Glucokinase activator

1. A compound represented by the general formula (I), or a pharmaceutically acceptable salt thereof:

(wherein, the carbon atom marked with an * is in the R-configuration, R 1 represents a hydrogen atom, a halogen atom, an amino group, a hydroxyl group, a hydroxyamino group, a nitro group, a cyano group, a sulfamoyl group, a C 1 -C 6 alkyl group, or a C 1 -C 6 alkoxy group, R 2 represents a C 3 -C 6 cycloalkylsulfanyl group, a C 3 -C 6 cycloalkylsulfinyl group, or a C 3 -C 6 cycloalkylsulfonyl group, and A represents a substituted or unsubstituted heteroaryl group).

2. The compound according to claim 1 , or a pharmaceutically acceptable salt thereof, wherein R 1 is a hydrogen atom and R 2 is a C 3 -C 6 cycloalkylsulfonyl group.

3. The compound according to claim 1 , or a pharmaceutically acceptable salt thereof, wherein R 1 is a hydrogen atom and R 2 is a cyclopropylsulfonyl group.

4. The compound according to claim 1 , represented by the general formula (1a), or a pharmaceutically acceptable salt thereof:

(wherein the *, R 1 , R 2 , and A are as defined in claim 1 ).

5. The compound according to claim 1 , represented by the general formula (1b), or a pharmaceutically acceptable salt thereof:

(wherein the *, R 1 , R 2 , and A are as defined in claim 1 ).

6. The compound according to claim 1 , or a pharmaceutically acceptable salt thereof, wherein A is a heteroaryl group that is unsubstituted or monosubstituted with a halogen atom, a C 1 -C 6 alkyl group, a C 1 -C 6 alkoxy group, a nitro group, a cyano group, or a group represented by the formula,

—(CH 2 ) m C(O)OR 3

(wherein R 3 represents a hydrogen atom or a C 1 -C 6 alkyl group and m is an integer of 0 to 2).

7. The compound according to claim 1 , or a pharmaceutically acceptable salt thereof, wherein A is a heteroaryl group unsubstituted or monosubstituted with a halogen atom or a C 1 -C 6 alkyl group.

8. The compound according to claim 6 , or a pharmaceutically acceptable salt thereof, wherein A is an unsubstituted or monosubstituted 5- or 6-membered aromatic heterocyclic ring that contains 1 to 3 heteroatoms selected from a sulfur atom, an oxygen atom, and a nitrogen atom, with one of those heteroatoms being a nitrogen atom adjacent to a ring-linking atom.

9. The compound according to claim 6 , or a pharmaceutically acceptable salt thereof, wherein A is an unsubstituted or monosubstituted fused heterocyclic ring having a 5- or 6-membered aromatic heterocyclic ring that contains 1 to 3 heteroatoms selected from a sulfur atom, an oxygen atom, and a nitrogen atom, with one of those heteroatoms being a nitrogen atom adjacent to a ring-linking atom.

10. The compound according to claim 6 , or a pharmaceutically acceptable salt thereof, wherein A is an unsubstituted or substituted aromatic heterocyclic ring selected from the following:

11. (−)-2-[4-(Cyclopropylsulfonyl)phenyl]-3-[(1α,3α,4α)-3,4-difluorocyclopentyl]-N-(thiazol-2-yl)propionamide or a pharmaceutically acceptable salt thereof.

12. (−)-2-[4-(Cyclopropylsulfonyl)phenyl]-3-[(1α,3α,4α)-3,4-difluorocyclopentyl]-N-(5-fluorothiazol-2-yl)propionamide or a pharmaceutically acceptable salt thereof.

13. (−)-2-[4-(Cyclopropylsulfonyl)phenyl]-3-[(1α,3α,4α)-3,4-difluorocyclopentyl]-N-(pyrazin-2-yl)propionamide or a pharmaceutically acceptable salt thereof.

14. (−)-2-[4-(Cyclopropylsulfonyl)phenyl]-3-[(1α,3α,4α)-3,4-difluorocyclopentyl]-N-(5-fluoropyridin-2-yl)propionamide or a pharmaceutically acceptable salt thereof.

15. A method of treating diabetes, comprising administering the compound according to claim 1 , or a pharmaceutically acceptable salt thereof.

16. A pharmaceutical composition comprising the compound according to claim 1 , or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier.

17. A compound represented by the general formula (3):

(wherein, the carbon atom marked with an * is in the R-configuration, R 1 represents a hydrogen atom, a halogen atom, an amino group, a hydroxyl group, a hydroxyamino group, a nitro group, a cyano group, a sulfamoyl group, a C 1 -C 6 alkyl group, or a C 1 -C 6 alkoxy group, and R 2 represents a C 3 -C 6 cycloalkylsulfanyl group, a C 3 -C 6 cycloalkylsulfinyl group, or a C 3 -C 6 cycloalkylsulfonyl group).

18. The compound according to claim 17 , wherein R 1 is a hydrogen atom and R 2 is a C 3 -C 6 cyclopropylsulfonyl group.

19. A method of treating diabetes, comprising administering the compound according to claim 11 , or a pharmaceutically acceptable salt thereof.

20. A method of treating diabetes, comprising administering the compound according to claim 12 , or a pharmaceutically acceptable salt thereof.

21. A method of treating diabetes, comprising administering the compound according to claim 13 , or a pharmaceutically acceptable salt thereof.

22. A method of treating diabetes, comprising administering the compound according to claim 14 , or a pharmaceutically acceptable salt thereof.

23. A pharmaceutical composition comprising the compound according to claim 11 , or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier.

24. A pharmaceutical composition comprising the compound according to claim 12 , or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier.

25. A pharmaceutical composition comprising the compound according to claim 13 , or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier.

26. A pharmaceutical composition comprising the compound according to claim 14 , or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier.