Metal–Free Radical Thiocyanatosulfonation of Terminal Alkynes in Aqueous Medium

Here we report a novel and practical approach for preparing (E)-β-(thiocyanato)vinyl sulfones through the 1,2-thiocyanatosulfonation of terminal alkynes with NH₄SCN and sulfonyl hydrazides. Advantages of this reaction include mild conditions, the absence of metal, readily available reagents, a broad substrate scope, good functional group compatibility, and excellent stereoselectivity. The radical species-induced pathway is also demonstrated by mechanistic studies.