Toward the Selection of Sustainable Catalysts for Suzuki-Miyaura Coupling: A Gate-to-Gate Analysis

Reports of homogeneous and heterogeneous methods for Pd-catalyzed Suzuki-Miyaura coupling provide a vast data set to establish sustainability targets and parameters for future catalyst development. In this gate-to-gate inventory we estimate energy and palladium usage along with reaction mass efficiency (RME) for a range of palladium catalysts (both single- and multiuse) for the generation of (a) 4-phenylphenol from 4-iodophenol and phenylboronic acid or (b) 4-methoxybiphenyl from 4-chloroanisole and phenylboronic acid. Small differences were found in calculated energy usage, RME values, and non-palladium reagent toxicities. Palladium usage, however, varied substantially and stood out as the main differentiating consideration from a sustainability standpoint. Reusable heterogeneous catalysts still use more palladium when compared to ultra-low-loading homogeneous techniques that are effective for conversion of aryl iodides. For aryl chloride substrates, highly active and reusable heterogeneous catalysts become a viable, sustainable alternative to traditional homogeneous systems.