Photochemical Reaction of (Z)-Jasmone under Various Conditions

(Z)-Jasmone (1) was irradiated with a 400W high-pressure mercury lamp under various conditions. Under nitrogen, 1 was converted to the (E)-isomer (2), to di-π-methane rearrangement products (3 and 4) and intramolecular cyclo-adducts (5 and 6) in methanol and ethanol, and to 2, 3, and 4 in ethyl acetate. Under oxygen, 1 was broken down to hydroperoxides (7 and 8), its reduction products (9 and 10), and dehydrates (11 and 12). These compounds were further photooxidized to yield compounds 13-17, 19, and 20 in methanol or ethanol. In ethyl acetate, an intramolecular cyclo-adduct (22) was obtained, together with a diol (21) and photoreaction products 23 and 24, and 11, 13-18, and 20. Hydroperoxides (7 and 8) and their reduction products (9 and 10) were obtained by a photosensitized reaction with rose bengal under oxygen. (Z)-Jasmone was converted to 2 so rapidly that suppressing the photoisomerization of 1 was difficult, except by cutting off the UV light.