Catalytic transformation of functionalized carboxylic acids using multifunctional rhenium complexes

Carboxylic acids (CAs) are one of the most ubiquitous and important chemical feedstocks available from biorenewable resources, CO2, and the petrochemical industry. Unfortunately, chemoselective catalytic transformations of CHnCO2H (n = 1-3) groups into other functionalities remain a significant challenge. Herein, we report rhenium(V) complexes as extremely effective precatalysts for this purpose. Compared to previously reported heterogeneous and homogeneous catalysts derived from high- or low-valent metals, the present method involves a alpha-C-H bond functionalization, a hydrogenation, and a hydrogenolysis, which affords functionalized alcohols with a wide substrate scope and high chemoselectivity under relatively mild reaction conditions. The results represent an important step toward a paradigm shift from 'low-valent' to 'high-valent' metal complexes by exploring a new portfolio of selective functional group transformations of highly oxygenated organic substrates, as well as toward the exploitation of CAs as a valuable biorenewable feedstock.