Additions of nucleophiles to 3-oxo-2,3-dihydrothiophene 1,1-dioxides. Formation of vinyl sulfides, thioacetals and enaminones

3-Oxo-2,3-dihydrothiophene 1,1-dioxide (1a) was prepared by oxidation of th e commercially available 3-methoxythiophene with dimethyldioxirane. Some ot her substituted 3-methoxythiophene derivatives were oxidized as well. Altho ugh the yields of these reactions were low, the one-step method is preferre d to the current literature procedures. 3-Oxo-2,3-dihydrothiophene 1,1-diox ide derivatives reacted with sulfur and nitrogen nucleophiles. Reactions to ok place with extrusion of sulfur dioxide even at room temperature. High yi elds of vinyl sulfides; thioacetals, bis-thioacetals, and enaminones were o btained from these reactions.