Oxa- and Azacycle Formation via Migrative Cyclization of Sulfonylalkynol and Sulfonylalkynamide with N-Heterocyclic Carbene.

An N-heterocyclic carbene promotes cyclization of sulfonylalkynols and sulfonylalkynamides that accompanies 1,2-migration of the sulfonyl groups. This reaction provides a novel access to oxa- and azacycles possessing a pendent vinyl sulfone functionality, which, in turn, is amenable for further transformations.