stereochemistry at the ketal centre of methylhallerin (6) has been established by X-ray analysis. The stereochemical outcome of the methylation of hallerin and of pairs of related anomeric sesquiterpene lactols has been studied by means of geometrical and theoretical calculations (MNDO method). Model lactols and methyl lactols were chosen with conformational features simulating the effects of the presence
通过X射线分析已经确定了甲基hallerin(6)的
缩酮中心的立体
化学。已通过几何和理论计算(MNDO方法)研究了Hallerin和相关对端异构
倍半萜烯内酯对的甲基化的立体
化学结果。选择具有构象特征的模型乳醇和甲基乳醇,其模拟在(6)固态中发现的十元环的存在的影响。结果表明,单独的热力学和空间效应都不能解释以下事实:仅用CH 3 I–Ag 2对异头
乳糖醇对进行烷基化即可获得一种甲基衍
生物。O.然而,研究的异头
乳糖醇显示出甲基化的可及性方面的差异,尽管与溶液无关,但当分子吸附在有望进行烷基化反应的Ag 2 O表面上时,它可能起重要作用。地方。