New radical route and insight for highly efficient benzimidazoles synthesis integrated with hydrogen evolution

Benzimidazoles are a versatile class of scaffolds with important biological activities, whereas their synthesis in a lower-cost and more efficient manner remains a challenge. Here, we demonstrate a conceptually new radical route for the high-performance photoredox coupling of alcohols and diamines to synthesize benzimidazoles along with stoichiometric hydrogen (H2) over Pd-decorated ultrathin ZnO nanosheets (Pd/ZnO NSs). Mechanistic study reveals the unique advantage of ZnO NSs over other supports and particularly that the features of Pd nanoparticles in facilitating the cleavage of the α-C-H bond of alcohols and adsorbing subsequently-generated C-centered radicals hold the key to turning on the reaction. This work highlights a new insight into radical-induced efficient benzimidazoles synthesis pairing with H2 evolution by rationally designing semiconductor-based photoredox systems.