Enantioselective Electrocatalytic Hydrogenation of α,β-Unsaturated Esters and Allylic Alcohols.

Abstract

Asymmetric electrocatalytic hydrogenation has long been of interest in the field of electrosynthesis. Nevertheless, explorations of highly enantioselective asymmetric electrocatalytic hydrogenation reactions are rare. Herein, we report the enantioselective electrocatalytic hydrogenation of conjugated olefins with high enantioselectivity. The catalyst precursor comprises cost-effective, earth-abundant nickel with a strongly σ-donating bis-phosphine (Me-DuPhos) ligand, and protons and electrons are used together directly as the hydrogen source. This strategy avoids the need for highly pressurized H₂, sensitive hydride sources, and expensive noble transition metals. Mechanistic studies confirm that suitable ligands must sufficiently stabilize the M-H intermediate to outcompete the hydrogen evolution reaction and avoid nickel deposition on the cathode. Optimal ligand properties are therefore crucial to promote reaction efficiency and maximize enantioselectivity. In addition, DFT calculations indicate that Ni(I)-H species might be the active intermediate and the enantiocontrol is determined by the stabilizing dispersion interaction between the substrate and the nickel(I) hydride.