2,3-Disubstituted Indoles via Palladium-Catalyzed Reaction of 2-Alkynyltrifluoroacetanilides with Arenediazonium Tetrafluoroborates

A novel palladium-catalyzed synthesis of free N-H 2,3-disubstituted indoles from arenediazonium tetrafluoroborates and 2-alkynyltrifluoroacetanilides is presented. The reaction tolerates a variety of useful substituents both in the starting alkyne and the arenediazonium salt, including bromo and chloro substituents, nitro, cyano, keto, ester, and ether groups, as well as ortho substituents such as methoxy and methyl groups.