Triethylamine-Catalyzed Domino Reactions of 1,3-Thiazolidinedione: A Facile Access to Functionalized Dihydrothiophenes

In the presence of triethylamine as base catalyst, aromatic amines have successfully been used as substrates in the domino reactions of 1,3-thiazolidinedione, malononitrile, and aromatic aldehydes. Through a domino ring-opening/recyclization process of 1,3-thiazolidinedione, a series of polysubstituted dihydrothiophenes in the trans configuration have been synthesized in high yields. Dihydrothiophene derivatives can be converted efficiently into the corresponding thiophenes by oxidation with DDQ under mild conditions. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)