Patent ID: 7923462

Claim:
A compound represented by general formula (I): or a pharmaceutically acceptable salt thereof, wherein R 1 and R 2 are each independently a hydrogen atom, a lower acyl group, a lower alkoxycarbonyl group, an aralkylcarbonyl group or —C(O)NR 11 R 12 , or R 1 and R 2 are joined together to form —C(O)— or a lower alkylene group; R 3 is: a) a halo-lower alkyl group, b) a lower acyl group, c) a halo-lower alkylcarbonyl group, d) a cycloalkylcarbonyl group, e) an arylcarbonyl group, wherein the ring of the arylcarbonyl group is unsubstituted or substituted with 1 to 5 substituents selected from the group consisting of a halogen atom, a lower alkyl group, a halo-lower alkyl group, a lower alkoxy group, a cycloalkyl-lower alkoxy group, a hydroxy group, a lower alkoxycarbonyl group, —C(O)NR 11 R 12 and a cyano group, f) a heteroarylcarbonyl group, wherein the ring of the heteroarylcarbonyl group is unsubstituted or substituted with 1 to 3 substituents selected from the group consisting of a halogen atom, a lower alkyl group, a halo-lower alkyl group and a lower alkoxy group, g) an aralkylcarbonyl group, wherein the ring of the aralkylcarbonyl group is unsubstituted or substituted with 1 to 5 substituents selected from the group consisting of a halogen atom, a lower alkyl group, a halo-lower alkyl group and a lower alkoxy group, h) an aryloxy-lower alkylcarbonyl group, wherein the ring of the aryloxy-lower alkylcarbonyl group is unsubstituted or substituted with 1 to 5 substituents selected from the group consisting of a halogen atom, a lower alkyl group, a halo-lower alkyl group and a lower alkoxy group, i) a lower alkoxycarbonyl group, j) a cycloalkyloxycarbonyl group, k) a lower alkoxy-lower alkoxycarbonyl group, l) a carboxy group, m) a cyano group, n) —C(O)NR 11 R 12 , o) —C(O)C(O)NR 11 R 12 , p) a lower alkylsulfonyl group, q) —SO 2 NR 11 R 12 or r) a heteroaryl group, wherein the ring of the heteroaryl group is unsubstituted or substituted with 1 to 3 substituents selected from the group consisting of a halogen atom, a lower alkyl group, a halo-lower alkyl group and a lower alkoxy group; R 4 is: a) a lower alkyl group, b) a halo-lower alkyl group, c) a cycloalkyl group, d) a heterocycloalkyl group, e) a lower alkoxy-lower alkyl group, f) an aryloxy-lower alkyl group, g) a lower alkoxycarbonyl-lower alkyl group or h) a hydroxy-lower alkyl group; and R 11 and R 12 are each independently a hydrogen atom, a lower alkyl group, a cycloalkyl group, a bridged cyclic hydrocarbon group, a phenyl group or an aralkyl group, or R 11 and R 12 , together with the nitrogen atom to which they are bonded, form a cyclic amino group.