Unveiling the Switchable Chemoselectivity Mechanism in Electrochemical Nickel-Catalyzed C(sp²)-O Coupling of Phenols and Aliphatic Alcohols

Achieving chemoselective C(sp²)-O bond formation in the presence of unprotected hydroxyl groups remains a formidable challenge, owing to the inherent oxidative sensitivity of phenols and the distinct acidity between phenols and aliphatic alcohols. Herein, we unveil a switchable chemoselectivity mechanism in an electrochemical nickel-catalyzed system that couples aryl and alkenyl halides with phenols and aliphatic alcohols under mild conditions. The addition of catalytic sodium acetate (NaOAc) promotes selective arylation of phenols potentially through modulating electron transfer kinetics and stabilizing a six-membered nickel-phenoxide metallacycle, which may facilitate ligand exchange and accelerate reductive elimination. Strikingly, the introduction of 4-dimethylaminopyridine (DMAP) inverts the chemoselectivity, favoring arylation of aliphatic alcohols. This tunable protocol enables access to a broad spectrum of aryl and alkenyl ethers with high functional-group tolerance, offering a powerful platform for the construction of complex ethers and shedding mechanistic light on ligand- and additive-controlled selectivity in nickel-catalyzed C(sp²)-O bond formation.