Abstract: Compounds of general formula (I) ##STR1## and physiologically acceptable salts thereof; wherein R.sub.1 represents CH.sub.2 CONR.sub.5 R.sub.6 or CH.sub.2 COR.sub.7 ;R.sub.2 represents a phenyl group optionally substituted by 1 or 2 substituents selected from halogen, alkyl, nitro, cyano, trifluoromethyl, trifluoromethoxy, alkylthio, alkylsulphinyl, alkylsulphonyl, amino, substituted amino, hydroxy, alkoxy, methylenedioxy, alkoxycarbonyl, oxazolyl or oxadiazolyl;A represents a C.sub.1-4 straight or branched alkylene chain;R.sub.3 and R.sub.4 independently represent hydrogen or C.sub.1-4 alkyl or R.sub.3 and R.sub.4 together with the nitrogen atom to which they are attached form a saturated 5-7 membered heterocyclic ring, which ring may contain an additional heteroatom selected from oxygen, sulphur or nitrogen;R.sub.5 represents hydrogen or C.sub.1-4 alkyl;R.sub.6 represents C.sub.1-4 alkyl or phenyl, optionally substituted by halogen, or R.sub.5 and R.sub.