Gold(I)-Catalyzed Tandem 1,2-Indole Migration–Cyclopropanation Reactions of 3‑Propargylindoles with Olefins

3-Propargylindoles with a terminal alkyne, efficiently prepared from direct alkylation of indoles, undergo a tandem 1,2-indole migration/cyclopropanation reaction under gold­(I) catalysis. Reaction conditions have been developed for suitable access to indole-substituted vinylcyclopropanes from 3-propargyl indoles and olefins. The corresponding 2-alkenyl-functionalized substrates evolve through an intramolecular cyclopropanation allowing the synthesis of various polycyclic indole derivatives. The presence of silver salts modifies the diastereoselectivity observed.