| abstract |
There is described a compound of the formula ##STR1## in which R 1 is hydrogen or C 1-4 alkyl, R 2 is hydrogen, C 1-4 alkyl, hydroxy C 1-4 alkyl, C 1-4 alkoxy C 1-4 alkyl, HSC 1-4 alkyl, C 1-4 alkyl-S-C 1-4 alkyl, C 1-4 alkylthio, optionally substituted arylthio or optionally substituted aralkylthio, and R 3 is hydrogen, C 1-4 alkyl, optionally substituted aryl or optionally substituted aralkyl; and salts thereof. The compounds show useful effects on the central nervous system. |