TrkA kinase inhibitors, compositions and methods thereof

1. A compound of formula I:

and pharmaceutically acceptable salts thereof, wherein:

R represents hydrogen, or C 1-6 alkyl;

R 1 is selected from C 5-10 heterocycle, selected from the group consisting of pyrazolyl, pyridyl, imidazolyl, imidazopyridinyl, thiazolyl, isoxazolyl, triazolyl, oxazolyl, pyrimidinyl, pyrrolopyridinyl, and imidazothiazolyl, said heterocycle, optionally substituted with 1 to 3 groups of R a ;

R a represents —CN, —(CH 2 ) n C 1-4 haloalkyl, —C 1-6 alkyl, —C 1-6 alkenyl, —C 1-6 alkynyl, —(CHR) n C 6-10 aryl, —(CHR) n C 5-10 heterocycle, —C 3-10 cycloalkyl, —O—(CH 2 ) n C 6-10 aryl, —O—C 5-10 heterocycle, —C(O)CF 3 , —(CH 2 ) n halo, —OR, —NRR, —NHC 6-10 aryl, —SCF 3 , —SO 2 CF 3 , —OC(F) 2 Cl, —OC 1-4 haloalkyl, —C(O)NRR, —SO 2 R, —SO 2 NRR, —OC(F) 2 C(F) 3 , —S(O) 2 CH(F) 2 , —OC(F) 2 CH(F) 2 , —C(CH 3 ) 2 C≡N, —COC 6-10 aryl, or —CO 2 R, said cycloalkyl, alkyl, aryl and heterocycle optionally substituted with 1 to 3 groups of R b , wherein the C 5-10 heterocycle is selected from the group consisting of pyrazolyl, pyridyl, imidazolyl, imidazopyridinyl, thiazolyl, isoxazolyl, triazolyl, oxazolyl, oxadiazolyl, thiadiazolyl, tetrazolyl, furanyl, pyrimidinyl, pyrrolopyridinyl, and imidazothiazolyl;

R b represents, —CN, —(CH 2 ) n C 1-4 haloalkyl, —OR, —C 1-6 alkyl, —(CH 2 ) n OR, —(CHR) n C 6-10 aryl, —(CHR) n C 5-10 heterocycle, —C 3-10 cycloalkyl, —(CH 2 ) n halo, said aryl and heterocycle optionally substituted with 1 to 3 groups of C 1-6 alkyl, or halo, wherein the C 5-10 heterocycle is selected from the group consisting of pyrazolyl, pyridyl, imidazolyl, imidazopyridinyl, thiazolyl, isoxazolyl, triazolyl, oxazolyl, oxadiazolyl, thiadiazolyl, tetrazolyl, furanyl, pyrimidinyl, pyrrolopyridinyl, and imidazothiazolyl, and

n represents 0-6.

2. The compound according to claim 1 wherein R a represents —CN, —CF 3 , —OCF 3 , —SCF 3 , —C 1-6 alkyl, —(CH 2 ) n halo, —NRR, —C(O)NRR, pyrazolyl, furanyl, phenyl, pyridyl, tetrazolyl, oxazolyl, thiazolyl, pyrrolyl, triazolyl, imidazolyl, oxadiazolyl, thiadiazolyl, or —O(CH 2 ) n phenyl, said pyrazolyl, furanyl, phenyl, pyridyl, tetrazolyl, oxazolyl, thiazolyl, pyrrolyl, triazolyl, imidazolyl, oxadiazolyl, thiadiazolyl, and —O(CH 2 ) n phenyl optionally substituted with 1 to 3 groups of R b .

3. The compound according to claim 1 of formula I represented by structural formula III:

or pharmaceutically acceptable salts there of wherein B is pyrazolyl or imidazolyl and R a is selected from the group consisting of —CN, —CF 3 , —OCF 3 , —SCF 3 , —C 1-6 alkyl, —(CH 2 ) n halo, —NRR, —C(O)NRR, pyrazolyl, furanyl, phenyl, pyridyl, tetrazolyl, oxazolyl, thiazolyl, pyrrolyl, triazolyl, imidazolyl, oxadiazolyl, thiadiazolyl, and —O(CH 2 ) n phenyl, said pyrazolyl, furanyl, phenyl, pyridyl, tetrazolyl, oxazolyl, thiazolyl, pyrrolyl, triazolyl, imidazolyl, oxadiazolyl, thiadiazolyl, and —O(CH 2 ) n phenyl optionally substituted with 1 to 3 groups of R b .

4. The compound according to claim 3 wherein B is pyrazolyl.

5. The compound according to claim 3 wherein B is imidazolyl.

6. The compound according to claim 1 of formula IV represented by structural formula IV:

or pharmaceutically acceptable salts there of wherein A is pyridyl or pyrimidinyl and R a is selected from the group consisting of —CN, —CF 3 , —OCF 3 , —SCF 3 , —C 1-6 alkyl, —(CH 2 ) n halo, —NRR, —C(O)NRR, pyrazolyl, furanyl, phenyl, pyridyl, tetrazolyl, oxazolyl, thiazolyl, pyrrolyl, triazolyl, imidazolyl, oxadiazolyl, thiadiazolyl, and —O(CH 2 ) n phenyl, said pyrazolyl, furanyl, phenyl, pyridyl, tetrazolyl, oxazolyl, thiazolyl, pyrrolyl, triazolyl, imidazolyl, oxadiazolyl, thiadiazolyl, and —O(CH 2 ) n phenyl, optionally substituted with 1 to 3 groups of R b .

7. The compound according to claim 6 wherein A is pyridyl.

8. The compound according to claim 6 wherein A is pyrimidinyl.

9. A compound which is:

1-(9H-fluoren-9-yl)-3-(6-methyl-2-phenylpyridin-3-yl)urea;

1-(9H-fluoren-9-yl)-3-(2-methyl-4-phenyl-1,3-thiazol-5-yl)urea;

1-(9H-fluoren-9-yl)-3-(2-methyl-4-phenylpyrimidin-5-yl)urea;

1-(9H-fluoren-9-yl)-3-[2-(4-fluorophenyl)-6-methylpyridin-3-yl]urea;

1-(9H-fluoren-9-yl)-3-(6-phenylimidazo[2,1-b][1,3]thiazol-5-yl)urea;

1-(9H-fluoren-9-yl)-3-(3-methyl-1-phenyl-1H-pyrazol-5-yl)urea;

1-(9H-fluoren-9-yl)-3-(5-methyl-3-phenylisoxazol-4-yl)urea;

1-(9H-fluoren-9-yl)-3-(1-methyl-4-phenyl-1H-pyrazol-5-yl)urea;

1-(1,3-dimethyl-4-phenyl-1H-pyrazol-5-yl)-3-(9H-fluoren-9-yl)urea;

1-(9H-fluoren-9-yl)-3-(2-phenylpyridin-3-yl)urea;

1-(9H-fluoren-9-yl)-3-(4-phenylpyridin-3-yl)urea;

1-(9H-fluoren-9-yl)-3-(6-methylpyridin-3-yl)urea;

1-(9H-fluoren-9-yl)-3-(1-phenyl-1H-pyrazol-5-yl)urea;

1-(1,3-diphenyl-1H-pyrazol-5-yl)-3-(9H-fluoren-9-yl)urea;

1-(3-tert-butyl-1-phenyl-1H-pyrazol-5-yl)-3-(9H-fluoren-9-yl)urea;

1-(9H-fluoren-9-yl)-3-[3-(2-methylpropyl)-1-phenyl-1H-pyrazol-5-yl]urea;

1-[3-tert-butyl-1-(2-methylphenyl)-1H-pyrazol-5-yl]-3-(9H-fluoren-9-yl)urea;

1-(3-cyclopropyl-1-phenyl-1H-pyrazol-5-yl)-3-(9H-fluoren-9-yl)urea;

1-[3-tert-butyl-1-(4-fluorophenyl)-1H-pyrazol-5-yl]-3-(9H-fluoren-9-yl)urea;

1-(9H-fluoren-9-yl)-3-(2-phenylimidazo[1,2-a]pyridin-3-yl)urea;

1-(9H-fluoren-9-yl)-3-(1-methyl-4-phenyl-1H-imidazol-5-yl)urea;

1- [4-cyano-1-(4-fluorophenyl)-3-methyl-1H-pyrazol-5-yl]-3-(9H-fluoren-9-yl)urea;

1-(9H-fluoren-9-yl)-3-[3-(4-methoxyphenyl)-1-phenyl-1H-pyrazol-5-yl]urea;

1-(9H-fluoren-9-yl)-3-[2-(methylamino)pyridin-3-yl]urea;

1-(9H-fluoren-9-yl)-3-(2-fluoro-6-methylpyridin-3-yl)urea;

1-(9H-fluoren-9-yl)-3-[4-(4-fluorophenyl)-2-methylpyrimidin-5-yl]urea;

1-(9H-fluoren-9-yl)-3-[4-(4-fluorophenyl)-6-methylpyridin-3-yl]urea;

1-(9H-fluoren-9-yl)-3-(4-phenylpyrimidin-5-yl)urea;

1-(9H-fluoren-9-yl)-3-(3-methyl-1-pyridin-2-yl-1H-pyrazol-5-yl)urea;

1-(2-cyclohexylpyridin-3-yl)-3-(9H-fluoren-9-yl)urea;

1-(9H-fluoren-9-yl)-3-[1-(4-fluorophenyl)-3-methyl-1H-pyrazol-5-yl]urea;

1-(2,4′-bipyridin-3-yl)-3-(9H-fluoren-9-yl)urea;

1-(2,3′-bipyridin-3-yl)-3-(9H-fluoren-9-yl)urea;

1-(9H-fluoren-9-yl)-3-[2-(4-fluorophenyl)pyridin-3-yl]urea;

1-(9H-fluoren-9-yl)-3-(2′-fluoro-2,4′-bipyridin-3-yl)urea;

1-(9H-fluoren-9-yl)-3-(2-furan-2-ylpyridin-3-yl)urea;

1-(9H-fluoren-9-yl)-3-(1-methyl-3-phenyl-1H-pyrazol-5-yl)urea;

1-(1,2-dimethyl-4-phenyl-1H-imidazol-5-yl)-3-(9H-fluoren-9-yl)urea;

1-(9H-fluoren-9-yl)-3-(2-methyl-4-phenyl-1H-imidazol-5-yl)urea;

1-(9H-fluoren-9-yl)-3-pyridin-3-ylurea;

1-(9H-fluoren-9-yl)-3-(1-phenyl-1H-1,2,4-triazol-5-yl)urea;

1-(9H-fluoren-9-yl)-3-(2-furan-2-ylimidazo[1,2-a]pyridin-3-yl)urea;

1-(9H-fluoren-9-yl)-3-(2-pyridin-4-ylimidazo[1,2-a]pyridin-3-yl)urea;

1-(9H-fluoren-9-yl)-3-(3-phenylisoxazol-4-yl)urea;

1-(9H-fluoren-9-yl)-3-(5-methyl-2-phenylpyridin-3-yl)urea;

1-(3,3′-bipyridin-5-yl)-3-(9H-fluoren-9-yl)urea;

1-(9H-fluoren-9-yl)-3-[5-(1-methyl-1H-pyrazol-5-yl)pyridin-3-yl]urea;

1-(9H-fluoren-9-yl)-3-[5-(1-methyl-1H-1,2,4-triazol-5-yl)pyridin-3- yl]urea;

1-(9H-fluoren-9-yl)-3-[2-(3-fluorophenyl)pyridin-3-yl]urea;

1-(9H-fluoren-9-yl)-3-[2-(2-fluorophenyl)pyridin-3-yl]urea;

1-(9H-fluoren-9-yl)-3-[2-(2-methylphenyl)pyridin-3-yl]urea;

1-(9H-fluoren-9-yl)-3-(3-methyl-1-phenyl-1H-1,2,4-triazol-5-yl)urea;

1-(9H-fluoren-9-yl)-3-(2-phenylpyridin-4-yl)urea;

1-(9H-fluoren-9-yl)-3-(2-methyl-4-phenyl-1,3-oxazol-5-yl)urea,

1-(9H-fluoren-9-yl)-3-[5-(1-methyl-1H-imidazol-2-yl)pyridin-3-yl]urea;

1-(9H-fluoren-9-yl)-3-[2-(1H-pyrazol-1-yl)pyridin-3-yl]urea;

1-(9H-fluoren-9-yl)-3-(5-fluoro-2-phenylpyridin-3-yl)urea;

1-(9H-fluoren-9-yl)-3-[1-methyl-3-(1-methyl-1H-imidazol-2-yl)-1H-pyrazol-5-yl]urea;

and pharmaceutically acceptable salts thereof.

10. A pharmaceutical composition comprising a therapeutically effective amount of a compound of claim 1 or a pharmaceutically acceptable salt thereof,

and a pharmaceutically acceptable carrier.