Photochemical Hydrogen Atom Transfer Catalysis for Dehydrogenation of Alcohols To Form Carbonyls

Org Lett. 2023 Jul 28;25(29):5486-5491. doi: 10.1021/acs.orglett.3c01917. Epub 2023 Jul 20.

Abstract

Controllable oxidation of alcohols to carbonyls is one of the fundamental transformations in organic chemistry. Herein, we report an unprecedented visible-light-mediated metal-free oxidation of alcohols to carbonyls with hydrogen evolution. By synergistic combination of organophotocatalyst 4CzIPN and a thiol hydrogen atom transfer catalyst, a broad range of alcohols, including primary and secondary benzylic alcohols as well as aliphatic alcohols, were readily oxidized to carbonyls in moderate to excellent yields. A site-selective oxidation has also been achieved by this protocol. Mechanistic investigation indicates that the oxidation proceeds through an oxidative radical-polar crossover process to obtain an α-oxy carbon cation.