Pharmaceutical compositions as inhibitors of dipeptidyl peptidase-IV (DPP-IV)

1. A compound of formula (I),

or pharmaceutically acceptable salt or prodrug thereof, wherein

X is a member selected from the group consisting of CH2, CHF and CF2;

R is selected from the group consisting of alkylcarbonyl, arylcarbonyl, cyano, heterocyclecarbonyl, R 4 R 5 NC(O)—, B(OR 6 ) 2 , (1,2,3)-dioxoborolane and 4,4,5,5-tetramethyl(1,2,3)-dioxoborolane;

R1 is selected from the group consisting of alkoxyalkyl, alkyl, alkylcarbonyl, alkenyl, alkynyl, allenyl, arylalkyl, cycloalkyl, cycloalkylalkyl, cyano, haloalkyl, haloalkenyl, heterocyclealkyl, and hydroxyalkyl;

R2 and R3 are independently selected from the group consisting of hydrogen, alkoxyalkyl, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkylalkyl, aryl, arylalkyl, heterocycle, heterocyclealkyl, hydroxyalkyl; or

R2 and R3 taken together with the atoms to which they are attached form a mono or bicyclic heterocycle selected from the group consisting of 2-indolinyl, 2-indolyl, 3-isoquinoline, 2-piperazine, 2-piperidine, 2-pyrrolidine, 2-pyrrole, 2-pyridine, 2-quinolinyl, 2-tetrahydroquinolinyl, and 3-tetrahydroisoquinolinyl, wherein said heterocycle may be substituted with 0, 1, 2 or 3 substituents independently selected from alkenyl, alkoxy, alkoxyalkyl, alkoxycarbonyl, alkoxycarbonylalkyl, alkyl, alkylcarbonyl, alkylcarbonylalkyl, alkylcarbonyloxy, alkylsulfonyl, alkylthio, alkynyl, aryl, arylalkoxy, arylalkyl, arylcarbonyl, aryloxy, carboxy, carboxyalkyl, cyano, cyanoalkyl, formyl, halogen, haloalkyl, hydroxy, hydroxyalkyl, mercapto, nitro, phenyl, R A R B N—, RcR D NC(0)-, and RcR D NS(0) 2 —;

R4, R5 and R6 are each independently selected from the group consisting of hydrogen, alkyl, and arylalkyl;

R A and R B are each independently selected from the group consisting of alkyl, alkylcarbonyl, alkoxycarbonyl, alkylsulfonyl; or R A and R B taken together with the nitrogen to which they are attached form a ring selected from the group consisting of piperidine, piperazine and morpholine; and

Rc and R D are each independently selected from the group consisting of hydrogen and alkyl.

2. The compound according to claim 1 , wherein

R is cyano.

3. The compound according to claim 1 , wherein

R is cyano; and

R1 is a member selected from the group consisting of alkyl, alkenyl, and alkynyl.

4. The compound according to claim 1 , wherein

R is cyano;

R1 is a member selected from the group consisting of alkyl, alkenyl, and alkynyl; and

R2 is a member selected from the group consisting of alkoxyalkyl, alkyl, cycloalkyl, cycloalkylalkyl, arylalkyl, and heterocyclealkyl.

5. The compound according to claim 1 , wherein

R is cyano;

R1 is a member selected from the group consisting of alkyl, alkenyl, and alkynyl; and

R2 is a member selected from the group consisting of hydrogen, alkyl, cycloalkyl, and heterocycle; and

R3 is hydrogen.

6. The compounds according to claim 5 , that is a member selected from the group consisting of

(2S,5R)-5-ethynyl-1-L-leucylpyrrolidine-2-carbonitrile;

(2S,5R)-1-{(2S)-2-amino-2-cyclopentylethanoyl)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-{(2S)-2-amino-2-cyclopentylethanoyl)-5-vinylpyrrolidine-2-carbonitrile;

(2S,5R)-1-((2S)-2-amino-2-cyclohexylethanoyl)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5S)-5-ethyl-1-L-leucylpyrrolidine-2-carbonitrile;

(2S,5S)-1-((2S)-2-amino-2-cyclohexylethanoyl)-5-ethylpyrrolidine-2-carbonitrile;

(2S,5S)-1-L-leucy1-5-methylpyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-L-leucylpyrrolidine-2-carbonitrile;

(2S,5R)-1-((2S)-2-amino-2-cyclopentylethanoyl)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-((2R)-2-amino-2-cyclohexylethanoyl)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5S)-1-((2S)-2-amino-2-cyclopentylethanoyl)-5-methylpyrrolidine-2-carbonitrile;

(2S,5R)-1-((2S)-2-amino-2-cyclopentylethanoyl)-5-prop-1-ynylpyrrolidine-2-carbonitrile;

(2S,5S)-4,4-difluoro-5-methyl-1-L-valylpyrrolidine-2-carbonitrile;

(2S,5S)-4,4-difluoro-1-L-leucyl-5-methylpyrrolidine-2-carbonitrile;

(2S,5R)-1-((2S)-2-amino-2-cyclohexylethanoyl)-5-vinylpyrrolidine-2-carbonitrile;

(2S,5R)-1-[((2R)-2-amino-2-cyclopentylethanoyl)-5-vinylpyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(2-methyl-L-valyl)pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(3-pyridin-4-yl-L-alanyl)pyrrolidine-2-carbonitrile;

(2S,5R)-1-L-leucyl-5-prop-1-ynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-(3-methyl-L-valyl)-5-prop-1-ynylpyrrolidine-2-carbonitrile;

(2S,5S)-1-L-isoleucyl-5-methylpyrrolidine-2-carbonitrile;

(2S,5S)-1-(3-cyclopropyl-L-alanyl)-5-methylpyrrolidine-2-carbonitrile;

(2S,5S)-5-methyl-1-L-valylpyrrolidine-2-carbonitrile;

(2S,5S)-5-methyl-1-(4-methyl-L-leucyl)pyrrolidine-2-carbonitrile;

(2S,5S)-1-(3-cyclohexyl-L-alanyl)-5-methylpyrrolidine-2-carbonitrile.

7. The compound according to claim 1 , wherein

R is cyano;

R1 is a member selected from the group consisting of alkyl, alkenyl, and alkynyl; and

R2 is hydrogen; and

R3 is cycloalkyl, wherein cycloalkyl is a member selected from the group consisting of cyclopropyl, cyclobutyl, cyclopentyl, cycloheptyl, and cyclooctyl.

8. The compound according to claim 7 , that is a member selected from the group consisting of

(2S,5R)-1-{N-((1R,2R,4S)-bicyclo(2.2.1)hept-2-yl)glycyl}-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-{N-((1R,4S)-bicyclo[2.2.1)hept-2-yl)glycyl}-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-1-adamantylglycyl)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-cyclohexylglycyl)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-{N-(1-(methoxymethyl)cyclopentyl)glycyl}pyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-cyclopentylglycyl)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-{N-((2S)-2-hydroxycyclopentyl)glycyl}pyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-cyclopentylglycyl)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-{N-(1-(hydroxymethyl)cyclopentyl)glycyl}pyrrolidine-2-carbonitrile;

(2S,5R)-1-{N-(1-(hydroxymethyl)cyclopentyl)glycyl}-5-prop-1-ynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-cyclopentylglycyl)-5-prop-1-ynylpyrrolidine-2-carbonitrile;

(2S,5S)-1-(N-cyclopentylglycyl)-5-methylpyrrolidine-2-carbonitrile;

(2S,5S)-1-{N-(1-(hydroxymethyl)cyclopentyl)glycyl}-5-methylpyrrolidine-2-carbonitrile;

(2S,5S)-1-{N-((2R,5S)-hexahydro-2,5-methanopentalen-3a(1H)-yl)glycyl}-5-methylpyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-{N-(1-(1-hydroxy-1-methylethyl)cyclopentyl)glycyllpyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-{N-((2R,5S)-hexahydro-2,5-methanopentalen-3a(1H)-yl)glycyl}pyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-cyclopentylglycyl-(N-methyl 1-aminocyclopentanecarboxy)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-cyclopropylglycyl)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-{N((5R,7S)-3-hydroxy-1-adamantyl)glycyl}pyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-cycloheptylglycyl)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-cyclobutylglycyl)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-cyclobutylglycyl)-5-prop-1-ynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-{N-((2S)-2-hydroxycyclopentyl)glycyl}-5-prop-1-ynylpyrrolidine-2-carbonitrile;

(2S,5S)-5-methyl-1-{N-((1S,2S,3S,5R)-2,6,6-trimethylbicyclo[3.1.1)hept-3-yl)glycyl}pyrrolidine-2-carbonitrile;

(2S,5S)-1-{N((5R,7S)-3-hydroxy-1-adamantyl)glycyl}-5-methylpyrrolidine-2-carbonitrile;

(1S,3R)-3-({2-[(2S,5R)-2-cyano-5-ethynylpyrrolidin-1-yl]-2-oxoethyl}amino)-N-(pyridin-2-ylmethyl)cyclopentanecarboxamide;

(1S,3R)-3-({2-[(2S,5R)-2-cyano-5-ethynylpyrrolidin-1-yl]-2-oxoethyl}amino)-N-quinolin-2-ylcyclopentanecarboxamide; and

methyl (1S,3R)-3-({2-[(2S,5R)-2-cyano-5-ethynylpyrrolidin-1-yl]-2-oxoethyl}amino)cyclopentanecarboxylate.

9. The compound according to claim 1 , wherein

R is cyano,

R1 is a member selected from the group consisting of alkyl, alkenyl, and alkynyl; and

R2 is hydrogen; and

R3 is

R7 is a member selected from the group consisting of hydrogen and alkyl; and

R9 is a member selected from the group consisting of hydrogen, aryl, and heterocycle.

10. The compound according to claim 9 , that is a member selected from the group consisting of

(2S,5R)-5-ethynyl-1-(N-(4-trans-hydroxycyclohexyl)glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-(4-trans-{(4′-fluoro-5-(trifluoromethyl)-1,1′-biphenyl-2-yl)oxy}cyclohexyl)glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-{4-trans (4-(trifluoromethoxy)phenoxy)cyclohexyl}glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-(4-hydroxy-1-methylcyclohexyl)glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-{N-(1-methyl-4-trans(pyridin-3-yloxy)cyclohexyl)glycyl}pyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-4-trans((5-chloropyridin-3-yl)oxy)cyclohexyl}glycyl)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-{N-(4-trans(4-cyanophenoxy)cyclohexyl)glycyl}-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-(4-trans{(5-(trifluoromethyl)pyridin-2-yl)oxy}cyclohexyl)glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-{4-trans(3-pyridin-4-yl-4-(trifluoromethyl)phenoxy)cyclohexyl}glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-{N-(4-trans(pyridin-2-yloxy)cyclohexyl)glycyl}pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-{N-(1-methyl-4-trans(5-cyano-pyridin-2-yloxy)cyclohexyl)glycyl}pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-{N-(4-trans(pyrimidin-2-yloxy)cyclohexyl)glycyl}pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-{N-(4-trans(5-cyano-pyridin-2-yloxy)cyclohexyl)glycyl}pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-{4-trans(4-(trifluoromethyl)phenoxy)cyclohexyl}glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-{4-((5-fluoropyridin-3-yl)oxy)-1-methylcyclohexyl}glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-(4-trans(4-carboxy-phenoxy)cyclohexyl)glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-{4-trans(2-(2-oxopyrrolidin-1-yl)-4-(trifluoromethyl)phenoxy)cyclohexyl}glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-1-{N-(4-trans(4-cyano-2-methoxyphenoxy)cyclohexyl)glycyl}-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-{4-trans((5-chloropyridin-2-yl)oxy)cyclohexyl}glycyl)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-{N-(1-methyl-4-trans(pyridin-2-yloxy)cyclohexyl)glycyl}pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-{4-trans((5-fluoropyridin-3-yl)oxy)cyclohexyl}glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-{4-trans((5-bromopyridin-2-yl)oxy)cyclohexyl}glycyl)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-{N-(4-trans(pyridin-3-yloxy)cyclohexyl)glycyl}pyrrolidine-2-carbonitrile;

(2S,5R)-5-prop-1-ynyl-1-(N-{4-(4-(trifluoromethyl)phenoxy)cyclohexyl}glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-1-{N-(4-trans(4-cyano-2-fluorophenoxy)cyclohexyl)glycyl}-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-{N-(4-trans(3-fluorophenoxy)-1-methylcyclohexyl)glycyl}pyrrolidine-2-carbonitrile;

(2S,5R)-1-{N-(4-trans(3-cyanophenoxy)cyclohexyl)glycyl}-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-5-ethyny1-1-(N-(1-methy 1-4-{(5-(trifluoromethyl)pyridin-2-yl)oxy}cyclohexyl)glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-{4-trans((5-chloropyridin-2-yl)oxy)cyclohexyl}glycyl)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-(4-trans{(4′-fluoro-2-(trifluoromethyl)-1,1′-biphenyl-4-yl)oxy}cyclohexyl)glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-(4-trans{(4′-fluoro-6-(trifluoromethyl)-1,1′-biphenyl-3-yl)oxy}cyclohexyl)glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-{4-(3-cyano-4-trans(trifluoromethyl)phenoxy)cyclohexyl}glycyl)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-{N-(4-trans(3-bromophenoxy)cyclohexyl)glycyl}-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-{N-(4-trans(4-cyano-3-fluorophenoxy)cyclohexyl)glycyl}-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-{4-(2-cyano-4-trans(trifluoromethyl)phenoxy)cyclohexyl}glycyl)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-{N-(4-trans(3-cyanophenoxy)-1-methylcyclohexyl)glycyl}-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-{N-(4-trans(4-chlorophenoxy)cyclohexyl)glycyl}-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-(4-trans{(6-methyl-4-(trifluoromethyl)pyridin-2-yl)oxy}cyclohexyl)glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-{4-trans(2-cyano-3-(trifluoromethyl)phenoxy)cyclohexyl}glycyl)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-{4-trans(4-pyridin-4-yl-3-(trifluoromethyl)phenoxy)cyclohexyl}glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-{4-trans(3-cyano-5-(trifluoromethyl)phenoxy)cyclohexyll glycyl)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-{N-(4-(4-fluorophenoxy)-1-methylcyclohexyl)glycyl}pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-{N-(4-(3-fluorophenoxy)-1-methylcyclohexyl)glycyl}pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-(1-methyl-4-{(5-(trifluoromethyl)pyridin-2-yl)oxy}cyclohexyl)glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-{4-trans(3-(tri fluoromethyl)phenoxy)cyclohexyl)glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-{4-trans((3-bromopyridin-2-yl)oxy)cyclohexyl}glycyl)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-(4-trans{(4-(trifluoromethyl)pyridin-2-yl)oxy}cyclohexyl)glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-{4-trans((5-chloropyridin-2-yl)oxy)-1-methylcyclohexylIglycyl)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-{N-(4-trans(3-cyanophcnoxy)-1-methylcyclohcxyl)glycyl}-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(Ar-{4-trans(2-carboxy-4-(trifluoromethyl)phenoxy)cyclohexyl}glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-1-{N-(4-trans(3-chlorophenoxy)cyclohexyl)glycyl}-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-(1-methy 1-4-trans{(5-(trifluoromethyl)pyridin-2-yl)oxy}cyclohexyl)glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-1-{N-(4-trans(4-bromophenoxy)cyclohexyl)glycyl}-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-(4-transhydroxycyclohexyl)glycyl)-5-prop-1-ynylpyrrolidine-2-carbonitrile;

(2S,5S)-1-(N-(4-transhydroxycyclohexyl)glycyl)-5-methylpyrro lidine-2-carbonitrile;

and

6-{[4-({2-[(2S,5R)-2-cyano-5-ethynylpyrrolidin-1-yl]-2-oxoethyl}amino)-4-methylcyclohexyl]oxy}-N,N-dimethylnicotinamide.

11. The compound according to claim 1 , wherein

R is cyano;

R1 is a member selected from the group consisting of alkyl, alkenyl, and alkynyl;

R2 is hydrogen;

R3 is alkyl; wherein the alkyl group of R3 is optionally substituted with a member of the group consisting of alkoxy, alkoxycarbonyl, alkoxycarbonylNRa, alkylNRa, carboxy, and hydroxy; and

Ra is a member selected from the group consisting of hydrogen and alkyl.

12. The compound according to claim 11 , that is selected from the group consisting of

(2S,5R)-5-ethynyl-1-(N-(1,1,3,3-tetramethylbutyl)glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-(tert-butyl)glycyl)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-(1,1-dimethylpropyl)glycyl)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-{N-(3-(methylamino)propyl)glycyl}pyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-(4-tert-butoxycarbonylbutyl)glycyl)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-(3-hydroxy-2,2-dimethylpropyl)glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-{N-(3-(N-tert-butoxycarbonyl-N-methylamino)propyl)glycyl}pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-(4-carboxybutyl)glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-(3-isopropoxypropyl)glycyl)pyrrolidine-2-carbonitrile;

(2S,5S)-1-(N-isopropylglycyl)-5-methylpyrrolidine-2-carbonitrile;

(2S,5S)-1-(N-(tert-butyl)glycyl)-5-methylpyrrolidine-2-carbonitrile; and

(2S,5S)-1-[(tert-butylamino)acetyl]pyrrolidine-2,5-dicarbonitrile.

13. The compound according to claim 1 , wherein

R is cyano;

R1 is a member selected from the group consisting of alkyl, alkenyl, and alkynyl; and

R2 is hydrogen; and

R3 is a member selected from the group consisting of aryl and heterocycle; wherein said heterocycle is a member selected from the group consisting of azetidinyl, azepanyl, aziridinyl, diazepinyl, 1,3-dioxolanyl, dioxanyl, dithianyl, furyl, imidazolyl, imidazolinyl, imidazolidinyl, isothiazolyl, isothiazolinyl, isothiazolidinyl, isoxazolyl, isoxazolinyl, isoxazolidinyl, morpholinyl, oxadiazolyl, oxadiazolinyl, oxadiazolidinyl, oxazolyl, oxazolinyl, oxazolidinyl, piperazinyl, pyranyl, pyrazinyl, pyrazolyl, pyrazolinyl, pyrazolidinyl, pyridinyl, pyrimidinyl, pyridazinyl, pyrrolyl, pyrrolinyl, pyrrolidinyl, tetrahydrofuranyl, tetrahydrothienyl, tetrazinyl, tetrazolyl, thiadiazolyl, thiadiazolinyl, thiadiazolidinyl, thiazolyl, thiazolinyl, thiazolidinyl, thienyl, thiomorpholinyl, 1,1-dioxidothiomorpholinyl (thiomorpholine sulfone), thiopyranyl, triazinyl, triazolyl, and trithianyl.

14. The compound according to claim 13 , that is a member selected from the group consisting of

(2S,5R)-5-ethynyl-1-(N-tetrahydro-2H-pyran-4-ylglycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-tetrahydrofuran-3-ylglycyl)pyrrolidine-2-carbonitrile; and

(2S,5S)-1-(N-2,3-dihydro-1H-inden-1-ylglycyl)-5-methylpyrrolidine-2-carbonitrile.

15. The compound according to claim 1 , wherein

R is cyano;

R1 is a member selected from the group consisting of alkyl, alkenyl, and alkynyl; and

R2 is hydrogen; and

R3 is a member selected from the group consisting of arylalkyl and heterocyclealkyl.

16. The compound according to claim 15 , that is a member selected from the group of

(2S,5R)-5-ethynyl-1-{N-(2-(4-fluorophenyl)-1,1-dimethylethyl)glycyl}pyrrolidine-2-carbonitrile;

(2S,5S)-1-{N-(2-(3,4-dimethoxyphenyl)ethyl)glycyl}-5-methylpyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-(tetrahydrofuran-2-ylmethyl)glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-(pyridin-2-ylmethyl)glycylpyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-(2-pyridin-4-ylethyl)glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-{N-((1-tert-butoxycarbonylpiperidin-4-yl)methyl)glycyl}pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-(4-iodobenzyl)glycyl)pyrrolidine-2-carbonitrile.

17. The compound according to claim 1 , wherein

R is cyano,

R1 is a member selected from the group consisting of alkyl, alkenyl, and alkynyl;

R2 is hydrogen;

R3 is

R 7 is a member selected from the group consisting of hydrogen, alkyl and alkoxyalkyl;

and

R 8 is a member selected from the group consisting of hydrogen, alkylcarbonyl, aryl and heterocycle.

18. The compound according to claim 17 , that is a member selected from the group consisting of

(2S,5R)-5-ethynyl-1-(N-(4-methyl-1-pyridin-2-ylpiperidin-4-yl)glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-(4-methyl-1-(3-cyano-pyridin-2-yl)piperidin-4-yl)glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-(1-(3-cyano-pyridin-3-yl)piperidin-4-yl)glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-{N-(4-methyl-1-(4-carboxy-pyridin-2-yl)piperidin-4-yl)glycylpyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-{4-methyl-1-(5-(trifluoromethylpyridin-2-yl)piperidin-4-yl}glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-1-{N-(1-(5-chloropyridin-2-yl)-4-methylpiperidin-4-yl)glycyl}-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-(1-pyridin-2-ylpiperidin-4-yl)glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-{4-methyl-1-(4-(trifluoromethyl)pyrimidin-2-yl)piperidin-4-yl glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-(4-methyl-1-(5-carboxy-pyridin-2-yl)piperidin-4-yl)glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-(4-methyl-1-(5-cyano-pyridin-3-yl)piperidin-4-yl)glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-(1-tert-butoxycarbonyl-piperidin-4-yl)glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-(1-5-cyano-pyridin-2-ylpiperidin-4-yl)glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-1-{N-(1-(3-cyanophenyl)-4-methylpiperidin-4-yl)glycyl}-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-{4-methyl-1-(4-(trifluoromethyl)pyridin-2-ylpiperidin-4-yl}glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-piperidin-4-ylglycyl)pyrrolidine-2-carbonitrile; and

(2S,5R)-5-ethynyl-1-({[4-methyl-1-(5-nitropyridin-2-yl)piperidin-4-yl]amino}acetyl)pyrrolidine-2-carbonitrile; and

(2S,5R)-5-ethynyl-1-[({4-methyl-1-[5-(methylsulfonyl)pyridin-2-yl]piperidin-4-yl}amino)acetyl]pyrrolidine-2-carbonitrile.

19. The compound according to claim 1 , wherein

R is cyano;

R1 is selected from the group consisting of alkyl, alkenyl, and alkynyl; and

R2 is hydrogen; and

R3 is

R7 is a member selected from the group consisting of hydrogen, alkyl and alkoxyalkyl;

and

R8 is a member selected from the group consisting of arylcarbonyl and heterocyclecarbonyl.

20. The compound according to claim 19 , that is a member selected from the group consisting of

(2S,5R)-5-ethynyl-1-{N-(4-methyl-1-(4-methoxycarbonylbenzoyl)piperidin-4-yl)glycyl}pyrr-olidine-2-carbonitrile;

(2S,5R)-1-{N-(1-(4-chlorobenzoyl)piperidin-4-yl)glycyl}-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-5-ethynyl-1-(N-(1-isonicotinoyl-4-methylpiperidin-4-yl) glycyl)pyrrolidine-2-carbonitrile;

(2S,5R)-1-{N-(1-(4-chlorobenzoyl)-4-methylpiperidin-4-yl)glycyl}-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-{N-(1-(4-cyanobenzoyl)-4-methylpiperidin-4-yl)glycyl}-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-{N-(1-(4-bromobenzoyl)-4-methylpiperidin-4-yl)glycyl}-5-ethynylpyrrolidine-2-carbonitrile.

21. The compound according to claim 1 , wherein

R is cyano;

R1 is a member selected from the group consisting of alkyl, alkenyl, alkynyl, allenyl and cycloalkyl; and

R2 is hydrogen; and

R3 is a member selected from the group consisting of aryl-O-alkyl-, aryl-NH-alkyl-, heterocycle-O-alkyl- and heterocycle-NH-alkyl-.

22. The compound according to claim 21 , that is a member selected from the group consisting of

(2S,5R)-1-{N-(1,1-dimethyl-2-(5-cyano-pyridin-2-yloxy)ethyl)glycyl}-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-{N-(1,1-dimethyl-2-(quinolin-4-ylamino)ethyl)glycyl}-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-{N-(2-(1,3-benzothiazol-2-ylamino)-1,1-dimethylethylglycyl}-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-{1,1-dimethyl-2-(3-cyano-6-methylpyridin-2-ylamino)ethyl}glycyl)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-(1,1-dimethyl-2-{(5-(trifluoromethyl)pyridin-2-yl)oxy}ethyl)glycyl)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-{1,1-dimethyl-2-((3-cyano-6-methylpyridin-2-yl)oxy)ethyl}glycyl)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-{N-(1,1-dimethyl-2-(3-cyanopyridin-2-ylamino)ethyl)glycyl}-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-(1,1-dimethyl-2-{(4-(trifluoromethyl)pyrimidin-2-yl)amino}ethyl)glycyl)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-{N-(1,1-dimethyl-2-(5-methoxycarbonylpyridin-2-ylamino)ethyl)glycyl}-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-{N-(2-(2-cyano-5-fluorophenoxy)-1,1-dimethylethyl)glycyl}-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-(2-{(3-chloro-5-(trifluoromethyl)pyridin-2-yl)amino}ethyl)glycyl)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-(1,1-dimethyl-2-(5-cyano-pyridin-2-ylamino)ethyl)glycyl}-5-ethynylpyrrolidine-2-carbonitrile;

(2S,5R)-1-(N-(2-(4-carboxy-anilino)-1,1-dimethylethyl)glycyl)-5-ethynylpyrrolidine-2-carbonitrile;

(2S,55)-5-methyl-1-{N-(2-(5-cyano-pyridin-2-ylamino)ethyl)glycyl}pyrrolidine-2-carbonitrile.

23. The compound according to claim 1 , wherein

R is cyano;

R1 is selected from the group consisting of alkyl, alkenyl, and alkynyl; and

R2 and R3 taken together with the atoms they are attached form a mono or bicyclic heterocycle selected from the group consisting of 3-isoquinoline, 2-pyrrolidinyl, 2-quinolinyl, 2-tetrahydroquinolinyl, and 3-tetrahydroisoquinolinyl.

24. The compound according to claim 23 , that is a member selected from the group consisting of

(2S,5R)-5-ethynyl-1-((3S)-1,2,3,4-tetrahydroisoquinolin-3-ylcarbonyl)pyrrolidine-2-carbonitrile;

(2S,5S)-4,4-difluoro-5-methyl-1-((5S)-5-methyl-L-prolyl)pyrrolidine-2-carbonitrile;

(2S,5S)-5-methyl-1-((3S)-1,2,3,4-tetrahydroisoquinolin-3-ylcarbonyl)pyrrolidine-2-carbonitrile;

(2S,5S)-5-methyl-1-L-prolyl)pyrrolidine-2-carbonitrile; 5S)-5-methyl-1-((5S)-5-methyl-L-prolyl)pyrrolidine-2-carbonitrile.

25. A method of treating diabetes, comprising administration of a therapeutically effective amount of a compound of formula (I) as described in claim 1 .

26. A method of treating type II diabetes, comprising administration of a therapeutically effective amount of a compound of formula (I) as described in claim 1 .

27. A method of treating hyperglycemia, comprising administration of a therapeutically effective amount of a compound of formula (I) as described in claim 1 .

28. A method of treating Syndrome X, comprising administration of a therapeutically effective amount of a compound of formula (I) as described in claim 1 .

29. A method of treating hyperisulinemia, comprising administration of a therapeutically effective amount of a compound of formula (I) as described in claim 1 .

30. A method of treating obesity, comprising administration of a therapeutically effective amount of a compound of formula (I) as described in claim 1 .