BiCYCLIC AND HETEROBICYCLIC DERIVATIVES, PROCESSES FOR PREPARING THEM AND THEIR USES The present invention concerns bicyclic and heterobicyclic derivatives, processes for preparing them, pharmaceutical compositions containing them and their use as pharmaceuticals.

The integrin α4β1 (also termed VLA-4 or Very Late Antigen-4 and designated CD49d/CD29) is predominantly expressed on eosinophils, lymphocytes, monocytes and basophils. It binds primarily to the vascular cell surface adhesion molecule VCAM-1 that is expressed on endothelium in response to inflammatory cytokines (TNF-α, IL-1 and selectively IL-4 and IL-13) and to the extracellular matrix protein fibronectin.

Because α4β1 is not expressed on circulating neutrophils, which are the first defense against infection, it is a target for the pharmacological control of inflammatory diseases.

Several in vitro and in vivo studies have indicated an important role of α4β1 in cell adhesion mediated inflammatory pathologies and that blocking its function is beneficial. Diseases include asthma, multiple sclerosis (MS), rheumatoid arthritis (RA) or inflammatory bowel diseases. α4-has also been related to cancers (including cancers, whether solid or haematopoietic) but not limited to, lung e.g. non-small cell lung, pancreatic, prostate, renal, cervical, ovarian, colorectal, mammary carcinoma, endometrial, bladder, malignant melanoma, seminomas, thyroid, acute myelogenous leukaemia and gastric cancer. α4β1 is also expressed on leukaemic cells that show increased survival through binding to fibronectin expressed on bone marrow stormal cells. Blocking this interaction in the presence of chemotherapy is beneficial in preventing relapse of acute myelogenous leukaemia. α4β1 and VCAM-1 have also been identified in smooth muscle cells from intimal atherosclerotic thickening of adult aorta. Blocking this interaction is beneficial in preventing smooth muscle differentiation and atherosclerosis.

The interaction of α4β1 on inflammatory cells with fibronectin has also been shown to increase chronic allograft failure. Blocking this interaction is beneficial in supporting transplant survival.

The integrin α4β7 (also termed LPAM-1 ) is expressed on certain sub-populations of T and B lymphocytes and on eosinophils. Like α4β1 , α4β7 binds VCAM-1 and fibronectin. In addition α4β7 binds to a cell surface adhesion molecule MAdCAM-1 that is expressed preferentially in the gastrointestinal tract and which is believed to be involved in

the homing of leukocytes to gastrointestinal mucosa. The interaction between α4β7 and MAdCAM-1 may also be important sites of inflammation outside of mucosal tissue.

Several studies have shown that α4β7 is involved in inflammatory bowel disease and that blocking its function is beneficial.

EP1323711 discloses novel phenylalanine derivatives of general structure, as shown below, having antagonistic effect on α4 intergrins.

EP1454898 discloses novel phenylalanine derivatives of general structure, as shown below, having antagonistic activity to α4 intergrins.

WO99/10312 discloses N-alkanoylphenylalanine derivatives of general structure, as shown below, which have activity as ihnibitors of binding between VCAM-1 and cells expressing VLA-4.

EP1477482 discloses novel phenylalanine derivatives of general structure, as shown below, having antagonistic activity to α4 intergrins and therapeutic agents for various diseases concerning α4 intergrin.

EP1568697 discloses 1 ,3-benzothiazinone derivatives of general structure, as shown below, as therapeutic agents for cardiovascular diseases , bone or joint diseases, infectious diseases inflammatory diseases, kidney diseases, having excellent effects on death cell inhibition, MIF binding.

WO03089410 discloses phenylalanine derivatives of general structure, as shown below, as useful α4 intergrin inhibitors.

Bioorganic & Medicinal Chemistry vol.10, no.6, 2002, pages 2051-2066 describes a series of novel N-benzoyl-L-biphenylalanine derivatives, as shown below, as potent inhibitors of dual oc4β7/α4β1 integrin antagonists.

WO2005077915 discloses novel compounds of general structure, as shown below, for the treatment of intergrin mediated disorders.

We have now found novel bicyclic and heterobicyclic compounds which are potent and selective inhibitors of α.4 integrins, such as α4β1 and/or α4β7.

In one aspect, the invention therefore provides a compound having formula I, its enantiomers, diastereoisomers, stereoisomeric forms, geometrical isomers or pharmaceutically acceptable salts thereof

formula I

wherein X ¹ is C or N; X ² is CH or N; X ³ is C or N; X ⁴ is C- R ^a , N- R ^b or N;

R ^a is hydrogen, halogen, 4 to 7 membered heterocycle or C^ .3 alkyl;

R^ is hydrogen, 4 to 7 membered heterocycle or C-μ 3 alkyl; R1 is hydrogen, halogen or C-|_β alkylamino; R ² is hydrogen or C-μβ alkylamino; R ³ is hydrogen or is 4 to 7 membered heterocycle (aromatic or non-aromatic) optionally substituted by a group selected from C-|_6 alkyl, halogen, amino, C^ .5 alkylamino, C-|.g dialkylamino; or is C-1.5 alkyl (linear or branched) optionally substituted by a group selected from halogen, C3.6 cycloalkyl, nitrile or C-1.3 alkylamino group; or is C3.6 cycloalkyl optionally substituted by a group selected from halogen or C-μβ alkyl; or forms a carbonyl group with the ring to which it is attached and when R ^D is hydrogen; R ⁴ is hydrogen or C-|_2 alkyl; χ5 is CH or N; R5 is hydrogen or halogen; R6 is hydrogen or halogen. In another aspect the invention provides a compound having formula Ia, its enantiomers, diastereoisomers, stereoisomeric forms, geometrical isomers or pharmaceutically acceptable salts thereof

formula I a

wherein X ¹ is C or N; X ² is CH or N; X ³ is C or N; X ⁴ is C- R ^a , N- R ^b or N;

R ^a is hydrogen, halogen, 4 to 7 membered heterocycle or C<| .3 alkyl;

Rb is hydrogen, 4 to 7 membered heterocycle or C-1.3 alkyl; R^ is hydrogen, halogen or C-] .Q alkylamino; R ² is hydrogen or C-μβ alkylamino; R ³ is hydrogen or is 4 to 7 membered heterocycle (aromatic or non-aromatic) optionally substituted by a group selected from C-|_6 alkyl, halogen, amino, C-μρ alkylamino, C-) .5 dialkylamino; or is C-|.β alkyl (linear or branched) optionally substituted by a group selected from halogen, C3.6 cycloalkyl, nitrile or C-1.3 alkylamino group; or is C3.6 cycloalkyl optionally substituted by a group selected from halogen or C-μβ ^alk Y'; ^or forms a carbonyl group with the ring to which it is attached and when R* ⁵ is hydrogen; R ⁴ is hydrogen or C-|_2 alkyl;

X ⁵ is CH or N; R5 is hydrogen or halogen; R6 is hydrogen or halogen. In another aspect the invention provides a compound having formula I b, its enantiomers, diastereoisomers, stereoisomeric forms, geometrical isomers or pharmaceutically acceptable salts thereof

formula I b

wherein X ¹ is C or N; X ² is CH or N; X ³ is C or N; X ⁴ is C- R ^a , N- R ^b or N;

R ^a is hydrogen, halogen, 4 to 7 membered heterocycle or C-1.3 alkyl;

R^ is hydrogen, 4 to 7 membered heterocycle or C-1.3 alkyl; R1 is hydrogen, halogen or C-] _Q alkylamino; R ² is hydrogen or C-|.g alkylamino; R ³ is hydrogen or is 4 to 7 membered heterocycle (aromatic or non-aromatic) optionally substituted by a group selected from C-μβ alkyl, halogen, amino, C-|.β alkylamino, C<|_6 dialkylamino; or is C-\ .Q alkyl (linear or branched) optionally substituted by a group selected from halogen, C3.6 cycloalkyl, nitrile or C-1.3 alkylamino group; or is C3.6 cycloalkyl optionally substituted by a group selected from halogen or C-|.g alkyl; or forms a carbonyl group with the ring to which it is attached and when R ^D is hydrogen; R ⁴ is hydrogen or C^ .2 alkyl; χ5 is CH or N; R5 is hydrogen or halogen; R6 is hydrogen or halogen. The term "alkyl", as used herein, represents saturated, monovalent hydrocarbon radicals having linear or branched moieties or combinations thereof and containing 1-6 carbon atoms. One methylene (-CH2-) group, of the alkyl, can be replaced by oxygen or sulfur. Alkyl moieties can be optionally substituted by halogen, C^.Q cycloalkyl, nitrile, amino, C-|.g alkylamino groups, C-i _6 dialkylamino groups. Usually alkyl groups, in the present case, are methyl, methoxy, ethyl, cyclopropylmethyl, iso-butyl, methyl- dimethylamine, n-propyl, 2,2 dimethyl-propyl, n-butyl, n-pentyl, 1-methylsulfanylethyl. Preferred alkyl groups are cyclopropylmethyl, methyl- dimethylamine, 2,2 dimethyl-propyl, methyl. Most preferred alkyl group is cyclopropylmethyl.

The term "cycloalkyl", as used herein, refers to a monovalent or divalent group of 3 to 6 carbon atoms, derived from a saturated cyclic hydrocarbon. Cycloalkyl groups can be optionally substituted by halogen or C<\ _Q alkyl groups as defined above. Usually cyclolakyl groups, in the present case are cyclopropyl and cyclohexyl. Preferred cycloalkyl group is cyclopropyl.

The term "amino", as used herein, refers to a group of formula -NH2.

The term "halogen", as used herein, refers to an atom of chlorine, bromine, fluorine, iodine. Usually halogen is chlorine or fluorine. Preferred halogen are chlorine and fluorine.

The term "nitrile", as used herein, refers to a group of formula -CN.

The term "carbonyl" as used herein refers to a group of formula C=O. The term "aryl" as used herein, refers to an organic moiety derived from an aromatic hydrocarbon consisting of a ring or multiple rings, containing 6 to 10 carbon atoms by removal of one hydrogen atom, which can optionally be substituted by 1-3 halogens, or by 1-3 C-μg alkyl groups as defined above. Usually aryl groups are, in the present case, 3-methoxy phenyl, 4-methoxyphenyl, 2-methylphenyl, phenyl. The term "alkylamino", as used herein, refers to a group of formula -NHR ^C , wherein R ^c is a C-\.Q alkyl group as defined above. Usually alkylamino group is methylamine.

The term "dialkylamino", as used herein, refers to a group of formula -NR^R ^e , wherein R^ is a C-μg alkyl group as defined above and R ^e is a C-] _β alkyl group as defined above. Usually dialkylamino group is dimethylamine.

The term "heterocycle", as used herein refers to a 4 to 7 membered ring, which can be aromatic or non -aromatic, containing at least one heteroatom selected from O or N or S or combinations of at least two thereof, interrupting the carbocyclic ring structure. The heterocyclic ring can be interrupted by -C=O. The S heteroatom can be oxidized. Heterocycles can be monocyclic or polycyclic. Heterocycles can optionally be substituted by 1 to 3 C-|.β alkyl, amino, C-1.3 alkylamino, C-1.3 dialkylamino, 1 to 3 halogens, as defined above. Usually heterocycle groups, in the present case are, 4-chloro-3-pyridine, 4- methylamine-3-pyridine, 3-pyridine, 2-piperidine, 3-furan, 2-furan, 1 methyl-1 H imidazol, 2- thiophene, 4-chloro-1 methyl-1 H pyrazole. Preferred heterocycle groups are 3-pyridine, 2- piperidine, 4-chloro-3-pyridine, 4-methylamine-3-pyridine. Most preferred heterocycles are 3-pyridine, 2-piperidine.

Usually X ¹ is C or N. Preferred X ¹ is C.

Usually X ² is CH or N. Most preferred X ² is N.

Usually X ³ is C or N. Preferred X ³ is N. Usually X ⁴ is C-R ^a , N- R ^b or N. Preferred X ⁴ are C- R ^a , N. Most preferred X ⁴ is N.

Usually R ^a is hydrogen, halogen, 4 to 7 membered heterocycle or C1.3 alkyl.

Preferred R ^a is methyl.

Usually R ^b is hydrogen, 4 to 7 membered heterocycle or C-1.3 alkyl. Preferred R ^b is hydrogen. Usually R^ is hydrogen, halogen or C^ .Q alkylamine. Preferred R^ is hydrogen.

Usually R ² is hydrogen or C-μ _β alkylamine. Preferred R ² is hydrogen.

Usually R ³ is hydrogen or is 4 to 7 membered heterocycle (aromatic or non- aromatic) optionally substituted by a group selected from C1.5 alkyl, halogen, amino, C- _j . _β alkylamino, C-μø dialkylamino; or is C-) .5 alkyl (linear or branched) optionally substituted by a group selected from halogen, C3.6 cycloalkyl, nitrile or C-|.β alkylamino group; or is C3.Q cycloalkyl optionally substituted by a group selected from halogen or C-1.5 alkyl.

Usually R ³ is hydrogen, 4-chloro-3-pyridine, 4-methylamine-3-pyridine, 3-pyridine, 2- piperidine, 3-furan, 2-furan, 1 methyl-I H imidazol, 2-thiophene, 4-chloro-1 methyl-1 H pyrazole, carbonyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-methylphenyl, N-methyl-2- piperidine, methyl, ethyl, cyclopropylmethyl, iso-butyl, methyl- dimethylamine, n-propyl, 2,2 dimethyl-propyl, n-butyl, n-pentyl, 1-methylsulfanylethyl. Preferred R ³ is N-methyl-2- piperidine, 4-chloro-3-pyridine, 4-methylamine-3-pyridine, 3-pyridine, 2-piperidine, carbonyl, methyl-dimethylamine, cyclopropylmethyl, hydrogen, iso-butyl. Most preferred R ³ is cyclopropylmethyl, 2-piperidine, 3-pyridine. Usually R ⁴ is hydrogen or C-] .2 alkyl. Preferred R ⁴ is hydrogen.

Usually X ⁵ is CH or N.

Usually R^ is hydrogen or halogen. Preferred R^ is hydrogen, chlorine. Usually R^ is hydrogen or halogen. Preferred R^ is hydrogen, fluoride. In a preferred embodiment of the invention X ¹ is C; and

X ² is CH, N; and X ³ is C, N; and X ⁴ is C- R ^a , N, N- R ^b ; and R ^a is methyl; and R^ is hydrogen; and

R^ is hydrogen; and R ² is hydrogen; and

R ³ is 4-chloro-3-pyridine, 4-methylamine-3-pyridine, 3-pyridine, 2-piperidine, carbonyl, methyl-dimethylamine, cyclopropylmethyl, hydrogen, N-methyl-2-piperidine, iso-butyl; and R ⁴ is hydrogen; and

X ⁵ is CH, N; and R5 is hydrogen, chlorine; and R6 is hydrogen, fluorine. Preferred compounds of the invention are:

N-(3,5-dichloroisonicotinoyl)-4-(2-pyridin-3-yl-3H-imidaz o[4,5-b]pyridin-3-yl)-L- phenylalanine;

4-[2-(6-chloropyridin-3-yl)-3H-imidazo[4,5-b]pyridin-3-yl ]-N-(3,5-dichloroisonicotinoyl)- L-phenylalanine; N-(3,5-dichloroisonicotinoyl)-4-(2-oxo-1 ,2-dihydro-3H-imidazo[4,5-b]pyridin-3-yl)-L- phenylalanine;

N^S.δ-dichloroisonicotinoyO^^-^methylaminoJpyridin-S-yll -SH-imidazo^.S- b]pyridin-3-yl}-L-phenylalanine;

N-(3,5-dichloroisonicotinoyl)-4-{2-[(dimethylamino)methyl ]-3H-imidazo[4,5-b]pyridin-3- yl}-L-phenylalanine;

N-(2-chloro-5-fluorobenzoyl)-4-[2-(cyclopropylmethyl)-3H- imidazo[4,5-b]pyridin-3-yl]-L- phenylalanine;

N-(3,5-dichloroisonicotinoyl)-3-(2-isobutyl-3H-imidazo[4, 5-b]pyridin-3-yl)-L- phenylalanine; N-(3,5-dichloroisonicotinoyl)-3-(2-pyridin-3-yl-3H-imidazo[4 ,5-b]pyridin-3-yl)-L- phenylalanine;

N-(3,5-dichloroisonicotinoyl)-4-(3-methyl-1 H-pyrrolo[2,3-b]pyridin-1-yl)phenylalanine;

N-^.S-dichloroisonicotinoyl^-O H-indol-S-yO-L-phenylalanine;

N-(3,5-dichloroisonicotinoyl)-4-(2-piperidin-2-yl-3H-imid azo[4,5-b]pyridin-3-yl)-L- phenylalanine;

N-(2,6-dichlorobenzoyl)-4-{2-[(2R)-piperidin-2-yl]-3H-imi dazo[4,5-b]pyridin-3-yl}-L- phenylalanine;

N-(3,5-dichloroisonicotinoyl)-4-{2-[(2R)-piperidin-2-yl]- 3H-imidazo[4,5-b]pyridin-3-yl}-L- phenylalanine; N-(3,5-dichloroisonicotinoyl)-4-{2-[(2R)-1-methylpiperidin-2 -yl]-3H-imidazo[4,5- b]pyridin-3-yl}-L-phenylalanine;

N-(3,5-dichloroisonicotinoyl)-4-{2-[(2S)-piperidin-2-yl]- 3H-imidazo[4,5-b]pyridin-3-yl}-L- phenylalanine;

N-(2,6-dichlorobenzoyl)-4-{2-[(2S)-piperidin-2-yl]-3H-inn idazo[4,5-b]pyridin-3-yl}-L- phenylalanine.

Most preferred compounds of the invention are:

N-(2-chloro-5-fluorobenzoyl)-4-[2-(cyclopropylmethyl)-3H- imidazo[4,5-b]pyridin-3-yl]-L- phenylalanine;

N-(3,5-dichloroisonicotinoyl)-4-(2-pyridin-3-yl-3H-imidaz o[4,5-b]pyridin-3-yl)-L- phenylalanine;

N-(3,5-dichloroisonicotinoyl)-4-{2-[(2S)-piperidin-2-yl]- 3H-imidazo[4,5-b]pyridin-3-yl}-L- phenylalanine;

N-(2,6-dichlorobenzoyl)-4-{2-[(2R)-piperidin-2-yl]-3H-imi dazo[4,5-b]pyridin-3-yl}-L- phenylalanine; N-(3,5-dichloroisonicotinoyl)-4-{2-[(2R)-piperidin-2-yl]-3H- imidazo[4,5-b]pyridin-3-yl}-L- phenylalanine;

N-(3,5-dichloroisonicotinoyl)-4-(2-piperidin-2-yl-3H-imid azo[4,5-b]pyridin-3-yl)-L- phenylalanine.

Compounds of formula I and some of their intermediates have at least one stereogenic centre in their structure. This stereogenic centre may be present in an R or an S configuration, said R and S notation is used in correspondence with the rules described in Pure Appl. Chem. (1976), 45, 11-30.

In all the above-mentioned scopes, the asymmetric carbon atom, is preferably in the "S" configuration. The "pharmaceutically acceptable salts" according to the invention include therapeutically active, non-toxic base and acid salt forms which the compounds of formula I are able to form.

The acid addition salt form of a compound of formula I that occurs in its free form as a base can be obtained by treating the free base with an appropriate acid such as an inorganic acid, for example, a hydrohalic such as hydrochloric, hydrobromic, sulfuric, nitric, phosphoric and the like; or an organic acid, such as, for example, acetic, hydroxyacetic, propanoic, lactic, pyruvic, malonic, succinic, maleic, fumaric, malic, tartaric, citric, methanesulfonic, ethanesulfonic, benzenesulfonic, p-toluenesulfonic, cyclamic, salicylic, p- aminosalicylic, pamoic, formic and the like (Handbook of Pharmaceutical Salts, P. Heinrich Stahl & Camille G. Wermuth (Eds), Verlag Helvetica Chimica Acta - Zurich, 2002, 329- 345).

The compounds of formula I containing acidic protons may be converted into their therapeutically active, non-toxic base addition salt forms, e.g. metal or amine salts, by treatment with appropriate organic and inorganic bases. Appropriate base salt forms include, for example, ammonium salts, alkali and earth alkaline metal salts, e.g. lithium, sodium, potassium, magnesium, calcium salts and the like, salts with organic bases, e.g. N-methyl-D-glucamine salts, and salts with amino acids such as, for example, arginine, lysine and the like (Handbook of Pharmaceutical Salts, P. Heinrich Stahl & Camille G. Wermuth (Eds), Verlag Helvetica Chimica Acta - Zurich, 2002, 329-345). Conversely said

salt forms can be converted into the free forms by treatment with an appropriate base or acid.

Compounds of formula I and their salts, can be in the form of a solvate, which is included within the scope of the present invention. Such solvates include for example hydrates, alcoholates and the like.

The invention also relates to all stereoisomeric forms such as enantiomeric and diastereoisomeric forms of the compounds of formula I or mixtures thereof (including all possible mixtures of stereoisomers).

Some of the compounds of formula I may also exist in tautomeric forms. Such forms although not explicitly indicated in the above formula are intended to be included within the scope of the present invention.

With respect to the present invention reference to a compound or compounds, is intended to encompass that compound in each of its possible isomeric forms and mixtures thereof unless the particular isomeric form is referred to specifically. Compounds according to the present invention may exist in different polymorphic forms. Although not explicitly indicated in the above formula, such forms are intended to be included within the scope of the present invention.

The invention also includes within its scope prodrug forms of the compounds of formula I and its various sub-scopes and sub-groups. The term "prodrug" as used herein includes compound forms, which are rapidly transformed in vivo to the parent compound according to the invention, for example, by hydrolysis in blood. Prodrugs are compounds bearing groups that are removed by biotransformation prior to exhibiting their pharmacological action. Prodrugs form a class of groups well known to practitioners of the art. In the present case they include, alkoxycarbonyl groups (such as methoxycarbonyl or ethoxycarbonyl). The compounds bearing this functional group are also used as synthetic intermediates. Prodrug compounds have the advantage that they may exhibit improved bioavailability as a result of enhanced solubility and/or rate of absorption (T. Higuchi and V. Stella, "Pro-drugs as Novel Delivery System", Vol. 14 of the A.C.S. Symposium Series; "Bioreversible Carriers in Drug Design", ed. Edward B. Roche, American Pharmaceutical Association and Pergamon Press, 1987).

Potential prodrugs of the invention are:

Ethyl 4-[2-(6-chloropyridin-3-yl)-3H-imidazo[4,5-b]pyridin-3-yl]-N -(3,5- dichloroisonicotinoyl)-L-phenylalaninate;

Ethyl N-(3,5-dichloroisonicotinoyl)-4-(2-pyridin-3-yl-3H-imidazo[4 ,5-b]pyridin-3-yl)- L-phenylalaninate;

Methyl N-(3,5-dichloroisonicotinoyl)-4-(3-methyl-1 H-pyrrolo[2,3-b]pyridin-1 - yl)phenylalaninate; Ethyl N-(3,5-dichloroisonicotinoyl)-4-{2-[(2S)-piperidin-2-yl]-3H- imidazo[4,5- b]pyridin-3-yl}-L-phenylalaninate;

Ethyl N-(2,6-dichlorobenzoyl)-4-{2-[(2R)-piperidin-2-yl]-3H-imidaz o[4,5-b]pyridin-3- yl}-L-phenylalaninate.

The present invention concerns also processes for preparing the compounds of formula I.

When compounds of formula I present one stereogenic center, and that non- stereoselective methods of synthesis are used, resolution of the mixture of stereoisomers can best be effected in one or several steps, involving generally sequential separation of mixtures of diastereomers into their constituting racemates, using preferably chromatographic separations on achiral or chiral phase in reversed or preferably in direct mode, followed by at least one ultimate step of resolution of each racemate into its enantiomers, using most preferably chromatographic separation on chiral phase in reversed or preferably in direct mode. Alternatively, when partly stereoselective methods of synthesis are used the ultimate step may be a separation of diastereomers using preferably chromatographic separations on achiral or chiral phase in reversed or preferably in direct mode.

It has now been found that compounds of formula I and their pharmaceutically acceptable salts are useful in a variety of pharmaceutical indications.

For example, the compounds according to the invention are useful for the treatment of asthma, allergic rhinitis, sinusitis, conjunctivitis, food allergy, inflammatory skin disorders including dermatitis, psoriasis, urticaria, pruritus and eczema, rheumatoid arthritis, inflammatory bowel diseases including Crohn's disease and ulcerative colitis, multiple sclerosis and other autoimmune disorders, acute myelogenous leukaemia, transplantation and atherosclerosis, transplant rejection, α4-related cancers such as lung e.g. non-small cell lung, pancreatic, prostate, renal, cervical, ovarian, colorectal, mammary carcinoma, endometrial, bladder, malignant melanoma, seminomas, thyroid, acute myelogenous leukaemia and gastric cancer.

Thus, the present invention, in a further aspect, concerns the use of a compound of formula I or a pharmaceutically acceptable salt thereof for the manufacture of a medicament for the treatment of disorders such as mentioned above.

In particular, the present invention concerns the use of a compound of formula I or a pharmaceutically acceptable salt thereof, for the manufacture of a medicament for the treatment of α4β1 and/or α4β7 dependent inflammatory or medical conditions such as for example asthma, allergic rhinitis, sinusitis, conjunctivitis, food allergy, inflammatory skin disorders including dermatitis, psoriasis, urticaria, pruritus and eczema, rheumatoid arthritis, inflammatory bowel diseases including Crohn's disease and ulcerative colitis, multiple sclerosis and other autoimmune disorders, acute myelogenous leukaemia, transplantation and atherosclerosis, transplant rejection, α4-related cancers such as lung e.g. non-small cell lung, pancreatic, prostate, renal, cervical, ovarian, colorectal, mammary carcinoma, endometrial, bladder, malignant melanoma, seminomas, thyroid, acute myelogenous leukaemia and gastric cancer.

The compounds of the invention are useful for treating conditions mediated by adhesion mechanisms. These conditions include asthma, allergic rhinitis, sinusitis, conjunctivitis, food allergy, inflammatory skin disorders including dermatitis, psoriasis, urticaria, pruritus and eczema, rheumatoid arthritis, inflammatory bowel diseases including Crohn's disease and ulcerative colitis, multiple sclerosis and other autoimmune disorders, acute myelogenous leukaemia, transplantation and atherosclerosis, transplant rejection, α4-related cancers such as lung e.g. non-small cell lung, pancreatic, prostate, renal, cervical, ovarian, colorectal, mammary carcinoma, endometrial, bladder, malignant melanoma, seminomas, thyroid, acute myelogenous leukaemia and gastric cancer.

Subjects in need of treatment for a α4β1 and/or α4β7 dependent inflammatory or medical condition, preferably asthma, allergic rhinitis, sinusitis, conjunctivitis, food allergy, inflammatory skin disorders including dermatitis, psoriasis, urticaria, pruritus and eczema, rheumatoid arthritis, inflammatory bowel diseases including Crohn's disease and ulcerative colitis, multiple sclerosis and other autoimmune disorders, acute myelogenous leukaemia, transplantation and atherosclerosis, transplant rejection, α4-related cancers such as lung e.g. non-small cell lung, pancreatic, prostate, renal, cervical, ovarian, colorectal, mammary carcinoma, endometrial, bladder, malignant melanoma, seminomas, thyroid, acute myelogenous leukaemia and gastric cancer, can be treated by administering to the patient an effective amount of one or more of the above-identified compounds or a pharmaceutically acceptable derivative or salt thereof in a pharmaceutically acceptable carrier or diluent to reduce formation of oxygen radicals. The active materials can be administered by any appropriate route, for example, orally, parenterally, intravenously, intradermally, subcutaneously, intramuscularly or topically, in liquid, cream, gel or solid form, via a buccal or nasal spray, or aerosol, syrup, a patch or suppositories. The invention

further concerns the use of the compounds of formula I for the manufacture of a medicament for therapeutic application. In particular, the invention concerns the use of the compounds of formula I for the manufacture of a medicament useful for treating conditions in which there is likely to be a α4β1 and/or α4β7 dependent component. The invention concerns the use of the compound of formula I for the manufacture of a medicament useful for treating asthma, allergic rhinitis, sinusitis, conjunctivitis, food allergy, inflammatory skin disorders including dermatitis, psoriasis, urticaria, pruritus and eczema, rheumatoid arthritis, inflammatory bowel diseases including Crohn's disease and ulcerative colitis, multiple sclerosis and other autoimmune disorders, acute myelogenous leukaemia, transplantation and atherosclerosis, transplant rejection, cc4-related cancers such as lung e.g. non-small cell lung, pancreatic, prostate, renal, cervical, ovarian, colorectal, mammary carcinoma, endometrial, bladder, malignant melanoma, seminomas, thyroid, acute myelogenous leukaemia and gastric cancer.

The invention further concerns the compounds of formula I for use as medicaments. The invention concerns the compounds of formula I for use as a medicament for treating asthma, allergic rhinitis, sinusitis, conjunctivitis, food allergy, inflammatory skin disorders including dermatitis, psoriasis, urticaria, pruritus and eczema, rheumatoid arthritis, inflammatory bowel diseases including Crohn's disease and ulcerative colitis, multiple sclerosis and other autoimmune disorders, acute myelogenous leukaemia, transplantation and atherosclerosis, transplant rejection, α4-related cancers such as lung e.g. non-small cell lung, pancreatic, prostate, renal, cervical, ovarian, colorectal, mammary carcinoma, endometrial, bladder, malignant melanoma, seminomas, thyroid, acute myelogenous leukaemia and gastric cancer.

The activity and properties of the active compounds, oral availability and stability in vitro or in vivo can vary significantly among the optical isomers of the disclosed compounds.

In a preferred embodiment, the active compound is administered in an enantiomerically enriched form, i.e., substantially in the form of one isomer.

The present invention also concerns a method for treating α4β1 and/or α4β7 dependent inflammatory or medical condition (asthma, allergic rhinitis, sinusitis, conjunctivitis, food allergy, inflammatory skin disorders including dermatitis, psoriasis, urticaria, pruritus and eczema, rheumatoid arthritis, inflammatory bowel diseases including Crohn's disease and ulcerative colitis, multiple sclerosis and other autoimmune disorders, acute myelogenous leukaemia, transplantation and atherosclerosis, transplant rejection, α4-related cancers such as lung e.g. non-small cell lung, pancreatic, prostate, renal,

cervical, ovarian, colorectal, mammary carcinoma, endometrial, bladder, malignant melanoma, seminomas, thyroid, acute myelogenous leukaemia and gastric cancer) in a mammal in need of such treatment, comprising administering a therapeutic dose of at least one compound of formula I or a pharmaceutically acceptable salt thereof to a patient. The methods of the invention comprise administration to a mammal (preferably human) suffering from above mentioned conditions or disorders, of a compound according to the invention in an amount sufficient to alleviate or prevent the disorder or condition.

The compound is conveniently administered in any suitable unit dosage form, including but not limited to one containing 0.01 to 2000 mg, preferably 0.05 to 500 mg of active ingredient per unit dosage form.

The term "treatment" as used herein includes curative treatment and prophylactic treatment.

The term "substantially" as used herein refers to a composition of equal or higher to 95% of the said isomer. By "curative" is meant efficacy in treating a current symptomatic episode of a disorder or condition.

By "prophylactic" is meant prevention of the occurrence or recurrence of a disorder or condition.

The compounds are of use in modulating cell adhesion and in particular are of use in the prophylaxis and treatment of diseases or disorders in which the extravasation of leukocytes plays a role and the invention extends to such a use and to the use of the compounds for the manufacture of a medicament for treating such diseases or disorders.

Diseases or disorders of this type include inflammatory arthritis such as rheumatoid arthritis, vasculitis or polydermatomyositis, multiple sclerosis, transplantation, diabetes, inflammatory dermatoses such as psoriasis or dermatitis, asthma and inflammatory bowel disease.

One aspect of the invention includes methods for treating α4-related cancers (including cancers, whether solid or haematopoietic). Examples of such cancers include, but are not limited to, lung e.g. non-small cell lung, pancreatic, prostate, renal, cervical, ovarian, colorectal, mammary carcinoma, endometrial, bladder, malignant melanoma, seminomas, thyroid, acute myelogenous leukaemia and gastric cancer.

Results obtained with compounds of formula I are indicative of a strong pharmacological effect.

For treating diseases, compounds of formula I or their pharmaceutically acceptable salts, may be employed at an effective daily dosage and administered in the form of a pharmaceutical composition.

Therefore, another embodiment of the present invention concerns a pharmaceutical composition comprising an effective amount of a compound of formula I or a pharmaceutically acceptable salt thereof in combination with a pharmaceutically acceptable diluent or carrier.

To prepare a pharmaceutical composition according to the invention, one or more of the compounds of formula I or a pharmaceutically acceptable salt thereof, is intimately admixed with a pharmaceutical diluent or carrier according to conventional pharmaceutical compounding techniques known to the skilled practitioner.

Suitable diluents and carriers may take a wide variety of forms depending on the desired route of administration, e.g., oral, rectal, or parenteral.

Pharmaceutical compositions comprising compounds according to the invention can, for example, be administered orally or parenterally, i.e., intravenously, intramuscularly, subcutaneously or intrathecal Iy.

Pharmaceutical compositions suitable for oral administration can be solids or liquids and can, for example, be in the form of tablets, pills, dragees, gelatine capsules, solutions, syrups, suppositories and the like. To this end the active ingredient may be mixed with an inert diluent or a non-toxic pharmaceutically acceptable carrier such as starch or lactose. Optionally, these pharmaceutical compositions can also contain a binder such as microcrystalline cellulose, gum tragacanth or gelatine, a disintegrant such as alginic acid, a lubricant such as magnesium stearate, a glidant such as colloidal silicon dioxide, a sweetener such as sucrose or saccharin, or colouring agents or a flavouring agent such as peppermint or methyl salicylate.

The invention also contemplates compositions which can release the active substance in a controlled manner. Pharmaceutical compositions which can be used for parenteral administration are in conventional form such as aqueous or oily solutions or suspensions generally contained in ampoules, disposable syringes, glass or plastics vials or infusion containers.

In addition to the active ingredient, these solutions or suspensions can optionally also contain a sterile diluent such as water for injection, a physiological saline solution, oils, polyethylene glycols, glycerine, propylene glycol or other synthetic solvents, antibacterial agents such as benzyl alcohol, antioxidants such as ascorbic acid or sodium

bisulphite, chelating agents such as ethylene diamine-tetra-acetic acid, buffers such as acetates, citrates or phosphates and agents for adjusting the osmolarity, such as sodium chloride or dextrose.

These pharmaceutical forms are prepared using methods which are routinely used by pharmacists.

The amount of active ingredient in the pharmaceutical compositions can fall within a wide range of concentrations and depends on a variety of factors such as the patient's sex, age, weight and medical condition, as well as on the method of administration. Thus the quantity of compound of formula I in compositions for oral administration is at least 0.5 % by weight and can be up to 80 % by weight with respect to the total weight of the composition.

For the preferred oral compositions, the daily dosage is in the range 0.01 to 2000 milligrams (mg) of compounds of formula I.

In compositions for parenteral administration, the quantity of compound of formula I present is at least 0.5 % by weight and can be up to 33 % by weight with respect to the total weight of the composition. For the preferred parenteral compositions, the dosage unit is in the range 0.01 mg to 2000 mg of compounds of formula I.

The daily dose can fall within a wide range of dosage units of compound of formula I and is generally in the range 0.01 to 2000 mg. However, it should be understood that the specific doses could be adapted to particular cases depending on the individual requirements, at the physician's discretion.

The compounds of the invention may be co-administered with another therapeutic agent most likely from a different therapeutic area.

Co-administration in this context means the dosing either of components, which are formulated together as a single dosage form; or the administration of separately formulated agents at substantially the same time, or sequential dosing of a compound of the invention followed by a therapeutic agent of a different therapeutic area.

In this context suitable examples of therapeutic agents may include, but are not limited to, histamine H1 antagonists such as cetihzine, histamine H2 antagonists, histamine H3 antagonists, leukotriene antagonists, PDE4 inhibitors such as 3-cyclo- propylmethoxy-4-difluoromethoxy-λ/-[3,5-di-chloropyrid-4-yl ]-benzamide, muscarinic M3 antagonists, β ₂ agonists, theophylline, sodium cromoglycate, anti-TNF antibodies such as certolizumab pegol or adalimumab, anti-IL6 antibodies, anti-IL17 antibodies, adhesion molecule inhibitors , inhibitors of cytokine synthesis such as P38 MAP kinase inhibitors and inhibitors of PI3 kinase, methotrexate.

The present invention concerns also processes for preparing the compounds of formula I.

The compounds of formula I according to the invention can be prepared analogously to conventional methods as understood by the person skilled in the art of synthetic organic chemistry.

The following processes description sets forth certain synthesis routes in an illustrative manner. Other alternative and/or analogous methods will be readily apparent to those skilled in this art.

Most compounds of formula I may be prepared according to one of the following schemes:

Scheme 1

In scheme 1 , starting with N-(tert-butyloxycarbonyl)-4-amino-L-phenylalanine ethyl ester (CAS No. 67630-01-7), the nitro group is reduced down to the aniline using palladium on carbon and Hydrogen. The corresponding methyl ester is also commercially available as well as the corresponding meta substituted phenyls. This is then reacted with a suitably substituted nitropyridine or nitrobenzene derivative, displacing the labile chloride in refluxing Ethanol. Reduction of the nitro group using palladium on carbon yields the corresponding aniline which could then be reacted with a variety of acids using EDC as a coupling reagent. Ring closure to afford the imidazole ring is performed using acetic acid, with heating in a microwave reactor. The t-butyl protecting group is removed using trifluoracetic acid in dicloromethane, followed by amide coupling with the free amine and a suitable aryl acid chloride. The ester is then saponified to the acid using 2N NaOH.

Scheme 2

In scheme 2, starting with N-(tert-butyloxycarbonyl)-4-amino-L-phenylalanine ethyl ester (CAS No. 67630-01-7), the nitro group is reduced down to the aniline using palladium on carbon and Hydrogen. This is then reacted with a suitably substituted nitropyridine or nitrobenzene derivative, displacing the labile chloride in refluxing Ethanol. The t-butyl protecting group is removed using Trifluoroacetic acid in dicloromethane, followed by amide coupling with the free amine and a suitable aryl acid chloride. Reduction of the nitro group using palladium on carbon yields the corresponding aniline which could then be reacted with a variety of acids using EDC as a coupling reagent. Ring closure to afford the imidazole ring is performed using acetic acid, with heating in a microwave reactor. The ester is then saponified to the acid using 2N NaOH.

N-^.S-DichloroisonicotinoyO-^S-methyl-I H-pyrroloβ.S-bjpyridin-i- yl)phenylalanine is synthesized from 4-iodobenzyloxybenzene (CAS No. 19578-68-8), 7- azaindole (CAS No. 271-63-6), copper (I) iodide frans-1 ,2-diaminocyclohexane through several chemical transformations.

N-(3,5-Dichloroisonicotinoyl)-4-(1 H-indol-3-yl)-L-phenylalanine is synthesized from

4-Bromo-N-[(1 ,1 -dimethylethoxy)carbonyl]-ethylester-L-phenylalanine (RN-591249-54-6), 2,6-dichloroisonicotinoyl chloride and 1-(phenylsulfonyl)-3-indoleboronic acid through several chemical transformations.

The present invention also relates to synthetic intermediates geometrical isomers, enantiomers, diastereoisomers, pharmaceutically acceptable salts and all possible mixtures thereof.

Specific synthetic intermediates are selected from the group consisting of:

Ethyl N-(tert-butoxycarbonyl)-4-[(3-nitropyridin-2-yl)amino]-L-phe nylalaninate;

Ethyl 4-[(3-aminopyridin-2-yl)amino]-N-(tert-butoxycarbonyl)-L-phe nylalaninate; Ethyl 4-[(3-nitropyridin-2-yl)amino]-L-phenylalaninate;

Ethyl N-(3,5-dichloroisonicotinoyl)-4-[(3-nitropyridin-2-yl)amino] -L-phenylalaninate;

Ethyl 4-[(3-aminopyridin-2-yl)amino]-N-(3,5-dichloroisonicotinoyl) -L- phenylalaninate;

Ethyl 4-[2-(cyclopropylmethyl)-3H-imidazo[4,5-b]pyridin-3-yl]-L-ph enylalaninate hydrochloride;

Ethyl N-(tert-butoxycarbonyl)-3-nitro-L-phenylalaninate;

Ethyl N-(tert-butoxycarbonyl)-3-[(3-nitropyridin-2-yl)amino]-L-phe nylalaninate;

1-{1-[4-(Benzyloxy)phenyl]-1 H-pyrrolo[2,3-b]pyridin-3-yl}-N,N- dimethylmethanamine; Methyl (2Z)-2-acetamido-3-[4-(3-methyl-1 H-pyrrolo[2,3-b]pyridin-1 - yl)phenyl]acrylate;

Ethyl 4-(2-{(2S)-1-[(benzyloxy)carbonyl]piperidin-2-yl}-3H-imidazo [4,5-b]pyridin-3- yl)-N-(tert-butoxycarbonyl)-L-phenylalaninate;

Ethyl 4-(2-{(2R)-1-[(benzyloxy)carbonyl]piperidin-2-yl}-3H-imidazo [4,5-b]pyridin-3- yl)-N-(tert-butoxycarbonyl)-L-phenylalaninate;

Ethyl 4-(2-{(2S)-1-[(benzyloxy)carbonyl]piperidin-2-yl}-3H-imidazo [4,5-b]pyridin-3- yl)-L-phenylalaninate;

Ethyl 4-(2-{(2R)-1-[(benzyloxy)carbonyl]piperidin-2-yl}-3H-imidazo [4,5-b]pyridin-3- yl)-L-phenylalaninate; Ethyl4-(2-{(2S)-1-[(benzyloxy)carbonyl]piperidin-2-yl}-3H-im idazo[4,5-b]pyridin-3- yl)-N-(3,5-dichloroisonicotinoyl)-L-phenylalaninate;

Ethyl 4-(2-{(2S)-1-[(benzyloxy)carbonyl]piperidin-2-yl}-3H-imidazo [4,5-b]pyridin-3- yl)-N-(2,6-dichlorobenzoyl)-L-phenylalaninate;

Ethyl 4-(2-{(2R)-1-[(benzyloxy)carbonyl]piperidin-2-yl}-3H-imidazo [4,5-b]pyridin-3- yl)-N-(2,6-dichlorobenzoyl)-L-phenylalaninate;

Ethyl 4-(2-{(2R)-1-[(benzyloxy)carbonyl]piperidin-2-yl}-3H-imidazo [4,5-b]pyridin-3- yl)-N-(3,5-dichloroisonicotinoyl)-L-phenylalaninate;

Ethyl 3-[(3-nitropyridin-2-yl)amino]-L-phenylalaninate;

Ethyl N-^.S-dichloroisonicotinoyO-S-KS-nitropyridin^-yOaminoJ-L-ph enylalaninate; Ethyl 3-[(3-aminopyridin-2-yl)amino]-N-(3,5-dichloroisonicotinoyl) -L- phenylalaninate;

Ethyl N-(tert-butoxycarbonyl)-4-[1 -(phenylsulfonyl)-i H-indol-3-yl]-L-phenylalaninate;

Ethyl 4-[1 -(phenylsulfonyl)-i H-indol-3-yl]-L-phenylalaninate;

Ethyl N-(3,5-dichloroisonicotinoyl)-4-[1 -(phenylsulfonyl)-i H-indol-3-yl]-L- phenylalaninate.

The following examples are provided for illustrative purposes only. Those skilled in the art will appreciate that routine variations and modifications of the following examples can be made without exceeding the spirit or scope of the invention.

Unless specified otherwise in the examples, characterization of the compounds is performed according to (LCMS) liquid chromatography mass spectra, preparative liquid chromatography LC, NMR, and silica gel chromatography methods. NMR spectra are recorded on Bruker AV300 and DRX 400 spectrometers at 300 and 400 MHz respectively.

Chromatographic separations are performed on Davis 5 μM silica gel. The Waters mass spectrometers used are of model ZMD or ZQ both Waters.

Various reactions took place in an Emrys Optimiser microwave reactor.

The following abbreviations are used in the examples: AcOH - acetic acid BSA - Bovine Serum Albumin

CDCI ₃ - Chloroform-d; DCE - Dichloroethane; DCM - Dichloromethane; DIBAL-H-Diisobutylaluminium hydride;

DIPEA - λ/,λ/-Diisopropylethylamine; DME - ethyleneglycol dimethylether DMF - λ/,λ/-Dimethylformamide;

DMSO - Dimethyl sulphoxide; d ₆ .DMSO - Dimethyl-d ₆ sulphoxide;

DPPF- 1 ,1'-Bis(diphenylphosphino)ferrocene; DPPP- 1 ,3-Bis(diphenylphosphino)propane;

EDC - 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride; Et ₂ O - Diethyl ether; EtOH - Ethanol;

EtOAc - Ethyl acetate; Et ₃ SiH - Triethylsilane; FCS - Foetal Calf Serum

HBTU - 2-[7H-Benzotriazole-1-yl]-1 ,1 ,3,3-tetramethyluronium hexafluorophosphate; HCI - hydrochloric acid HOBT - 1-Hydroxybenzotriazole hydrate; LHMDS - Lithium bis(trimethylsilyl)amide; MeCN - Acetonitrile; d ₄ -MeOH - Methanol-d ₄ ;

MeOH - Methanol; MTBE - Methyl terf-butyl ether;

MgSO ₄ - Magnesium Sulfate MnCl2 - manganese dichloride

NaHCO ₃ - Sodium Hydrogen Carbonate NaOH - sodium hydroxide Na2SO4 - sodium sulfate N2 - Nitrogen

NMP - 1 -Methyl-2-pyrrolidinone; Pd/C - Palladium on carbon;

Pd(dppf)CI ₂ - [1,1'-Bis(diphenylphosphino)ferrocene]dichloropalladium(ll) complex with

CH ₂ CI ₂ PBS - Phosphate buffered saline

RPMI -Roswell Park Memorial Institute (Cell Media)

K ₃ PO ₄ - Potasium triphosphate

RT - Retention time; TEA - Triethylamine;

TFA - Trifluoroacetic acid; THF - Tetrahydrofuran TBS - Tris buffered saline

LCMS Prep LC conditions and abbreviations

The following LCMS conditions are used to obtain the retention times (RT) as described herein:

LCMS conditions (Method A): HP1100 (Diode Array) linked to a Finnigan LC-Q Mass Spectrometer, ESI mode with Pos/Neg ionisation

Column: Luna C18(2) 100χ4.6mm, 5μm particle size Analytical column

Column Temp: 35°C

Mobile Phase: A: Water + 0.08% formic acid B: Acetonitrile + 0.08% formic acid

Flow rate: 3ml/min

Gradient: Time (mins): % Composition B:

0 5

4.4 95 5.30 95

5.32 5

6.5 5

Run time: 6.5 mins Typical Injection VoI: 10μl Detector Wavelength: DAD 200-400nm LCMS conditions (Method B - pH5.8):

HP1100 (Diode Array) linked to a Finnigan LC-Q Mass Spectrometer, ESI mode with Pos/Neg ionisation

Column: Luna C 18(2) 100χ4.6mm, 5μm particle size Analytical column

Column Temp: 35°C

Mobile Phase:

A: 5mM NH ₄ OAc pH 5.8

B: 95 : 5, MeCN : 10OmM NH ₄ OAc pH 5.8

Flow rate: 3ml/mιn

Gradient: Time (mins): % Composition B:

0 5

4. 4 95

5. 30 95

5 .33 5

6 .5 5

Run time: 6.5 mins Typical Injection VoI: 10μl Detector Wavelength: DAD 200-400nm Preparative LC conditions (Method C): Gilson 215 liquid handler setup.

Column: Luna C18(2) 250x21.2mm, 5μM particle size prep column

Column Temp: Ambient

Gradient: Variable - depends on retention time of sample in LC-MS analysis. Run Time: 20 mins Flow rate: 25ml/min Typical Injection VoI: 0.5 - 4.0ml at 25mg/ml Detector Wavelength:210 and 254nm Mobile Phase: A: Water + 0.08% formic acid

B: Acetonitrile + 0.08% formic acid

Preparative LC conditions (Method D):

Gilson 215 liquid handler setup.

Column: Luna C18(2) 250x21.2mm, 5μM particle size prep column

Column Temp: Ambient Gradient: Variable - depends on retention time of sample in LC-MS analysis. Run Time: 20 mins Flow rate: 25ml/min Typical Injection VoI: 0.5 - 4.0ml at 25mg/ml

Detector Wavelength:210 and 254nm Mobile Phase: A: 1OmM NH4OAC in water

B: 1OmM NH4OAC in acetonitrile

The IUPAC names of the compounds mentioned in the examples are generated with ACD version 6.00.

Unless specified otherwise in the examples, characterization of the compounds is performed according to the following methods:

NMR spectra are recorded on a Bruker AV-300 or DRX-400 Spectrometers operating at 300.13 MHz or 400.13 MHz for protons, and running the Bruker XWINNMR software package. Spectra are acquired at room temperature unless otherwise stated. Chemical shifts are given in ppm referenced either to internal TMS or to the residual solvent signal. Example 1

Ethyl N-(tert-butoxycarbonyl)-4-[(3-nitropyridin-2-yl)amino]-L-phe nylalaninate (Intermediate 1)

To a stirred solution of N-(tert-butyloxycarbonyl)-4-amino-L-phenylalanine ethyl ester (2Og) (CAS No. 67630-01-7) and DIPEA (13ml) in EtOH (200ml) is added 2-Chloro- 3-nitropyridine (11.85g) (CAS No. 34515-82-7). The reaction is heated at 85°C for 18 hours. The reaction is allowed to cool and the majority of the EtOH removed in vacuo. The residue is partitioned between EtOAc (100ml) and water (50ml). The aqueous layer is extracted with EtOAc (50ml) and the combined organic layers are washed with brine (20ml), dried (MgSO ₄ ) and concentrated in vacuo. The residue is purified in two batches by chromatography on silica, eluting with EtOAc-heptane to afford the title compound as an orange solid (13.17g, 46%). LCMS (Method A) 429 [M-H]-, RT 4.17 mins. ¹ H NMR 300 MHz (CDCI ₃ ) 51.25 (t, 3H), 1.40 (s, 9H), 3.1 (m, 2H), 4.2 (q, 2H), 4.6 (dd, 1 H), 5.00 (d,

1 H), 6.8 (dd, 1 H), 7.15 (d, 2H), 7.6 (d, 2H), 8.45-8.55 (m, 2H).

Example 2

Ethyl 4-[(3-aminopyridin-2-yl)amino]-N-(tert-butoxycarbonyl)-L-phe nylalaninate

(Intermediate 2)

To a stirred solution of Intermediate 1 (9.27g) in EtOH (100ml) under N ₂ (g) is added 10% Pd on carbon (500mg). The mixture is flushed with H ₂ (g) and stirred at atmospheric pressure for 2 hours. The mixture is filtered through a pad of celite, and the filtrate concentrated in vacuo to afford the title compound (8.05g, 93%). LCMS (Method A) 401 [M+H]\ RT 2.07 mins. ¹ H NMR 300MHz (d4-MeOH) .51.25 (t, 3H), 1.4 (s, 9H), 2.9 (dd, 1H), 3.1 (dd, 1 H), 4.2 (q, 2H), 4.35 (m, 1H), 6.8 (dd, 1 H), 7.1-7.4 (m, 6H), 7.85 (m, 1 H) 8.00 (s, 1 H). Example 3 Ethyl 4-[(3-nitropyridin-2-yl)amino]-L-phenylalaninate (Intermediate 3)

To a stirred solution of Intermediate 1 (3.63g) in DCM (28ml) at 0 ⁰ C is added TFA (6.5ml) in portions over 5-10 mins. The ice-bath is removed and the reaction stirred at room temperature for 18 hours. The reaction mixture is concentrated in vacuo. EtOAc (10ml) is added and the mixture treated with sat. NaHCO ₃ solution (50ml), followed by solid NaHCO ₃ in small portions until the effervescence ceases. A further 90ml EtOAc is added and the layers separated. The aqueous layer is extracted with EtOAc (2 x 50ml) and the combined organic layers are washed with brine (10ml), dried (MgSO ₄ ) and concentrated in vacuo to afford the title compound as an orange solid (2.61 g, 93%). LCMS (Method A) 329 [M-H] ^" , RT 1.97 mins. 1 H NMR 300 MHz (CDCI ₃ ) 51.25 (t, 3H), 2.9 (dd,

1H), 3.1 (dd, 1 H), 3.7 (dd, 1H), 4.2 (q, 2H), 6.8 (dd, 1 H), 7.25 (d, 2H), 7.6 (d, 2H), 8.45-

8.55 (m, 2H).

Example 4 Ethyl N-tS.S-dichloroisonicotinoyO^-^S-nitropyridin^-yOaminoJ-L-ph enylalaninate

(Intermediate 4)

To a stirred solution of Intermediate 3 (200mg) in DCM (10ml) is added TEA

(0.17ml) followed by 2,6-dichloroisonicotinoyl chloride (140mg) {Bioorg. Med. Chem. Lett.

2002, 12, 1591-1594) in DCM (0.5ml) dropwise. The reaction is stirred for 60 hours. The solvent is removed in vacuo and the residue partitioned between EtOAc (10ml) and water

(10ml). The aqueous layer is extracted with EtOAc (2x1 OmI) and the combined organic layers are washed with sat. NaHCO ₃ solution (2x1 OmI), brine (5ml), dried (MgSO ₄ ) and concentrated in vacuo to afford the title compound as an orange solid (316mg, 100%).

LCMS (Method A) 504 [M+H] ⁺ , RT 3.75 mins. ¹ H NMR 300 MHz (CDCI3) 51.3 (t, 3H), 3.3

(d, 2H), 4.2 (q, 2H), 5.2 (m, 1 H), 6.4 (d, 1 H), 6.8 (dd, 1 H), 7.2 (d, 2H), 7.6 (d, 2H), 8.45- 8.55 (m, 4H).

Intermediate 5 is prepared in a similar manner to the method described in Example 2. The reagents used and the results obtained are tabulated below, base of the compound is obtained unless otherwise stated. ^* lnt. means Intermediate

Example 5

Ethyl ^^-(cyclopropylmethylJ-SH-imidazo^.S-blpyridin-S-yll-L-pheny lalaninate hydrochloride (Intermediate 6) To Intermediate 2 (11.17g) in DCM (150ml) is added cyclopropyl acetic acid (2.7g)

(CAS No. 5239-82-7) followed by HOBT (25mg) and then EDC (5.67g). The reaction is stirred for 18 hours and then the DCM is removed in vacuo. The residue is partitioned between EtOAc (100ml) and 5% aqueous citric acid (10ml). The organic layer is washed with sat. NaHCO ₃ (10ml), brine (10ml) dried (MgSO ₄ ) and concentrated in vacuo. The residue is dissolved in acetic acid (60ml) and heated in a microwave in 3 batches (3χ20ml) at 130 ⁰ C for 10mins. The solvent is removed in vacuo and the residue dissolved in 15% TFA / DCM (150ml) and stirred at room temperature for 18 hours. The solvent is removed in vacuo and MeOH (10ml) is added, followed by 2M HCI in Et ₂ O (20ml). The solvent is removed in vacuo to afford the title compound (7.76g, 72%). LCMS (Method A) 365 [M+H] ⁺ , RT 1.66 mins. ¹ H NMR 300MHz (d6-DMSO) δθ.2 (m, 2H), 0.5 (m, 2H), 1.2 (m,

4H), 2.85 (d, 2H), 3.2 (dd, 1 H), 3.3 (dd, 1 H), 4.1 (m, 2H), 4.35 (m, 1 H), 7.5-7.6 (m, 5H), 8.3

(m, 1 H), 8.4 (m, 1 H), 8.8 (m, 2H).

Example 6

Ethyl N-(tert-butoxycarbonyl)-3-nitro-L-phenylalaninate (Intermediate 7) To Boc-3-Nitro-L-Phenylalanine (1Og) (CAS No. 131980-29-5) and NaHCO ₃ (5.41 g) in anhydrous DMF (100ml) is added Ethyl Iodide (12.9ml) in one portion. The reaction is stirred at room temperature for 48 hours. The mixture is extracted into EtOAc (300ml) and

washed with 10% aqueous lithium bromide (200ml), brine (200ml), dried (MgSO ₄ ) and the solvent removed in vacuo. The residue is re-dissolved in DMF (20ml) and then added to water (400ml). The resulting solid is collected by filtration and dried to afford the title compound (10.13g, 93%). LCMS (Method A) 239 [M+H] ⁺ , RT 3.85 mins. ¹ H NMR 300MHz (d6-DMSO) δϊ .15 (t, 3H) ₁ 1.3 (s, 9H), 3.0 (dd, 1 H), 3.2 (dd, 1 H), 4.1 (q, 2H), 4.2 (m, 1 H), 7.4 (d, 1 H), 7.6 (m, 1H), 7.75 (m, 1 H), 8.1-8.2 (m, 2H). Example 7

Ethyl N-(tert-butoxycarbonyl)-3-[(3-nitropyridin-2-yl)amino]-L-phe nylalaninate (Intermediate 8) To Intermediate 7 (10.13g) in EtOH (200ml) under N ₂ (g) is added 5% Pd on carbon

(2g). The mixture is flushed with H ₂ (g) and stirred at atmospheric pressure for 48 hours. The mixture is filtered through a pad of celite, and the filtrate concentrated in vacuo. EtOH (100ml) is added followed by DIPEA (2.25ml) and 2-Chloro-3-nitropyridine (2.02g). The reaction is heated at 85 ⁰ C for 72 hours. Purification by chromatography on silica, eluting with EtOAc-heptane affords the title compound (2.64g, 20%). LCMS (Method A) 331 [M+H]\ RT 4.20 mins. ¹ H NMR 300MHz (d6-DMSO) £1.15 (t, 3H), 1.35 (s, 9H), 2.9 (dd, 1H), 3.0 (dd, 1H), 4.0-4.2 (m, 3H), 7.0-7.05 (m, 2H), 7.2-7.3 (m, 2H), 7.45 (s, 1H), 7.6 (d, 1 H), 8.5-8.6 (m, 2H). Example 8 Ethyl 4-[2-(6-chloropyridin-3-yl)-3H-imidazo[4,5-b]pyridin-3-yl]-N -(3,5- dichloroisonicotinoyl)-L-phenylalaninate ( Compound 1)

Intermediate 5 (2.08g), 4-Chloronicotinic acid (760mg) (CAS No. 5326-23-8), DIPEA (1.53ml) and EDC (1.02g) are stirred in DCM (50ml) at room temperature for 18 hrs. The reaction is diluted with EtOAc (100ml) and washed with NaHCO ₃ solution (saturated, 100ml) and brine (100ml), before the solvent is removed in vacuo to yield a brown oil. This is taken up in AcOH and heated in a microwave at 130 ⁰ C for 10 minutes. On cooling the reaction is poured in to a NaHCO ₃ solution (saturated, 10ml) and extracted with EtOAc (3 x 10ml). The combined organics are washed with brine (10ml) and dried over MgSO ₄ . Filtration and removal of the solvent afford the title compound as a orange oil (993mg, 38%). LCMS (Method A) 595 [M+H] ⁺ , RT 3.49 mins. ¹ H NMR 300MHz (CDCI ₃ ) .51.32 (t, 3H), 3.34 (dd, 1 H), 3.41 (dd, 1 H), 4.26 (q, 2H), 5.22 (q, 1 H), 6.58 (1 H, d), 7.28- 7.39 (m, 5H), 7.45 (d, 1 H), 7.84 (d, 1 H), 8.16 (d, 1 H), 8.41 (d, 1 H), 8.57 (s, 3H). Example 9 Ethyl N-(3,5-dichloroisonicotinoyl)-4-(2-pyridin-3-yl-3H-imidazo[4 ,5-b]pyridin-3-yl)-L- phenylalaninate (Compound 2)

To a stirred solution of Intermediate 5 (146mg) in DCM (5ml) is added TEA (0.13ml) followed by Nicotinoylchloride hydrochloride (82mg). The reaction is stirred for 18 hours. The mixture is diluted with water (5ml) and the layers are separated. The aqueous layer is extracted with DCM (10ml) and the combined organic layers are washed with sat. NaHCO ₃ solution (2χ10ml), brine (5ml), dried (MgSO ₄ ), filtered and concentrated in vacuo. The residue is purified by chromatography on silica eluting with MeOH/DCM. The purified material is dissolved in AcOH (1ml) and heated in a microwave at 125 ⁰ C for 5 minutes. The reaction mixture is concentrated in vacuo, partitioned between DCM (5ml) and NaHCO ₃ solution (5ml), the layers separated, the aqueous layer extracted with DCM (5ml), the organic layers combined, washed with brine (10ml) dried over MgSO ₄ , filtered and evaporated to dryness in vacuo to afford the title compound as a colourless solid (92mg, 78%) LCMS (Method A) 561 [M+H] ⁺ , RT 2.93 mins. ¹ H NMR 300MHz (CDCI ₃ ) 51.32 (t, 3H), 3.38 (m, 2H), 4.23 (q, 2H), 5.17 (m, 1 H), 6.62 (d, 1 H), 7.30 (m, 4H) ₁ 7.39 (d, 2H), 7.40 (dd, 1 H), 8.18 (dd, 1 H), 8.39 (dd, 1 H), 8.53 (s, 2H), 8.57 (dd, 1 H), 8.78 (d, 1 H). Example 10

1-{1-[4-(Benzyloxy)phenyl]-1 H-pyrrolo[2,3-b]pyridin-3-yl}-N,N-dimethylmethanamine (Intermediate 9)

A flask is charged with 4-iodobenzyloxybenzene (7.75g) (CAS No. 19578-68-8), 7- azaindole (3.54g) (CAS No. 271 -63-6), copper (I) iodide (250mg), frans-1 ,2- diaminocyclohexane (0.30ml) and potassium phosphate (11.15g). 1 ,4-Dioxane is added (25ml) and the reaction heated at 11O ⁰ C for 5 hours. The reaction is cooled, poured into water (50ml) and extracted with EtOAc (3x50ml). The organic layers are combined, dried over MgSO ₄ , filtered and concentrated in vacuo. 250mg of this crude material is dissolved in AcOH (4ml), λ/,λ/-dimethylmethyleneiminium iodide (180mg) added in one portion, and the reaction stirred at room temperature for 18 hours. The solution is poured into saturated sodium bicarbonate solution (40ml), extracted with EtOAc (2x20ml), and the organic layers combined, dried over MgSO ₄ , filtered and concentrated in vacuo to afford the title compound as an orange oil (230mg) LCMS (Method A) 358 [M+H]\ RT 2.16 mins. ¹ H NMR 300MHz (d4-MeOH) 52.24 (s, 6H), 3.66 (s, 2H), 5.02 (s, 2H), 7.00 (d, 2H), 7.08 (dd, 1H), 7.23 (m, 3H), 7.32 (dd, 2H), 7.42 (d, 2H), 8.02 (dd, 1 H), 8.11 (dd, 1 H). Example 11

Methyl (2Z)-2-acetamido-3-[4-(3-methyl-1 H-pyrrolo[2,3-b]pyridin-1-yl)phenyl]acrylate (Intermediate 10)

Intermediate 9 (230mg) is dissolved in THF / MeOH (1 :1 , 6ml), DIPEA (0.23ml) and 10% Palladium on Carbon (50mg) are added and the mixture subjected to atmospheric

hydrogenation for 5 hours. The reaction mixture is filtered through celite, evaporated to dryness in vacuo, DCM (8ml) and pyridine (0.1ml) added consecutively, followed by trifluoromethylsulfonic anhydride (0.22ml). The reaction is stirred at room temperature for 30 minutes, quenched with water (20ml), extracted with DCM (2x1 OmI), the organic layers combined, dried over MgSO ₄ , filtered and concentrated in vacuo to give 235mg of crude solid. The crude material is dissolved in DMF (7ml), ύ/s-triphenylphosphine palladium dichloride (46mg), methylacetamidoacrylate (300mg) (CAS No. 35356-70-8), TEA (0.29ml), lithium iodide (173mg) and tributylammonium chloride (390mg) are added, and the solution heated to 9O ⁰ C for 6 hours. The reaction is quenched by the addition of water (30ml), extracted with EtOAc (2x20ml), the organic layers are combined, dried over MgSO ₄ , filtered, concentrated in vacuo, purified using flash chromatography (eluent EtOAc/heptane) to afford the title compound as a off-white solid (85mg) LCMS (Method A) 350 [M+H] ⁺ , RT 3.22 mins. ¹ H NMR 300MHz (CDCI ₃ ) 62.19 (s, 3H), 2.38 (s, 3H), 3.47 (s,

1 H), 3.87 (s, 3H), 7.14 (dd, 1 H), 7.32 (s, 1H), 7.41 (s, 1 H), 7.60 (d, 2H), 7.86 (d, 2H), 7.91 (d, 1 H), 8.38 (d, 1 H). Example 12

Methyl N-(3,5-dichloroisonicotinoyl)-4-(3-methyl-1 H-pyrrolo[2,3-b]pyridin-1 - yl)phenylalaninate (Compound 3)

Intermediate 10 (85mg) is dissolved in THF / MeOH (1 :1 , 5ml), DIPEA (0.17ml) and 10% Palladium on Carbon (50mg) are added, and the mixture subjected to atmospheric hydrogenation for 6 hours. The mixture is filtered through celite, evaporated to dryness in vacuo, dissolved in 1 ,4-dioxane (3ml) and HCI (6.0M, 5ml) and heated to 11O ⁰ C. After 4 hours the reaction is cooled to room temperature, evaporated to dryness in vacuo, dissolved in MeOH (6ml), and thionyl chloride (1ml) is added. After 16 hours the reaction is quenched by the addition of saturated sodium bicarbonate solution (20ml), extracted with EtOAc (2x1 OmI), the organic layers combined, dried over MgSO ₄ , filtered and concentrated in vacuo. The crude material is dissolved in DCM (4ml), DIPEA (0.17ml) is added followed by 2,6-dichloroisonicotinoyl chloride (210mg) and the reaction stirred at room temperature. After 1 hour the reaction is quenched by the addition of water (10ml), extracted with DCM (2x1 OmI), the organic layers combined, dried over MgSO ₄ , filtered and chromatographed in EtOAc / heptane to afford the title compound as a white solid (35mg) LCMS (Method A) 483 [M+H]\ RT 3.86 mins. ¹ H NMR 300MHz (CDCI ₃ ) 52.37 (d, 3H), 3.33 (d, 2H), 3.81 (s, 3H), 5.25 (m, 1 H), 6.42 (d, 1 H), 7.12 (dd, 1 H), 7.30 (m, 4H), 7.72 (m, 2H), 7.90 (dd, 1 H), 8.34 (dd, 1 H), 8.53 (s, 2H). Example 13

Ethyl 4-(2-{(2S)-1-[(benzyloxy)carbonyl]piperidin-2-yl}-3H-imidazo [4,5-b]pyridin-3-yl)- N-(tert-butoxycarbonyl)-L-phenylalaninate (Intermediate 11)

Intermediate 2 (8.0Og) ₁ EDC (5.7Og), HOBt (540mg) and (S)-λ/-(Cbz)-pipecolinic acid (5.0Og) (CAS No. 28697-11-2) are dissolved in DCM (100ml) and stirred at room temperature for 20 hours. The reaction is quenched by the addition of water (100ml), extracted with DCM (2x100ml), the organic layers combined, dried over MgSO ₄ , filtered and concentrated in vacuo. The crude material is dissolved in AcOH / EtOH (1 :9, 100ml) and heated in a microwave at 16O ⁰ C for 13 minutes. The reaction mixture is cooled to room temperature, concentrated in vacuo partitioned between DCM (100ml) and NaHCO ₃ solution (100ml), the layers separated, the aqueous layer extracted with DCM (100ml), the organic layers combined, dried over MgSO ₄ , filtered, concentrated in vacuo and purified using flash chromatography (eluent EtOAc / heptane) to afford the title compound as a pale yellow solid, (6.19g, 50%) LCMS (Method A) 628.2 [M+H]\ RT 4.42 mins. ¹ H NMR 300MHz (d6-DMSO) δ1.15 (t, 3H), 1.34 (s, 9H), 1.45-1.92 (m, 6H), 3.00 (m, 2H), 3.65 (m, 1 H), 3.94 (m, 1 H), 4.09 (dq, 2H), 4.25 (m, 1 ), 4.93 (m, 2H), 5.40 (m, 1 H), 7.00-7.50 (m, 11 H), 8.13 (dd, 1H), 8.25 (m, 1 H).

Intermediate 15 is prepared in a similar manner to the method described in Example 13. The reagents used and the results obtained are tabulated below.

Example 14

Ethyl 4-(2-{(2S)-1-[(benzyloxy)carbonyl]piperidin-2-yl}-3H-imidazo [4,5-b]pyridin-3-yl)-

L-phenylalaninate (Intermediate 12)

To a stirred solution of Intermediate 11 (2g) in DCM (7.8ml) under N ₂ (g) at 0 ⁰ C is added TFA (1.96ml) dropwise over 10 minutes. The reaction is allowed to warm to room temperature and stirred for 18 hours. A further 0.98ml TFA is added and the reaction stirred for 2 hours. The solution is concentrated in vacuo and the residue partitioned between sat. NaHCO ₃ solution and EtOAc (20ml). The layers are separated and the aqueous layer extracted with EtOAc (20ml). The combined organic layers are washed with brine (10ml), dried (MgSO ₄ ) and concentrated in vacuo to afford the title compound as a brown oil (1.79g, 100%). LCMS (Method A) 529 [M+H]\ RT 2.37 mins. ¹ H NMR 300 MHz (d6-DMSO) 61.16 (m, 3H), 1.31-1.96 (m, 7 H), 2.25 (m, 1 H), 2.90 (m, 2H), 3.62 (m, 2H), 3.93 (m, 1 H), 4.05 (m, 2H), 4.86-5.17 (m, 2H), 5.41 (m, 1 H), 7.01-7.51 (m, 10H), 8.15 (dd, 1 H), 8.25 (dd, 1 H).

Intermediate 16 is prepared in a similar manner to the method as described in Example 14. The reagents used and the results obtained are tabulated below.

Example 15

Ethyl4-(2-{(2S)-1-t(benzyloxy)carbonyl]piperidin-2-yl}-3H -imidazo[4,5-b]pyridin-3-yl)- N-(3,5-dichloroisonicotinoyl)-L-phenylalaninate (Intermediate 13)

To a stirred solution of Intermediate 12 (321 mg) in DCM (2ml) is added DIPEA (0.21ml) followed by 2,6-dichloroisonicotinoyl chloride (141 mg) in DCM (1 ml). The reaction is stirred at room temperature for 18 hours. The mixture is partitioned between DCM (10ml) and water (10ml) and the aqueous layer is extracted with DCM (10ml). The combined organic layers are washed with sat. NaHCO ₃ solution (10ml), brine (5ml), dried (MgSO ₄ ), filtered and concentrated in vacuo. The residue is purified by chromatography on silica eluting with 50 to 60% EtOAc/heptane to afford the title compound as a colourless solid (202mg, 47%). LCMS (Method A) 702 [M+H] ⁺ , RT 4.03 mins. ¹ H NMR 300MHz

(CDCI ₃ ) 51.32 (t, 3H), 1.54-1.78 (m, 8H), 3.23-3.44 (m, 2H), 3.96 (m, 1 H), 4.27 (m, 2H), 4.96 (m, 2H), 5.23 (m, 1 H), 5.56 (m, 1 H), 7.09-7.44 (m, 10H), 8.07 (m, 1 H), 8.29 (m, 1 H), 8.51 (s, 2H).

Intermediates 14, 17 and 18 are prepared in a similar manner to the method as described in Example 15. The reagents used and the results obtained are tabulated below.

Example 16

EthylN-(3,5-dichloroisonicotinoyl)-4-{2-[(2S)-piperidin-2 -yl]-3H-imidazo[4,5-b]pyridin- 3-yl}-L-phenylalaninate (Compound 4)

To a stirred solution of Intermediate 13 (199mg) in EtOH (6ml) under N ₂ (g) is added 10% Pd on carbon (40mg). The mixture is flushed with H ₂ (g) and stirred at atmospheric pressure for 4.5 hours. The mixture is filtered through a pad of celite, and the filtrate concentrated in vacuo to afford the title compound (143mg, 88%). LCMS (Method A) 567 [M+H]\ RT 2.09 mins. ¹ H NMR 300MHz (CDCI ₃ ) .51.33 (t, 3H), 1.39-2.20 (m, 6H), 2.66 (m, 1 H), 3.24 (m, 1 H), 3.41 (m, 2H), 3.93 (m, 1H), 4.29 (m, 2H), 5.25 (m, 1 H), 6.62 (d, 1 H), 7.24 (m, 1 H), 7.47 (s, 4H), 8.05 (dd, 1 H), 8.30 (m, 1 H), 8.54 (m, 2H).

Compound 5 is prepared in a similar manner to the method as described in Example 16. The reagents used and the results obtained are tabulated below.

Example 17

Ethyl 3-[(3-nitropyridin-2-yl)amino]-L-phenylalaninate (Intermediate 19)

To a stirred solution of intermediate 8 (2.64g) in DCM (100ml) is added 2N HCI in Et ₂ O (18.4ml) in one portion at room temperature. The mixture is stirred at room temperature for 22 hours then diluted with Et ₂ O (200ml). The solid formed is collected by filtration, washed with Et ₂ O and dried in vacuo to afford the title compound as its bis-HCI salt (2.37g, 95%). LCMS (Method A) 331 [M+H] ⁺ , RT 1.86 mins. ¹ HNMR 300MHz (d ₆ - DMSO) δ1.1 (t, 3H), 3.1 (dd, 1 H), 3.25 (dd, 1 H), 4.05-4.2 (m, 2H), 4.2-4.3 (m, 1 H), 6.95-7.1 (m, 2H), 7.35 (t, 1 H), 7.5 (s, 1 H), 7.7 (d, 1 H), 8.5-8.6 (m, 2H), 8.75 (br s, 3H), 9.95 (s, 1 H).

Example 18

Ethyl N-(3,5-dichloroisonicotinoyl)-3-[(3-nitropyridin-2-yl)amino] -L-phenylalaninate (Intermediate 20)

To Intermediate 19 (1g) in THF (40ml) is added 2,6-dichloroisonicotinoyl chloride (781 mg) and DIPEA (2.15ml) at room temperature. The reaction is stirred at room temperature for 24 hours and the solvent removed in vacuo. The residue is purified by flash chromatography on silica eluting with 30 to 75% EtOAc/heptane to afford the title compound as a red solid (1.03g, 82%). LCMS (Method A) 504/506 [M+H] ⁺ , RT 3.81 mins. ¹ HNMR 300MHz (d ₆ -DMSO) 51.2 (t, 3H), 2.95 (dd, 1 H), 3.15 (dd, 1 H), 4.15 (q, 2H), 4.7- 4.85 (m, 1 H), 7.0 (dd, 1 H), 7.1 (d, 1 H), 7.3 (t, 1H), 7.55 (s, 1 H), 7.65 (d, 1 H), 8.5-8.6 (m, 2H), 8.65 (s, 2H), 9.45 (d, 1 H), 9.95 (s, 1 H). Example 19

Ethyl 3-[(3-aminopyridin-2-yl)amino]-N-(3,5-dichloroisonicotinoyl) -L-phenylalaninate (Intermediate 21)

To Intermediate 20 (1.03g) are added AcOH (4ml) and EtOH (24ml) and the mixture heated to 50 ⁰ C. Iron powder (570mg) is added and the mixture heated to reflux for 2 hours. The mixture is cooled to room temperature and extracted with EtOAc (200ml). The organic layer is washed with sat. NaHCO ₃ (2 x 100ml), brine, dried over MgSO _4, filtered and concentrated in vacuo to afford the title compound as a solid (960mg, 99%). LCMS (Method A) 474/476 [M+H] ⁺ , RT 1.83 mins. ¹ HNMR 300MHz (d ₆ -DMSO) 51.2 (t, 3H), 2.9 (dd, 1 H), 3.1 (dd, 1 H), 4.15 (q, 2H), 4.65-4.8 (m, 1 H), 5.05 (s, 2H), 6.6 (dd, 1 H), 6.75 (d, 1 H), 6.9 (d, 1 H), 7.15 (t, 1 H), 7.45-7.5 (m, 2H), 7.6 (d, 1 H), 7.7 (s, 1 H), 8.65 (s, 2H), 9.45 (d, 1 H). Example 20 Ethyl N-(tert-butoxycarbonyl)-4-[1 -(phenylsulfonyl)-i H-indol-3-yl]-L-phenylalaninate (Intermediate 22)

To 4-Bromo-N-[(1 ,1-dimethylethoxy)carbonyl]-ethylester-L-phenylalanine (RN- 591249-54-6) (675mg) in water (5ml) are added 1-(phenylsulfonyl)-3-indoleboronic acid (600mg) (CAS No. 129271-98-3), Pd(dppf)CI ₂ (15mg) (CAS No. 72287-26-4) and K ₃ PO ₄ (767mg). The mixture is flushed with N ₂ and heated to 9O ⁰ C for 20 hours. The mixture is cooled and extracted with EtOAc (20ml), the organic layer is washed with water, brine, dried over MgSO ₄ , filtered and the solvent removed in vacuo. Purification of the crude compound by chromatography on silica eluting with 0 to 50% EtOAc/heptane affords the title compound as a white solid (565mg, 57%). LCMS (Method A) 449 [M+H] ⁺ , RT 4.66mins. ¹ HNMR 300MHz (d ₆ -DMSO) D1.15 (t, 3H), 1.25-1.40 (m, 9H), 2.85-3.1 (m, 2H), 4.0-4.25 (m, 3H), 7.3-7.5 (m, 5H), 7.55-7.75 (m, 5H), 7.8 (d, 1 H), 8.0-8.1 (m, 4H).

Example 21

Ethyl 4-[1-(phenylsulfonyl)-1H-indol-3-yl]-L-phenylalaninate (Intermediate 23)

To Intermediate 22 (565mg) in DCM (50ml) is added TFA (795μl) in one portion at room temperature. The mixture is stirred for 3 days and the solvent removed in vacuo. The residue is extracted into DCM (50ml), washed with sat. NaHCO ₃ (100ml), brine, dried over MgSO4, filtered and concentrated in vacuo to afford the title compound as an orange oil (400mg, 87%). LCMS (Method A) 449 [M+H]\ RT 2.47mins. ¹ HNMR 300MHz (d ₆ - DMSO) δ1.15 (t, 3H), 1.85 (br s, 2H), 2.85 (dd, 1 H), 2.95 (dd, 1 H), 3.6 (t, 1 H), 4.05 (q, 2H), 7.25-7.7.4 (m, 3H), 7.45 (t, 1 H), 7.55-7.75 (m, 5H), 7.8 (d, 1 H), 8.0-8.1 (m, 4H). Example 22

Ethyl N-(3,5-dichloroisonicotinoyl)-4-[1 -(phenylsulfonyl)-i H-indol-3-yl]-L- phenylalaninate (Intermediate 24)

To Intermediate 23 (200mg) in anhydrous THF (4ml) is added DIPEA (78μl). 2,6- dichloroisonicotinoyl chloride (94mg) in anhydrous THF (1 ml) is added to the mixture at room temperature. The reaction is stirred at room temperature for 4 hours and then the solvent removed in vacuo. The residue is purified by chromatography on silica eluting with 20 to 70% EtOAc/heptane to afford the title compound as a yellow solid (205mg, 74%). LCMS (Method A) 622/624 [M+H]\ RT 4.41mins. ¹ HNMR 300MHz (d ₆ -DMSO) 61.21 (t, 3H), 3.01 (dd, 1 H), 3.24 (dd, 1 H), 4.17 (q, 2H), 4.84 (m, 1 H), 7.32-7.47 (m, 4 H), 7.57-7.72 (m, 5 H), 7.80 (d, 1 H) ₁ 8.01-8.12 (m, 4 H), 8.67 (s, 2 H), 9.45 (d, 1 H).

The compounds of the invention are prepared according to the following examples: Example 23

4-[2-(6-Chloropyridin-3-yl)-3H-imidazo[4,5-b]pyridin-3-yl]-N -(3,5- dichloroisonicotinoyO-L-phenylalanine (Compound 6) Compound 1 (993mg) is taken up in THF (2ml) and added dropwise over a 3 hour period to a stirred solution of 2N NaOH (2ml). After addition the THF is removed in vacuo and the resulting solution acidified to pH-4 using 2M HCI. The resulting precipitate is collected by filtration and dried over night in a vacuum oven (40 ⁰ C) to afford the title compound as a white solid (979mg). LCMS (Method A) 567 [M+H] ⁺ , RT 2.89 mins. ¹ H NMR 300MHz (d6-DMSO) 53.04 (dd, 1 H), 3.30 (dd, 1 H), 4.75 (m, 1 H), 7.40-7.58 (m, 6H), 7.89 (d, 1 H), 8.26 (d, 1 H), 8.37 (d, 1 H), 8.61 (d, 1 H), 8.66 (s, 2H), 9.30 (bs, 1 H), 13.05 (bs, 1 H).

Compound 7 is prepared in a similar manner to the method described in Example 23. The reagents used and the results obtained are tabulated below. ^* Comp means Compound - Int. means Intermediate

Comp IUPAC Name Starting LCMS ¹ H NMR

No Materials (Solvent,

5 ppm)

7 N-(3,5- Comp. 2 LCMS (d6-DMSO) .53.04 (dd, 1 H), 3.28

Dichloroisonicotinoyl) (Method (dd, 1 H), 4.75 (m, 1 H), 7.47-7.53

-4-(2-pyridin-3-yl-3H- A) 533 (m, 6H), 7.87 (dt, 1 H), 8.26 (d, 1H), imidazo[4,5-b]pyridin- [M+H]\ 8.37 (d, 1 H), 8.64 (dd, 1H), 8.65 (s,

3-yl)-L-phenylalanine RT 2.38 2H), 8.79 (d, 1 H), 9.33 (bs, 1 H), mins. 13.17 (bs, 1 H).

Example 24

N-(3,5-Dichloroisonicotinoyl)-4-{2-[6-(methylamino)pyridi n-3-yl]-3H-imidazo[4,5- b]pyridin-3-yl}-L-phenylalanine (Compound 8)

To a stirred suspension of Compound 6 (100mg) in EtOH (4ml) is added Methylamine (33% in EtOH, 1.32ml). The suspension is heated in a microwave at 13O ⁰ C for 2.5 hours. The solvent is removed in vacuo and the residue is purified by preparative HPLC (Method D) to afford the title compound as an off white solid (37mg, 37%). LCMS (Method B) 562 [M+H]\ RT 2.04 mins. ¹ H NMR 300MHz (d6-DMSO) 52.8 (d, 3H), 3.0 (dd, 1 H), 3.3 (m, 1 H), 4.8 (m, 1 H), 6.4 (d, 1 H), 7.05 (m, 1 H), 7.3-7.4 (m, 3H), 7.5 (m, 3H), 8.1 (d, 1 H), 8.2-8.25 (m, 2H), 8.65 (s, 2H), 9.4 (d, 1 H). Example 25

N-^-Chloro-S-fluorobenzoyO-A-^-fcyclopropylmethyO-SH-imid azo^.S-blpyridin-S- yl]-L-phenylalanine (Compound 9)

Intermediate 6 (250mg), 2-Chloro-5-fluorobenzoic acid (130mg) (CAS No. 2252-50- 8) and EDC (156mg) are stirred in DCM (1 OmI) at room temperature for 18 hrs. The DCM is removed in vacuo and the slurry is taken up in THF (5ml) and added dropwise over a 3 hour period to a stirred solution of 2N NaOH (5ml). After addition the THF is removed in vacuo and the resulting solution acidified to pH-4 using 2M HCI. The resulting solution is concentrated and purified by preparative HPLC (Method C) to afford the title compound as a white solid (49mg, 16%). LCMS (Method A) 193 [M+H] ⁺ , RT 2.70 mins. ¹ H NMR 300MHz (CDCI ₃ ) 50.12 (dt, 2H), 0.50 (dt, 2H), 1.02-1.13 (m, 1 H), 2.75 (d, 2H), 3.31 (dd, 1 H), 3.59 (dd, 1H), 5.08 (m, 1H), 7.04-7.18 (m, 2H), 7.29-7.48 (m, 7H), 8.19 (d, 1 H), 8.30 (d, 1 H). Example 26 N-^S-DichloroisonicotinoylM-^-oxo-i^-dihydro-SH-imidazoμ.S- blpyridin-S-ylJ-L- phenylalanine (Compound 10)

To Intermediate 5 (750mg) in DCM (5ml) is added DIPEA (0.6ml) followed by dimethylcarbamyl chloride (204mg) at room temperature. The reaction is stirred for 24 hours. The solvent is removed in vacuo and the residue is dissolved in AcOH (1 ml) and heated in a microwave at 125 ⁰ C for 10 minutes. The solvent is removed in vacuo and the residue is purified by chromatography on silica eluting with EtOAc/heptane. The purified material (60mg) in THF (0.3ml) is added dropwise to 2N NaOH (0.36ml) over 2 hours. The solvents are removed in vacuo and the residue partitioned between 2N HCI (5ml) and EtOAc (5ml), the organic layer is washed with brine (2OmI) ₁ dried over Na ₂ SO ₄ , filtered and evaporated to dryness in vacuo to afford the title compound (30mg, 53%). LCMS (Method A) 470 [M+H] ⁺ , RT 2.03 mins. ¹ H NMR 300MHz (CDCI ₃ ) 83.35 (dd, 1 H), 3.55 (dd, 1 H), 5.2 (q, 1 H), 6.85 (d, 1 H), 7.25-7.35 (m, 3H), 7.5 (d, 2H), 8.1 (d, 1H), 8.3 (d, 1 H), 8.5 (s, 2H). Example 27

N-(3,5-Dichloroisonicotinoyl)-4-(2-piperidin-2-yl-3H-imidazo [4,5-b]pyridin-3-yl)-L- phenylalanine (Compound 11) To Intermediate 2 (3.41g) in DCM (40ml) is added 1-Cbz-2-piperidinecarboxylic acid (4.48g), HOBt (346mg) and EDC (4.88g). The reaction is stirred at room temperature for 3 days. The reaction is partitioned between DCM (40ml) and water (40ml) and the organic layer washed with 10% AcOH solution (40ml). The solvent is removed in vacuo and the residue dissolved in AcOH (12ml) and heated in a microwave at 120 ⁰ C for 10 minutes. The mixture is evaporated to dryness in vacuo and partitioned between EtOAc (40ml) and saturated NaHCO ₃ (40ml), the organic layer is dried over Na ₂ SO ₄ , filtered, evaporated to dryness and the residue purified by chromatography on silica eluting with EtOAc/heptane. To a portion of the purified material (1.25g) in DCM (20ml) is added TFA (1.51 ml) at room temperature. The reaction is stirred at room temperature for 20 hours. The reaction is partitioned between DCM (50ml) and saturated NaHCO ₃ (50ml), dried over Na ₂ SO ₄ , filtered and the evaporated to dryness. To a portion of the obtained material (348mg) in DCM (4ml) is added DIPEA (138μl) followed by 2,6-dichloroisonicotinoyl chloride (169mg) in DCM (2ml). The reaction is stirred at room temperature for 1 hour. The reaction is partitioned between DCM (40ml) and water (40ml). The organic layer is dried over Na ₂ SO ₄ , filtered and evaporated to dryness in vacuo and the residue purified by chromatography on silica eluting with EtOAc/heptane. To the purified material (310mg) in EtOH (10ml) under N ₂ (g) is added 10% Pd on carbon (50mg). The mixture is flushed with H ₂ (g) and stirred at atmospheric pressure for 3 days. The mixture is filtered through a pad of celite, and the filtrate evaporated to dryness in vacuo. The crude material is dissolved in THF (4ml) and added slowly over 1 hour to a stirred solution of NaOH (2.0M, 5ml). Once

addition is complete the reaction is stirred at room temperature for 1 hour, the reaction mixture acidified to acidic pH with HCI (6.0M), concentrated in vacuo and purified by preparative HPLC (Method C) to afford the title compound as a white solid (61 mg, 1%). LCMS (Method A) 539 [M+H]\ RT 1.72 mins. ¹ H NMR 300MHz (CDCI ₃ ) .81.10-1.41 (m, 2H), 1.43-1.60 (m, 2H), 1.70 (m, 2H), 1.88 (d, 1 H), 2.41 (m, 1 H), 3.00 (m, 2H), 3.39 (d, 1 H), 3.75 (d, 1 H), 4.77 (m, 1 H), 7.25 (m, 3H), 7.50 (d, 2H), 8.00 (d, 1 H), 8.09 (dd, 1 H), 8.40 (s, 2H). Example 28

N-(2,6-Dichlorobenzoyl)-4-{2-[(2S)-piperidin-2-yl]-3H-imi dazo[4,5-b]pyridin-3-yl}-L- phenylalanine (Compound 12)

To a stirred solution of Intermediate 14 (361 mg) in EtOH (11ml) under N ₂ (g) is added 10% Pd on carbon (72mg). The mixture is flushed with H ₂ (g) and stirred at atmospheric pressure for 11 hours. The mixture is filtered through a pad of celite, and the filtrate concentrated in vacuo. A portion (136mg) of the crude product in 6M HCI (2ml) is heated to 100 ⁰ C for 3 hours. The mixture is allowed to cool and concentrated in vacuo. Purification of the crude compound by preparative HPLC (Method C) affords the title compound as a yellow solid (62mg, 47%). LCMS (Method A) 538 [M+H] ⁺ , RT 1.81 mins. ¹ H NMR 300MHz (d6-DMSO) 81.25-1.88 (m, 6H), 2.69 (m, 1 H), 3.07 (m, 2H), 3.30 (dd, 1H), 4.01 (m, 1 H), 4.72 (m, 1 H), 7.31-7.60 (m, 8H), 8.14 (dd, 1 H), 8.20 (s, 1 H), 8.29 (dd, 1H), 8.97 (d, 1 H).

Compounds 13 and 15 are prepared in a similar manner to the method described in Example 28. The reagents used and the results obtained are tabulated below.

15 N-(2,6- Comp. 5 LCMS (d6-DMSO) δ 0.41 (m, 1 H), 1.54-2.00 (m,

Dichlorobenzoy (Method 5H) ₁ 3.06 (m, 2H), 3.34 (m, 2H), 4.46 (m, l)-4-{2-[(2R)- A) 538 1 H) ₇ 4.80 (m, 1 H), 7.44 (m, 4H), 7.58 (m, piperidin-2-yl]- [M+H] ⁺ , 4H), 8.23 (dd , 1 H) , 8.37 (dc J, 1 H), 9.21

3H- RT 1.88 (m, 1 H), 9.43 (m, I H), 10.05 (m, 1 H). imidazo[4,5- mins. b]pyridin-3-yl}-

I L-- phenylalanine

Example 29

N-(3,5-Dichloroisonicotinoyi)-4-{2-[(2S)-piperidin-2-yl]- 3H-imidazo[4,5-b]pyridin-3-yl}- L-phenylalanine (Compound 14)

Compound 4 (126mg) in 6M HCI (2ml) is heated to 100 ⁰ C for 2.5 hours. The mixture is allowed to cool and concentrated in vacuo. Purification of the crude compound by preparative HPLC (Method C) affords the title compound as a colourless solid (79mg, 66%). LCMS (Method A) 539 [M+H] ⁺ , RT 1.66 mins. ¹ H NMR 300MHz (d6-DMSO) 61.28- 1.88 (m, 6H), 2.70 (m, 1 H), 3.07 (m, 2H), 3.32 (dd, 1 H), 4.05 (m, 1 H), 4.72 (m, 1 H), 7.35 (m, 1 H), 7.45-7.57 (m, 4H), 8.14 (dd, 1 H), 8.21 (s, 1 H), 8.29 (m, 1 H), 8.63 (s, 2H), 9.18 (d, 1 H).

Example 30

N-tS.S-dichloroisonicotinoyO-A^-^RJ-i-methylpiperidin-Z-y ll-SH-imidazo^.S- b]pyridin-3-yl}-L-phenylalanine (Compound 16)

To a stirred solution of Intermediate 18 (140mg) in EtOH (5ml) under N ₂ (g) is added 10% Pd on carbon (28mg). The mixture is flushed with H ₂ (g) and stirred at atmospheric pressure for 2.5 hours. The mixture is filtered through a pad of celite, and the filtrate concentrated in vacuo. The residue is dissolved in EtOH (5ml) and formaldehyde (37% in water) (2ml) is added followed by sodium cyanoborohydride (150mg). The reaction is stirred at room temperature for 15 minutes. EtOAc (20ml) and sat. NaHCO ₃ (20ml) are added and the layers separated. The aqueous layer is extracted with EtOAc (20ml) and the combined organic layers dried (MgSO ₄ ) and concentrated in vacuo. The residue in 6M HCI (3ml) is heated to 60 ⁰ C for 4 hours. The mixture is allowed to cool and concentrated in vacuo. Purification of the crude compound by preparative HPLC (Method C) affords the title compound (31.5mg, 28%). LCMS (Method A) 553 [M+H] ⁺ , RT 1.79 mins. ¹ H NMR 300MHz (d4-MeOH) 51.49 (m, 1 H), 1.88 (s, 3H), 2.11 (m, 2H), 2.63 (s, 3H), 2.98 (m, 1 H), 3.23 (m, 1 H), 3.49 (m, 2H), 4.11 (m, 1 H), 4.96 (m, 1 H), 7.44 (m, 3H), 7.68 (m, 2H), 8.21 (dd, 1 H), 8.26 (s, 1 H), 8.35 (dd, 1 H), 8.58 (s, 2H).

Example 31

N-IS.S-DichloroisonicotinoyO^a-methyl-IH-pyrroloIZ.S-blpy ridin-i-ylJphenylalanine (Compound 17)

Compound 3 (33mg) is dissolved in THF (2ml), added dropwise over 1 hour to a stirred solution of sodium hydroxide (2.0M, 2ml), stirred for 1 hour at room temperature, the organic solvent removed in vacuo, diluted with water (4ml) and the solution neutralised to pH<7.0 using HCI (12M). The resulting precipitated solid is removed via filtration and dried in vacuo to afford the title compound as a white solid (25mg). LCMS (Method A) 469 [M+H] ⁺ , RT 3.40 mins. ¹ H NMR 300MHz (d ₆ -DMSO) 52.34 (m, 3 H), 2.98 (m, 1 H), 3.23 (m, 1 H), 4.79 (m, 1 H), 7.20 (dd, 1 H), 7.43 (d, 2 H), 7.72 (d, 1 H), 7.84 (d, 2 H), 8.04 (dd, 1 H), 8.31 (dd, 1 H), 8.64 (s, 2 H), 9.36 (d, 1 H), 12.97 (m, 1 H). Example 32

N-(3,5-Dichloroisonicotinoyl)-3-(2-isobutyl-3H-imidazo[4, 5-b]pyridin-3-yl)-L- phenylalanine (Compound 18) To isovaleric acid (58μl) (CAS No. 503-74-2) in DCM (5ml) is added DIPEA (92μl),

HOBt (43mg) and EDC (102mg) at room temperature. After stirring for 5 minutes Intermediate 26 (100mg) is added and stirring is continued for 4 days. The mixture is diluted with DCM (10ml) and washed with sat. NaHCO ₃ solution (20ml), brine, dried over MgSO ₄ , filtered and concentrated in vacuo. The residue is dissolved in AcOH (3ml) and heated to 125°C by microwave irradiation for 300 seconds. The solvent is removed in vacuo and the residue heated to 100 ⁰ C in 6N HCI (3ml) for 30 minutes. The solvent is removed in vacuo. Purification of the crude compound by preparative HPLC (Method C) affords the title compound (50mg, 46%). LCMS (Method A) 512/514 [M+H] ⁺ , RT 2.66 mins. ¹ HNMR 300MHz (d ₆ -DMSO)δ0.85 (dd, 6H), 2.13 (m, 1 H), 2.67 (d, 2H), 3.02 (dd, 1 H), 3.2-3.4 (m, 1 H), 4.80 (m, 1 H), 7.29 (dd, 1 H), 7.36 (d, 1 H), 7.41 -7.58 (m, 3H), 8.07 (dd, 1H), 8.22 (dd, 1 H), 8.62 (s, 2H), 9.31 (d, 1 H), 13.0 (bs, 1 H). Example 33

N-tS.S-DichloroisonicotinoylJ-S^-pyridin-S-yl-SH-imidazo^.S- bJpyridin-S-yO-L- phenylalanine (Compound 19) To Intermediate 21 (100mg) in DCM (5ml) is added DIPEA (81 μl) and nicotinoyl chloride hydrochloride (42mg) (CAS No. 20260-53-1 ) at room temperature. The reaction is stirred at room temperature for 21 hours, diluted with DCM (10ml), washed with sat. NaHCO ₃ solution (20ml), brine, dried over MgSO ₄ , filtered and concentrated in vacuo. The residue is dissolved in AcOH (3ml) and heated to 125°C by microwave irradiation for 300 seconds. The solvent is removed in vacuo and the residue heated to 100 ⁰ C in 6N HCI

(3ml) for 30 minutes. The solvent is removed in vacuo. Purification of the crude compound by preparative HPLC (Method C) affords the title compound (65mg, 58%). LCMS (Method A) 533/535 [M+H]\ RT 2.33 mins. ¹ HNMR 300MHz (d ₆ -DMSO) 82.99 (dd, 1H), 3.23 (dd, 1 H), 4.69 (m, 1 H), 7.30-7.39 (m, 2H), 7.40-7.51 (m, 4H), 7.80 (dt, 1 H), 8.27 (dd, 1 H), 8.37 (dd, 1 H), 8.61 (dd, 1 H), 8.63 (s, 2H), 8.84 (d, 1 H), 9.34 (d, 1H), 12.97 (bs, 1H).

Example 34 N-(3,5-Dichloroisonicotinoyl)-4-(1 H-indol-3-yl)-L-phenylalanine (Compound 20)

To a mixture of Intermediate 21 (205mg) in 5N HCI (5ml) is added THF (1ml). The mixture is heated to reflux for 24 hours, cooled to room temperature and the solvent removed in vacuo. To the residue is added MeOH (5ml), water (5ml) and potassium hydroxide (1 pellet) and the mixture is heated to reflux for 4 hours. The mixture is cooled and the solvent removed in vacuo. Purification of the crude compound by preparative HPLC (Method C) affords the title compound (88mg, 59%). LCMS (Method A) 454/456 [M+H] ⁺ , RT 3.17 mins. ¹ HNMR 300MHz (d ₆ -DMSO) 62.96 (dd, 1 H), 3.21 (dd, 1 H) ₁ 4.77 (h, 1H), 7.09 (td, 1 H), 7.15 (td, 1 H), 7.34 (d, 2H), 7.45 (d, 1 H), 7.61 (d, 2H), 7.66 (d, 1 H), 7.84 (d, 1 H) ₁ 8.65 (s, 2H), 9.33 (d, 1 H), 11.33 (d, 1 H), 12.93 (bs, 1 H). Example 35 N^S.S-DichloroisonicotinoyO^^-KdimethylaminoJmethyll-SH-imid azo^.S-blpyridin- 3-yl}-L-phenylalanine (Compound 21)

To a stirred solution of Intermediate 2 (500mg) in anhydrous DMF (5ml) is added λ/,λ/-dimethylglycine (128mg) (CAS No. 1118-68-9), DIPEA (330μl) and HBTU (475mg) (CAS No. 94790-37-1). The reaction is stirred at room temperature for 21 hours then poured into EtOAc (150ml), washed with saturated NaHCO ₃ solution and then water. The organic layer is dried over MgSO ₄ , filtered and the solvent removed in vacuo. The crude material (560mg) is dissolved in AcOH (5ml) and heated to 125°C by microwave irradiation for 300 seconds. The reaction is evaporated to dryness in vacuo and the residue dissolved in DCM then washed with saturated NaHCO ₃ solution. The organic layer is washed with brine, dried over MgSO ₄ and evaporated to dryness in vacuo. The crude material is dissolved in DCM (40ml) and treated with TFA (855μl) at room temperature. The reaction is stirred at room temperature for 20 hours. The reaction is diluted with DCM (110ml) and washed with saturated NaHCO ₃ solution. The organic layer is dried over MgSO ₄ and evaporated to dryness in vacuo. The residue (100mg) is taken up in Dioxane (4ml). DIPEA (0.14ml) is added followed by 2,6-dichloroisonicotinoyl chloride (57mg). The reaction is stirred at room temperature for 4.5 hours. The mixture is partitioned between

DCM (100ml) and sat. NaHCO ₃ solution (50ml) and the organic layer is dried (MgSO ₄ ), filtered and concentrated in vacuo. The crude compound is purified by preparative HPLC (Method D). The ester is dissolved in THF (1ml) and added dropwise over 1 hour to a stirred solution of NaOH (2.0M, 0.28ml). Once addition is complete the reaction is stirred for a further 5 minutes and then acetic acid (1 ml) is added. The solvent is removed in vacuo and the residue purified by preparative HPLC (Method C) to afford the title compound (29mg, 55%). LCMS (Method A) 513 [M+H]\ RT 1.54 mins. ¹ H NMR 300MHz (d6-DMSO) 52.2 (s, 6H), 3.0 (dd, 1 H), 3.3 (m, 1 H), 3.6 (s, 2H), 4.8 (m, 1 H), 7.3 (dd, 1H), 7.55 (s, 4H), 8.1 (m, 2H), 8.3 (m, 1 H), 8.65 (s, 2H), 9.4 (d, 1 H). Example 36

Parallel synthesis

The following examples are all prepared by the synthetic route shown below. All solvents and reagents are obtained from commercial sources and used without further purification. Parallel syntheses are performed using a PLS (orbital shaker) from Advanced Chemtech.

Volume used 10 ml/g resin

"3*" means washed 3 times with the respective solvent.

(1) Prewash with 3*C, 3*DMF, 20% (piperidine in DMF) 5 mins. Filtration and reaction

25 mins with 20% piperidine in DMF. Washing with 6 ^* DMF, 3 ^* DCM, 3 ^* MeOH, 3 ^* DCM

(2) Reaction 4 h with 5 eq of COCI2 in DCM and 5 eq of diisopropylethylamine

(DIPEA).

Washing with 3*DCM, 3* DMF, 3 ^* DCM, 3*MeOH, 3*DCM, 3 ^* DMF

(3) Reaction with SnCl2 2M in DMF overnight RT.

Washing with 3*DCM, 3*(DCM + 10%TEA), 3 ^* DMF, 3 ^* DCM, 3*MeOH, 3 ^* DCM, 3 ^* DMF.

(4) Reaction 24h, 100 ⁰ C with 5 eq 2-Chloro-3-nitropyridine and 5 eq DIPEA in DMF

Washing with 3 ^* DMF, 3*DCM, 3 ^* MeOH, 3 ^* DCM, 3 ^* DMF (5) Reaction with SnCl2 2 M in NMP overnight RT.

(6) Reaction 24h, 100 ⁰ C with acid in DMAc + 5% AcOH Washing with 3*DMF, 3*DCM, 3*MeOH

(7) Cleavage with TFA/Water 95%/5% 30 min (twice).

Analytic mass spectrometric measurements in LC/MS mode are performed as follows: HPLC conditions

An Agilent 1100 series HPLC system mounted with an INERTSIL ODS 3 C18, DP 5 μm, 250 X 4.6 mm column. The chromatography is carried out at 35° C. The gradient runs from 100 % solvent A (acetonitrile, water, TFA (10/90/0.1 , v/v/v)) to 100 % solvent B (acetonitrile, water, TFA (90/10/0.1 , v/v/v)) in 7 min with a hold at 100 % B of 4 min. The flow rate is set at 2.5 ml/min and a split of 1/25 is used just before the APCI source. MS conditions

Samples are dissolved in acetonitrile/water, 70/30, v/v at a concentration of about 250 μg/ml. APCI spectra are performed using a FINNIGAN (San Jose, CA, USA) LCQ ion trap mass spectrometer. The APCI source is operated at 450 ⁰ C and the capillary heater at 160 °C.

Preparative purification in LC/MS mode are performed as follows: HPLC conditions

A WATERS Prep 4000 HPLC system is connected to a Waters 996 PDA, and the chromatography is carried out at room temperature with a flow of 35 ml/min. Acidic gradient on a YMC CombiPrep ODS-AQ: 50 X 20 mm ID 5 μm column and 10 X 20 mm ID precolumn:

Time(min) A% B% C%

0 90 0 10

6 0 90 10

8 0 90 10

8,5 90 0 10

10,5 90 0 10

With A: Water; B: Acetonitrile; C: H ₂ O/CH ₃ CN/TFA 50/50/1.

MS conditions

Samples are dissolved in acetonitrile/water, 70/30, v/v with the concentration depending on the solubility of the sample. ESI spectra are performed using an LCZ: Waters Micromass MS Technologies operated under Masslynx 4.0, sp1. The ESI source operated at 3.5 kV, Cone: 25 V, source temp.: 150° C, desolvation temp. : 300° C, desolvation gaz: 530 Ub. Experimental data.

Example 37

The following cellular assays are used to demonstrate the potency and selectivity of the compounds according to the invention. In each of these assays an IC50 value is determined for each test compound and represents the concentration of compound necessary to achieve 50% inhibition of cell adhesion where 100% = adhesion assessed in the absence of the test compound and 0% = absorbance in wells that did not receive cells, a). α4β1 Integrin-dependent Jurkat cell adhesion to VCAM-Ig : 96 well NUNC plates are coated with F(ab)2 fragment goat anti-human IgG Fcy- specific antibody [Jackson lmmuno Research 109-006-098: 100 μl at 2 μg/ml in 0.1 M NaHCO3, pH 8.4], overnight at 4°C. The plates are washed (3x) in PBS and then blocked for 1 h in PBS/1% BSA at RT on a rocking platform. After washing (3x in PBS) 9 ng/ml of purified 2d VCAM-Ig diluted in PBS/1% BSA is added and the plates left for 60 minutes at

RT on a rocking platform. The plates are washed (3x in PBS) and the assay then performed at 37 ⁰ C for 30 min in a total volume of 200 μl containing 2.5 x 105 Jurkat cells in the presence or absence of titrated test compounds.

Each plate is washed (2x) with medium and the adherent cells are fixed with 100μl MeOH for 10 minutes followed by another wash. 100μl 0.25% Rose Bengal (Sigma R4507) in PBS is added for 5 minutes at RT and the plates washed (3x) in PBS. 100μl 50% (v/v) EtOH in PBS is added and the plates left for 60min after which the absorbance (570nm) is measured.

Compound 1 , 4-[2-(6-Chloropyridin-3-yl)-3H-imidazo[4,5-b]pyridin-3-yl]-N -(3,5- dichloroisonicotinoyl)-L-phenylalanine shows a IC50 value of <200nM. b). α4β7 Integrin-dependent JY cell adhesion to MAdCAM-Ig: This assay is performed in the same manner as the α4β1 assay except that MAdCAM-Ig (150ng/ml) is used in place of 2d VCAM-Ig and a sub-line of the β- lymphoblastoid cell-line JY is used in place of Jurkat cells. The IC50 value for each test compound is determined as described in the α4β1 integrin assay.

The compounds of the invention are tested in this assay (a and b and c ) and show IC50 values of 1 μM and below.

Compound 1 , 4-[2-(6-Chloropyridin-3-yl)-3H-imidazo[4,5-b]pyridin-3-yl]-N -(3,5- dichloroisonicotinoyl)-L-phenylalanine shows a IC50 value of <200nM. c). Whole blood VCAM-binding assay for α4 integrins:

The following reagents are added to FACS tubes: 3μl 10OmM MnCl2 (100X required cone), 1μl 1 mg/ml streptavidin-FITC (supplier Pierce 100X required cone), 2μl 500 μg/ml biotinylated hVCAM-1-mFc (5OX required cone), and 2μl serially-diluted test compound at 5OX desired final concentrations. 100μl heparinised blood from healthy human donors is then added to each FACS tube which are then sealed and rocked for 30 minutes at RT. 2ml "FACS Lysing Solution" (BD Biosciences) solution is added to tubes for 5 minutes at room temperature RT, and tubes are spun at 1200 rpm and washed 2X in 3ml TBS, before final suspension in 100μl TBS. Flow cytometry is then performed on a Becton Dickinson FACScan to assess the % of cells in the lymphocyte gate capable of binding VCAM.

The compounds of the invention are tested in this assays and show IC50 values of 1μM and below.

Compound 1 , 4-[2-(6-Chloropyridin-3-yl)-3H-imidazo[4,5-b]pyridin-3-yl]-N -(3,5- dichloroisonicotinoyl)-L-phenylalanine shows a IC50 value of < 200 nM. d). α5β1 Integrin-dependent K562 cell adhesion to fibronectin:

96 well tissue culture plates are coated with human plasma fibronectin (Sigma F0895) at 5μg/ml in PBS for 2 hr at 37oC. The plates are washed (3x in PBS) and then blocked for 1 h in 100μl PBS/1% BSA at RT on a rocking platform. The blocked plates are washed (3x in PBS) and the assay then performed at 37 ⁰ C in a total volume of 200μl containing 2.5x 105 K562 cells, phorbol-12-myristate-13-acetate at 10ng/ml, and in the presence or absence of titrated test compounds. Incubation time is 30 minutes. Each plate is fixed and stained as described in the α4β1 assay above. e). αmβ2-dependent human polymorphonuclear neutrophils adhesion to plastic: 96 well tissue culture plates are coated with RPMI 1640/10% FCS for 2h at 37oC. 2 x 105 freshly isolated human venous polymorphonuclear neutrophils (PMN) are added to the wells in a total volume of 200 μl in the presence of 10ng/ml phorbol-12-myristate-13- acetate, and in the presence or absence of test compounds, and incubated for 20min at 37 ⁰ C followed by 30min at room temperature RT. The plates are washed in medium and 100μl 0.1% (w/v) hexadecyl trimethyl ammonium bromide (Sigma H5882) in 0.05M potassium phosphate buffer, pH 6.0 added to each well. The plates are then left on a rocker at room temperature RT for 60 min. Endogenous peroxidase activity is then assessed using TMB as follows: PMN lysate samples mixed with 0.22% H2O2 (Sigma) and 50μg/ml TMB (Boehringer Mannheim) in 0.1 M sodium acetate/citrate buffer, pH 6.0 and absorbance measured at 630nm. f). αllb/β3 -dependent human platelet aggregation:

Human platelet aggregation is assessed using impedance aggregation on the Chronolog Whole Blood Lumiaggregometer. Human platelet-rich plasma (PRP) is obtained by spinning fresh human venous blood anticoagulated with 0.38% (v/v) tri-sodium citrate at

220xg for 10 min and diluted to a cell density of 6 x 108/ml in autologous plasma. Cuvettes contained equal volumes of PRP and filtered Tyrode's buffer (g/liter: NaCI 8.0; MgCl2-H2θ

0.427; CaCI ₂ 0.2; KCI 0.2; D-glucose 1.0; NaHCO ₃ 1.0; NaH ₂ PO ₄ .2H ₂ O 0.065).

Aggregation is monitored following addition of 2.5μM ADP (Sigma) in the presence or absence of inhibitors. g). αvβ3 integrin-dependent JY adhesion to vitronectin: 96 well NUNC plates are coated with human vitronectin (Promega) at 2.5μg/ml in

PBS for 2 hours at 37oC. The plates are washed (2X in PBS) and then blocked for 1 h in 100μl PBS/1 %BSA at RT on a rocking platform. The blocked plates are then washed (2X in PBS) and the assay is then performed at 37oC in a total volume of 200μl containing 2X105 JY cells, phorbol-12-myristate-13-aceteate at 10ng/ml, and in the absence or presence of titrated test compound. The JY cells are preincubated for 15 minutes with 5

μg/ml monoclonal antibody against β2 integrins, called 6.5E, to prevent β2-dependent nonspecific binding. Each plate is fixed and stained as described above in the α4β1 assay above.

In the assays featuring αintegrins of other subgroups, the compounds of the invention have IC50 values of > 50 μM and above thus demonstrating the potency and selectivity of their action against α4 integrins.