3,5-Cycloergosta-6,8(14),22-triene

Journal of the American Chemical Society, 1952, 74(21):469-74.

An i-Steroid Hydrocarbon from Ergosterol1.[Reference: WebLink]

METHODS AND RESULTS:
Reinvestigation of a hydrocarbon resulting from dehydration of ergosterol with either phosphorus oxychloride or p-toluenesulfonyl chloride in pyridine and heretofore regarded as an ergostatetraene has shown that the substance is 3,5-cyclo-Δ6, 8(14), 22-ergostatriene (3,5-Cycloergosta-6,8(14),22-triene, V), the first known i-steroid in the ergosterol series. Reaction of the hydrocarbon with hydrogen chloride and its acid-catalyzed hydration result in opening of the cyclopropane ring with formation of mixtures of ergosteryl chlorides or of ergosterol isomers; ergosterol-B1 of reasonable purity has been isolated from the product of hydration. A hydrocarbon, first described by Windaus, resulting from acid-catalyzed dehydration of 3α- and 3β-hydroxy-Δ4,7,22-ergostatriene was investigated to see if it corresponded to a highly dextrorotatory, alumina-isomerized impurity accompanying the i-steroid V.
CONCLUSIONS:
The results indicate that the Windaus hydrocarbon is Δ4,6,8(14),22-ergostatetraene (XIV). Formulas attributed earlier to hydrocarbons resulting from dehydration of epialloergosterol (NaOAc-Ac2O, see III) and of lumisterol (C10-epimer of III) are consistent with present evidence. "Ergosterol-E" is shown to consist largely of a mixture of dihydroergosterols.