Interfacial Proton Ordering Near the Electrode Surface Directs Carbonyl Electroreduction to Methylene

Abstract

ABSTRACT Carbonyl‐to‐methylene deoxygenation is a fundamental transformation in organic synthesis, but conventional Clemmensen and Wolff–Kishner–Huang reductions require harsh acidic or basic conditions. Electrochemical reduction offers a milder alternative, yet commonly stops at the alcohol stage because the initially formed alcohol intermediate desorbs from the electrode before further C─O bond activation. Here, we report a ‐Gly interfacial catalytic system for aqueous electrochemical carbonyl‐to‐methylene conversion. In this system, the Pd‐rich electrode and glycine‐mediated interfacial regulation cooperate to retain alcohol intermediates at the electrified interface and promote their subsequent deoxygenation to methylene products. Time‐dependent reaction analysis supports a stepwise pathway involving initial carbonyl hydrogenation to an alcohol intermediate followed by further deoxygenation. Mechanistic and structural studies suggest that Pd sites supply surface H*, electron‐deficient Ni‐related sites generated through Ni─Pd coordination assist alcohol‐intermediate retention, and glycine regulates local proton availability and H* coverage in the interfacial region. This work highlights the ‐Gly system as an effective interfacial platform for directing carbonyl electroreduction beyond the alcohol endpoint under mild aqueous conditions.