作者:Marie-T. Nolan、Leticia M. Pardo、Aisling M. Prendergast、Gerard P. McGlacken
DOI:10.1021/acs.joc.5b02027
日期:2015.11.6
worked well. The methodology was extended to 2-coumarins and applied to the synthesis of flemichapparin C and a novel analogue. Deuterium isotope effects, typical of a concerted metalation-deprotonation (CMD) mechanism, were observed in the case of a bromopyrone, but a highly unusual, inverse kinetic isotope effect was evident using a chlorocoumarin, implying that a different mechanism is operating.
直接芳基化代表了传统交叉偶联的有利替代方法,并已发现可广泛用于简单的芳基和坚固的杂环。在此,直接芳基化方案已被优化并应用于2-吡喃酮,2-吡喃酮是精致且具有特权的生物基序。在3-位的区域选择性卤化允许通过激活吡喃酮C-Br或C-Cl键和苯氧基CH键进行分子内偶联。重要的是,贫电子苯氧基底物也能很好地工作。该方法扩展到了2-香豆素,并用于合成氟苯丙胺林C和一种新的类似物。在溴吡喃酮的情况下,观察到氘同位素效应,这是协同金属化-去质子化(CMD)机制的典型特征,但是使用氯香豆素可明显观察到非常不寻常的逆动力学同位素效应,