Abstract: Compounds of the general formula I: ##STR1## and physiologically acceptable salts thereof and N-oxides and hydrates, in which R.sub.1 and R.sub.2 which may be the same or different represent hydrogen, lower alkyl, cycloalkyl, lower alkenyl, aralkyl or lower alkyl interrupted by an oxygen atom or a group ##STR2## in which R.sub.4 represents hydrogen or lower alkyl or R.sub.1 and R.sub.2 may, together with the nitrogen atom to which they are attached, form a heterocyclic ring which may contain other heteroatoms selected from O and ##STR3## R.sub.3 is hydrogen, lower alkyl, lower alkenyl or alkoxyalkyl; X is --CH.sub.2 --, O or S;Y represents .dbd.S, .dbd.O, .dbd.NR.sub.5 or .dbd.CHR.sub.6 ;Alk denotes a straight or branched alkylene chain of 1 to 6 carbon atoms;R.sub.5 is H, nitro, cyano, lower alkyl, aryl, alkylsulphonyl, or arylsulphonyl;R.sub.6 represents nitro, arylsulphonyl or alkylsulphonyl;m is an integer from 2 to 4; andn is 1 or 2; or when X.dbd.S, or --CH.sub.2 --, n is zero, 1 or 2.