General and Efficient Synthesis of Indoles through Triazene-Directed C-H Annulation

Unprotected indoles are prepared with the title method, which has a wide scope for alkynes. Excellent regioselectivity was accomplished for aryl–alkyl and alkyl–alkyl disubstituted acetylenes. This reaction features an unusual 1,2 rhodium migration and ring‐contraction‐triggered NN bond cleavage. It allows rapid conversion of the reaction products into several functional molecules.