Paired electrocatalysis unlocks cross-dehydrogenative coupling of C(sp<sup>3</sup>)-H bonds using a pentacoordinated cobalt-salen catalyst.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 38575564.
- Also identified by DOI 10.1038/s41467-024-47220-9 and PMC identifier 10995126.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Cross-dehydrogenative coupling of C(sp<sup>3</sup>)-H bonds is an ideal approach for C(sp<sup>3</sup>)-C(sp<sup>3</sup>) 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<sup>3</sup>)-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<sup>3</sup>)-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.