Catalytic Reductive\nHomocoupling of Benzyl Chlorides\nEnabled by Zirconocene and Photoredox Catalysis

The bibenzyl skeleton is prevalent in numerous natural\nproducts\nand other biologically active compounds. Radical homocoupling provides\na straightforward approach for synthesizing bibenzyls in a single\nstep with the reductive homocoupling of benzyl halides undergoing\nextensive development. Unlike benzyl bromides and other tailored precursors\nused in visible-light-mediated homocoupling, benzyl chlorides offer\ngreater abundance and chemical stability. Nevertheless, achieving\nchemoselective cleavage of the C–Cl bond poses significant\nchallenges, with only a limited number of studies reported to date.\nHerein, we demonstrate a catalytic reductive homocoupling of benzyl\nchlorides facilitated by zirconocene and photoredox catalysis. This\ncooperative catalytic system promotes C–Cl bond cleavage in\nbenzyl chlorides under mild conditions and supports the homocoupling\nof a wide range of benzyl chlorides, including those derived from\npharmaceutical agents. Our preliminary mechanistic investigations\nhighlight the pivotal role of hydrosilane in the catalytic cycle.