| abstract |
A compound of formula (I) wherein X1 is bond or -OCH2-; X2 is -(CH2)n-, in which n is 1, 2 or 3; X3 is bond, -O-, -S-, -OCH2-, or -NH-; R1 is phenyl or pyridyl each of which may have one or two substituent(s) selected from the group consisting of hydroxy, halogen, etc.; R2 is hydrogen, (lower)alkoxycarbonyl, etc.; R3 is hydroxy(lower)alkyl; halo(lower)alkyl, etc.; R4 is aryl or unsaturated heterocyclic group, each of which may have one or two substituent(s) selected from the group consisting of lower alkyl, hydroxy, carbamoyl, halogen, lower alkoxy, etc.; and a salt thereof which is useful as a medicament. |