The rearrangement of the carbanion and of the ylide derived from 5, 5-diphenyl-4- thiacyclohexene to (E) 2, 2-diphenyle-1-methylthiovynylcyclopropane is shown to depend on the presence of a stabilizing substituent at C-5. A non concerted mechanism is proposed for this rearrangement. The carbanions from the 4-thiacyclohexene and from the sulfone of the 5, 5-diphenyl-4-thiacyclohexene are stable. The cycloaddition of an aromatic ...