Attempted Simmon-Smith reaction on β-alkylthio-α,β-unsaturated ketones: a regiospecific synthesis of 2,4-disubstituted thiophenes

A new regiospecific route to 2,4-disubstituted thiophenes has been developed through Simmon-Smith reaction on β-methylthio-α,β-unsaturated ketones. Extension of the reaction to β-ethyl/benzylthio-α,β-unsaturated ketones also gave the corresponding 2,4-disubstituted thiophenes in a regiospecific manner. A probable mechanism involving a carbenoid methylene insertion to divalent sulfur followed by intramolecular aldol condensation has been suggested.