Visible Light Induced Oxidation of a-Diazo Esters for the Transition Metal-Free Synthesis of a-Keto Esters

Herein, an aerobic oxidation approach for the synthesis of a-keto esters using oxygen as a cheap and pollution-free oxidant has been developed. By using readily available alpha-diazo esters as starting materials, the transformation was achieved by the inducement of visible light with eosin Y as the light sensitizer. The reactions proceed at room temperature under air atmosphere, tolerating substrates with broad scope, thus providing a green and facile synthetic approach to structurally diverse a-keto esters.