Selenosulfonation of Acetylenes: Preparation of Novel β-(Phenylseleno)vinyl Sulfones and Their Conversion to Acetylenic and β-Functionalized Sulfones

Article abstract of DOI:10.1021/jo00166a030

The 1,2-additions of Se-phenyl p-tolueneselenosulfonate (1) to acetylenes under mild conditions afford β-(phenylseleno)vinyl sulfones 3, generally in high yields.The reaction is highly regioselective (anti-Markovnikov) and stereoselective (anti) and proceeds via a free-radical chain mechanism initiated by the thermolysis of the selenosulfonate.The oxidation of β-(phenylseleno)vinyl sulfones with m-chloroperbenzoic acid generates the corresponding selenoxides 4, which undergo syn or base-catalyzed elimination to furnish acetylenic sulfones 5.Base-catalyzed alcoholyses of selenoxides 4 in methanol or ethylene glycol produce β-keto sulfone ketals 8 or 10, respectively.Free β-keto sulfones 11 are formed by the acid-catalyzed hydrolysis of the corresponding β-(phenylseleno)vinyl sulfones 3.