Abstract: Compounds of the general formula (I): ##STR1## in which R.sup.1 represents hydrogen or a straight or branched chain alkyl group, or an acyl group of the formula --COR.sup.5 (in which R.sup.5 represents a hydrogen atom or a straight or branched chain alkyl group);R.sup.2 represents an aryl group of the formula: ##STR2## (in which R.sup.6 represents a hydrogen atom or independently one or more of the following groups, that is, hydroxy, alkoxy, alkyl, halogen, dialkylamino and trifluoromethyl, or may represent a 3,4-methylenedioxy group ##STR3## R.sup.3 and R.sup.4 may independently represent hydrogen or a straight or branched chain alkyl group; andN represents 1, 2 or 3; and pharmaceutically acceptable salts thereof; and hydrates of said compounds or salts thereof. The invention also includes processes for the production of these compounds, compositions containing them and methods of treatment using them.