Substituted aminopiperidines as dipeptidyl peptidase-IV inhibitors for the treatment of diabetes

1. A compound of structural formula I:

or a pharmaceutically acceptable salt thereof; wherein

V is selected from the group consisting of:

Ar is phenyl optionally substituted with one to five R 1 substituents;

each R 1 is independently selected from the group consisting of:

halogen,

cyano,

hydroxy,

C 1-6 alkyl, optionally substituted with one to five fluorines, and

C 1-6 alkoxy, optionally substituted with one to five fluorines;

each R 2 is independently selected from the group consisting of hydrogen, halogen, cyano, and

C 1-4 alkyl optionally substituted with one to five fluorines;

R 3a and R 3b are each independently hydrogen or C 1-4 alkyl optionally substituted with one to five fluorines;

R a is selected from the group consisting of:

hydrogen,

—C 1-6 alkyl, wherein alkyl is substituted with one to five substituents independently selected from CO 2 H, cyano, deuterium, fluorine, hydroxy, and C 1-4 alkoxycarbonyl,

—C 1-4 alkylcarbonyl, wherein the alkyl moiety is optionally substituted with one to five fluorines,

—C(═O)CH 2 aryl, wherein aryl is optionally substituted with one to five substituents independently selected hydroxy, halogen, cyano, nitro, CO 2 H, C 1-6 alkyloxycarbonyl, C 1-4 alkylsulfonyl, C 1-6 alkyl, and C 1-6 alkoxy, wherein alkyl and alkoxy are optionally substituted with one to five fluorines,

—C(═O)CH 2 heteroaryl, wherein heteroaryl is optionally substituted with one to five substituents independently selected hydroxy, halogen, cyano, nitro, CO 2 H, C 1-6 alkyloxycarbonyl, C 1-4 alkylsulfonyl, C 1-6 alkyl, and C 1-6 alkoxy, wherein alkyl and alkoxy are optionally substituted with one to five fluorines,

(CH 2 ) n -heteroaryl, wherein heteroaryl is pyrrolyl, isoxazolyl, isothiazolyl, pyrazolyl, 2-oxo-(1H)-pyridinyl (2-hydroxy-pyridinyl), oxazolyl, 1,2,4-oxadiazolyl, 1,3,4-oxadiazolyl, thiadiazolyl, thiazolyl, imidazolyl, triazolyl, tetrazolyl, furyl, triazinyl, thienyl, pyrimidinyl, pyrazinyl, benzisoxazolyl, benzoxazolyl, benzothiazolyl, benzothiadiazolyl, dihydrobenzofuranyl, indolinyl, pyridazinyl, indazolyl, isoindolyl, dihydrobenzothienyl, indolizinyl, cinnolinyl, phthalazinyl, quinazolinyl, naphthyridinyl, carbazolyl, benzodioxolyl, quinoxalinyl, purinyl, furazanyl, isobenzylfuranyl, benzimidazolyl, benzofuranyl, benzothienyl, quinolyl, indolyl, isoquinolyl, dibenzofuranyl, imidazo[1,2-a]pyridinyl, [1,2,4-triazolo][4,3-a]pyridinyl, pyrazolo[1,5-a]pyridinyl, [1,2,4-triazolo][1,5-a]pyridinyl, 2-oxo-1,3-benzoxazolyl, 4-oxo-3H-quinazolinyl,3-oxo-[1,2,4]-triazolo[4,3-a]-2H-pyridinyl, 5-oxo-[1,2,4]-4H-oxadiazolyl, 2-oxo-[1,3,4]-3H-oxadiazolyl, 2-oxo-1,3-dihydro-2H-imidazolyl or 3-oxo-2,4-dihydro-3H-1,2,4-triazolyl, and wherein heteroaryl is optionally substituted with one to three substituents independently selected from hydroxy, halogen, cyano, pyrrolidin-1-yl, morpholin-1-yl, nitro, CO 2 H, C 1-6 alkyloxycarbonyl, C 1-4 alkylsulfonyl, C 1-6 alkyl, and C 1-6 alkoxy, wherein alkyl and alkoxy are optionally substituted with one to five fluorines,

(CH 2 ) n -N-heteroaryl, wherein heteroaryl is optionally substituted with one to three substituents independently selected from hydroxy, halogen, cyano, nitro, CO 2 H, C 1-6 alkyloxycarbonyl, C 1-4 alkylsulfonyl, C 1-6 alkyl, and C 1-6 alkoxy, wherein alkyl and alkoxy are optionally substituted with one to five fluorines,

(CH 2 ) n -heterocyclyl, wherein heterocyclyl is tetrahydrofuran (THF), dihydrofuran, 1,4-dioxane, morpholine, 1,4-dithiane, piperazine, piperidine, 1,3-dioxolane, imidazolidine, imidazoline, pyrroline, pyrrolidine, tetrahydropyran, dihydropyran, oxathiolane, dithiolane, 1,3-dioxane, 1,3-dithiane, oxathiane, thiomorpholine, pyrrolidinone, oxazolidin-2-one, imidazolidine-2-one or pyridone and wherein the heterocyclyl is optionally substituted with one to three substituents independently selected from oxo, hydroxy, halogen, cyano, nitro, CO 2 H, C 1-6 alkyloxycarbonyl, C 1-4 alkylsulfonyl, C 1-6 alkyl, and C 1-6 alkoxy, wherein alkyl and alkoxy are optionally substituted with one to five fluorines,

(CH 2 ) m —C 3-6 cycloalkyl, wherein cycloalkyl is optionally substituted with one to three substituents independently selected from halogen, hydroxy, cyano, nitro, CO 2 H, C 1-6 alkyloxycarbonyl, C 1-4 alkylsulfonyl, C 1-6 alkyl, and C 1-6 alkoxy, wherein alkyl and alkoxy are optionally substituted with one to five fluorines,

(CH 2 ) n —COOH,

(CH 2 ) n —COOC 1-6 alkyl,

(CH 2 ) n —NR 4 R 5 ,

(CH 2 ) n —CONR 4 R 5 ,

(CH 2 ) n —OCONR 4 R 5 ,

(CH 2 ) m —SO 2 NR 4 R 5 ,

(CH 2 ) n —SO 2 R 6 ,

(CH 2 ) n —NR 7 SO 2 R 6 ,

(CH 2 ) n —NR 7 CONR 4 R 5 ,

(CH 2 ) n —NR 7 COR 7 , and

(CH 2 ) n —NR 7 CO 2 R 6 ;

wherein any individual methylene (CH 2 ) carbon atom in (CH 2 ) n is optionally substituted with one to two substituents independently selected from fluorine, hydroxy, C 1-4 alkyl, and C 1-4 alkoxy, wherein alkyl and alkoxy are optionally substituted with one to five fluorines;

R 4 and R 5 are each independently selected from the group consisting of

hydrogen,

(CH 2 ) m -phenyl,

(CH 2 ) m -heteroaryl, wherein the heteroaryl is pyrrolyl, isoxazolyl, isothiazolyl, pyrazolyl, 2-oxo-(1H)-pyridinyl (2-hydroxy-pyridinyl), oxazolyl, 1,2,4-oxadiazolyl, 1,3,4-oxadiazolyl, thiadiazolyl, thiazolyl, imidazolyl, triazolyl, tetrazolyl, furyl, triazinyl, thienyl, pyrimidinyl, pyrazinyl, benzisoxazolyl, benzoxazolyl, benzothiazolyl, benzothiadiazolyl, dihydrobenzofuranyl, indolinyl, pyridazinyl, indazolyl, isoindolyl, dihydrobenzothienyl, indolizinyl, cinnolinyl, phthalazinyl, quinazolinyl, naphthyridinyl, carbazolyl, benzodioxolyl, quinoxalinyl, purinyl, furazanyl, isobenzylfuranyl, benzimidazolyl, benzofuranyl, benzothienyl, quinolyl, indolyl, isoquinolyl, dibenzofuranyl, imidazo[1,2-a]pyridinyl, [1,2,4-triazolo][4,3-a]pyridinyl, pyrazolo[1,5-a]pyridinyl, [1,2,4-triazolo][1,5-a]pyridinyl, 2-oxo-1,3-benzoxazolyl, 4-oxo-3H-quinazolinyl, 3-oxo-[1,2,4]-triazolo[4,3-a]-2H-pyridinyl, 5-oxo-[1,2,4]-4H-oxadiazolyl, 2-oxo-[1,3,4]-3H-oxadiazolyl, 2-oxo-1,3-dihydro-2H-imidazolyl or 3-oxo-2,4-dihydro-3H-1,2,4-triazolyl,

(CH 2 ) m -heterocyclyl wherein the heterocyclyl is tetrahydrofuran (THF), dihydrofuran, 1,4-dioxane, morpholine, 1,4-dithiane, piperazine, piperidine, 1,3-dioxolane, imidazolidine, imidazoline, pyrroline, pyrrolidine, tetrahydropyran, dihydropyran, oxathiolane, dithiolane, 1,3-dioxane, 1,3-dithiane, oxathiane, thiomorpholine, pyrrolidinone, oxazolidin-2-one, imidazolidine-2-one or pyridone,

(CH 2 ) m -C 3-6 cycloalkyl, and

C 1-6 alkyl, wherein alkyl is optionally substituted with one to five substituents independently selected from fluorine and hydroxy and wherein phenyl, heteroaryl, heterocyclyl, and cycloalkyl are optionally substituted with one to five substituents independently selected from halogen, hydroxy, C 1-6 alkyl, and C 1-6 alkoxy, wherein alkyl and alkoxy are optionally substituted with one to five fluorines;

or R 4 and R 5 together with the nitrogen atom to which they are attached form a heterocyclic ring selected from azetidine, pyrrolidine, piperidine, piperazine, and morpholine wherein said heterocyclic ring is optionally substituted with one to three substituents independently selected from halogen, hydroxy, C 1-6 alkyl, and C 1-6 alkoxy, wherein alkyl and alkoxy are optionally substituted with one to five fluorines; and wherein said heterocyclic ring is optionally fused with a five or six-membered heteroaryl group containing one to three heteroatoms selected from oxygen, sulfur, and nitrogen, said fused heterocyclic ring being optionally substituted with one to two substituents independently selected from halogen and C 1-4 alkyl optionally substituted with one to five fluorines;

R 8 is selected from the group consisting of:

hydrogen,

C 1-6 alkyl, wherein alkyl is optionally substituted with hydroxy or one to five fluorines,

(CH 2 ) p -phenyl, wherein phenyl is optionally substituted with one to five substituents independently selected from halogen, hydroxy, C 1-6 alkyl, and C 1-6 alkoxy, wherein alkyl and alkoxy are optionally substituted with one to five fluorines,

(CH 2 ) p -C 3-6 cycloalkyl, wherein cycloalkyl is optionally substituted with one to five substituents independently selected from halogen, hydroxy, C 1-6 alkyl, and C 1-6 alkoxy, wherein alkyl and alkoxy are optionally substituted with one to five fluorines,

—SO 2 C 1-6 alkyl,

—SO 2 C 3-6 cycloalkyl,

—SO 2 -aryl,

—SO 2 -heteroaryl,

—C(O)C 1-6 alkyl,

—C(O)C 3-6 cycloalkyl,

—C(O)-aryl,

—C(O)-heteroaryl,

—C(O)OC 1-6 alkyl,

—C(O)OC 3-6 cycloalkyl,

—C(O)O-aryl,

—C(O)O-heteroaryl,

—C(O)NHC 1-6 alkyl,

—C(O)NHC 3-6 cycloalkyl,

—C(O)NH-aryl, and

—C(O)NH-heteroaryl;

wherein alkyl and cycloalkyl are optionally substituted with one to five fluorines and wherein aryl and heteroaryl are optionally substituted with one to five substituents independently selected from the group consisting of hydroxy, halogen, cyano, nitro, CO 2 H, C 1-6 alkyloxycarbonyl,

C 1-6 alkyl, and C 1-6 alkoxy, wherein alkyl and alkoxy are optionally substituted with one to five fluorines;

each R 6 is independently C 1-6 alkyl, wherein alkyl is optionally substituted with one to five substituents independently selected from fluorine and hydroxyl;

R 7 is hydrogen or R 6 ;

p is an integer selected from 0 and 1;

each n is an integer independently selected from 1, 2 and 3; and

each m is an integer independently selected from 0, 1, and 2.

2. The compound of claim 1 wherein Ar is optionally substituted with one to three substituents independently selected from the group consisting of fluorine, chlorine, bromine, methyl, trifluoromethyl, and trifluoromethoxy.

3. The compound of claim 2 wherein Ar is 2,5-difluorophenyl or 2,4,5-trifluorophenyl.

4. The compound of claim 1 wherein R 3a and R 3b are both hydrogen.

5. The compound of claim 1 wherein V is selected from the group consisting of:

6. The compound of claim 5 wherein R 2 is hydrogen.

7. The compound of claim 5 wherein V is

8. The compound of claim 7 wherein R 2 is hydrogen.

9. The compound of claim 1 wherein R 8 is selected from the group consisting of:

hydrogen,

C 1-6 alkyl, wherein alkyl is optionally substituted with hydroxy or one to five fluorines,

—SO 2 C 1-6 alkyl, and

—SO 2 C 3-6 cycloalkyl,

wherein alkyl and cycloalkyl are optionally substituted with one to five fluorines.

10. The compound of claim 9 wherein R 8 is selected from the group consisting of hydrogen, —SO 2 C 1-3 alkyl, and —SO 2 cyclopropyl.

11. The compound of claim 1 of structural formula Ia or Ib having the indicated stereochemical configuration at the two stereogenic carbon atoms marked with an *;

12. The compound of claim 11 of structural formula Ia having the indicated absolute stereochemical configuration at the two stereogenic carbon atoms marked with an *:

13. The compound of claim 11 of structural formulae Ic and Id having the indicated stereochemical configuration at the three stereogenic carbon atoms marked with an *:

14. The compound of claim 13 of structural formula Ic having the indicated absolute stereochemical configuration at the three stereogenic carbon atoms marked with an *:

15. The compound of claim 14 wherein V is selected from the group consisting of:

16. The compound of claim 15 wherein R 2 is hydrogen, and R 8 is selected from the group consisting of hydrogen, —SO 2 C 1-3 alkyl, and —SO 2 cyclopropyl.

17. The compound of claim 11 of structural formulae Ie and If having the indicated stereochemical configuration at the three stereogenic carbon atoms marked with an *:

18. The compound of claim 17 of structural formula Ie having the indicated absolute stereochemical configuration at the three stereogenic carbon atoms marked with an *:

19. The compound of claim 18 wherein V is selected from the group consisting of:

20. The compound of claim 19 wherein R 2 is hydrogen, and R 8 is selected from the group consisting of hydrogen, —SO 2 C 1-3 alkyl, and —SO 2 cyclopropyl.

21. The compound of claim 1 wherein each R 2 is independently selected from the group consisting of

hydrogen;

cyano;

C 1-6 alkyl, wherein alkyl is optionally substituted with hydroxy or one to five fluorines; and

C 3-6 cycloalkyl, wherein cycloalkyl is optionally substituted with one to three substituents independently selected from halogen, hydroxy, C 1-4 alkyl, and C 1-4 alkoxy, wherein alkyl and alkoxy are optionally substituted with one to five fluorines.

22. The compound of claim 21 wherein each R 2 is hydrogen.

23. A pharmaceutical composition which comprises a compound of claim 1 and a pharmaceutically acceptable carrier.