Synthesis of 3-iodoindoles by electrophilic cyclization of N,N-dialkyl-2-(1-alkynyl)anilines

A wide variety of N-alkyl-3-iodoindoles are readily prepared under very mild reaction conditions by the palladium/copper-catalyzed cross-coupling of N,N-dialkyl-o-iodoanilines and terminal alkynes, followed by electrophilic cyclization by I-2. Alkyl-, aryl-, and vinylic-substituted alkynes all undergo iodocyclization in excellent yields.