Flow electrooxidation of chiral alcohols with high enantioselectivity via integrated metal-organic frameworks and aminoxyl radicals

Abstract

Chiral compounds play a pivotal role in pharmaceutical chemistry, and the oxidation of chiral alcohols to corresponding carboxylic acids is a crucial step. However, the enantioselectivity is susceptible to degradation due to sensitivity to enol isomerization and racemization. In this study, Ru/S-Ni-MOFs electrocatalysts with high specific surface area were synthesized. After undergoing electrochemical reconfiguration, which combined with 4-acetamido-TEMPO (ACT) as co-catalysts to achieve efficient oxidation of chiral alcohols, with enantioselectivity reaching 99% at industrial-grade current density of 500 mA/cm². Additionally, 100 g of chiral acid were successfully synthesized with a yield of 98% and an enantioselectivity of 99% in the large-scale electrolyzer. In situ experiments and theoretical calculations demonstrated that S doping shifts the center of d-band toward the Fermi level, which stabilizes ACTH and inhibits the dissociation of OH, thereby enhancing electrocatalytic activity. This study presents an efficient synergistic electrocatalytic strategy for practical large-scale electrosynthesis of chiral carboxylic acid compounds.