Gold(I)-Catalyzed Intermolecular Dimerization of Internal Alkynes: Access to Bis-Indolic trans-Fused Pentacycles with a Central Seven-Membered Ring.

Intermolecular gold(I)-catalyzed dimerization of internal alkynes remains a significant challenge. Herein, we report an efficient and mild gold(I)-catalyzed domino process that converts internal 1,3-diynoanilines into structurally complex bis-indolic trans-fused pentacyclic frameworks featuring a central seven-membered ring. This transformation forges three C-C bonds and constructs a five-ring molecule in a single operation. Mechanistic investigations, including DFT calculations, elucidate the key intermediates that govern this process.