One-Pot Relay Gold(I) and Brønsted Acid Catalysis: Cyclopenta[b]annulation of Indoles via Hydroamination/Nazarov-Type Cyclization Cascade of Enynols

An expedient relay gold­(I) and Brønsted acid catalyzed hydroamination/Nazarov cyclization of 1-(2-aminophenyl)­pent-4-en-2-ynols for the synthesis of various polyfunctionalized cyclopenta­[b]­indoles is described. The synthetic utility of this method has been demonstrated by the synthesis of a few unprecedented pentacyclic indoles and indole–steroidal hybrids. Further, the new methodology has been successfully applied to the enantioselective synthesis of core carbon structure of the polyveoline family of natural products.