Photochemical transformations. Part 34. Structures of the toxisterols2

Abstract

The isolation and identification of twelve new compounds formed on photolysis of ergosterol in ethanol are described. These include four C₁₉ and C₂₀ hydrocarbon photofragments derived by loss of ring A, two related vinyl ethers, and six toxisterols₂. Three of the previously elusive toxisterols₂ have a novel spiro-steroid structure isomeric with ergosterol. The other three are ethers containing the dihydrotachysterol chromophore. Photolysis of ergosterol in cyclohexane also gave a disteroid C₄₀ hydrocarbon; a structure is suggested.