Photophthalimidation of unactivated double bonds. Synthesis of protected phenethylamines

At low hydroxide ion concentrations, the photoaddition of phthalimide to cy clohexene, indene or styrene derivatives takes place. The cation radical ob tained in the electron transfer from the alkene to excited phthalimide is t rapped by phthalimide anion. At high hydroxide ion concentrations concerted [2+2] cycloaddition occurs that yields benzazepinediones, whatever the ion ization potential of the alkene. The most suitable reaction conditions can be inferred from the observed fluorescence of phthalimide anion. (C) 1999 E lsevier Science Ltd. All rights reserved.