The photochemistry of N-phenyl phthalonimide: Formation of substituted dihydroisocoumarins in the presence of tertiary amines

Article abstract of DOI:10.1016/0040-4020(95)00271-9

N-Phenyl phthalimide and 3,4-Dihydroisocoumarins were obtained by irradiation of N-phenyl phthalonimide in the presence of tertiary amines. The δ-lactone structure was demonstrated via an alternative synthesis that gave the isomeric γ-lactone as well. The key steps of the photoreaction, and the role of the amine, oxygen and several potential intermediates are discussed.