The photochemistry of amides and amide derivatives 3: The photolysis of methyl-2-phenoxybenzohydroxamate

TLDR: In this article, the photochemistry of methyl 2-phenoxybenzohydroxamate was studied and it was found that the relative amounts of the type II product and the phenyl migration product were solvent dependent.

Abstract: The photochemistry of methyl-2-phenoxybenzohydroxamate was studied. This compound was found to undergo the type I reaction followed by intramolecular cyclization to generate xanthone, the type II reaction to generate 2-phenoxybenzamide, and a formal 1,5 shift of the phenyl group from the benzohydroxamate ring to the nitrogen. It was also found that the relative amounts of the type II product and the phenyl migration product were solvent dependent. Photolysis in methanol favored the phenyl migration process whereas photolysis in cyclohexane favored the type II process. These results are attributed to an increased amount of single electron transfer from the phenoxy group to the carbonyl group relative to the type II process in methanol. The photolysis of N,N-dimethyl-2-phenoxybenzamide, which cannot undergo phenyl migration, gives xanthone as the only product.