| abstract |
A compound of formula (I): ##STR1## or a tautomeric form thereof, or a pharmaceutically acceptable salt thereof, wherein: n R represents hydrogen or alkyl; n R 1 represents an alkyl group or a substituted or unsubstituted aryl group; n R 2 and R 3 each represent hydrogen, or R 2 and R 3 together represent a bond; n A represents a benzene ring having in total up to five substituents; n X represents oxygen, sulphur or a moiety NR 4 wherein R 4 represents hydrogen or alkyl; and n n represents an integer in the range of from 2 to 6; a process for preparing such a compound, a composition containing such a compound and the use of the compound and composition in medicine. |