Epoxyannulation. 5. Reactions of 1-Butadienylsulfonium Salts

Article abstract of DOI:10.1021/jo00149a004

Treatment of the lithium enolate from three aldehydes, cycloheptanone, and four unhindered cyclohexanones with (1,3-butadien-1-yl)dimethylsulfonium fluoborate (1) provides a 7-oxabicyclo<4.1.0>hept-4-ene stereoselectively in 30-58percent yield.These epoxides are accompanied by 2-<2-<(methylthio)methyl>-3-butenyl>ketones.This alkylated ketone is the sole product from the enolates of three hindered cyclic ketones and three acyclic ketones.Five related sulfonium salts, 2, 21, 46, 50, and 63, and the enolate from cyclohexanone gave these alkylated ketones accompanied by 5-40percent yield of the epoxyannulated product.