Nickel-Catalyzed Efficient, Regioselective One-Pot Synthesis of 1-Methyleneindenes via Tandem C-C Bond Formation: Computational Mechanistic Insights and Docking Studies.

Abstract

Herein, we report a nickel-catalyzed tandem cyclization-coupling method for the regioselective synthesis of 1-methyleneindenes and benzofulvenes from 1-(2,2-dibromovinyl)-2-alkynylbenzenes and aryl boronic acids. The transformation proceeds in the presence of a suitable ligand and base, enabling sequential activation of the C─Br bonds and intra-molecular alkyne moiety under relatively mild reaction conditions with yields 72%-85%. This robust protocol offers wide range of functional group tolerance in substrate and boronic acid part. Density functional theory (DFT) calculations, in addition, provide thorough mechanistic insights that point to a tandem process of oxidative addition, migratory insertion, and reductive elimination, with key energetic preferences explaining the observed product selectivity.