PHOTOCHEMISTRY OF LATIFOLIN AND SOME RELATED COMPOUNDS

Article abstract of DOI:10.1016/S0040-4020(01)82062-7

Latifolin (1), the major constituent of D. latifolia gave trans 1-(2,4-dimethoxy-3-hydroxyphenyl)-2-(2-hydroxyphenyl) cyclopropane as the sole photo di-?-methane rearrangement product.In contrast, its simpler analogues, 3-(2,4,5-trimethoxyphenyl)-3-phenyl prop-1-ene (3) and 3-(2,4-dimethoxyphenyl)-3-phenyl prop-1-ene (4), gave 1:1 mixture of cis and trans cyclopropanes.Dye-sensitized photooxidation of latifolin (1) and dihydrolatifolin (16) gave novel xanthan derivatives (15) and (17) involving a crucial step of photooxidative demethylation followed by cyclisation.Similar reaction of the closely related propane 19 gave, interestingly the benzofuran 20.The propene 22, lacking free hydroxyl or double bond, gave only the quinone 23 indicating that quinones are intermediates in the above oxidations.The allyl alcohol 24, having similar feature, undergoes oxidation to the corresponding aldehyde 26 and the benzophenone 28 but not to a quinone.