One-pot multialkylation reactions of sulphol-3-enes

Abstract

The one-pot multialkylation reactions of sulphol-3-enes have been studied. By varying the ratio of the reagents, the degree of alkylation could be controlled. In most cases, the multiple deprotonation/alkylation took place sequentially at the C-2, C-5, C-2, and C-5 positions. The regiochemistry of the third alkylation of an unsymmetrically disubstituted sulpholene was determined by the pre-existing substituents. The multialkylated 3-sulpholenes should be easily transformed into the 1,4-multialkylated buta- 1,3-dienes by cheletropic extrusion of sulphur dioxide. Dicyclohexylidene–ethane was easily prepared by this way.