Dimsyl anion mediated tandem fragmentation cyclization reactions of alkenoyl ketenedithioacetals: A facile synthesis of substituted 2,3-dihydro-4H-thiopyran-4-ones

Dimsyl sodium induced anionic ring cleavage of 1-(1,3-dithiolane-2-ylidene) -4-aryl-3-butene-2-ones followed by intramolecular cyclisation of the inter mediate thiolate anion gave 2-aryl, 6(vinylsulfanyl)-2,3-dihydro-4H-thiopyr an-4-ones in good yields.