Ag(I)-Catalyzed Indolization/C3-Functionalization Cascade of 2-Ethynylanilines via Ring Opening of Donor–Acceptor Cyclopropanes

Abstract

A AgSbF6-catalyzed cascade involving the ring opening of donor-acceptor cyclopropanes (DACs) preceded by the cyclization of N-protected 2-ethynylaniline is described. The method discloses a step-economy route to 2,3-disubstituted indole, where a Ag catalyst is found to trigger the cascade by activating both alkyne and DACs. Various functionalities at different ends of both substrates offer rapid access to 2,3-disubstituted indole derivatives in one pot in good to excellent yields. Elaboration of the cascade product to useful intermediates is also depicted.