Palladium-catalyzed synthesis of 2-substituted indoles

TLDR: The palladium(0)-catalyzed cross-coupling reaction of alkynylstannanes with 2-bromoanilines or 2-trifloxyanilines results in the formation of 2-alkynylanilines.

Abstract: The palladium(0)-catalyzed cross-coupling reaction of alkynylstannanes with 2-bromoanilines or 2-trifloxyanilines results in the formation of 2-alkynylanilines. The coupling reaction tolerates substituents on the anilines, including ester, ether, chloro, and trifloxy groups. A palladium(II)-catalyzed intramolecular cyclization provides 2-substituted indoles. The cyclization proceeds without the need to reoxidize the metal and is most efficient with aliphatic substituents on the alkynyl terminus.