Ethanol's Dual Role as a Mediator and Green Solvent in Photocatalytic Hydrogen Atom Transfer-Enabled Formal Ring-Closing Metathesis toward 2-Quinolinones
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Published on: November 9, 2019
Yangyang Yu1, Shanyu Liu1, Jing-Mei Yuan1
1Guangxi Key Laboratory of Natural Polymer Chemistry and Physics, College of Chemistry and Materials, Nanning Normal University, Nanning 530001, China.
Abstract:
Ethanol, a widely available, low-cost, and environmentally friendly biomass-derived platform molecule, holds untapped potential beyond its conventional use as a solvent. Herein, we report a visible-light-induced hydrogen atom transfer approach that harnesses ethanol's dual function as a mediator and green solvent to accomplish the formal ring-closing metathesis of o-cyano and o-alkynyl acrylamides. This transition metal- and oxidant-free protocol provides efficient access to biologically important 2-quinolinones. Mechanistic studies support a pathway in which ethanol mediates key C=C bond cleavage via an in-situ-generated α-hydroxyethyl radical, and a plausible reaction mechanism for this transformation is proposed.
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