Rhodium-catalyzed electrochemical [2 + 2 + 2] cyclotrimerization of 1,3-butadiynes toward hexasubstituted arenes

Abstract

Electrochemical transition metal catalysis has been regarded as a synthetically attractive method for the construction of diverse organic frameworks because it obviates the use of chemical redox reagents. Herein, we report an elegant rhodium-catalyzed electrochemical [2 + 2 + 2] cyclotrimerization of 1,3-butadiynes for the regioselective synthesis of structurally diverse hexasubstituted arenes in an undivided cell. This methodology features excellent regioselectivity, good functional group tolerance, and high atom economy. Mechanistic studies show that the formation of five-membered C–Rh metallacycle species is crucial, and it would sequentially undergo consecutive coordination, migratory insertion and reductive elimination to deliver the desired arenes.