A Simple Preparation of Alkylzinc Reagents Compatible with Carbonyl Functions

Herein, we report a direct method to prepare alkylzinc compounds from functionalized alkyl bromides using cobalt catalysis under mild conditions. This procedure only requires a simple catalytic system composed of CoBr2 and bipyridine as ligand in a mixture of acetonitrile/pyridine. This reaction is stable under air and moisture conditions opening the way to an accessible procedure. A wide range of functional groups such as esters, cyano and halogens on primary and secondary alkyl bromides was well tolerated and gave high yields of the corresponding alkylzinc compounds. Additionally, we managed to form alkylzinc reagents bearing sensitive functional groups such as ketones and aldehydes with good yields. The direct application of these alkylzinc derivatives in palladium-catalyzed Negishi cross-coupling with various functionalized aryl bromides proved the efficiency and robustness of this methodology.

Automated summary

In this study, a direct method for preparing alkylzinc compounds from functionalized alkyl bromides using cobalt catalysis under mild conditions was reported. The reaction is stable under air and moisture conditions, making it an accessible procedure. Various functional groups on primary and secondary alkyl bromides, including esters, cyano, and halogens, were well-tolerated, resulting in high yields of the corresponding alkylzinc compounds. The alkylzinc derivatives were successfully applied in palladium-catalyzed Negishi cross-coupling with different functionalized aryl bromides, demonstrating the efficiency and robustness of the methodology.