Convenient synthesis of 2-substituted indoles from 2-ethynylanilines with tetrabutylammonium fluoride

The cyclization reaction of various 2-ethynylanilines, which were easily sy nthesized from 2-haloanilines by the palladium-catalyzed reaction with term inal alkynes, with tetrabutylammonium fluoride (TBAF) to yield 2-substitute d indoles proceeded at refluxing or room temperature in THF in excellent yi elds without affecting the bromo, chloro, cyano, ethoxycarbonyl, and ethyny l groups.