ORGANIC SYNTHESIS WITH SULFONES. XXXVIII. ON THE MECHANISM OF THE STEREOSPECIFIC HYDROGENOLYSIS OF VINYLIC SULFONES BY SODIUM DITHIONITE.

Article abstract of DOI:10.1016/0040-4020(86)80011-4

The stereospecific hydrogenolysis of vinylic sulfones by sodium dithionite in a protic medium proceeds by addition of HSO2^- to give an intermediate which could be isolated after alkylation in situ to a 1,2-bissulfone.The mechanism is therefore of the β-addition-elimination type.In the case of E-2-benzenesulfonyl-2-butene and ethyl iodide a single crystalline diastereoisomer was obtained and shown to have the threo configuration by X-ray crystallography.The addition step follows the syn and the elimination step the anti stereochemistry, thus accounting for the overall retention of configuration observed.