Rhenium-Catalyzed Intramolecular Carboalkoxylation and Carboamination of Alkynes for the Synthesis of C3-Substituted Benzofurans and Indoles.

A rhenium-catalyzed carboalkoxylation and carboamination of alkyne is reported. This reaction provides an efficient route to synthesize de novo C3-substituted benzofurans and indoles under mild conditions in moderate to good yields. Mechanistic studies revealed that the rhenium played the role of a π acid catalyst to activate the alkynes, followed by a charge-accelerated [3,3]-sigmatropic rearrangement.