摘要:
Compounds of the following general formula (1) and salts thereof are useful pharmaceuticals having central nervous system activitv: wherein one of R 1 and R 2 represents a substituted lower alkyl group, an azido group, an amino group, a lower acylamino group, a mercapto group or a lower alkylthio group and the other represents a hydrogen group, or both represent a hydrogen atom or a lower alkyl group; R 3 represents a hydrogen atom or a group shown by formula: [wherein X represents
(wherein R 5 represents a hydrogen atom or a lower alkyl group) and Y represents a hydroxy group, a lower alkoxy group, an amino group, a mono- or di-lower alkylamino group]; and R 4 represents a hydrogen atom, a substituted or unsubstituted lower alkyl group or a group shown by formula -CH 2 CO-A [wherein A represents an amino group or a group shown by formula (wherein X and Y are as defined above)]; provided that (a) at least one of R 3 and R 4 is other than a hydrogen atom and (b) when R 1 and R 2 are both hydrogen atoms at least R 4 is other than a hydrogen atom.