Kulig M J, Teng J I, Smith L L
Lipids. 1975 Feb;10(2):93-8. doi: 10.1007/BF02532162.
The facile acid-catalyzed conversion of cholest-5-ene-3 beta, 7 alpha-diol (but not of cholest-5-ene-3 beta, 7 beta-diol) in methanol or ethanol solution to the corresponding 7 alpha-methyl or 7 alpha-ethyl ethers and epimerization of the 7 alpha-alkyl ethers to the corresponding 7 beta-alkyl ethers were established. The epimeric cholest-5-ene-3 beta, 7-diols, their 7-methyl ethers, and their 7-ethyl ethers are readily interconverted in acidified solvents, the quasiequatorial 7 beta-epimer predominating in each case. Both 7 alpha- and 7 beta-alkyl ethers may be encountered as artifacts in analyses of sterol mixtures from mamalian tissues.
已证实，在甲醇或乙醇溶液中，胆甾-5-烯-3β,7α-二醇（但胆甾-5-烯-3β,7β-二醇不行）可通过简便的酸催化转化为相应的7α-甲基或7α-乙基醚，且7α-烷基醚会差向异构化为相应的7β-烷基醚。差向异构的胆甾-5-烯-3β,7-二醇、其7-甲基醚和7-乙基醚在酸化溶剂中很容易相互转化，每种情况下准赤道面的7β-差向异构体占主导。在分析哺乳动物组织中的甾醇混合物时，7α-和7β-烷基醚都可能作为假象出现。
