Episulfones. IV. The Decomposition Reaction of Episulfones by Bases

The present paper deals with the decomposition reaction of episulfones in the presence of several bases. The treatment of cis-stilbene episulfone (I) with 2 n NaOH gave trans-stilbene in a 92% yield, and a hydrogen-deuterium exchange experiment using NaOD showed that 66% of the methine protons of the episulfone were exchanged. On the other hand, the reaction of n-butyllithium yielded cis-stilbene predominantly, along with trans-1,2-diphenylvinyl sulfinate in about a 20% yield. Styrene episulfone (II) gave styrene (80%) and a trace of benzyl methyl sulfone when II was treated with alkali. Tetraphenylethylene episulfone (III) afforded tetraphenylethylene almost quantitatively. The cleavage mechanism by bases is then discussed on the basis of the above results. Ethylene episulfone (IV) is oligomerized by tertiary-amine catalysis.