Visible-light-induced phenylchalcogenyl-oxygenation of allenes having aryl or electron withdrawing substituents with ambient air as a sole oxidant

The synthesis of regio-and stereoselective aryl substituted alpha, beta-unsaturated aldehydes and ketones from activated allenes was achieved. This mild and non-metallic oxidation is exclusively driven by benign ambient air and triggered by visible light. The same starting materials under ideal anaerobic conditions led to the 2,3-diphenylselenation adduct with no trace of oxygenated products, demonstrating dissolved oxygen as a chemical switch for two different reaction pathways. The salient feature of this protocol is the single electron transfer (SET) achieved by irradiation of one of two organic molecules thereby avoiding a sensitizer to form a radical ion pair.