Visible-Light-Mediated ipso -Carbosulfonylation of Alkynes: Synthesis of 3-Sulfonylspiro[4,5]trienones from Propiolamides and Sulfonyl Chlorides under Transition-Metal-Free Conditions

An efficient and convenient strategy to synthesize diverse 3-sulfonylspiro[4,5]trienones has been developed. This ipso-carbosulfonylation of alkynes proceeds by visible-light catalysis under transition-metal-free conditions and represents a new sulfonylation and ipso-cyclization of alkynes. In this transformation, the O atom in the newly generated carbonyl is derived from H2O and it features a broad substrates scope, especially for alkyl propiolamides and aliphatic sulfonyl chlorides.