Abstract: A compound, with hypolgycaemic activity, having formula (II) or a pharmaceutically acceptable quaternary ammonium or acid addition salt thereof: ##STR1## wherein X represents oxygen or sulphur; n.sub.7 represents zero or 1;R.sup.7 represents hydrogen or C.sub.1-6 alkyl;R.sup.1 and R.sup.2 are the same or different and represent hydrogen, C.sub.1-6 alkyl, phenyl, benzyl, or C.sub.3-6 cycloalkyl;R.sup.3 represents hydrogen, C.sub.1-6 alkyl, phenyl or benzyl;R.sup.4 represents hydrogen or C.sub.1-6 alkyl;R.sup.5 represents C.sub.1-6 alkyl, phenyl optionally substituted with up to 3 groups selected from halogen, C.sub.1-6 alkyl, and C.sub.1-6 alkoxy; or benzyl optionally substituted with up to 3 groups selected from halogen, C.sub.1-6 alkyl and C.sub.1-6 alkoxy; or R.sup.4 and R.sup.5 together represent the remaining members of a 5- or 6-membered ring optionally containing an oxygen, sulphur or additional nitrogen atom and being optionally substituted with C.sub.1-6 alkyl, carboxy or C.sub.