A photooxygenation reaction of 2′, 2′, 4′, 4′-tetramethyl tetrahydroindole (9) followed by a pinacoltype rearrangement furnished 2′, 2′, 4′, 4′-tetramethyl-3- spirocyclopentylsuccinimide (11). This transformation constitutes a model study for the synthesis of the spirosuccinimide ring system of asperparaline A.
