Photophthalimidation of unactivated double bonds. Synthesis of protected phenethylamines

Article abstract of DOI:10.1016/S0040-4039(99)00103-3

At low hydroxide ion concentrations, the photoaddition of phthalimide to cyclohexene, indene or styrene derivatives takes place. The cation radical obtained in the electron transfer from the alkene to excited phthalimide is trapped by phthalimide anion. At high hydroxide ion concentrations concerted [2+2] cycloaddition occurs that yields benzazepinediones, whatever the ionization potential of the alkene. The most suitable reaction conditions can be inferred from the observed fluorescence of phthalimide anion.