A two-step biomimetic synthesis of the pentacyclic pyrido[2,3,4-klacridine marine alkaloid ascididemin (3a) from quinolinequinone 5a and N-trifluoroacetamidokynuramine (4) is described. The crucial step (6 to 7) involves the simultaneous formation of two pyridine rings in a process which might well offer an explanation for the biogenetic synthesis in marine organisms. The preparation of substituted ascididemins by either starting from substituted quinoline-quinones, e.g., 5b to afford 11-methoxyascididemin (3b), or by nitration of 3a to the mono 1- or 3-nitroascididemins (8 and 9 respectively) is reported.
本研究描述了一种五环
吡啶并[2,3,4-klacridine]海洋
生物碱 ascidemin(3a)的两步仿
生物合成法,其原料是
喹啉醌 5a 和 N-三
氟乙酰胺基
奎宁胺(4)。关键步骤(6 至 7)涉及两个
吡啶环的同时形成,这一过程很可能为海洋
生物的
生物合成提供了解释。报告还介绍了从取代的
喹啉醌(如 5b 生成 11-甲氧基蛔虫素(3b))开始,或通过硝化 3a 生成单 1-或
3-硝基蛔虫素(分别为 8 和 9)来制备取代的蛔虫素的方法。