Patent ID: 8258162

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 or —C(O)NR 11 R 12 , or R 1 and R 2 are joined together to form —C(O)—; R 3 is: a) a lower alkyl group, b) a halo-lower alkyl group, c) a cycloalkyl group, d) a hydroxycycloalkyl group, e) a heterocycloalkyl group, f) an aryl group, wherein the ring of the aryl group is unsubstituted or substituted with 1 to 5 substituents independently selected from the group consisting of a halogen atom, a lower alkyl group, a halo-lower alkyl group, a cyano group, a lower acyl group, a lower alkoxy group, a hydroxy group and a lower alkoxycarbonyl group, g) a heteroaryl group, wherein the ring of the heteroaryl group is unsubstituted or substituted with 1 to 3 substituents independently selected from the group consisting of a halogen atom, a lower alkyl group, a halo-lower alkyl group, a lower alkoxy group and a hydroxy group, h) an aralkyl group, wherein the ring of the aralkyl group is unsubstituted or substituted with 1 to 5 substituents independently 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 alkoxy group, j) a halo-lower alkoxy group, k) a lower alkoxy-lower alkoxy group, l) a cycloalkyloxy group, or m) —NR 11 R 12 ; R 4 is: a) a cyano group, b) a lower alkoxycarbonyl group, c) a halo-lower alkoxycarbonyl group, d) a lower alkoxy-lower alkoxycarbonyl group, e) a cycloalkyloxycarbonyl group, or f) a carboxy group; R 11 and R 12 are each independently a hydrogen atom, a lower alkyl group, a cycloalkyl 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.