Process for the preparation of thiophenes

摘要

A process for the preparation of 3-substituted thiophenes which involves cyclization of a novel intermediate, avoids the use of previously employed expensive starting materials. The thiophenes are useful for the preparation of penicillins and cephalosporins. The process is for the preparation of a thiophene of formula (I): <IMAGE> (I) where R1 represents a carboxylic acid group, or an ester or amide thereof or a nitrile group; R2 represents a group suitable for use as an alpha -substituent in the side-chain of a penicillin or cephalosporin; which comprises treating a compound of formula (II): <IMAGE> (II) wherein X represents halogen or optionally functionalized hydroxyl, Y represents halogen, hydroxyl, or alkoxy; with a source of nucleophilic sulphur under basic conditions.