Programming Chemoselectivity in Aerobic Oxidation through Zr-MOF/Quinone Multicatalysis for Benzazole Synthesis

Selectivity control in aerobic oxidation reactions containing several oxidizable functional groups remains challenging. Herein, we show that the chemoselectivity of a Zr-MOF/quinone multicatalytic platform can be controlled through modulation of the organic redox co-catalyst. In contrast to previously reported Zr-MOF-808/(hydro)quinone combinations that promote direct heteroatom oxidation in anilines or thiols to yield the corresponding azoxy or disulfide compounds, Zr-MOF-808/1,8-dichloroanthraquinone unlocks a different reaction pathway to selectively oxidize primary alcohols in the presence of aromatic diamines and aminothiophenols. This pathway enables the one-pot synthesis of 2-substituted benzimidazoles and benzothiazoles under atmospheric air. Mechanistic experiments and post-reaction catalyst characterization support coupled catalytic cycles in which Lewis-acidic Zr sites in the MOF facilitate quinone-mediated alcohol oxidation, while the redox-active MOF/semiquinone interface regenerates the catalytic cycle using atmospheric oxygen as the terminal oxidant. This method furnishes a highly practical and sustainable synthesis of 31 benzimidazoles and benzothiazoles including commercially relevant products such as thiabendazole and fuberidazole, permitting recovery and reuse of both catalytic components.