) in dioxane-1 ,4 (20.00 ml) was stirred for 1 h at 130°C. The mixture was allowed to cool to room temperature and the solvent was removed in vacuo. The residue was purified by column chromatography (CH2Cl2:MeOH (10:1)) to afford 4-hydroxy-8-(1-methyl-1 H-indazol-4-yl)-6-[(1S)-1-phenylethyl]- 3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine-3, 5-dione as light brown solid (240 mg).

LC/MS (HALO C18;Mobile Phase A:Water/0.1% FA, Mobile Phase B: ACN/0.1% FA): purity: 83.7 %, Rt 0.561 min; [M+H]⁺ 416.05.

Separation into both stereoisomers Example 14 and Example 15 can be achieved as described above.

The examples of Table 1 were prepared according to Scheme C and the procedures described for Example 14 and Example 15 above using the appropriate aminoethanol intermediate, wherein the aminoethanol intermediate is prepared from the appropriate starting materials according to Scheme B and the procedures described above for amino alcohol intermediate 1-(1- methyl-1 H-indazol-4-yl)-2-{[(1S)-1-phenylethyl]amino}ethan-1-ol.

Table 1

^tereoinformation regarding the stereocenter at position 8 is assigned arbitrarily in both the structural formula and the IUPAC name.

Synthesis of Example 38 and Example 39 Example 38 and Example 39 were prepared from 4-hydroxy-6-[(1S)-1-phenylethyl]-8-(pyridin-2- yl)-3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine-3, 5-dione (mixture of Example 5 and Example 6 before chromatographic separation) as described in the following.

Intermediate 4-(benzyloxy)-6-[(1S)-1-phenylethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyri- dazino[1 ,6-a]pyrazine-3, 5-dione To a stirred mixture of 4-hydroxy-6-[(1S)-1-phenylethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyri- dazino[1 ,6-a]pyrazine-3, 5-dione (1.00 g; 2.76 mmol; 1.00 eq.) and (bromomethyl)benzene (745.00 mg; 4.14 mmol; 1.50 eq.) in DMF (10.00 ml) was added K2CO3 (802.00 mg; 5.51 mmol; 2.00 eq.) at room temperature under N2 atmosphere. The resulting mixture was stirred 2h at 80°C. The resulting mixture was diluted with water. The aqueous layer was extracted with EtOAc. The combined organic layers were washed with brine and dried over anhydrous Na2SC>4. The resulting mixture was concentrated under vacuum. The residue was purified by column chromatography (PE/EtOAc) to afford 4-(benzyloxy)-6-[(1S)-1-phenylethyl]-8-(pyridin-2- yl)-3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3, 5-dione (780.00 mg) as yellow solid.

LCMS (Shim-Pack C18; Mobile phase A: water/5mM NH4HCO3; Mobile phase B: acetonitrile): purity 100.00 %, Rt 0.52 min., [M+H]⁺ 453.00 m/z.

Intermediate 4-(benzyloxy)-2-chloro-6-[(1S)-1-phenylethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyr- idazino[1 ,6-a]pyrazine-3, 5-dione

To a stirred mixture of 4-(benzyloxy)-6-[(1S)-1-phenylethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H- pyridazino[1 ,6-a]pyrazine-3, 5-dione (780.00 mg; 1.72 mmol; 1.00 eq.) in ACN (10.00 ml) was added NCS (484.00 mg; 3.44 mmol; 2.00 eq.) at room temperature under N2 atmosphere. The resulting mixture was stirred 2h at 80°C. The resulting mixture was concentrated under vacuum. The residue was purified by column chromatography (PE/EtOAc) to afford 4-(benzyloxy)-2- chloro-6-[(1S)-1-phenylethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3,5-di- one (500.00 mg) as yellow solid.

LCMS (HALO C18;Mobile Phase A :Water+0.05%TFA;Mobile Phase B:ACN+0.05%TFA): purity 100.00 %, Rt 0.85 min., [M+H]⁺ 487.00 m/z.

Intermediate 4-(benzyloxy)-2-methyl-6-[(1S)-1-phenylethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H- pyridazino[1 ,6-a]pyrazine-3, 5-dione

To a stirred mixture of 4-(benzyloxy)-2-chloro-6-[(1S)-1-phenylethyl]-8-(pyridin-2-yl)- 3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3, 5-dione (200.00 mg; 0.41 mmol; 1.00 eq.) and methylboronic acid (104.00 mg; 1.65 mmol; 4.02 eq.) in THF (4.00 ml) and H2O (1.00 ml) was added K2CO3 (180.00 mg; 1.24 mmol; 3.01 eq.) and PdAMPHOS (92.00 mg; 0.12 mmol; 0.30 eq.) at room temperature under N2 atmosphere. The resulting mixture was stirred 2h at 80°C. The resulting mixture was concentrated under vacuum. The residue was purified by column chromatography (PE/EtOAc) to afford 4-(benzyloxy)-2-methyl-6-[(1S)-1-phenylethyl]-8-(pyridin- 2-yl)-3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3, 5-dione (80.00 mg) as yellow solid.

LCMS (HALO C18;Mobile Phase A :Water+0.05%TFA;Mobile Phase B:ACN+0.05%TFA): purity 85.55 %, Rt 0.66 min., [M+H]⁺ 467.00 m/z.

Intermediate 4-hydroxy-2-methyl-6-[(1S)-1-phenylethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyri- dazino[1 ,6-a]pyrazine-3, 5-dione

4-(benzyloxy)-2-methyl-6-[(1S)-1-phenylethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyridazino[1 ,6- a]pyrazine-3, 5-dione (80.00 mg; 0.15 mmol; 1.00 eq.) was added to TFA (1.00 ml) at room temperature under N2 atmosphere and stirred 2h at 80°C. The resulting mixture was concentrated under reduced pressure to afford 4-hydroxy-2-methyl-6-[(1S)-1-phenylethyl]-8-(pyridin-2-yl)- 3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3, 5-dione (40.00 mg) as yellow solid.

LCMS(HALO C18;Mobile Phase A :Water+0.05%TFA; Mobile Phase B: ACN+0.05%TFA): purity 41.71 %, Rt 0.54 min., [M+H]⁺ 377.00 m/z.

Example 38 and Example 39: (8S)-4-hydroxy-2-methyl-6-[(1S)-1-phenylethyl]-8-(pyridin-2-yl)- 3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3, 5-dione and (8R)-4-hydroxy-2-methyl-6-[(1S)-1- phenylethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3, 5-dione (stereocenter at 8 position arbitrarily assigned).

4-hydroxy-2-methyl-6-[(1S)-1-phenylethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyridazino[1 ,6-a]py- razine-3, 5-dione (40.00 mg; 0.044 mmol; 1.000 eq.) was separated in both diastereoisomers by column chromatography (Column: Xselect CSH C18 OBD Column, 30*150 mm, 5pm; Mobile Phase A: Water(0.1 % FA), Mobile Phase B: ACN; Flow rate: 60 mL/min; Gradient: 20% B to 40% B in 10 min; Wave Length: 254nm) to afford examples 38 and 39 with randomly assigned stereocenter at 8 position.

Example 38: (8S)-4-hydroxy-2-methyl-6-[(1S)-1-phenylethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H- pyridazino[1 ,6-a]pyrazine-3, 5-dione (4.30 mg)

1 H NMR (400 MHz, DMSO-d6) <5 8.53 (d, J = 4.7 Hz, 1 H), 7.92 "C 7.84 (m, 1 H), 7.43 "C 7.26 (m, 7H), 5.83 (d, J = 3.7 Hz, 1 H), 5.68 (q, J = 7.0 Hz, 1 H), 3.86 (dd, J = 13.8, 4.0 Hz, 1 H), 3.71 (dd, J = 13.7, 2.1 Hz, 1 H), 2.17 (s, 3H), 0.87 (d, J = 7.0 Hz, 3H), LCMS (Column: HALO C18, 2 pm, 3.0 x 30 mm, Column Oven: 40C;Mobile phase A:Water/0.1 % FA; Mobile phase B:Acetoni- trile/0.1 % FA; Flow rate: 1.5 mL/min; Gradient:5%B to 100%B in 1.2 min, hold 0.5 min; 254nm): purity 96.21 %, Rt 0.77 min., [M+H]⁺ 377.00 m/z.

Example 39: (8R)-4-hydroxy-2-methyl-6-[(1S)-1-phenylethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H- pyridazino[1 ,6-a]pyrazine-3, 5-dione (10.70 mg;).

1 H NMR (400 MHz, DMSO-d6) 5 8.28 (d, J = 4.7 Hz, 1 H), 7.60 (dd, J = 8.8, 6.9 Hz, 1 H), 7.26 (dd, J = 7.5, 4.9 Hz, 1 H), 7.11 (t, J = 7.3 Hz, 1 H), 7.04 "C 6.91 (m, 3H), 6.74 (d, J = 7.6 Hz, 2H), 5.82 "C 5.66 (m, 2H), 4.31 (dd, J = 13.5, 4.1 Hz, 1 H), 3.50 (d, J = 13.3 Hz, 1 H), 2.17 (s, 3H), 1.52 (d, J = 7.1 Hz, 3H); LCMS (Column: HALO C18, 2 pm, 3.0 x 30 mm, Column Oven: 40C;Mobile phase A:Water/0.1 % FA; Mobile phase B:Acetonitrile/0.1% FA; Flow rate: 1.5 mL/min; Gradient:5%B to 100%B in 1.2 min, hold 0.5 min; 254nm): purity 98.18 %, Rt 0.72 min., [M+H]⁺ 377.05 m/z.

BIOLOGICAL DATA

EXO1 nuclease assay - determination of EXO1 inhibition (IC50 EXO1):

The IC50 values were determined by a biochemical EXO1 nuclease assay. EXO1 (Exonuclease 1) exhibits both 5' to 3' exonuclease as well as endonuclease activity. A mixture of EXO1 protein and the test substance were incubated at different concentrations with addition of fluorescently labelled 5’ pseudo Y DNA substrate. Cleavage of a FAM I BHQ1 dual labelled pseudo Y DNA substrate released the fluorescently tagged oligonucleotide causing an increase in fluorescent signal that is proportional to the amount of product generated.

In detail: The enzymatic EXO1 assay was carried out as Fluorescence Intensity (Fl) based 384- well assay. Purified human recombinant EXO1 (human EXO1 , full length, UniProt ID Q9UQ84, expressed in E. coli) was incubated in assay buffer for 30 minutes with the EXO1 inhibitor in various concentrations and without test substance as negative or neutral control. The assay buffer comprised 20 mM TRIS pH 7.5, 5 % (v/v) Glycerol, 5 mM MgCI2, 1 mM DTT, 0.01 % (v/v) IGEPAL® CA-630. The test-substance solutions were dispensed into the microtitre plates using a Hummingbird capillary pipettor (Hummingbird Nano). Reactions were initiated by the addition of FAM I BHQ1 dual labelled pseudo Y DNA substrate (generated by annealing of oligo 1 : CTAAGTTCGTCAGGATTCCACACAG-[FAM], oligo 2: CGCTATGACTGTTAGAATGCT-[BHQ]- GGAATCCTGACGAACTTAG (Integrated DNA Technologies)) in assay buffer. The pharmacologically relevant assay volume was 5 pl. The final concentrations in the assay during incubation of the reaction mixture were 1 .2 - 1 .6 nM EXO1 and 40 nM DNA substrate. After 60 min at room temperature, reactions were quenched by the addition of 3 pl of stop buffer (270 mM EDTA, 45 mM TRIS pH 7.5). The plates were analysed in a plate reader (PheraStar FSX, BMG LabTech) measuring fluorescence at 520 nm following excitation at 485 nm. The amount of product generated is directly proportional to the amounts of light emitted, i.e. the relative fluorescence units (RFU) at 520 nm. The measurement data were processed by means of the Genedata Screener software. In particular, IC50 values were determined by fitting a dose-response curve to the data points using nonlinear regression analysis.

IC50 = half-maximum inhibitory concentration

FAM = Carboxyfluorescein

BHQ1 = Black Hole Quencher 1

TRIS = Tris(hydroxymethyl)aminomethane

MgCh = magnesium chloride DTT = dithiothreitol

EDTA = ethylenediamine tetraacetate

Results

The results are summarized in Table Ex-1 below, wherein the following classifications were applied.

EXO1 IC50: A: IC50 < 100 nm; B: 100 nM < IC50 < 1000 nM; C: 1000 nM < IC50 < 10000 nM;

D: 10000 nM < IC50 < 100 pM

Table Ex-1

Claims

1 . A compound of formula (I) or a stereoisomer, tautomer, /V-oxide, or pharmaceutically acceptable salt thereof; wherein

R⁴ is H or Ci-C4-alkyl; and

R⁵ is H, Ci-C₄-alkyl, Ci-C₄-alkoxy, or C(=O)NR^N1R^N2; and wherein

R^x is halogen or Ci-C4-alkyl;

R^Y1 is halogen or Ci-C4-alkyl;

R^Y2 is halogen or Ci-C4-alkyl;

R^z is halogen, Ci-C4-alkyl, or Ci-C4-haloalkyl;

R^N1 is H or Ci-C4-alkyl; and

R^N2 is H or Ci-C4-alkyl.

2. The compound according to claim 1 , wherein the compound is a compound of formula (IA)

3. The compound according to claim 1 or 2, wherein

R^x is halogen or Ci-C2-alkyl.

4. The compound according to any one of claims 1 to 3, wherein

R^x is Cl or F.

5. The compound according to any one of claims 1 to 4, wherein

6. The compound according to any one of claims 1 to 5, wherein

R² is methyl; or R² and R^x, if present, together with the atoms by which they are connected form a fused 6- membered partially unsaturated carbocyclyl; and wherein preferably

R² is methyl.

7. The compound according to any one of claims 1 to 6, wherein

R³ is a 6-membered aromatic carbocyclyl, carbocyclyl-Ci-alkyl, heterocyclyl, heterocyclyl- Ci-alkyl, or an 9- or 10-membered aromatic carbobicyclyl or heterobicyclyl, wherein the aforementioned heterocyclic and heterobicyclic rings independently comprise one or more, same or different heteroatoms selected from O, N, or S, wherein said N- and/or S- atoms are independently oxidized or non-oxidized, and wherein each of the aforementioned aromatic rings is independently unsubstituted or substituted with one or more, same or different, substituents R^z; wherein

R^z is halogen, Ci-C2-alkyl, or Ci-C2-haloalkyl; and wherein preferably

R^z is F, CH₃, or CF₃.

8. The compound according to any one of claims 1 to 7, wherein R⁴ is H or CH₃, preferably H.

9. The compound according to any one of claims 1 to 8, wherein

R⁵ is H or CH₃, preferably H.

10. The compound according to any one of claims 1 to 9, wherein the compound is a compound of formula (IA-1)

11. The compound according to any one of claims 1 to 9, wherein the compound is a compound of formula (IA-2)

12. The compound according to any one of claims 1 to 11 , wherein the compound of formula

(I) is selected from the group consisting of:

(8R)-4-hydroxy-8-(1-methyl-1 H-indazol-4-yl)-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyri- dazino[1,6-a]pyrazine-3, 5-dione; 8-(4-fluorophenyl)-4-hydroxy-6-[(1S)-1-phenylethyl]-3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine- 3,5-dione;

3H,5H,6H,7H,8H-pyridazino[1,6-a]pyrazine-3, 5-dione;

(8S)-6-[(1S)-1-(4-fluorophenyl)ethyl]-4-hydroxy-8-(1-methyl-1 H-indazol-4-yl)-3H,5H,6H,7H,8H- pyridazino[1,6-a]pyrazine-3, 5-dione; 4-hydroxy-6-[(1 S)-1 -(1 -methyl-1 H-indazol-5-yl)ethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyri- dazino[1 , 6-a]pyrazine-3,5-dione;(8R)-4-hydroxy-6-[(1S)-1-(1 -methyl-1 H-indazol-5-yl)ethyl]-8- (pyridin-2-yl)-3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3, 5-dione;

(8S)-4-hydroxy-6-[(1 S)-1-(1 -methyl-1 H-indazol-5-yl)ethyl]-8-(pyridin-2-yl)-3H,5H,6H,7H,8H-pyri- dazino[1 ,6-a]pyrazine-3, 5-dione;

4-hydroxy-8-(1 -methyl-1 H-indazol-4-yl)-6-[(1S)-1-phenylpropyl]-3H,5H,6H,7H,8H-pyridazino[1 , 6- a]pyrazine-3, 5-dione;

(8S)-4-hydroxy-8-(1 -methyl-1 H-indazol-4-yl)-6-[(1S)-1-phenylpropyl]-3H,5H,6H,7H,8H-pyri- dazino[1 ,6-a]pyrazine-3, 5-dione;

(8R)-4-hydroxy-8-(1 -methyl-1 H-indazol-4-yl)-6-[(1S)-1-phenylpropyl]-3H,5H,6H,7H,8H-pyri- dazino[1 ,6-a]pyrazine-3, 5-dione;

6-(diphenylmethyl)-4-hydroxy-8-(1 -methyl-1 H-indazol-4-yl)-3H,5H,6H,7H,8H-pyridazino[1 , 6- a]pyrazine-3, 5-dione; and

(8R)-4-hydroxy-8-(1 -methyl-1 H-indazol-4-yl)-6-[(1S)-1 , 2, 3, 4-tetrahydronaphthalen-1-yl]- 3H,5H,6H,7H,8H-pyridazino[1 ,6-a]pyrazine-3, 5-dione.

13. A pharmaceutical composition comprising a pharmaceutically effective amount of the compound according to any one of claims 1 to 12 and optionally a pharmaceutically acceptable carrier, diluent or excipient.

14. A compound according to any one of claims 1 to 12 or a pharmaceutical composition according to claim 13 for use in medicine.

15. A compound according to any one of claims 1 to 12 or a pharmaceutical composition according to claim 13 for use in the treatment of cancer, preferably for use in the treatment of a cancer selected from the group consisting of hepatocellular carcinoma (HCC), glioma, colon cancer/colorectal cancer, in particular nonpolyposis colorectal cancer (HNPCC), breast cancer, ovarian cancer, lung cancer, pancreatic cancer, gastric tract cancer, cancer of the small intestine, oral cancer, and cervical cancer.