Photooxygenation of some potentially skin‐photosensitizing furocoumarins: Imperatorin, alloimperatorin and its methyl ether and acetate derivatives

Abstract

The photooxygenation of imperatorin (1a) afforded the corresponding allylic hydroperoxides 2a and 3a in very good yields. Similarly, the photooxygenation of alloimperatorin derivatives 1c, d gave the allylic hydroperoxides 2c, d and 3c, d in quantitative yields. On the other hand, on photooxygenation of alloimperatorin (1b) exclusively the dienone hydroperoxide 4b was obtained. When the reaction time was prolonged, the bis(hydroperoxide) 5b was also formed by successive photooxygenation of 4b.