Self-sensitized photooxygenation of 3,4-dialkoxyfurans to vitamin C or itsderivatives

Self-sensitized photooxygenation of 3,4-dialkoxyfurans 3a-d with molecular oxygen and UV- or sunlight at room temperature gave vitamin C derivatives 2 a-d in good to excellent yields. Furan 3c, having photodegradable protectin g groups, was also photooxygenated to give L-ascorbic acid (1) in a "one-po t" reaction. Furthermore, a novel photolytic transformation was developed f or deuteration of furan 3b at the C-2 position with D2O to give furan 3d in 95% yield. Toxicity of furans 3a-c and butenolides 2a-c against human embr yonic cell, murine embryo fibroblasts, normal fibroblasts, HeLa, and Vero c ell lines in the presence of oxygen and indirect solar light was found to b e much less than those of the antipsoriasis drugs anthralin and 8-methoxyps oralen.