Abstract: The invention provides lactam derivatives of the general formula (I) ##STR1## wherein R.sup.1 represents a hydrogen atom or a group selected from C.sub.1-6 alkyl, C.sub.3-6 alkenyl, C.sub.3-10 alkynyl, C.sub.3-7 cycloalkyl, C.sub.3-7 cycloalkylC.sub.1-4 alkyl, phenyl, phenylC.sub.1-3 alkyl, phenylmethoxymethyl, phenoxyethyl, phenoxymethyl, --CO.sub.2 R.sup.3, --COR.sup.3, --CONR.sup.3 R.sup.4 or --SO.sub.2 R.sup.3 (wherein R.sup.3 and R.sup.4, which may be the same or different each represents a hydrogen atom, a C.sub.1-6 alkyl or C.sub.3-7 cycloalkyl group, or a phenyl or phenylC.sub.1-4 alkyl group, in which the phenyl group is optionally substituted by one or more C.sub.1-4 alkyl, C.sub.1-4 alkoxy or hydroxy groups or halogen atoms, with the proviso that R.sup.3 does not represent a hydrogen atom when R.sup.1 represents a group --CO.sub.2 R.sup.3 or --SO.sub.2 R.sup.3);and R.sup.2 represents a group of formula (a), (b) or (c): ##STR2## wherein R.sup.5 represents a hydrogen atom or a C.sub.1-6 alkyl, C.sub.