Photo-oxygenation of 2,4,4,6-tetraphenyl-1,4-dihydropyridine
Abstract
Sensitized photo-oxygenation of 2,4,4,6-tetraphenyl-1,4-dihydropyridine (1) in acetone or cyclic ethers gave an unstable peroxide which was assumed to be 3-hydroperoxy-2,4,4,6-tetraphenyl-3,4-dihydropyridine (2). The peroxide (2) easily decomposed to give 2,4,4,6-tetraphenyl-3-pyridone (3). In aromatic hydrocarbons or methylene dichloride, sensitized photo-oxygenation of (1) afforded two products, (4) and (5). The product (4) was a stable hydroperoxide which was determined to be N-(2-hydroperoxy-4-oxo-1,3,3-triphenylbutan-1-ylidene) benzamide. The product (5) was not a peroxide, and it was assigned the structure 3-hydroxy-2,4,4,6-tetraphenyl-3,4-dihydropyridine. Possible mechanisms are suggested for the formation of the reaction products.