Metal-catalyzed Organic Photoreactions. The Photooxidation of Olefins in the Presence of Uranyl Acetate

Abstract The photooxidation of olefins in pyridine in the presence of uranyl acetate afforded β-hiydroxy hydroperoxides. It was confirmed by spectroscopic studies and isotope-incorporation experiments that (1) the stereochemistry of the hydroxyl and hydroperoxyl groups in the β-hiydroxy hydroperoxides was trans, (2) the hydroxyl group was added to the less substituted carbon of the double bond, and (3) the oxygen atom in the hydroxyl group originated mainly from the water molecule, while the oxygen atoms in the hydroperoxyl group originated mainly from molecular oxygen. From these results, we proposed a reaction scheme of: (i) the formation of the hydroxyl radical from water by uranyl acetate-catalyzed photolysis, (ii) the addition of the hydroxyl radical to the double bond, (iii) the combination of the resulted radical with molecular oxygen, and (iv) the hydrogen abstraction of the peroxyl radical to give the product. The scheme was further supported by the photoreaction of 2-methyl-2-butene with bromotrichloromethane in the presence of uranyl acetate, which afforded 3-bromo-3-methyl-2-butanol as the major product.