1. Direct Hydroxylarylation of Benzylic Carbons (sp 3 /sp 2 /sp) via Radical-Radical Cross-Coupling Powered by Paired Electrolysis.
- Author
-
Wang XW, Li RX, Deng Y, Fu MQ, Zhao YN, Guan Z, and He YH
- Subjects
- Carbon chemistry, Ethanol, Catalysis, Benzyl Alcohol, Aldehydes
- Abstract
Diaryl alcohol moieties are widespread in pharmaceuticals. Existing methods for the synthesis of diaryl alcohols require the use of pre-functionalized benzylic alcohols, aromatic aldehydes, or ketones as starting materials. Herein, the first convergent paired electrochemical approach to the direct hydroxylarylation of unactivated benzylic carbons (sp
3 /sp2 /sp) is proposed. This protocol features direct functionalization of unactivated benzylic C(sp3 )-H bonds and benzylic sp2 /sp-carbons, mild conditions (open air, room temperature), an environmentally friendly procedure (without any external catalyst/mediator/additive), and direct access to sterically hindered alcohols from inexpensive and readily available alkyl/alkenyl/alkynylbenzenes. Mechanistic studies, including divided-cell experiments, isotope labeling, radical trapping, electron paramagnetic resonance, reaction kinetics, and cyclic voltammetry, strongly support the proposed radical-radical cross-coupling between transient ketyl radicals and persistent radical anions. Gram-scale synthesis and diversification of drug derivatives have visualized the tremendous potential of this protocol for practical applications.- Published
- 2023
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