Zeolite NaY‐Promoted Monocyclization of Epoxy Polyene Terpenes: A Unique Route for the Direct Synthesis of Incompletely Cyclized Naturally Occurring Terpenols
作者:Constantinos Tsangarakis、Christos Raptis、Elias Arkoudis、Manolis Stratakis
DOI:10.1002/adsc.200800180
日期:2008.7.7
the brown algae Cystophora monoliformis. The optical rotation of achilleol A derived from the cyclization of (S)-2,3-epoxysqualene matches with that of the natural product, thus the absolute configuration of achilleol A was established as 1S,3R. From the mechanistic point of view, the NaY-promoted cyclization of 9,10-epoxygeranylacetone, selectively deuterium labelled at the C-10 methyl group, is >97%
通过限制在NaY沸石中,各种环氧多烯萜容易环化,主要形成单环化产物。不管环氧萜烯的侧链如何,单环化途径都非常占优势,而单环产物具有区域选择性地具有外亚甲基双键。在乙酸法呢烯基乙酸酯,环氧法呢烯基丙酮或2,3-环氧角鲨烯的情况下,选择性单环化为合成多种天然产物(例如榄香二醇,法呢香酚B–D,阿奇儿醇A,山茶酚C和四种法呢基丙酮)提供了直接途径。褐藻中提取的代谢产物。由(S的环化引起的Achilleol A的旋光。基)-2,3-环氧角鲨烯与天然产物的匹配,从而achilleol A的绝对构型确定为1小号,3 - [R 。从机理的角度来看,NaY促进的9,10-环氧香叶基丙酮(在氘代C-10甲基上进行选择性氘标记)的环化相对于宝石-二甲基基团的局部立体选择性> 97%。这一结果与协调机制相吻合。最后,我们首次通过标记实验证明,环氧多烯萜烯在酸催化下向2,3,4-三甲基环己酮的仿生转化是高度立体选