Compounds of formula (I) are active as dopaminergic compounds or as compounds which or as compounds which diminish the symptoms of dopamine deficiency: wherein: R.sub.1 and R.sub.2 are independently selected from --C(.dbd.O)R.sub.5 or --C(.dbd.O)OR.sub.5; or one of R.sub.1 and R.sub.2 is hydrogen and the other is --C(.dbd.O)R.sub.5 or --C(.dbd.O)OR.sub.5; R.sub.3 and R.sub.4 are independently selected from hydrogen, optionally substituted C.sub.1-C.sub.6 alkyl, C.sub.3-C.sub.6 cycloalkyl, C.sub.2-C.sub.6 alkenyl, or C.sub.2-C.sub.6 alkynyl, --CH2Q, --C(.dbd.O)R.sub.5, --C(.dbd.O)OR.sub.5, --C(.dbd.O)NR.sub.5R.sub.6, or R.sub.5 is hydrogen or optionally substituted C.sub.1-C.sub.6 alkyl or --CH.sub.2Q; R.sub.6 is hydrogen or optionally substituted C.sub.1-C.sub.6 alkyl Or --CH.sub.2Q; and Q is an optionally substituted monocyclic carbocyclic or heterocyclyl ring of 3 to 6 ring atoms. ##STR00001##