Preparation of pharmaceutically useful benzofurans or benzothiophene derivatives in high yield, by cyclization of substituted benzaldehyde using carboxylic anhydride in presence of (bi)carbonate salt

摘要

Preparation of a benzofuran or benzothiophene compound (I) from an aromatic compound (II), involves cyclization of (II) in a medium comprising a carboxylic acid anhydride in presence of at least one base selected from metal or ammonium carbonates and/or bicarbonates. Preparation of a benzofuran or benzothiophene compound (I) from an aromatic compound (II), having (i) a side-chain of at least 2C, one C of which is bonded to the benzene ring via O or S and another of which is in carboxylic form and (ii) a formyl group in the ortho-position to the side-chain (i), involves cyclization of (II) in a medium comprising a carboxylic acid anhydride in presence of at least one base selected from metal or ammonium carbonates and/or bicarbonates.