Tandem Transformations of Bromo-Substituted β-(Methylsulfonyl)styrenes in Reactions with Dimethyl Malonate, Methyl Cyanoacetate, and Methyl Acetoacetate

摘要

β-Bromo-β-(methylsulfonyl)styrene reacted with dimethyl malonate and methyl cyanoacetate in the presence of sodium hydride to give sulfonyl-substituted cyclopropanes, and sulfonyl-substituted 2,3-dihydro-furan was also formed in the reaction with methyl acetoacetate. Reactions of α-bromo-β-(bromomethylsul-fonyl)styrene with dimethyl malonate and methyl cyanoacetate led to the formation of 2,3-dihydro-λ~6-thio-phene S,S-dioxide derivatives. In the reaction of a-bromo-β-(bromomethylsulfonyl)styrene with methyl acetoacetate, 2,3-dihydro-λ~6-thiophene 5,5-dioxide and 2,5-dihydro-λ~6-thiophene S,S-dioxide derivatives and methyl acetoacetate O-alkylation product, methyl 3-[(E)-2-(bromomethylsulfonyl)-1-phenylvinyloxy]but-2-enoate, were obtained at a ratio of 2.7:1.2:1. α-Bromo-β-(methylsulfonyl)styrene reacted with dimethyl malonate to produce dimethyl 2-[2-(methylsulfonyl)-1-phenylethylidene]malonate. The reaction of β-bromo-β-(bromo-methylsulfonyl)styrene with dimethyl malonate and methyl cyanoacetate were strictly stereoselective, and they afforded tetrahydro-λ~6-thiophene S,S-dioxide derivatives. The reaction of the same substituted styrene with methyl acetoacetate was not stereoselective, and the products were two diastereoisomeric tetrahydro-λ~6-thio-phene S,S-dioxides and sulfonyl-substituted 2,3-dihydrofuran at a ratio of 2.3:2.7:1.