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

Abstract

3-Oxo-2,3-dihydrothiophene 1,1-dioxide (1a) was prepared by oxidation of the commercially available 3-methoxythiophene with dimethyldioxirane. Some other substituted 3-methoxythiophene derivatives were oxidized as well. Although the yields of these reactions were low, the one-step method is preferred to the current literature procedures. 3-Oxo-2,3-dihydrothiophene 1,1-dioxide derivatives reacted with sulfur and nitrogen nucleophiles. Reactions took place with extrusion of sulfur dioxide even at room temperature. High yields of vinyl sulfides, thioacetals, bis-thioacetals, and enaminones were obtained from these reactions.