Selective Debromination and α‐Hydroxylation of α‐Bromo Ketones Using Hantzsch Esters as Photoreductants

Two transformations initiated by photoinduced one‐electron transfer to α‐bromo ketones have been demonstrated. Hantzsch esters donate one electron to α‐bromo ketones under photoirradiation, promoting reductive debromination. Subsequent reactions of the resulting radical species of the ketones with molecular oxygen and Hantzsch esters lead to α‐hydroxylation or debromination, respectively. The relative dominance of the two pathways depends profoundly on the reaction conditions, including solvent, O 2 levels, and the concentration of the Hantzsch esters. The synthetic protocols feature advantages because they require the environmentally benign sources, molecular oxygen and visible light. magnified image