Gold(l)-catalyzed intermodular oxyarylation of alkynes: Unexpected regiochemistry in the alkylation of arenes

The reaction between acetylenes and sulfoxides, studied as a test case for gold-catalyzed intermolecular addition, provides the oxyarylation compounds 3 In good yields. Unpredictably, In all cases a single regioisomer arising from the electrophilic aromatic alkylation at the position adjacent to the sulfur atom Is obtained Instead of the expected Friedel-Crafts regioisomer. A new concerted mechanism based on DFT calculations Is proposed to account for the products In this lntermolecular gold(l)-catalyzed reaction.