Copper‐Catalyzed Dearomative Cyclization of Indolyl Ynamides for Synthesis of Pentacyclic Spiroindolines

Abstract

The dearomatization of indoles with ynamides is a convenient access towards polycyclic spiroindolines, which can be initiated by α‐ and β‐additions of ynamides. Currently, the related β‐addition initiated dearomative cyclization requires noble‐metal catalyst or stoichiometric oxidant. Herein, we report a copper‐catalyzed dearomative cyclization of aryl‐substituted indolyl ynamides through regioselective β‐addition onto ynamides, providing pentacyclic spiroindolines in 81–97% yields with >25:1 diastereoselectivities. Moreover, preliminary success has been obtained for the catalytic enantioselective dearomative cyclization.