Paired electrocatalysis unlocks cross-dehydrogenative coupling of C(sp3)-H bonds using a pentacoordinated cobalt-salen catalyst

• Published in: Nature communications Vol. 15; no. 1; p. 2897
• Main Authors: Liu, Ke, Lei, Mengna, Li, Xin, Zhang, Xuemei, Zhang, Ying, Fan, Weigang, Li, Man-Bo, Zhang, Sheng
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 04.04.2024; Nature Publishing Group; Nature Portfolio
• Subjects: 140/131; 639/638/161/886; 639/638/403/933; 639/638/77/888; Bonding; Catalysis; Catalysts; Cobalt; Construction; Coupling; Dehydrogenation; Electrocatalysis; Electrochemical oxidation; Electrochemistry; Electrode potentials; Evolution; Functional groups; Humanities and Social Sciences; Hydrides; Hydrogen; Hydrogen evolution reactions; multidisciplinary; Oxidants; Oxidation; Oxidizing agents; Reaction mechanisms; Redox potential; Science; Science (multidisciplinary); Selectivity; Synergistic effect
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-024-47220-9

Cross-dehydrogenative coupling of C(sp 3 )-H bonds is an ideal approach for C(sp 3 )-C(sp 3 ) bond construction. However, conventional approaches mainly rely on a single activation mode by either stoichiometric oxidants or electrochemical oxidation, which would lead to inferior selectivity in the reaction between similar C(sp 3 )-H bonds. Herein we describe our development of a paired electrocatalysis strategy to access an unconventional selectivity in the cross-dehydrogenative coupling of alcoholic α C(sp 3 )-H with allylic (or benzylic) C-H bonds, which combines hydrogen evolution reaction catalysis with hydride transfer catalysis. To maximize the synergistic effect of the catalyst combinations, a HER catalyst pentacoordinated Co-salen is disclosed. The catalyst displays a large redox-potential gap (1.98 V) and suitable redox potential. With the optimized catalyst combination, an electrochemical cross-dehydrogenative coupling protocol features unconventional chemoselectivity (C-C vs . C-O coupling), excellent functional group tolerance (84 examples), valuable byproduct (hydrogen), and high regio- and site-selectivity. A plausible reaction mechanism is also proposed to rationalize the experimental observations. Cross-dehydrogenative coupling (CDC) of C-H bonds is an ideal approach for C-C bond construction but suffers from low selectivity of similar C-H bonds. Here, the authors describe a highly selective paired electrocatalysis strategy towards CDC combining hydrogen evolution reaction catalysis with hydride transfer catalysis.