Metal-Free Direct Electrochemical Deoxygenation of Benzylic Alcohols

An operationally simple electrochemical deoxygenation of benzylic alcohols is reported. The one-step, one-pot process is metal-free and is conducted at room temperature in an undivided cell, offering a more sustainable and step-economical alternative to conventional derivatization-cleavage deoxygenation sequences. The applicability of the reaction is demonstrated using an electronically and sterically diverse set of primary, secondary, and tertiary benzylic alcohols; excellent functional-group tolerance is exhibited, permitting the presence of esters, amides, and even unactivated alcohols in the substrate scope. Based on preliminary mechanistic investigations using chemical probes, electroanalytical techniques, and computational studies, the reaction is postulated to proceed via the reaction of an alcohol with a phosphine radical cation that is formed in situ.