An approach to modified heterocyclic analogues of huperzine A and isohuperzine A. Synthesis of the pyrimidone and pyrazole analogues, and their anticholinesterase activity
作者:Alan P. Kozikowski、Giuseppe Campiani、Vito Nacci、Alessandro Sega、Ashima Saxena、Bhupendra P. Doctor
DOI:10.1039/p19960001287
日期:——
and the pyrazole analogues of the naturally occurring acetylcholinesterase (AChE) inhibitor huperzine A and its unnatural regioisomer, isohuperzine, are described. The pyrimidone analogues of huperzine A were obtained starting from cyclohexane-1,4-dione monoethylene ketal by first annealing to this monocycle a pyrimidine ring and then constructing the unsaturated three-carbon bridge using the previously
描述了天然存在的乙酰胆碱酯酶(AChE)抑制剂石杉碱A及其非天然区域异构体异石杉碱的嘧啶酮和吡唑类似物的合成方法。石杉碱甲的嘧啶酮类似物是从环己烷-1,4-二酮单亚乙基缩酮开始,首先退火至该单环一个嘧啶环,然后使用前述的钯催化双环化方法构建的不饱和三碳桥基。事实证明,该合成过程中的主要问题是将亚乙基附属物引入三轮车10。尽管Wittig和Takai烯烃化方案均未成功,最终使用Danheiser方法引入亚乙基部分,该方法涉及两步反应序列,该过程由β-内酯的中间结构组成,该结构继而经历[2 + 2]环还原反应,从而生成所需的烯烃。已经发现这种先前未应用于β-酮酯的β-内酯合成以优异的非对映选择性进行。反过来,β-内酯进行立体有择的脱羧反应以提供作为唯一异构体的E-烯烃产物。此外,从双环[3.3.1]壬烯中间体2开始,我们描述了一种合成策略,用于购买异石杉碱A的修饰杂环类似物。该化学方法提供了一种诱人的方法,用于合成6