abstract |
The invention comprises compounds of general formula <FORM:0901892/IV (b)/1> wherein R1, R2, R3 and R4 stand for hydrogen or hydrocarbon radicals, acid-addition salts thereof, and the preparation thereof by reduction of the corresponding amide, e.g. by catalytic hydrogenation or the use of lithium aluminium hydride. Specifications 901,880 and 901,891 are referred to. |