Epoxidation of some natural furocoumarins and furochromones using gamma-ray.

Epoxidation of imperatorin (1a) with m-chloroperbenzoic acid (mcpba) under the irradiation of gamma-ray gave a mixture of epoxide 3a and dioxofuran 4a. Whereas, alloimperatorin (1b) under the same condition obtained the epoxide 3b as a sole product. On the other hand, it was successfully epoxidized xanthotoxin (1c) with mcpba under the same condition as above. In addition, visnagin (2a) was epoxidized to give a mixture of epoxides 5a, 6a. While, khellin (2b) gave the epoxide 5b, no other products were observed.

Photosynthesis of furocoumarin- and furochromone-types potential intercalative alkylating and oxidizing agents of DNA through photooxidations using gamma-ray.

The photooxygenation of imperatorin (1a) under gamma-ray irradiation afforded the hydroperoxides 2a and 3a. Similarly, the photooxygenation of alloimperatorin (1b) gave the hydroperoxide (2b). Visnagin (1c) was also photooxygenated to give the hydroperoxide (2c) as sole product. On the other hand, the photooxygenation of khellin (1d) gave the endoperoxide (2d) as a sole product. The epoxidation of imperatorin (1a) using hydrogen peroxide under gamma-ray irradiation afforded the epoxide 5a. Similarly visnagin (1c) and khellin (1d) were epoxidized to give the epoxides 5c and 5d.