Harnessing the<i>ortho</i>-Directing Ability of the Azetidine Ring for the Regioselective and Exhaustive Functionalization of Arenes
作者:Marina Zenzola、Leonardo Degennaro、Piera Trinchera、Laura Carroccia、Arianna Giovine、Giuseppe Romanazzi、Piero Mastrorilli、Rosanna Rizzi、Luisa Pisano、Renzo Luisi
DOI:10.1002/chem.201403141
日期:2014.9.15
reagent nBuLi. Two different reaction protocols were discovered for regioselective lithiation at the ortho positions adjacent to the azetidine ring, which served as a toolbox when other competing directing groups were installed on the aromatic ring. The coordinating ability of the azetidine nitrogen atom, as well as the involvement of dynamic phenomena related to the preferential conformations of 2‐arylazetidine
这项工作表明氮杂环丁烷环的定向能力如何可能是区域选择性有用邻-C ħ芳基化合物的官能化。稳健的极性有机金属(锂化)中间体参与了这种合成策略。试剂Ñ -hexyllithium成为更安全的,但仍有效的,基本试剂中的氢/锂置换相对于广泛使用的试剂Ñ丁基锂。在邻位发现了两种不同的反应方案用于区域选择性锂化与氮杂环丁烷环相邻的位置,当其他竞争性的导向基团安装在芳环上时,氮杂环丁烷环用作工具箱。氮杂环丁烷氮原子的配位能力,以及与2-芳基氮杂环丁烷衍生物的优先构象有关的动力学现象的参与,被认为是所观察到的反应性和区域选择性的原因。芳族氮杂环丁烷具有配位活性基团(例如甲氧基)或感应吸电子取代基(例如氯和氟)可实现芳香环的位点选择性官能化。通过微调反应条件,可以实现芳香环上几个取代基的区域选择性引入。完成了多种替换模式,包括1,2,3-三取代,1,2,3,