Synthetic and Mechanistic Aspects of Some Free-Radical and Electrophilic Organoselenium Reactions

Selenenic derivatives such as selenosulfonates (PhSeSO2Ar) and selenenyl sulfonates (PhSeOSO2Ar) undergo free-radical and electrophilic additions to unsaturated organic substrates, often with high regio- and stereoselectivity. These processes can be employed in tandem with selenoxide eliminations, [2,3]-sigmatropic rearrangements and various types of substitution and reduction reactions of the selenium moiety. Applications include preparations of various types of synthetically useful unsaturated sulfones and a new protocol for the synthesis of sterol side chains, such as that of the plant growth-promoter brassinolide.