Et3N mediated synthesis of polysubstituted thiophenes from α-oxo ketene dithioacetals

An efficient synthetic route to approach polysubstituted thiophene derivatives was achieved via the Et3N-mediated (Claisen) rearrangement reaction from α-oxo S-methyl-S-propargyl ketenes, followed by regioselective intramolecular cyclization. This method is very efficacious due to its environmental benignity, metal-free mediation, and high atom economy.