14 and 5 beta-delta 8,14 isomers in a 5:1:1 ratio. Epoxidation of the crude diene mixture with m-chloroperbenzoic acid, followed by hydrolysis in acetone containing concentrated HClO4 (0.1%) gave (25R)-3 beta,26-diacetoxy-5 alpha-cholest-8(14)-en-15-one (VIII), accompanied by numerous minor byproducts, including the 5 alpha,14 beta-delta 7, 5 alpha, 14 beta-delta 8 and 5 beta,14 beta-delta 8 isomers
(25R)-3 beta,26-Dihydroxy-5 alpha-cholest-8(14)-en-15-(I)由(25R)-3 beta,26-diacetoxycholesta-5,7-分四步合成二烯(III),总收率30%。在-60°C下于
氯仿-
二氯甲烷中用HCl将III异构化,得到(25R)-3 beta,26-diacetoxy-5 alpha-cholesta-7,14-diene和5 alpha-delta 8,14和5 beta-比例为5:1:1的δ8,14异构体。将粗制二烯混合物与间
氯过
苯甲酸环氧化,然后在含有浓HClO4(0.1%)的
丙酮中
水解,得到(25R)-3 beta,26-diacetoxy-5 alpha-cholest-8(14)-en-15- (VIII)伴随着许多次要的副产物,包括VIII的5α,14β-δ7、5α,14β-δ8和5β,14β-δ8异构