Synthesis of Cu(0) Catalyst for Borylation of Alkyl Halides and Hydroboration of Alkenes: Scalable Access to Alkyl Boronate Esters

Abstract

Lower catalyst loadings with high conversion rates are desirable parameters for large-scale industrial applications to reduce the cost and environmental impact of the catalyst. Herein, we developed a simple method for the synthesis of an air-stable zerovalent Cu catalyst without using any external stabilizing agents for the efficient borylation of alkyl halides and hydroboration of alkenes with bis(pinacolato)diboron (B₂pin₂). The desired alkyl boronate esters were obtained in excellent yields with a striking TON of up to 2142 under mild reaction conditions via alkyl bromide borylation. Additionally, a wide range of alkenes were well tolerated to give alkyl boronate esters via hydroboration, thereby showcasing the remarkable versatility and functional-group tolerance of this protocol. Recyclability of the catalyst, gram scale reaction, and synthetic transformations of alkyl boronate esters are the key features of this work.