Lewis Acid Catalyzed Atom-Economic Synthesis of C2-Substituted Indoles from o-Amido Alkynols.

Herein we have disclosed a Zn(OTf)2 catalyzed synthesis of C2-alkyl substituted indole derivatives via unprecedented carbonyl group migration from o-amido alkynols. The key features of this protocol involve N,O-carbonyl group migration, broad substrate scope with varied functionality tolerance, moderate to good yields, and 100% atom economy. The crossover experiments proved that the migration is happening via an intramolecular pathway.