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

A photocatalyzed oxidation of functionalized cyclobutanones to access -lactones has been performed in acetonitrile at room temperature, using anthraquinone derivatives as catalysts in the presence of TFA. The best condition for the reaction was studied investigating a series of substituted antraquinones and irradiating the reaction at different wavelengths under O2 environment. The scope of the reaction was studied using both 2- and 3-substituted cyclobutanones, as well as enantiopure ketones obtain full preservation of its stereochemical identity after the oxidation. The process furnishes in most cases the desired compounds with high purity after simple filtration of the catalyst, reducing the production of solvents waste.