Direct Deoxygenative Homocoupling of Alcohols to Access C(sp3)-C(sp3) Bonds via Synergistic Ruthenium/Nickel Catalysis

With an ever-increasing emphasis on green synthesis of chemicals, there has been growing interest in deoxygenative conversion of alcohols as widely available organic feedstocks for chemical synthesis. However, the effective construction of the C(sp3)-C(sp(3)) bond via the direct homocoupling of simple alcohols is still challenging, due to the involvement of multistep reaction processes. Herein, we propose a general strategy for the direct deoxygenative coupling of alcohols via the synergetic catalysis of earth-abundant nickel and ruthenium, using hydrazine as a mediator. This protocol features the in situ formation of carbonyl intermediates via Ru-catalyzed alcohol dehydrogenation, followed by deoxygenative homocoupling to construct the C(sp(3))-C(sp(3)) bond under Ni catalysis. The successful C(sp(3))-O bond cleavage of alcohol does not require a hydrogen acceptor, and only environmentally friendly byproducts (nitrogen, hydrogen, and water) are generated. The method is particularly effective for benzyl alcohols with broad substrate scope and for late-stage elaborations of complex biological molecules, exemplifying the efficiency and practicability of the system.