METHOD OF SYNTHESIS OF THE SUBSTITUTED BENZOFURAN DERIVATIVES OR THEIR PHARMACEUTICALLY ACCEPTABLE SALTS

摘要

The present invention relates to a process for the preparation of a compound of the following formula (I) wherein one of R1 and R2 is hydrogen or halogen and the other is independently, an amino group or a C2-C4 alkanoyl amino group; R3 is hydrogen; a linear or branched alkyl, C1-C4 alkoxy or C2-C4 alkoxycarbonyl group; halogen; or phenyl unsubstituted or substituted by a C1-C4 alkyl group; A is a group -(CH2)n-Het wherein Het is an optionally substituted heteromonocyclic or heterobicyclic ring containing one or two nitrogen atoms and n is zero or an integer of 1 to 3; and the symbol .... represents a single or double bond and the pharmaceutically acceptable salts thereof. The compounds of the invention can be useful as 5HT3 receptor antagonists.