Being interested in the photochemical reactions which are potentially applied in the biogenetic-type chemical derivations of natural products, the appropriate photochemical means have been sought to produce the 11α,12α-epoxy-13β,28-lactone moiety in the oleanane skeleton, which is one of the unique functions of eupteleogenin (2). Photooxidation of oleanolic acid (6a) in acidic medium has been undertaken
由于对可能用于
天然产物的
生物遗传类型
化学衍生反应的光
化学反应感兴趣,已寻求适当的光
化学方法以在齐墩果骨架中产生11α,12α-环氧-13β,28-内酯部分,这是eupteleogenin的独特功能之一(2)。已经进行了
齐墩果酸(6a)在酸性介质中的光氧化,并且获得了所需的11α,12α-环氧-
油醇内酯(12a)。赤藓糖醇(8a)经历了光氧化作用,并引入11α,12α-环氧-13β ,28-氧化物部分(24a)和骨架重排,从而提供11α,12α-环氧-taraxerene衍
生物(25a)。期间的光氧化8a中,已经注意到,11ξ羟基齐墩果-12-烯衍
生物(28,42)是相当不稳定的,从而允许反式形成dihydropriverogenin A(的10A)转换成异构体priverogenin乙热力学不太有利的(9)。