Catalytic Hydroboration of Ketones Using Mn(CO)5Br and Mn2(CO)10

Abstract

The commercially available and easy-to-handle manganese complexes Mn(CO)5Br and Mn2(CO)10 effectively catalyze the hydroboration of ketones under mild conditions, yielding secondary alcohols after hydrolysis. These simple catalysts exhibit broad tolerance to different functional groups including esters, halides, and nitroarenes. Moreover, the reaction proceeds with high chemoselectivity toward C-O bonds in the presence of esters, nitriles, nitro groups, or double C-C bond. The proposed procedure enables fast, efficient synthesis of O-borylated products, which are easily hydrolyzed in a one-pot manner to various aryl and alkyl alcohols (even unsaturated ones) in excellent yields. Thus, the developed procedure compares favorably with other Mn catalytic systems, which require lengthy preparation, the application of structurally and electronically advanced ligands, and oxygen- and moisture-free conditions.