Photocyclisation of enamides. Part V. Photocyclisation of αβ-unsaturated anilides

Abstract

Irradiation of N-methyl- and N-benzyl-cyclohex-1-enecarboxanilide (Ia and b) and N-methyl-3,4-dihydronaphthalene-1-carboxanilide (VIII) with a low pressure mercury lamp afforded a mixture of cis- and trans-photocyclised products [the phenanthridones (II) and (III), and the benzophenanthridinones (IX) and (X), respectively], whose ratios were dependent upon the solvent employed. Equilibration and deuterium incorporation experiments provided important information on the reaction mechanism.