WO2009145719A1 - Isoindoline derivatives comprising a cyano group and their use in the treatment of pain disorders - Google Patents

Abstract

Compounds of formula I are claimed, wherein R¹ is hydrogen, C_{1_3}alkyl, C_{1_3}alkoxy, cyano, hydroxy or halo; and wherein said C_1-3alkyl is optionally substituted by one or more substituents independently selected from hydroxy, C_{1_3}alkoxy andfluoro; and said C_{1_3}alkoxy is optionally substituted by one or more fluoro; m is 1, 2 or 3; R² and R³ is each and independently selected from hydrogen, C_1-4haloalkyl, C_1-4haloalkoxy, halo, C_1-4alkoxy, C_1-4alkyl and C_{3_7}Cycloalkyloxy; wherein said C_{3_7}cycloalkyloxy is optionally substituted by one or more fluoro; and R² and R³ may not both be hydrogen; L₁ is C_1-4alkylene, pentylene, or C_3-6 cycloalkylene, wherein said C_1-4alkylene, pentylene or C_3-6 cycloalkylene may be optionally substituted by one or more X⁴; X⁴ is fluoro, C_{1_3}alkyl, C_{3_7}Cycloalkyl, C_{1_3}alkylOCi_3alkyl, C_{1_3}alkoxy, cyano, hydroxy, R⁴O(C=O)-, R⁴NR⁵(C=O)-, R⁴O(C=O)NR⁵-, R⁴NR⁵(C=O)NR⁵-, R⁴(C=O)O-, R⁴(C=O)NR5-, R⁴NR⁵(C=O)O-, R⁴NR⁵⁽C=O)NR⁵-, C_5-6 heteroaryl(C=O), or C_5-6 heteroaryl; R⁴ is C_1-4 alkylOC_1-4 alkyl, C_5-6 cycloalkyl, aryl, or aryl-C_1-2 alkyl; R⁵ is H or methyl; and wherein said C_1-3 alkylOC_1-3alkyl, C_1-3alkoxy and C_1-4alkylsulfonyl is optionally substituted by one or more fluoro; L₂ is C_1-3 alkylene, optionally substituted by one or more X⁴; as well as pharmaceutically acceptable salt, or isomer thereof, or a salt of said isomer. Compounds of the invention are useful in therapy, such as pain therapy.

Description

Isoindoline derivatives comprising a cyano group and their use in the treatment of pain disorders

FIELD OF THE INVENTION

The present invention relates to new compounds, to a pharmaceutical composition containing said compounds and to the use of said compounds in therapy. The present invention also relates to processes for the preparation of said compounds.

BACKGROUND

The current treatment regimes for pain conditions utilise compounds which exploit a very limited range of pharmacological mechanisms. One class of compounds, the opioids, stimulates the endogenous endorphine system; an example from this class is morphine. Compounds of the opioid class have several drawbacks that limit their use, e.g. emetic and constipatory effects and negative influence on respiratory capability. The second major class of analgesics, the non-steroidal antiinflammatory analgesics of the COX-I or COX-2 types, also have liabilities such as insufficient efficacy in severe pain conditions and at long term use the COX-I inhibitors cause ulcers of the mucosa. Mechanisms of analgesic effects of other currently used medicines are insufficiently characterized and/or have limited therapeutic potential.

Local anesthetics, that are known to block most types of sodium channels in nerves, are useful for relieving pain in small areas of the human body and for blocking nerve conduction from the periphery to the central nervous system. They can also be used in the last-mentioned way to block sensory signalling by instilling solutions of local anesthetics at the spinal cord. Due to their high toxicity, in particular heart toxicity, they can not, however, be used for systemic administration as generally useful analgesics. There remains thus a need for more selective modulators of sodium channels involved in pain signal conduction.

Nine sodium channel subtypes have been cloned and functionally expressed to date. (Wood JN, Baker M.. Current Opinion in Pharmacology 2001, 1, 17-21). They are differentially expressed throughout muscle and nerve tissues and show distinct biophysical properties. All voltage-gated sodium channels (NaV:s) are characterized by a high degree of selectivity for sodium over other ions and by their voltage-dependent gating. By application of genetic analysis it has been shown that a mutation in the gene coding for sodium channel NaVl .7, making this protein non-functional, can make a human become almost insensitive to pain (Cox JJ et al. Nature 2006, 444, 894-898).

It is well known that the voltage-gated sodium channels in nerves play a critical role in neuropathic pain (Baker MD and Wood JN. Trends in Pharmacological Sciences 2001, 22, 27-31). Injuries of the peripheral nervous system often result in neuropathic pain persisting long after the initial injury resolves. Examples of neuropathic pain include, but are not limited to, postherpetic neuralgia, trigeminal neuralgia, diabetic neuropathy, chronic lower back pain, phantom limb pain, pain resulting from cancer and chemotherapy, chronic pelvic pain, complex regional pain syndrome and related neuralgias. It has been shown in human patients as well as in animal models of neuropathic pain, that damage to primary afferent sensory neurons can lead to neuroma formation and spontaneous activity, as well as evoked activity in response to normally innocuous stimuli. NaVl .7 is expressed in human neuromas, which are swollen and hypersensitive nerves and nerve endings that are often present in chronic pain states {Acta Neurochirurgica 2002, 144, 803-810).

In rat models of peripheral nerve injury, ectopic activity in the injured nerve corresponds to the behavioral signs of pain. In these models, intravenous application of the sodium channel blocker and local anesthetic lidocaine can suppress the ectopic activity and reverse the tactile allodynia at concentrations that do not affect general behavior and motor function (Mao J and Chen LL, Pain, 2000, 87, 7-17).

In addition to neuropathic pain, sodium channel blockers have clinical uses in the treatment of epilepsy and cardiac arrhythmias. Recent evidence from animal models suggests that sodium channel blockers may also be useful for neuroprotection under ischaemic conditions caused by stroke or neural trauma and in patients with multiple sclerosis (MS). DISCLOSURE OF THE INVENTION

According to the invention there is provided a compound of formula I

wherein

R¹ is hydrogen, Ci_3alkyl, Ci_3alkoxy, cyano, hydroxy or halo; and wherein said Cisalkyl is optionally substituted by one or more substituents independently selected from hydroxy,

andfluoro; and said

is optionally substituted by one or more fluoro;

m is 1, 2 or 3;

R² and R³ is each and independently selected from hydrogen, C^haloalkyl, Ci_4haloalkoxy, halo, Ci_4alkoxy, Ci_4alkyl and C3_7Cycloalkyloxy; wherein said Cs.ycycloalkyloxy is optionally substituted by one or more fluoro; and R² and R³ may not both be hydrogen;

Li is Ci_4alkylene, pentylene or C_3-6 cycloalkylene, wherein said

pentylene or Ci-6 cycloalkylene may be optionally substituted by one or more X*;

X⁴ is fluoro, Ci_₃alkyl, C₃_₇cycloalkyl, Ci_₃alkyl0Ci_₃alkyl, Ci_₃alkoxy, cyano, hydroxy, R⁴O(C=O)-, R⁴NR⁵(C=O)-, R⁴O(C=O)NR⁵-, R⁴NR⁵(C=O)NR⁵-, R⁴(C=O)O-, R⁴(C=O)NR⁵-, R⁴NR⁵(C=O)O- , R⁴NR⁵(C=O)NR⁵-, C₅.₆ heteroaryl(C=O), or C5_6 heteroaryl; R⁴ is Ci_₄alkyl, Ci_₄alkylOCi_₄alkyl, Cs_₆cycloalkyl, aryl, or aryl-Ci_₂alkyl; R⁵ is H or methyl;

and wherein said C1.3a.lkyl,

and

is optionally substituted by one or more fluoro;

L₂ is Ci_3alkylene, optionally substituted by one or more X*;

as well as a pharmaceutically acceptable salt, or isomer thereof, or a salt of said isomer.

Yet an embodiment of the invention, is a compound of formula I, wherein

R¹ is hydrogen, Ci_₃alkyl, Ci_₃alkoxy, or halo; m is 1;

R² and R³ is each and independently selected from hydrogen, C^haloalkyl,

Ci_4haloalkoxy, and Ci_4alkyl;

Li is Ci_4alkylene, pentylene or C_3-6 cycloalkylene, wherein said

pentylene or

C3-6 cycloalkylene may be optionally substituted by one or more X*; X⁴ is Ci_₃alkyl; and

L₂ is Ci_3alkylene.

One embodiment of the invention is a compound of formula I, wherein Li is an ethylene group.

Yet an embodiment of the invention is a compound of formula I, wherein Li is a methylene group.

Yet an embodiment of the invention is a compound of formula I, wherein Li is a pentylene group. Yet an embodiment of the invention is a compound of formula I, wherein Li is cyclohexylene.

Yet an embodiment of the invention is a compound of formula I, wherein Li is

4 substituted by at least one X .

4

Yet an embodiment of the invention is a compound of formula I, wherein X is methyl.

Still an embodiment of the invention is a compound of formula I, wherein L2 is a methylene group.

Yet an embodiment of the invention is a compound of formula I, wherein L2 is substituted

4 by at least one X .

4

Yet an embodiment of the invention is a compound of formula I, wherein X is methyl.

Still an embodiment of the invention is a compound of formula I, wherein m is 1.

One embodiment of the invention is a compound of formula I , wherein R is hydrogen.

Yet an embodiment of the invention is a compound of formula I, wherein R is methoxy.

Yet an embodiment of the invention is a compound of formula I, wherein R is methyl.

Yet an embodiment of the invention is a compound of formula I, wherein R is fluoro.

2 One embodiment of the invention is a compound of formula I , wherein R is hydrogen. 2 Yet an embodiment of the invention is a compound of formula I, wherein R is -OCF3.

2 Yet an embodiment of the invention is a compound of formula I, wherein R is -CH2-CF3.

3

A compound according to any one of the preceding claims, wherein R is hydrogen.

One embodiment of the invention is a compound of formula I , wherein R is -OCF3.

3 Yet an embodiment of the invention is a compound of formula I, wherein R is methyl.

Yet an embodiment of the invention is a compound selected from any one of:

2-(2-Cyanoethyl)-3-oxo-N-(4-(trifluoromethoxy)benzyl)isoindoline-l-carboxamide; 2-((trα/?5)-4-Cyanocyclohexyl)-3-oxo-N-(4-(trifluoromethoxy)benzyl)isoindoline-l- carboxamide ;

2-((cis)-4-Cyanocyclohexyl)-3-oxo-N-(4-(trifluoromethoxy)benzyl)isoindoline-l- carboxamide;

2-(2-Cyanoethyl)-7-methoxy-3-oxo-N-(4-(trifluoromethoxy)benzyl)isoindoline-l- carboxamide;

2-(2-Cyanoethyl)-7-methyl-3-oxo-N-(4-(trifluoromethoxy)benzyl)isoindoline-l- carboxamide;

2-(2-Cyanoethyl)-3-oxo-N-(l-(4-(trifluoromethoxy)phenyl)ethyl)isoindoline-l- carboxamide, ISOMER 4; 2-(2-Cyanoethyl)-3-oxo-N-(3-(trifluoromethoxy)benzyl)isoindoline- 1 -carboxamide;

2-(2-Cyanoethyl)-N-(2-methyl-4-(trifluoromethoxy)benzyl)-3-oxoisoindoline-l- carboxamide;

2-(2-Cyanoethyl)-4-fluoro-3-oxo-N-(4-(trifluoromethoxy)benzyl)isoindoline-l- carboxamide; 2-(2-Cyanoethyl)-7-fluoro-3-oxo-N-(4-(trifluoromethoxy)benzyl)isoindoline- 1 - carboxamide; 2-(Cyanomethyl)-3 -oxo-N-(4-(trifluoromethoxy)benzyl)isoindoline- 1 -carboxamide; 2-(l-Cyanopropan-2-yl)-3-oxo-N-(4-(trifluoromethoxy)benzyl)isoindoline-l- carboxamide ;

2-(3 -Cyano-3 -methylbutyl)-3 -oxo-N-(4-(trifluoromethoxy)benzyl)isoindoline- 1 - carboxamide;

2-(5-Cyanopentyl)-3-oxo-N-(4-(trifluoromethoxy)benzyl)isoindoline-l -carboxamide; and 2-(2-Cyanoethyl)-3-oxo-N-(4-(2,2,2-trifluoroethyl)benzyl)isoindoline-l -carboxamide.

For the avoidance of doubt it is to be understood that in this specification 'C_1-6' means a carbon containing group having 1, 2, 3, 4, 5 or 6 carbon atoms.

In this specification, unless stated otherwise, the term "alkyl" includes both straight and branched chain alkyl groups and may be, but are not limited to methyl, ethyl, n-propyl, i- propyl, n-butyl, i-butyl, s-butyl, t-butyl, n-pentyl, i-pentyl, neo-pentyl, n-hexyl or i-hexyl. The term Ci_₄alkyl having 1 to 4 carbon atoms and may be but are not limited to methyl, ethyl, n-propyl, i-propyl or tert-butyl.

The term Ci_4alkyl as used herein is defined as a straight, branched or cyclic (cyclic where at least three carbon atoms are present) alkyl chain, having from 1 to 4 carbon atoms and may be but are not limited to methyl, ethyl, n-propyl, i-propyl, cyclopropyl, cyclobutyl or tert-butyl. The term Ci_3 alkyl as used herein is defined as a straight, branched or cyclic alkyl chain (cyclic when three carbon atoms are present), having from 1 to 3 carbon atoms, namely: methyl, ethyl, n-propyl, iso-propyl, or cyclopropyl.

The term Ci_4alkylene as used herein for I4 may be a straight, branched or cyclic alkylene group, and includes but is not limited to, a methylene, ethylene, n-propylene, i-propylene, n-butylene, iso-butylene, and te/t-butylene hydrocarbon chain. Each such I4 group may

4 optionally be substituted by one or more X as defined throughout the present specification and claims. The term Ci_₃alkylene as used herein for L₂, may be a straight, branched or cyclic alkylene group, and includes but is not limited to a methylene, ethylene, n-propylene, and i- propylene hydrocarbon chain. Each such L₂ group may optionally be substituted by one or

4 more X as defined throughout the present specification and claims.

The term "C3-6 cycloalkylene" used herein for Li, includes cyclopropylene, cyclobutylene, cyclopentylene, and cyclohexylene. Each such Li group may optionally be substituted by

4 one or more X as defined throughout the present specification and claims.

The term "alkoxy", unless stated otherwise, refers to radicals of the general formula -O-R, wherein R is selected from a hydrocarbon radical. The term "Ci_₆alkoxy" may include, but is not limited to methoxy, ethoxy, propoxy, isopropoxy, butoxy, t-butoxy, isobutoxy, cyclopropylmethoxy, allyloxy or propargyloxy.

The term "C₁-₃ alkoxy" as used herein may include, but is not limited to methoxy, ethoxy, or propoxy. The term "Ci_4 alkoxy" as used herein may include, but is not limited to methoxy, ethoxy, propoxy, isopropoxy, butoxy, t-butoxy, isobutoxy.

In one embodiment of the invention, "Ci_₃ alkoxy" may be substituted by one or more fluoro atoms whereby one or more hydrogen atoms in the alkoxy group is replaced by one or more fluoro atoms such as -0-CH₂-CF₃; -0-CH₂-CH₂-CF₃; -0-CH-F₂.

The term "Ci_₃alkyl0Ci_₃alkyl", unless stated otherwise, refers to an ether group with the general formula R-O-R, wherein R is selected from a hydrocarbon radical. The term "Ci_₃alkyl0Ci_₃alkyl" may include, but is not limited to dimethylether, metylethylether, methylpropylether, diethylether, dipropylether or methylisopropylether. "Ci_₃alkyl0Ci_₃alkyl" may include, but is not limited to dimethylether, metylethylether, methylpropylether, diethylether, dipropylether or methylisopropylether. In this specification, unless stated otherwise, the term "haloalkyl" means an alkyl group as defined above, which is substituted with halo as defined above. The term "Ci-4haloalkyl" may include, but is not limited to fluoromethyl, difluoromethyl, trifluoromethyl, chloromethyl, dichloromethyl, trichloromethyl or fluorochloromethyl.

In this specification, unless stated otherwise, the term "haloalkoxy" means an alkoxy group as defined above, which is substituted with halo as defined above. The term "Ci_4haloalkoxy" may include, but is not limited to fluoromethoxy, difluoromethoxy, trifluoromethoxy, fluoroethoxy or difluoroethoxy.

In this specification, unless stated otherwise, the term "cycloalkyl" refers to an optionally substituted, partially or completely saturated monocyclic, bicyclic or bridged hydrocarbon ring system. The term "C₃-₇cycloalkyl" may be, but is not limited to cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl. The term "C₅_₆ cycloalkyl" is defined as cyclopentyl or cyclohexyl.

The term "cycloalkyloxy-" refers to a cycloalkyl group attached to the rest of the molecule via the 0-atom of the oxy-group. Examples of C3.7 cycloalkyloxy as used herein, are without limitation -O-cyclohexyl, -O-cyclopropyl, O-cyclobutyl, and -O-cyclopentyl.

The term "aryl" used alone or as suffix or prefix, refers to a hydrocarbon radical having one or more polyunsaturated carbon rings having aromatic character, (e.g., 4n + 2 delocalized electrons) and comprising 5 up to about 14 carbon atoms, wherein the radical is located on a carbon of the aromatic ring. The term "C₆-ioaryl", may be, but is not limited to phenyl, naphthyl and the like.

Unless otherwise specified, aryl group may be substituted by one or more substituents including -OH, halo, cyano, nitro, Ci_6alkyl, Ci_6alkoxy or sulfamoyl. When substituted, aryl is preferably substituted by between one and three substitutents.

The term "R⁵(C=O)", unless stated otherwise, refers to a acyl group with the general formula R-C=O. The term "R⁴O(C=O)", unless stated otherwise, refers to an alkoxycarbonyl group with the general formula R-O-(C=O).

The term "heteroaryl" used alone or as suffix or prefix, refers to an aromatic ring in which at least one atom in the ring are elements other than carbon, such as N, S and O. Each heteroaryl may be bonded to the rest of the molecule either via a carbon atom of said heteroaryl, or via one nitrogen atom of said heteroaryl.

The term "Cs_6 heteroaryl" as used herein is an aromatic ring having from 5 to 6 ring atoms and wherein at least one of said 5 to 6 ring atoms is a heteroatom selected from N, S and O. Examples of such "Cs_6 heteroaryl" are pyridinyl, thiophenyl, imidazolyl, pyrazolyl.

In this specification, unless stated otherwise, the terms "halo" and "halogen" may be fluorine, iodine, chlorine or bromine.

The term "alkylsulfonyl", unless stated otherwise, refers to radicals of the general formula -SO₂-R, wherein R is selected from a hydrocarbon radical. The term "Ci_₄alkylsulfonyl" may include, but is not limited to methylsulfonyl, ethylsulfonyl, n-propylsulfonyl, iso- propylsulfonyl, n-butylsulfonyl, iso-butylsulfonyl or te/t-butylsulfonyl.

It will be appreciated that throughout the specification, the number and nature of substituents on rings in the compounds of the invention will be selected so as to avoid sterically undesirable combinations.

For the avoidance of doubt it is to be understood that where in this specification a group is qualified by 'hereinbefore defined', 'defined hereinbefore' or 'defined above' the said group encompasses the first occurring and broadest definition as well as each and all of the particular definitions for that group. The present invention relates to compounds of formula I as hereinbefore defined, as well as to pharmaceutically acceptable salts thereof. Salts for use in pharmaceutical formulations will be pharmaceutically acceptable salts.

Examples of useful pharmaceutically acceptable salts of a compound of the invention is, for example an acid-addition salt such as a salt formed with an inorganic or organic acid. A further example of useful salts is an alkali metal salt such as an alkaline earth metal salt; or a salt formed with an organic base. Examples of useful salts in accordance with the invention are an acetate, fumarate, maleate, tartrate, citrate, hydrochloride, hydrobromide, sulphate and phosphate salt.

Still other pharmaceutically acceptable salts useful in accordance with the invention and methods of preparing these salts may be found in, for example, Remington's Pharmaceutical Sciences (18^th Edition, Mack Publishing Co.).

The compounds of the invention may exhibit tautomerism. All tautomeric forms and mixtures thereof are included within the scope of the invention. The wording "tautomerism" refers to a chemical equilibrium between a keto form and an enol form where the enol and keto forms are tautomers of each other.

The compounds of the invention may also contain one or more asymmetric carbon atoms and may therefore exhibit optical isomerism, such as one or more enantiomers and/or diastereoisomers. Diastereoisomers may be separated using conventional techniques, e.g. chromatography or fractional crystallisation. The various stereoisomers may be isolated by separation of a racemic or other mixture of the compounds using conventional, e.g. fractional crystallisation or HPLC, techniques. Alternatively the desired optical isomers may be made by reaction of the appropriate optically active starting materials under conditions which will not cause racemisation or epimerisation, or by derivatisation, for example with a homochiral acid followed by separation of the diastereomeric esters by conventional means (e.g. HPLC, chromatography over silica). All stereoisomers are included within the scope of the invention. PHARMACEUTICAL COMPOSITIONS

According to one embodiment of the present invention there is provided a pharmaceutical composition comprising as active ingredient a therapeutically effective amount of a compound of the invention, or a pharmaceutically acceptable salt thereof, in association with one or more pharmaceutically acceptable diluents, excipients and/or inert carriers.

The pharmaceutical composition may be in a form suitable for oral administration, for example as a tablet, pill, syrup, powder, granule or capsule, for parenteral injection (including intravenous, subcutaneous, intramuscular, intravascular or infusion) as a sterile solution, suspension or emulsion, for topical administration e.g. as an ointment, patch or cream or for rectal administration e.g. as a suppository.

In general the above compositions may be prepared in a conventional manner using one or more conventional excipients, pharmaceutical acceptable diluents and/or inert carriers.

A suitable daily dose of a compound of the invention in the treatment of a mammal, including man, is approximately from 5 to 100 mg/kg bodyweight at peroral administration and from about 0.01 to 250 mg/kg bodyweight at parenteral administration.

The typical daily dose of the active ingredient varies within a wide range and will depend on various factors such as the relevant indication, severity of the illness being treated, the route of administration, the age, weight and sex of the patient and the particular compound being used, and may be determined by a physician.

MEDICAL USE

Compounds according to the present invention are contemplated to be useful in therapy. Compounds of formula I as herein described and claimed, or a pharmaceutically acceptable salt thereof, as well as their corresponding active metabolites, exhibit a high degree of potency at the sodium channel NaVl .7 and also selectivity for this channel compared with other essential sodium channels. Accordingly, compounds of the present invention are expected to be useful in the treatment of conditions associated with upregulation of NaVl.7 and other sodium channels present in C-fϊbers.

Compounds of the invention may be used to produce an inhibitory effect of sodium channels in mammals, including man.

One embodiment of the invention relates to the use of a compound of formula I as hereinbefore defined, in the manufacture of a medicament for the treatment of NaV 1.7 mediated disorders.

Compounds of formula I according to the invention are expected to be useful for the treatment of a pain disorder such as: acute pain; chronic pain; neuropathic pain such as diabetic neuropathies; inflammatory pain associated with arthritis and rheumatoid diseases; low back pain; post-operative pain; pain associated with various conditions including cancer, angina, renal or billiary colic, menstruation, fibromyalgia, low back pain, post-operative pain, cancer pain, visceral pains such as chronic pelvic pain, cystitis, IBS, pancreatitis, ischeamic pain, or gout.

Still an aspect of the invention is the use of a compound of formula I, for the treatment of a vascular headache such as migraine.

Yet an aspect of the invention is the use of a compound of formula I, for the treatment of pain conditions related to erythermalgia, psoriasis, emesis, urinary incontinence and hyperactive bladder.

Still an embodiment of the present invention is the use of a compound of formula I, for the treatment of epilepsy.

One embodiment of the invention relates to the use of a compound of formula I as hereinbefore defined, for the treatment of pain conditions related to arthritis, fibromyalgia, low back pain, post-operative pain, cancer pain, visceral pains such as chronic pelvic pain, cystitis, IBS, pancreatitis or ischeamic pain. One embodiment of the invention relates to the use of a compound of formula I as hereinbefore defined, in therapy.

Still an embodiment of the invention relates to the use of a compound of formula I as hereinbefore defined, for the manufacture of a medicament for the treatment of a pain disorder such as: acute pain; chronic pain; neuropathic pain such as diabetic neuropathies; inflammatory pain associated with arthritis and rheumatoid diseases; low back pain; post-operative pain; pain associated with various conditions including cancer, angina, renal or billiary colic, menstruation, fibromyalgia, low back pain, post-operative pain, cancer pain, visceral pains such as chronic pelvic pain, cystitis, IBS, pancreatitis, ischeamic pain, or gout.

Still an aspect of the invention is the use of a compound of formula I, for the manufacture of a medicament for use in the treatment of a vascular headache such as migraine.

Yet an aspect of the invention is the use of a compound of formula I, for the manufacture of a medicament for use in the treatment of pain conditions related to erythermalgia, psoriasis, emesis, urinary incontinence and hyperactive bladder.

Still an embodiment of the present invention is the use of a compound of formula I, for the manufacture of a medicament for use in the treatment of of epilepsy.

Still an embodiment of the invention relates to a method for the treatment of any one of the following pain disorders such as: acute pain; chronic pain; neuropathic pain such as diabetic neuropathies; inflammatory pain associated with arthritis and rheumatoid diseases; low back pain; post-operative pain; pain associated with various conditions including cancer, angina, renal or billiary colic, menstruation, fibromyalgia, low back pain, post-operative pain, cancer pain, visceral pains such as chronic pelvic pain, cystitis, IBS, pancreatitis, ischeamic pain, or gout; whereby a compound of formula I as hereinbefore defined, is administered to a subject in need of such treatment.

Still an aspect of the invention is a method for the treatment of a vascular headache such as migraine, whereby a compound of formula I as hereinbefore defined, is administered to a subject in need of such treatment.

Yet an aspect of the invention is a method for the treatment of pain conditions related to erythermalgia, psoriasis, emesis, urinary incontinence and hyperactive bladder, whereby a compound of formula I as hereinbefore defined, is administered to a subject in need of such treatment.

Still an embodiment of the present invention is a method for the treatment of epilepsy, whereby a compound of formula I as hereinbefore defined is administered to a subject in need of such treatment.

Yet an embodiment of the invention is a compound of formula I as hereinbefore defined, for use in the treatment of a pain disorder such as: acute pain; chronic pain; neuropathic pain such as diabetic neuropathies; inflammatory pain associated with arthritis and rheumatoid diseases; low back pain; post-operative pain; pain associated with various conditions including cancer, angina, renal or billiary colic, menstruation, fibromyalgia, low back pain, post-operative pain, cancer pain, visceral pains such as chronic pelvic pain, cystitis, IBS, pancreatitis, ischeamic pain, or gout.

Still an aspect of the invention is a compound of formula I as hereinbefore defined, for use in the treatment of a vascular headache such as migraine.

Yet an aspect of the invention is a compound of formula I as hereinbefore defined, for use in the treatment of pain conditions related to erythermalgia, psoriasis, emesis, urinary incontinence and hyperactive bladder. Still an embodiment of the present invention is a compound of formula I as hereinbefore defined, for use in the treatment of epilepsy.

COMBINATIONS Pain treatment as defined herein may be applied as a sole therapy or may involve, in addition to a compound according to the invention, administration of other analgesics or adjuvant therapy. Such therapy may for example include in combination with a compound of the present invention, one or more of the following categories of pain-relieving ingredients:

a) opioid analgesics, for example morphine, ketobemidone or fentanyl; b) analgesics of the NSAID or COX- 1/2 class, for example ibuprofene, naproxene, celecoxib or acetylsalicylic acid, and their analogues containing nitric oxide- donating groups; c) analgesic adjuvants such as amitriptyline, imipramine, duloxetine or mexiletine; d) NMDA antagonists for example ketamine or dextrometorfan; e) sodium channel blocking agents, for example lidocaine; f) anticonvulsants, for example carbamazepine, topiramate or lamotrigine; g) anticonvulsant/analgesic amino acids such as gabapentin or pregabalin; h) cannabinoids.

Each active compound of such a combination may be administered simultaneously, separately or sequentiallly.

METHODS OF PREPARATION

An aspect of the present invention provides a process for preparing a compound of formula I or a salt thereof.

Throughout the following description of such processes it is understood that, where appropriate, suitable protecting groups will be added to, and subsequently removed from, the various reactants and intermediates in a manner that will be readily understood by one skilled in the art of organic synthesis. Conventional procedures for using such protecting groups as well as examples of suitable protecting groups are described, for example, in "Green's Protective Groups in Organic Synthesis" P. G. M. Wuts, T.W. Green, Wiley, New York, 2007. References and descriptions of other suitable reactions are described in textbooks of organic chemistry, for example, "Advanced Organic Chemistry", March, 4^th ed. McGraw Hill (1992) or, "Organic Synthesis", Smith, McGraw Hill, (1994). For representative examples of heterocyclic chemistry see for example "Heterocyclic Chemistry", J. A. Joule, K. Mills, G. F. Smith, 3^rd ed. Chapman and Hall (1995), p. 189- 224 and "Heterocyclic Chemistry", T. L. Gilchrist, 2^nd ed. Longman Scientific and Technical (1992), p. 248-282.

The term "room temperature" and "ambient temperature" shall mean, unless otherwise specified, a temperature between 16 and 25 ⁰C.

Abbreviations:

DMF N,N-dimethylformamide

NaOH sodium hydroxide HCl hydrochloric acid

M molar

PG protective group

One embodiment of the invention relates to a process for the preparation of a compound of formula I according to Methods A and B, wherein R¹, R², R³, Li, L₂ and m unless otherwise specified, are defined as in formula I. Method A

Compounds of formula I may be prepared by a 3 -component Ugi reaction (Journal of Organic Chemistry (1999), 64(3), 1074-1076) using appropriately substituted 2- formylbenzoic acid, amine and isonitrile reacting in a protic solvent, for example methanol at ambient temperature.

Method B

Compounds of formula I may be prepared by an amide coupling reaction using appropriately substituted indolone carboxylic acid II and amine III and a suitable activator, for example but not limited to, fluoro-N,N,N',N'-tetramethylformamidinium hexafluorophosphate, O-benzotriazol- 1 -yl-N,N,N',N'-tetramethyluronium hexafluorophosphate or O-(7-azabenzotriazol- 1 -yl)-N,N,N',N'-tetramethyluronium hexafluoro-phosphate reacting in precence of an organic base such as triethylamine, N ,N- diisopropylamine or 4-(dimethylamino)pyridine in an aprotic solvent such as DMF, acetonitrile, tetrahydrofuran or dioxane at 0-45 ⁰C.

The carboxylic acids II are available via procedures described in the literature, for example: Othman, M. and Decroix, B., Synthetic communications 1996, 26 (15), 2803- 2809 and Othman, M. et. al, Tetrahedron 1998, 54 (30), 8737-8744 where a homophtalic ester is brominated by for example N-bromosuccinimide (NBS) in carbontetrachloride and then ring closed with an amine in precence of an organic base such as triethylamine, N ,N- diisopropylamine or 4-(dimethylamino)pyridine in a solvent such as acetonitrile at 0-25 ⁰C, as shown below.

EXAMPLES General Methods Mass spectra were recorded on one of the following instruments:

A) A LC-MS system consisting of a Waters Alliance 2795 HPLC, a Waters PDA 2996 diode array detector, a Sedex 85 ELS detector and a ZQ single quadrupole mass spectrometer. The mass spectrometer was equipped with an electrospray ion source (ES) operated in positive or negative ion mode. The capillary voltage was set to 3.2 kV and the cone voltage to 30 V, respectively. The mass spectrometer scanned between m/z 100-700 with a scan time of 0.3 s. The diode array detector scanned from 200-400 nm. The temperature of the ELS detector was adjusted to 40 ⁰C and the pressure was set to 1.9 bars. Separation was performed on an X-Terra MS C8, 3.0 mm x 50 mm, 3.5 μm (Waters) run at a flow rate of 1 ml/min. A linear gradient was applied starting at 100 % A (A: 10 mM ammonium acetate in 5 % acetonitrile, or 8 mM formic acid in 5 % acetonitrile) ending at 100% B (B: acetonitrile). The column oven temperature was set to 40 ⁰C.

B) A LC-MS system consisting of a Waters sample manager 2111 C, a Waters 1525 μ binary pump, a Waters 1500 column oven, a Waters ZQ single quadrupole mass spectrometer, a Waters PDA 2996 diode array detector and a Sedex 85 ELS detector. The mass spectrometer was configured with an atmospheric pressure chemical ionisation (APCI) ion source which was further equipped with atmospheric pressure photo ionisation (APPI) device. The mass spectrometer scanned in the positive mode, switching between APCI and APPI mode. The mass range was set to m/z 120-800 using a scan time of 0.3 s. The APPI repeller and the APCI corona were set to 0.86 kV and 0.80 μA, respectively. In addition, the desolvation temperature (300⁰C), desolvation gas (400 L/Hr) and cone gas (5 L/Hr) were constant for both APCI and APPI mode. Separation was performed using a Gemini column C 18, 3.0 mm x 50 mm, 3 μm, (Phenomenex) and run at a flow rate of 1 ml/min. A linear gradient was used starting at 100 % A (A: 10 mM ammonium acetated in 5 % methanol) and ending at 100% B (methanol). The column oven temperature was set to 40 ⁰C.

C) A LC-MS system consisting of a Waters Alliance 2795 HPLC and a Waters Micromass ZQ detector operating at 120 ⁰C. The mass spectrometer was equipped with an electrospray ion source (ES) operated in a positive or negative ion mode. The mass spectrometer was scanned between m/z 100-1000 with a scan time of 0.3 s. The LC system used was 75 % acetonitrile and 25 % of a 0.1 % formic acid solution in water.

Preparative chromatography was run on one of the following instruments:

A) A Waters FractionLynx system with a Autosampler combined Automated Fraction Collector (Waters 2767), Gradient Pump (Waters 2525), Column Switch (Waters CFO) and PDA (Waters 2996). Column; XTerra® Prep MS C8 10 μm OBD™ 19 x 300 mm or XTerra® Prep MS C8 10 μm OBD™ 30 x 150 mm both with the guard column XTerra ® Prep MS C 8 10 μm 19 x 10 mm Cartridge. A gradient from 100 % A (95 % 0.1 M ammonium acetate in MiIIiQ water and 5 % acetonitrile) to 100 % B (100 % acetonitrile) was applied for LC-separation at flow rate 20 ml/min. The PDA was scanned from 210- 350 nm. UV triggering determined the fraction collection.

B) A Waters FractionLynx system with a Autosampler combined Automated Fraction Collector (Waters 2767), Gradient Pump (Waters 2525), Regeneration Pump (Waters 600), Make Up Pump (Waters 515), Waters Active Splitter, Column Switch (Waters CFO), PDA (Waters 2996) and Waters ZQ mass spectrometer. Column; XBridge™ Prep C8 5 μm OBD™ 19 x 100 mm, with guard column; XTerra ® Prep MS C8 10 μm 19 x 10 mm Cartridge. A gradient from 100 % A (95 % 0.1 M ammonium acetate in MiIIiQ water and 5 % acetonitrile) to 100 % B (100 % acetonitrile) was applied for LC-separation at flow rate 25 ml/min. The PDA was scanned from 210-350 nm. The ZQ mass spectrometer was run with ESI in positive mode. The Capillary Voltage was 3kV and the Cone Voltage was 30V. Mixed triggering, UV and MS signal, determined the fraction collection.

Purity analyses were performed on one of the following instruments:

A) An Agilent HPl 100 system consisting of a G1379A Micro Vacuum Degasser, a G1312A Binary Pump, a G1367 Well-Plate Autosampler, a G1316A Thermostatted Column Compartment and a G1315C Diode Array Detector. The column used was a Gemini Cl 8 3.0 x 50, 3 μm (Phenomenex) run at a flow rate of 1.0 ml/min. The purity method consisted of three parts: firstly a 3 -minute column wash was applied, secondly a blank run was performed and finally the sample was analysed. A linear gradient was used for both the blank and the sample, starting at 100 % A (A: 10 mM ammonium acetate in 5 % acetonitrile) and ending at 100 % B (B: acetonitrile) after 3.5 minutes. The blank run was subtracted from the sample run at the wavelengths 220 nm, 254 nm and 290 nm.

B) A Water Acquity system with PDA (Waters 2996) and Waters ZQ mass spectrometer. Column; Acquity UPLC™ BEH Cs 1.7 μm 2.1 x 50 mm. The column temperature was set to 65 ⁰C. A linear 2 min 15 sec gradient from 100 % A (A: 95 % 0.01 M ammonium acetate in MiIIiQ water and 5 % acetonitrile) to 100 % B (5 % 0.01 M ammonium acetate in MiIIiQ water and 95 % acetonitrile) was applied for LC-separation at flow rate 1.0 ml/min. The PDA was scanned from 210-350 nm and 25 4nm was extracted for purity determination. The ZQ mass spectrometer was run with ESI in pos/neg switching mode. The Capillary Voltage was 3kV and the Cone Voltage was 30V.

C) A Waters 600 Controller system with a Waters 717 Plus Autosampler and a Waters 2996 Photodiode Array Detector. The column used was an ACE C₁₈, 5 μm, 6O x 150 mm. A linear gradient was applied, starting at 95 % A (A: 0.1 % H₃PO₄ in water) and ending at 55 % B (B: acetonitrile) in 20 min run. The column was at ambient temperature with the flow rate of 1.0 mL/min. The Diode Array Detector was scanned from 200-400 nm.

NMR spectra were recorded on a Varian Mercury Plus 400 NMR Spectrometer, operating at 400 MHz and equipped with a Varian 400 ATB PFG probe; or on a Varian Unity+ 400 NMR Spectrometer, operating at 400 MHz for proton and 100 MHz for carbon-13, and equipped with a 5 mm BBO probe with Z-gradients; or on a Bruker av400 NMR spectrometer operating at 400 MHz for proton and 100 MHz for carbon-13, and equipped with a 3 mm flow injection SEI ¹HZD-¹³C probe head with Z-gradients, using a BEST 215 liquid handler for sample injection; or on a Bruker DPX400 NMR spectrometer, operating at 400 MHz for proton and 100 MHz for carbon-13, and equipped with a 4-nucleus probe with Z-gradients. The following reference signals were used: TMS δ 0.00, or the residual solvent signal Of DMSO-J₆ δ 2.49, CD₃OD δ 3.31 or CDCl₃ δ 7.25 (unless otherwise indicated). Resonance multiplicities are denoted s, d, t, q, m and br for singlet, doublet, triplet, quartet, multiplet and broad, respectively.

Diastereomers may or may not be denoted in spectra depending upon ease of interpretation of spectra. Unless otherwise stated, chemical shifts are given in ppm with the solvent as internal standard.

Column chromatography was performed using Merck Silica gel 60 (0.040-0.063 mm), or employing a Combi Flash^® Companion^™ system using RediSep^™ normal-phase flash columns.

Compounds have been named using ELN V. 2.1 software from Cambridgesoft, www.cambridgesoft.com, 2008. Preparation of intermediates

The invention will now be illustrated by the following non-limiting examples.

Example 1-1 tert-Butyl (ϊrø«s)-4-carbamoylcvclohexylcarbamate

Intermediate 1

(£rans)-4-(tert-Butoxycarbonylamino)cyclohexanecarboxylic acid (314 mg, 1.29 mmol) was dissolved in THF (4 mL) under argon atmosphere and triethylamine (0.233 mL, 1.68 mmol) was added. The resulting mixture was cooled to -15 ⁰C and ethyl chloro formate

(0.148 mL, 1.55 mmol) was added. The resulting white suspension was stirred at -15 ⁰C for one hour before ammonium hydroxide (8 mL, 67.80 mmol) was added in one portion.

The reaction mixture was allowed to reach room temperature and stirring continued for Ih.

THF was evaporated and the resulting precipitate was collected by filtration and dried in vacuo to give 240 mg (77 %) of the title compound.

MS (ESI) m/z 241 [M-H].

Example 1-2 tert-butyl (;m«s)-4-Cyanocvclohexylcarbamate

tert-butyl (£ra/?s)-4-Carbamoylcyclohexylcarbamate (230 mg, 0.95 mmol) was dissolved in pyridine (4 mL) and cooled to 0 ⁰C. Phosphorus oxychloride (0.444 mL, 4.75 mmol) was added dropwise and the resulting yellow slurry was stirred for 30 minutes before being poured onto a mixture of ice and water. The resulting mixture was extracted twice with ethyl acetate and the combined organic extracts were washed with water and brine and dried over sodium sulphate, filtered and concentrated to give 146 mg (68.6 %) of the title compound.

MS (EI) m/z 224 [M+].

Example 1-3 føvmsM-aminocvclohexanecarbonitrile

b = relative absolute

tert-butyl (£ra/?s)-4-cyanocyclohexylcarbamate (140 mg, 0.62 mmol) was dissolved in dichloromethane (4 mL) and trifluoroacetic acid (1.5 mL, 19.54 mmol) was added. The resulting mixture was stirred at ambient temperature over night. Solvent and excess TFA was evaporated in vacuo to give 219 mg (147 %) of the title compound as the TFA-salt. MS (EI) m/z 124 [M+].

Example 1-4 tert-Butyl (c/s)-4-carbamoylcvclohexylcarbamate

Intermediate 4

a = relative absolute

The title compound was prepared according to the method described for intermediate 1 employing (cώ)-4-(tert-butoxycarbonylamino)cyclohexanecarboxylic acid (500 mg, 2.06 mmol), triethylamine (0.37 mL, 2.67 mmol), ethyl chloroformate (0.24 mL, 2.47 mmol) and ammonium hydroxide (12.8 mL, 108.30 mmol). White solid, 405 mg (81 %). 1H NMR (500 MHz, DMSO-J₆) δ (ppm) 3.43 (br.s., 1 H) 2.08 - 2.14 (m, 1 H) 1.70 - 1.80 (m, 2 H) 1.52 - 1.60 (m, 2 H) 1.37 - 1.48 (m, 4 H) 1.37 (s, 9 H). MS (ESI) m/z 243 [M+H]. Example 1-5 tert-Butyl fc/s)-4-cvanocvclohexylcarbamate

Intermediate 5

a = relative absolute The title compound was prepared according to the method described for intermediate 2 using tert-butyl (cώ)-4-carbamoylcyclohexylcarbamate (323 mg, 1.33 mmol) and phosphorus oxychloride (0.623 mL, 6.66 mmol) to give 300 mg (100 %) of the title compound.

¹H NMR (500 MHz, DMSO-J₆) δ (ppm) 3.23 - 3.30 (m, 1 H) 3.00 (t, 1 H) 1.80 - 1.89 (m, 2 H) 1.75 - 1.85 (m, 2 H) 1.53 - 1.63 (m, 2 H) 1.37 - 1.43 (m, 2 H) 1.37 (s, 9 H). MS (EI) m/z 225 [M+H].

Example 1-6 (ctV)-4-aminocvclohexanecarbonitrile

Intermediate 6

a = relative absolute

The title compound was prepared according to the method described for intermediate 3 using tert-butyl (cώ)-4-cyanocyclohexylcarbamate (298 mg, 1.33 mmol) and trifluoroacetic acid (3 mL, 38.94 mmol) affording 200 mg (107 %) of the title compound as the TFA-salt. MS (EI) m/z 125 [M+H].

Example 1-7 N-Q-(4-(ϊrifluoromethoxy)phenyl)ethyl)fbrmamide

Intermediate 7

l-(4-(trifluoromethoxy)phenyl)ethanamine (0.352 g, 1.72 mmol) was dissolved in dichloromethane (4 niL), set under N₂ atmosphere and was cooled down to 0⁰C. Phenyl formate (0.187 mL, 1.72 mmol) was added dropwise and the mixture was stirred at room temperature for 16 hours. The solvent was removed in vacuo and the residue was purified on silica column using heptane : ethyl acetate = 100:0 to 0:100 as gradient. Colorless oil, 284 mg (71 %).

¹H NMR (500 MHz, CDCl₃) δ (ppm) 8.20 (s, 1 H) 7.36 (d, 2 H) 7.17 - 7.22 (m, 2 H) 5.77 (br. s., 1 H) 5.24 (t, 1 H) 1.53 (d, 3 H). MS (ESI) m/z 234 [M+H].

Example 1-8 l-fl-Isocvanoethyl)-4-ftrifluoromethoxy)benzene

Intermediate 8

N-(l-(4-(Trifluoromethoxy)phenyl)ethyl)formamide (0.275 g, 1.18 mmol) was dissolved in dichloromethane (4 mL) and cooled to -15°C under N₂ atmosphere. N ,N- diisopropylethylamine (0.780 mL, 4.72 mmol) followed by phosphorus oxychloride (0.132 mL, 1.42 mmol) were added and the resulting mixture was allowed to slowly reach room temperature (3 hours). Then methanol (1.5 mL) was added to quench the reaction. The mixture was diluted with dichloromethane and washed twice with sat. NaHCO₃ solution. The combined organic extracts were washed with brine, dried over anhydrous sodium sulfate, filtered and evaporated to give the product as a brown oil, 284 mg (112 %) which was used without further purification. 1H NMR (500 MHz, CDCl₃) δ (ppm) 7.41 (d, 2 H) 7.24 - 7.29 (m, 2 H) 4.85 (q, 1 H) 1.70 (d, 2 H). MS (ESI) m/z 216 [M+H]. Example 1-9 N-f3-fTrifluoromethoxy)benzyl)formamide

intermediate 9

The title compound was prepared according to the method described for example 7 using (3-(trifluoromethoxy)phenyl)methanamine (0.2 g, 1.05 mmol) and phenyl formate (0.117 mL, 1.05 mmol). Colorless oil, 120 mg (52 %).

¹H NMR (500 MHz, CDCl₃) δ (ppm) 8.31 (s, 1 H) 7.35 - 7.40 (m, 1 H) 7.22 - 7.26 (m, 1 H) 7.15 (br. s., 2 H) 5.92 (br. s., 1 H) 4.53 (d, 2 H). MS (ESI) m/z 220 [M+H].

Example I- 10 l-fIsocvanomethyl)-3-ftrifluoromethoxy)benzene

Intermediate 10

The title compound was prepared according to the method described for example 8 using N-(3-(trifluoromethoxy)benzyl)formamide (120 mg, 0.55 mmol), N ,N- diisopropylethylamine (0.362 mL, 2.19 mmol) and phosphorus oxychloride (0.061 mL, 0.66 mmol). Brown oil, 110 mg (100 %) which was used without further purification.

¹H NMR (500 MHz, CDCl₃) δ (ppm) 7.43 - 7.49 (m, 1 H) 7.31 (d, 1 H) 7.21 - 7.25 (m, 2 H) 4.69 (s, 2 H). MS (ESI) m/z 202 [M+H]. Example I- 11 N-f2-Methyl-4-ftrifluoromethoxy)benzyl)formamide

P

Intermediate 11

The title compound was prepared according to the method described for example 7 using (2-methyl-4-(trifluoromethoxy)phenyl)methanamine (0.35 g, 1.71 mmol) and phenyl formate (0.191 mL, 1.71 mmol). The crude was purified on silica column using dichloromethane : (dichloromethane/methanol/ammonia 90:10:1) = 100:0 to 30:70 as gradient. White solid, 252 mg (63 %).

¹H NMR (500 MHz, CDCl₃) δ (ppm) 8.28 (s, 1 H) 7.27 (t, 1 H) 7.06 (br. s., 2 H) 5.68 (br. s., 1 H) 4.49 (d, 2 H) 2.36 (s, 3 H). MS (ESI) m/z 232 [M-H].

Example 1-12 l-(lsocvanomethyl)-2-methyl-4-(ϊrifluoromethoxy)benzene

Intermediate 12

The title compound was prepared according to the method described for example 8 usin^ N-(2-methyl-4-(trifluoromethoxy)benzyl)formamide (0.250 g, 1.07 mmol), N₅N- diisopropylethylamine (0.742 mL, 4.29 mmol) and phosphorus oxychloride (0.120 mL, 1.29 mmol). Brown oil, 300 mg (130 %) which was used without further purification. MS (ESI) m/z 216 [M+H]. Example 1-13 l-Cyanopropan-2-aminium 2,2,2-trifluoroacetate

Intermediate 13

tert-Butyl l-cyanopropan-2-ylcarbamate (100 mg, 0.54 mmol) was dissolved in dichloromethane (2 niL) and trifluoroacetic acid (0.209 niL, 2.71 mmol) was added. The mixture was stirred for 16 hours at room temperature then concentrated in vacuo affording a yellow oil (110 mg, 100 %) which was used without further purification. 1U NMR (400 MHz, CD₃OD) δ (ppm) 2.78 - 2.96 (m, 2 H) 2.35 - 2.52 (m, 1 H) 1.43 (d, 3 H).

Example 1-14 tert-Butyl 4-amino-3.,3-dimethyl-4-oxobutylcarbamate

Intefτredate14

The title compound was prepared according to the method described for intermediate 1 employing 4-(tert-butoxycarbonylamino)-2,2-dimethylbutanoic acid (0.5 g, 2.16 mmol), triethylamine (0.391 mL, 2.81 mmol), ethyl chloroformate (0.248 mL, 2.59 mmol) and ammonium hydroxide (10 mL, 64.20 mmol). White solid, 290 mg (58 %). 1H NMR (500 MHz, DMSO-J₆) δ (ppm) 7.04 (br. s., 1 H) 6.81 (br. s., 1 H) 6.73 (t, 1 H) 2.84 (m, 2 H) 1.53 (m, 2 H) 1.36 (s, 9 H) 1.04 (s, 6 H).

Example 1-15 tert-Butyl 3-cvano-3-methylbutylcarbamate

Intermediate 15

The title compound was prepared according to the method described for intermediate 2 using tert-butyl 4-amino-3,3-dimethyl-4-oxobutylcarbamate (0.290 g, 1.26 mmol) and phosphorus oxychloride (0.589 mL, 6.30 mmol). White solid, 212 mg (79 %). 1H NMR (500 MHz, DMSO-J₆) δ (ppm) 6.93 (t, 1 H) 3.05 (m, 2 H) 1.63 (m, 2 H) 1.37 (s, 9 H) 1.29 (s, 6 H).

Example 1-16 4-Amino-2,2-dimethylbutanenitrile

Intermediate 16

The title compound was prepared according to the method described for intermediate 3 using tert-butyl 3-cyano-3-methylbutylcarbamate (70 mg, 0.33 mmol) and trifluoroacetic acid (0.75 mL, 9.7 mmol). The product was obtained as TFA-salt, 95 mg (127 %). 1H NMR (500 MHz, DMSO-J₆) δ (ppm) 7.85 (br. s., 3 H) 2.82 - 2.98 (m, 2 H) 1.75 - 1.85 (m, 2 H) 1.33 (s, 6 H).

Example 1-17 4-f2,2,2-Trifluoroethyl)benzonitrile

Intermediate 17

To the DMF (25 mL) solution of l-bromo-4-(2,2,2-trifiuoroethyl)benzene (2.15 g, 9.00 mmol) were zinc cyanide (2.11 g, 18.0 mmol) then Pd(PPh₃)₄ (0.828 g, 0.720 mmol) added. The mixture was heated at 100⁰C for 18 hours then cooled to room temperature, diluted with ethyl acetate (50 mL) and filtered through a short bed of celite. The filtrate was concentrated under reduced pressure. The crude residue was purified by silica gel column chromatography using hexane : ethyl acetate = 90:10 as eluent to give the title compound as a white solid, 800 mg (48%). 1H NMR (400 MHz, CDCl₃) δ (ppm) 7.67 (d, 2 H) 7.43 (d, 2 H) 3.44 (q, 2 H). ¹⁹F NMR (400 MHz, CDCl₃) δ (ppm) -65.85, -65.88 and -65.91. MS (ESI) m/z 186 [M+H]. Example 1-18 f4-f2,2,2-Trifluoroethyl)phenyl)methanamine

Intermediate 18

5 IM borane in tetrahydrofuran (9.40 mL, 9.40 mmol) was added to the tetrahydrofuran (15 mL) solution of 4-(2,2,2-trifluoroethyl)benzonitrile (0.580 g, 3.13 mmol). The mixture was heated at 6O⁰C for 18 hours, cooled to room temperature and concentrated under reduced pressure. The residue was redissolved in methanol (15 mL), refluxed for 2 hours and concentrated under reduced pressure. The crude residue was dissolved in dichloromethaneo (50 mL), washed with 2M NaOH solution (20 mL), brine (20 mL), dried over anhydrous sodium sulfate and filtered. The filtrate was concentrated under reduced pressure to give the title compound as a pale yellow oil, 600 mg (100 %).

¹H NMR (400 MHz, CDCl₃) δ (ppm) 7.27 - 7.34 (m, 4 H) 3.88 (s, 2 H) 3.36 (q, 2H) (NH₂ not shown). ¹⁹F NMR (400 MHz, CDCl₃) δ (ppm) -66.42, -66.45 and -66.48. MS (ESI) m/zs 190 [M+H].

Example 1-19 N-f4-f2,2,2-Trifluoroethyl)benzyl)formamide 0

Intermediate 19

A solution of (4-(2,2,2-trifluoroethyl)phenyl)methanamine (0.650 g, 3.40 mmol) in ethylformate (5 mL) was refluxed for 18 hours. The reaction mixture was concentrated5 under reduced pressure and the crude residue was purified by silica gel column chromatography using hexane: ethyl acetate = 100:0 to 50:50 as eluent to afford the desired compound as a white solid, 620 mg (84%).

¹H NMR (400 MHz, CDCl₃) δ (ppm) 8.30 (s, 1 H) 7.29 (s, 4 H) 5.77 (m, 1 H) 4.51 (d, 2 H) 3.36 (q, 2 H). ¹⁹F NMR (400 MHz, CDCl₃) δ (ppm) -66.36, -66.39 and -66.41. MS (ESI)o m/z 218 [M+H]. Example 1-20 l-Isocvanomethyl-4-f2,2,2-trifluoroethyl)benzene

Intermediate 20

Phosphorus oxychloride (0.320 rnL, 3.43 mmol) was added dropwise to a solution of N-(4- (2,2,2-trifluoroethyl)benzyl)formamide (0.620 g, 2.86 mmol) and N₅N- diisopropylethylamine (1.97 mL, 11.4 mmol ) in dichloromethane (20 mL) at -2O⁰C. The mixture was slowly warmed to room temperature and stirred for 16 hours. Afterwards the reaction mixture was concentrated, the residue was dissolved in methanol (3 mL) and triethylamine (2.5 mL) was added. The reaction mixture was stirred for 5 minutes and concentrated under reduced pressure. The crude compound was purified by silica gel column chromatography using hexane: ethyl acetate = 100:0 to 80:20 as eluent yielding the title compound as a white solid, 442 mg (78%). 1H NMR (400 MHz, CDCl₃) δ (ppm) 7.36 (s, 4 H) 4.66 (s, 2 H) 3.39 (q, 2 H). ¹⁹F NMR (400 MHz, CDCl₃) δ (ppm) -66.31, -66.34 and -66.37. MS (ESI) m/z 200 [M+H].

Example 1 (general procedure 1) 2-f2-Cvanoethyl)-3-oxo-N-f4-ftrifluoromethoxy)benzyl)isoindoline-l-carboxamide

2-Carboxybenzaldehyde (112 mg, 0.75 mmol) and 3-aminopropionitrile (0.055 mL, 0.75 mmol) were dissolved in methanol (6 mL) under argon atmosphere and 1- (isocyanomethyl)-4-(trifluoromethoxy)benzene (0.150 mL, 0.75 mmol) was added. The resulting mixture was stirred at ambient temperature over night. The solvent was stripped and the residue was purified by silica gel column chromatography using 0-100% ethyl acetate in heptane as eluent to give the title compound (183 mg, 60.8 %). ¹H NMR (500 MHz, DMSO-J₆) δ ppm 9.21 (t, 1 H) 7.74 (d, 1 H) 7.68 - 7.60 (m, 2 H) 7.56 (t, 1 H) 7.38 (d, 2 H) 7.32 (d, 2 H) 5.42 (s, 1 H) 4.42 - 7.31 (m, 2 H) 4.13 - 7.05 (m, 1 H) 3.37 - 7.28 (m, 1 H) 2.94 - 2.80 (m, 2 H); MS (ESI) m/z 404 [M+H].

Example 2

2-f^m«s)-4-Cvanocvclohexyl)-3-oxo-N-f4-ftrifluoromethoxy)benzyl)isoindoline-l- carboxamide

_(trα/?5)-4-Aminocyclohexanecarbonitrile (0.077 g, 0.62 mmol) was dissolved in methanol (4 mL) under argon atmosphere and 2-carboxybenzaldehyde (0.093 g, 0.62 mmol) was added. The pH was adjusted to ~6 by addition of triethylamine (0.086 mL, 0.62 mmol). After stirring for five minutes 4-(trifluoromethoxy)benzylisocyanide (0.125 mL, 0.62 mmol) was added and the resulting mixture was stirred at ambient temperature o/n. Purification by preparative HPLC gave 87.5 mg (30.9 %) of the title compound.

¹H NMR (500 MHz, DMSO-J₆) δ ppm 9.11 (t, 1 H) 7.68 (d, 1 H) 7.61 - 7.56 (m, 1 H) 7.54 - 7.45 (m, 2 H) 7.39 - 7.32 (m, 4 H) 5.25 (s, 1 H) 4.31 (d, 2 H) 3.89 - 3.80 (m, 1 H) 2.09 - 2.02 (m, 1 H) 2.01 - 1.94 (m, 1 H) 1.86 - 1.77 (m, 2 H) 1.69 - 1.53 (m, 3 H) 1.49 - 1.38 (m, 1 H); MS (ESI) m/z 458 [M+H].

Example 3

2-(Ycis)-4-Cvanocvclohexyl)-3-oxo-N-(4-(Εrifluoromethoxy)benzyl)isoindoline-l- carboxamide

a =relatιve absolute

The title compound was prepared according to the method described in example 2, from (cώ)-4-aminocyclohexanecarbonitrile (165 mg, 1.33 mmol), triethylamine (0.555 mL, 3.99 mmol), 2-formylbenzoic acid (200 mg, 1.33 mmol) and l-(isocyanomethyl)-4- (trifluoromethoxy)benzene (0.219 mL, 1.33 mmol). The residue was purified by silica gel column chromatography using heptane : ethyl acetate = 70:30 to 10:90 as gradient. White solid, 403 mg (66 %).

¹H NMR (500 MHz, DMSO-J₆) δ (ppm) 9.25 (t, 1 H) 7.70 (d, 1 H) 7.60 (t, 1 H) 7.52 (t, 1 H) 7.48 (d, 1 H) 7.40 (d, 2 H), 7.33 (d, 2H) 5.35 (s, 1 H) 4.32 - 4.40 (m, 2 H) 3.90 - 4.00 (m, 1 H) 3.15 (br.s., 1 H) 1.89 - 1.96 (d, 1 H) 1.83 - 1.88 (m, 2 H) 1.82 (d, 2 H) 1.62 - 1.75 (m, 3H). MS (ESI) m/z 458 [M+H].

Example 4

2-(2-Cvanoethyl)-7-methoxy-3-oxo-N-(4-(ϊrifluoromethoxy)benzyr)isoindoline-l- carboxamide

The title compound was prepared according to the general procedure 1 , described in example 1, from 3-hydroxy-4-methoxyisobenzofuran-l(3H)-one (45 mg, 0.25 mmol, prepared according to Journal of Organic Chemistry 2007, 72, 3419), 3- aminopropanenitrile (0.018 niL, 0.25 mmol) and l-(isocyanomethyl)-4- (trifluoromethoxy)benzene (0.050 niL, 0.25 mmol). White solid, 43 mg (40 %). 1H NMR (500 MHz, DMSO-J₆) δ (ppm) 9.22 (t, 1 H) 7.52 (t, 1 H) 7.39 (m, 4 H) 7.30 (d, 1 H) 7.24 (d, 1 H) 5.30 (s, 1 H) 4.52 (dd, 1 H) 4.25 (dd, 1 H) 4.03 (ddd, 1 H) 3.80 (s, 3 H) 3.10 - 3.24 (m, 1 H) 2.75 - 2.94 (m, 2 H). MS (ESI) m/z 434 [M+H].

Example 5 2-f2-Cvanoethyl)-7-methyl-3-oxo-N-f4-ftrifluoromethoxy)benzyl)isoindoline-l- carboxamide

The title compound was prepared according to the general procedure 1 , described in example 1, from 3-hydroxy-4-methylisobenzofuran-l(3H)-one (30 mg, 0.18 mmol, prepared according to the procedure described in Tetrahedron Letters 2002, 43, 7315 for the unsubstituted analog), 3 -aminopropanenitrile (12.8 mg, 0.18 mmol) and 1- (isocyanomethyl)-4-(trifluoromethoxy)benzene (36.8 mg, 0.18 mmol). After 24 hours stirring at room temperature the mixture was heated to 50⁰C and stirred for 24 hours. White solid, 19 mg (25 %).

¹H NMR (500 MHz, DMSO-J₆) δ (ppm) 9.31 (t, 1 H) 7.55 (d, 1 H) 7.44 (t, 1 H) 7.41 (d, 3 H) 7.32 - 7.37 (m, 2 H) 5.34 (s, 1 H) 4.30 - 4.42 (m, 2 H) 4.07 (dt, 1 H) 3.13 - 3.21 (m, 1 H) 2.78 - 2.93 (m, 2 H) 2.24 (s, 3 H). MS (ESI) m/z 418 [M+H].

Example 6 2-f2-Cvanoethyl)-3-oxo-N-fl-f4-ftrifluoromethoxy)phenyl)ethyl)isoindoline-l- carboxamide, ISOMER 4

g = unknown absolute h = unknown absolute

The title compound was prepared according to the general procedure 1 , described in example 1, from 2-formylbenzoic acid (0.105 g, 0.70 mmol), 3-aminopropionitrile (0.051 mL, 0.70 mmol) and l-(l-isocyanoethyl)-4-(trifluoromethoxy)benzene (0.151 g, 0.70 mmol). White solid, 144 mg (49 %). The diasteromeric mixture (0.140 g, 0.34 mmol) was separated by chiral chromatography, which was performed on LaPrep system 1. Column: Chiralpak AD; 50*300 mm, lOμm; Mobilephase: 0-20 minutes: 5/5/90 methanol:ethanol:heptane; 20-40 minutes: 10/10/80 methanol:ethanol:heptane; Flow: 120 mL/minute. The separated isomers were eluted at 12 minutes (ISOMER 1), 17 minutes (ISOMER 2), 26 minutes (ISOMER 3) and 31 minutes as ISOMER 4. The isomers were collected, concentrated and handled separately. The samples were analyzed by HPLC using GILSON HPLC System; Column: Reprosil-AM (AD); 4.6*250 mm; 5μm; Mobilephase: 7/3/90 methanol:ethanol:heptane; Flow: 0.8 mL/minute, ISOMER 4 (24 minutes), 14 mg, enatiomeric purity: 91 %. The compound epimerizes in solution to a 1 :1 mixture of isomer 3 and 4 under 24 hours at room temperature.

¹H NMR (500 MHz, DMSO-J₆) δ (ppm) 9.09 (t, 1 H), 7.74 (d, 1 H), 7.64 (m, 2 H), 7.56 (t, 1 H), 7.31 (d, 1 H), 7.21 (s, 1 H), 7.15 (d, 1 H), 5.43 (s, 1 H), 4.33 (m, 2 H), 4.10 (m, 1 H), 3.30 (m, 1 H), 2.87 (m, 2 H), 2.29 (s, 3 H). MS (ESI) m/z 416 [M-H]. Example 7 2-(7-Cvanoethyl)-3-oxo-N-(3-(ϊrifluoromethoxy)benzyl)isoindoline-l-carboxamide

The title compound was prepared according to the general procedure 1 , described in example 1, from 2-formylbenzoic acid (0.060 g, 0.40 mmol), 3-aminopropanenitrile (0.029 mL, 0.40 mmol) and l-(isocyanomethyl)-3-(trifluoromethoxy)benzene (0.080 g, 0.40 mmol). White solid, 37.9 mg (23 %).

¹H NMR (500 MHz, DMSO-J₆) δ (ppm) 9.24 (t, 1 H) 7.74 (d, 1 H) 7.66 - 7.61 (m, 2 H) 7.59 - 7.54 (m, 1 H) 7.45 (t, 1 H) 7.28 (d, 1 H) 7.24 (d, 1 H) 7.18 (s, 1 H) 5.44 (s, 1 H) 4.44 - 4.34 (m, 2 H) 4.10 (m, 1 H) 3.34 - 3.28 (m, 1 H) 2.93 - 2.81 (m, 2 H). MS (ESI) m/z 404 [M+H].

Example 8

2-f2-Cvanoethyl)-N-f2-methyl-4-ftrifluoromethoxy)benzyl)-3-oxoisoindoline-l- carboxamide

The title compound was prepared according to the general procedure 1 , described in example 1, from 2-formylbenzoic acid (37.5 mg, 0.25 mmol), 3-aminopropanenitrile (0.018 mL, 0.25 mmol) and l-(isocyanomethyl)-2-methyl-4-(trifluoromethoxy)benzene (53.8 mg, 0.25 mmol). White solid, 11 mg (10.5 %). ¹H NMR (500 MHz, DMSO-J₆) δ (ppm) 9.09 (t, 1 H), 7.74 (d, 1 H), 7.64 (m, 2 H), 7.56 (t, 1 H), 7.31 (d, 1 H), 7.21 (s, 1 H), 7.15 (d, 1 H), 5.43 (s, 1 H), 4.33 (m, 2 H), 4.10 (m, 1 H), 3.30 (m, 1 H), 2.87 (m, 2 H), 2.29 (s, 3 H). MS (ESI) m/z 416 [M-H].

Example 9

2-(7-Cvanoethyl)-4-fluoro-3-oxo-N-(4-(Εrifluoromethoxy)benzyl)isoindoline-l- carboxamide

The title compound was prepared according to the general procedure 1 , described in example 1, from 7-fluoro-3-hydroxyisobenzofuran-l(3H)-one (56 mg, 0.33 mmol), 3- aminopropanenitrile (0.023 mL, 0.33 mmol) and l-(isocyanomethyl)-4- (trifluoromethoxy)benzene (0.067 mL, 0.33 mmol). White solid, 39 mg (28 %). 1H NMR (400 MHz, CDCl₃) δ (ppm) 7.62 (m, 1 H) 7.42 (d, 1 H) 7.14 - 7.22 (m, 5 H) 6.54 (t, 1 H) 5.29 (s, 1 H) 4.40 - 4.48 (m, 2 H) 4.07 - 4.13 (dt, 1 H) 3.50 - 3.57 (dt, 1 H) 2.82 (t, 2 H). MS (ESI) m/z 422 [M+H].

Example 10 l-fl-CvanoethvD-T-fluoro-S-oxo-N-^-ftrifluoromethoxy^enzvDisoindoline-l- carboxamide

The title compound was prepared according to the general procedure 1 , described in example 1, from 4-fluoro-3-hydroxyisobenzofuran-l(3H)-one (56 mg, 0.33 mmol), 3- aminopropanenitrile (0.023 niL, 0.33 mmol) and l-(isocyanomethyl)-4- (trifluoromethoxy)benzene (0.067 niL, 0.33 mmol). White solid, 30 mg (21 %). 1H NMR (400 MHz, CDCl₃) δ (ppm) 7.72 (d, 1 H) 7.56 (m, 1 H) 7.30 (m, 3 H) 7.21 (d, 2 H) 6.39 (br. s., 1 H) 5.43 (s, 1 H) 4.48 - 4.58 (m, 2 H) 4.17 - 4.24 (dt, 1 H) 3.54 - 3.61 (m, 1 H) 2.85 - 2.92 (dt, 1 H) 2.73 - 2.79 (dt, 1 H). MS (ESI) m/z 422 [M+H].

Example 11 2-fCvanomethyl)-3-oxo-N-f4-ftrifluoromethoxy)benzyl)isoindoline-l-carboxamide

The title compound was prepared according to the general procedure 1 , described in example 1, from 2-formylbenzoic acid (50 mg, 0.33 mmol), 2-aminoacetonitrile (18.7 mg, 0.33 mmol) and l-(isocyanomethyl)-4-(trifluoromethoxy)benzene (0.067 mL, 0.33 mmol). White solid, 25 mg (19 %). 1H NMR (500 MHz, DMSO-J₆) δ (ppm) 9.27 (t, 1 H) 7.77 (d, 1 H) 7.71 - 7.62 (m, 2 H) 7.58 (t, 1 H) 7.40 (m, 2 H) 7.32 (m, 2 H) 5.40 (s, 1 H) 4.80 (d, 1 H) 4.44 (d, 1 H) 4.38 (d, 2 H). MS (ESI) m/z 390 [M+H].

Example 12 2-fl-Cvanopropan-2-yl)-3-oxo-N-f4-ftrifluoromethoxy)benzyl)isoindoline-l- carboxamide

The title compound was prepared according to the general procedure 1 , described in example 1, from l-cyanopropan-2-aminium 2,2,2-trifluoroacetate (79 mg, 0.40 mmol), triethylamine (0.112 niL, 0.80 mmol), 2-formylbenzoic acid (60.1 mg, 0.40 mmol) and 1-

(isocyanomethyl)-4-(trifluoromethoxy)benzene (80 mg, 0.40 mmol). Colorless oil, 21 mg

(12 %), 1 :1 mixture of diastereomers. isomer 1 : ¹H NMR (400 MHz, CDCl₃) δ (ppm) 7.71 (d, 1 H) 7.45 - 7.66 (m, 3 H) 7.03 - 7.24 (m, 4 H) 6.87 (t, 1 H) 5.15 (s, 1 H) 4.41 - 4.51 (m, 2 H) 2.98 (dd, 1 H) 2.71 - 2.85 (m,

2 H) 1.46 (d, 3 H). isomer 2: ¹H NMR (400 MHz, CDCl₃) δ (ppm) 7.71 (d, 1 H) 7.46 - 7.66 (m, 3 H) 7.07 -

7.21 (m, 4 H) 6.44 (t, 1 H) 5.22 (s, 1 H) 4.31 - 4.39 (m, 1 H) 4.13 (ddd, 1 H) 3.52 (dd, 1 H)

2.71 - 2.84 (m, 2 H) 1.55 (d, 3 H). MS (ESI) m/z 418 [M+H].

Example 13 2-f3-Cvano-3-methylbutyl)-3-oxo-N-f4-ftrifluoromethoxy)benzyl)isoindoline-l- carboxamide

The title compound was prepared according to the general procedure 1 , described in example 1, from 2-formylbenzoic acid (0.050 g, 0.33 mmol), 4-amino-2,2- dimethylbutanenitrile (0.075 g, 0.33 mmol) and l-(isocyanomethyl)-4- (trifluoromethoxy)benzene (0.066 g, 0.33 mmol). White solid, 61 mg (41 %). 1H NMR (500 MHz, DMSO-J₆) δ (ppm) 9.22 (t, 1 H) 7.71 (d, 1 H) 7.62 (m, 1 H) 7.55 (m, 2 H) 7.39 (m, 2 H) 7.32 (m, 2 H) 5.35 (s, 1 H) 4.37 (d, 2 H) 3.99 (m, 1 H) 3.14 (m, 1 H) 1.86 (m, 2 H) 1.31 (d, 6 H). MS (ESI) m/z 446 [M+H]. Example 14 l-fS-CvanopentvD-S-oxo-N-^-ftrifluoromethoxy^enzvDisoindoline-l-carboxamide

The title compound was prepared according to the general procedure 1 , described in example 1, from 2-formylbenzoic acid (65 mg, 0.43 mmol), 6-aminohexanenitrile (48.6 mg, 0.43 mmol) and l-(isocyanomethyl)-4-(trifluoromethoxy)benzene (0.087 mL, 0.43 mmol). White solid, 110 mg (57 %). 1H NMR (500 MHz, DMSO-J₆) δ (ppm) 9.17 (t, 1 H) 7.70 (d, 1 H) 7.61 (d, 1 H) 7.51 - 7.57 (m, 2 H) 7.35 (q, 4 H) 5.27 (s, 1 H) 4.35 (dd, 2 H) 3.81 (ddd, 1 H) 3.01 (ddd, 1 H) 2.46 (t, 2 H) 1.55 (dd, 3 H) 1.49 - 1.63 (m, 1 H) 1.32 (t, 2 H). MS (ESI ) m/z 446 [M+H].

Example 15 l-fl-CyanoethvD-S-oxo-N-^-fl^^-trifluoroethvDbenzvDisoindoline-l-carboxamide

The title compound was prepared according to the general procedure 1 , described in example 1, from 2-formylbenzoic acid (54 mg, 0.36 mmol), 3-aminopropanenitrile (25.3 mg, 0.36 mmol) and l-isocyanomethyl-4-(2,2,2-trifluoroethyl)benzene (72 mg, 0.36 mmol). The crude was purified by silica gel column chromatography using dichloromethane : methanol = 100:0 to 95:5 as eluent to give the title compound as yellow solid, 37 mg (26 %). ¹H NMR (400 MHz, CDCl₃) δ (ppm) 7.71 (d, IH) 7.61 (d, 2 H) 7.46 - 7.52 (m, 1 H) 7.22 (d, 2 H) 7.15 (d, 2 H) 6.41 (m, 1 H) 5.28 (s, 1 H) 4.38 - 4.50 (m, 2 H) 4.09 - 4.18 (m, 1 H) 3.52 - 3.62 (m, 1 H) 3.28 - 3.38 (m, 2 H) 2.73 - 2.83 (m, 2 H). ¹⁹F NMR (400 MHz, CDCl₃) δ (ppm) -66.27, -66.30 and -66.33. MS (ESI) m/z 402 [M+H].

BIOLOGICAL TESTS

Gene(s) encoding the full-length protein of the voltage-gated sodium channel of interest are cloned and expressed under a suitable promoter in a suitable cell line, as well known in the art. The so constructed stable cell lines are used in screening assays to identify suitable compounds active on voltage-gated sodium channels. Suitable screening assays are as follows.

Li+ influx assay The cell line expressing the voltage-gated sodium channel of interest is plated in conventional 96 or 384 well tissue plates at a suitable cell density (for example 40000 cells/well in 96 well plate, or 20000 cells/well in 384 well plate). The cells are then repeatedly washed with a suitable Na free buffer using a suitable commercially available washer (for example EL-405 washer) until all tissue culture medium is removed from the wells. A suitable Na- free buffer could have the composition (mM) Choline chloride 137, KCl 5.4, MgSO₄ 0.81, CaCl₂ 0.95, glucose 5.55 and HEPES 25 at pH 7.4, but may also have other suitable composition. After completion of all wash steps, cells are incubated in the suitable Na free buffer for 15 min. Then, the Na free buffer is removed and cells are incubated with a buffer rich in LiCl for 60 min at 37⁰C. The LiCl buffer is also enriched in potassium ions, causing a depolarizing stimulus to the cells. Such a buffer may have the composition (mM): LiCl 100, KCl 50, MgSO₄ 0.81, CaCl₂ 0.95, glucose 5.55 and HEPES 25 at pH 7.4, but may also have other suitable composition. To enhance signal-to-noise ratio, an effective concentration (for example 100 μM) of the voltage-gated sodium channel opener veratridine, or any other suitable voltage-gated sodium channel opener, may be added to the medium to enhance signal detection. Furthermore, and also to enhance signal-to-noise ratio, an effective concentration (for example 10 μg/ml) of suitable scorpion venom may also be added to the medium to delay channel inactivation. In order to find a modulator of the voltage-gated sodium channel of interest, the assay can be complemented with compounds from a compound library. Compounds of interest are added to the Li-rich solution, one in each well. At the end of the incubation period cells are repeatedly washed with Na free buffer until all extracellular LiCl is removed. Cell lysis is obtained through incubation of cells with triton (1%) for 15 min, or any other suitable method. The resulting cell lysate is then introduced into an atomic absorption spectrophotometer, thus quantifying the amount of Li-influx during the procedure described above.

The described assay can be run with any atomic absorption spectrophotometer using plates of 96-well format, 384-well format, or any other conventional plate format. The described assay can be applied to cell lines expressing any given one or more of the voltage-gated sodium channel alpha subunits, as well as any given combination of one of the voltage- gated alpha subunits with any one or more beta subunit. If needed the cell line of choice can be further hyperpolarised by expression of a suitable potassium leak ion channel, for example TREK-I, either by transient co-trans fection or through establishment of a stable co-transfected cell line. The successful expression of a leak K current can be verified using traditional intracellular electrophysiology, either in whole cell patch-clamp, perforated patch-clamp or conventional two-electrode voltage- clamp. A cell line of choice modified to successfully express a voltage-gated sodium channel of interest together with a suitable potassium leak ion channel transfected can then be used for screening using atomic absorptions spectrometry, as described above.

Whole-cell voltage clamp electrophysiology assay Electrophysiological recordings of sodium currents in cells stably expressing the voltage- gated sodium channel of interest confirms activity and provides a functional measure of the potency of compounds that specifically affect such channels.

Electrophysiological studies can be performed using automated patch-clamp electrophysiology platforms, like Ion Works HT, Ion Works Quattro, PatchXpress, or any other suitable platform. The cell line expressing the voltage-gated sodium channel of interest is plated in appropriate well tissue plates, as provided by the manufacturer of the automated patch-clamp platforms. Suitable extracellular and intracellular buffer for such experiments are applied according to the instructions given by the manufacturer of the automated patch-clamp platforms. Cells that express the voltage-gated sodium channel protein of interest are exposed to drugs through the pipetting system integrated in the platforms. A suitable voltage stimulus protocol is used to activate the voltage-gated sodium channel proteins of interest. A suitable stimulus protocol may consist of eight voltage pulses, each to -20 mV and 50 ms in length, and separated from each other by 330 ms intervals at a potential of -90 mV or -65 mV, but may also have other suitable parameters.

Electrophysiological studies can also be performed using the whole cell configuration of the standard patch clamp technique as described in the literature. In this assay, cells that express the human voltage-gated sodium channel protein of interest are exposed to the drugs by conventional microperfusion systems and a suitable voltage stimulus protocol is used to activate the voltage-gated sodium channels.

In vivo experiments

A compound of the invention when given by systemic injection to mice or rats, may specifically reduce pain behavior in the formalin test. This test is an accepted model of clinical pain in man, involving elements of nociceptor activation, inflammation, peripheral sensitization and central sensitization (A Tjølsen et al. Pain 1992, 51, 5/ It can therefore be inferred that a compound of the present invention is usefulas a therapeutic agent to relieve pain of various origins.

Compounds of formula I may showin analgesic activity in the intraarticular FCA (Freund's complete adjuvant) test in the rat, a model of inflammatory pain (Iadarola et al. Brain Research 1988, 455, 205-12) and in the Chung nerve lesion test in the rat, a model for neuropathic pain (Kim and Chung. Pain 1992, 50, 355). The analgesic effects in the animal models may be obtained after doses that do not produce tissue concentrations leading to conduction block in nerve fibers. Thus, the analgesic effects can not be explained by the local anesthetic properties of the compounds mentioned in the publication by Kornet and Thio. Analgesic efficacy after systemic administration is not a general property of drugs with local anesthetic effects (Scott et al. British Journal of Anaesthesia 1988, 61, 165-8). Generally, compounds of the invention are active in the Whole-cell voltage clamp electrophysiology assay above with IC50 values less than 10 μM. In one aspect of the invention, the IC50 value is less than 1 μM.

Title compounds of the above Examples were tested in the Whole-cell voltage clamp electrophysiology assay mentioned above. IC50 represents the compound concentration required for 50% inhibition. Specimen results are shown in the following table as pIC50 values, i.e. -log (IC50). Thus the larger the pIC50 the more potent the compound. For example, a pIC50 of 6.5 indicates an IC50 of 10 ^' M.

Claims

1. A compound of formula I

wherein

R¹ is hydrogen, Ci_3alkyl, Ci_3alkoxy, cyano, hydroxy or halo; and wherein said

is optionally substituted by one or more substituents independently selected from hydroxy,

andfluoro; and said

is optionally substituted by one or morefluoro;

m is 1, 2 or 3;

R² and R³ is each and independently selected from hydrogen, Ci_₄haloalkyl, Ci_₄haloalkoxy, halo, Ci_₄alkoxy, Ci_₄alkyl and C₃_₇cycloalkyloxy; wherein said Cs.ycycloalkyloxy is optionally substituted by one or morefluoro; and R² and R³ may not both be hydrogen;

Li is Ci_₄alkylene, pentylene, or C_3-6 cycloalkylene, wherein said

pentylene or Ci-6 cycloalkylene may be optionally substituted by one or more X*;

X⁴ is fluoro, Ci_₃alkyl, C₃-₇cycloalkyl, Ci_₃alkylOCi_₃alkyl, Ci_₃alkoxy, cyano, hydroxy, R⁴O(C=O)-, R⁴NR⁵(C=O)-, R⁴O(C=O)NR⁵-, R⁴NR⁵(C=O)NR⁵-, R⁴(C=O)O-, R⁴(C=O)NR⁵-, R⁴NR⁵(C=O)O- , R⁴NR⁵(C=O)NR⁵-, C₅-₆ heteroaryl(C=O), or C5_6 heteroaryl; R⁴ is Ci_₄alkyl, Ci_₄alkyl0Ci_₄alkyl, C₅_₆cycloalkyl, aryl, or aryl-Ci_₂alkyl; R⁵ is H or methyl;

and wherein said

and

is optionally substituted by one or more fluoro;

L₂ is Ci_3alkylene, optionally substituted by one or more X⁴;

as well as a pharmaceutically acceptable salt, or isomer thereof, or a salt of said isomer.

2. A compound according to claim 1, wherein

R¹ is hydrogen, Ci_₃alkyl, Ci_₃alkoxy, or halo; m is 1;

R² and R³ is each and independently selected from hydrogen, Ci_₄haloalkyl,

Ci_₄haloalkoxy, and Ci_₄alkyl;

Li is Ci_₄ alkylene, pentylene or C3-6 cycloalkylene, wherein said

pentylene or C3.6 cycloalkylene may be optionally substituted by one or more X*; X⁴ is Ci_₃alkyl; and

L₂ is C i_3 alkylene.

3. A compound according to claim 1 or 2, wherein Li is an ethylene group.

4. A compound according to claim 1 or 2, wherein Li is a methylene group.

5. A compound according to claim 1 or 2, wherein Li is a pentylene group.

6. A compound according to claim 1 or 2, wherein Li is cyclohexylene.

7. A compound according to any one of claims claim 1-6, wherein Li is substituted

4 by at least one X . 4

8. A compound according to claim 7, wherein X is methyl.

9. A compound according to any one of the preceding claims, wherein L2 is a methylene group.

4

10. A compound according to claim 9, wherein L2 is substituted by X .

4

11. A compound according to claim 10, wherein X is methyl.

12. A compound according to any one of the preceding claims, wherein m isl .

13. A compound according to any one of the preceding claims, wherein R is hydrogen.

14. A compound according to any one of claims 1-12, wherein R is methoxy.

15. A compound according to any one of claims 1-12, wherein R is methyl.

16. A compound according to any one of claims 1-12, wherein R is fluoro.

2 17. A compound according to any one of the preceding claims, wherein R is hydrogen.

2 18. A compound according to any one of claims 1-16, wherein R is -OCF3.

19. A compound according to any one of claims 1-16, wherein R is -CH2-CF3.

20. A compound according to any one of the preceding claims, wherein R is hydrogen.

21. A compound according to any one of claims 1-19, wherein R is -OCF3.

3

22. A compound according to any one of claims 1-19, wherein R is methyl.

23. A compound according to any one of the preceding claims, which compound is any one of:

2-(2-Cyanoethyl)-3-oxo-N-(4-(trifluoromethoxy)benzyl)isoindoline-l-carboxamide;

2-((trα/?5)-4-Cyanocyclohexyl)-3-oxo-N-(4-(trifluoromethoxy)benzyl)isoindoline-l- carboxamide ;

2-((cis)-4-Cyanocyclohexyl)-3-oxo-N-(4-(trifluoromethoxy)benzyl)isoindoline-l- carboxamide;

2-(2-Cyanoethyl)-7-methoxy-3-oxo-N-(4-(trifluoromethoxy)benzyl)isoindoline-l- carboxamide;

2-(2-Cyanoethyl)-7-methyl-3-oxo-N-(4-(trifluoromethoxy)benzyl)isoindoline-l- carboxamide; 2-(2-Cyanoethyl)-3 -OXO-N-(I -(4-(trifluoromethoxy )phenyl)ethyl)isoindo line- 1- carboxamide, ISOMER 4;

2-(2-Cyanoethyl)-3-oxo-N-(3-(trifluoromethoxy)benzyl)isoindoline-l -carboxamide;

2-(2-Cyanoethyl)-N-(2-methyl-4-(trifluoromethoxy)benzyl)-3-oxoisoindoline-l- carboxamide; 2-(2-Cyanoethyl)-4-fluoro-3-oxo-N-(4-(trifluoromethoxy)benzyl)isoindoline-l- carboxamide ;

2-(2-Cyanoethyl)-7-fluoro-3-oxo-N-(4-(trifluoromethoxy)benzyl)isoindoline-l- carboxamide;

2-(Cyanomethyl)-3-oxo-N-(4-(trifluoromethoxy)benzyl)isoindoline-l -carboxamide; 2-(l -Cyanopropan-2-yl)-3-oxo-N-(4-(trifluoromethoxy)benzyl)isoindoline- 1 - carboxamide ; 2-(3 -Cyano-3 -methylbutyl)-3 -oxo-N-(4-(trifluoromethoxy)benzyl)isoindoline- 1 - carboxamide;

2-(5-Cyanopentyl)-3-oxo-N-(4-(trifluoromethoxy)benzyl)isoindoline- 1 -carboxamide; and

2-(2-Cyanoethyl)-3-oxo-N-(4-(2,2,2-trifluoroethyl)benzyl)isoindoline-l -carboxamide.

24. A compound according to any one of the preceding claims, for use in therapy.

25. Use of a compound according to any one of claims 1-23, for the manufacture of a medicament for use in the treatment of a pain disorder.

26. A method for the treatment of a pain disorder, whereby a compound according to any one of claims 1-23 is administered to a subject in need of such pain treatment.

27 ^'. A compound according to any one of claims 1-23, for use in the treatment of a pain disorder.

28. A pharmaceutical composition comprising a compound according to any one of claims 1-23, in admixture with a pharmaceutically and pharmacologically acceptable excipient.