Low‐Impact Synthesis of γ‐Lactones through Photoinduced Baeyer‐Villiger Oxidation of Cyclic Ketones

A photocatalyzed oxidation of functionalized cyclobutanones to access γ‐lactones has been performed in acetonitrile at room temperature, using anthraquinone derivatives as catalysts in the presence of TFA. The best reaction results were obtained by using 3 mol % of 9,10‐anthraquinone as a catalyst under 370 nm irradiation in an O 2 environment. The scope and the limitations of this reaction have been investigated using both 2‐ and 3‐substituted cyclobutanones, as well as enantiopure ketones, to obtain full preservation of their stereochemical identity after the oxidation. The process furnishes in most cases the desired compounds with high purity after catalyst removal by simple filtration, and reducing the production of solvents waste.