Convenient Methods for the Preparation of Vinylic and Allylic Sulfones from Alkenes, Haloalkanes, and Aldehydes. Stereochemistry of the Conversion of Vinylic Sulfones to the Corresponding Allylic Sulfones

Abstract 1- or 2-p-Tolylsulfonyl(=tosyl)-1-alkenes, vinylic sulfones, were regioselectively prepared from 1-alkenes via iodosulfonization or sulfonylmercuration and also from 1-haloalkanes by the homologation or unhomologation methods. The vinylic sulfones thus prepared were further converted to the corresponding allylic sulfones under basic conditions. The stereochemistry of this conversion was discussed. One-carbon homologated allylic sulfones were directly obtained from aldehydes in good yields by the reaction with diethyl phenylsulfonylmethylphosphonate and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) under mild conditions.