Co-Catalyzed Suzuki-Miyaura Coupling of Organoboronic Acids and Alkynyl Chlorides Using Potassium Bicarbonate as Base.

Abstract

Organoboronic acids, some of the most common and widely used organoboron compounds, have not yet been used in the cobalt-catalyzed cross coupling reactions, despite cobalt demonstrating good reactivity with zinc reagents, Grignard reagents, and metal organoborates that are formed by n-butyl lithium or alkaline metal alkoxide salts and organoboron esters. Herein, a highly efficient and practical cobalt-catalyzed coupling reaction of aryl/alkenyl boronic acids and alkynyl chloride under mild reaction conditions is reported. The advantages of the organoboronic acids, along with a broad functional group compatibility and the reaction's tolerance to moisture and air, enable this reaction to be a synthetically useful protocol for the construction of a C(sp²)-C(sp) bond. Lastly, the synthesis of two natural products and a key intermediate of roxadustat was effectively accomplished using the methodology to construct the critical alkynyl-aryl bond.