First General, Direct, and Regioselective Synthesis of Substituted Methoxybenzoic Acids by Ortho Metalation
作者:Thi-Huu Nguyen、Nguyet Trang Thanh Chau、Anne-Sophie Castanet、Kim Phi Phung Nguyen、Jacques Mortier
DOI:10.1021/jo070082a
日期:2007.4.1
adjacente to the carboxylate. On the other hand, a reversal of regioselectivity is observed with n-BuLi/t-BuOK. With LTMP at 0 °C, the two directors of m-anisic acid (2) function in concert to direct introduction of the metal between them while n-BuLi/t-BuOK removes preferentially the proton located ortho to the methoxy and para to the carboxylate (H-4). s-BuLi/TMEDA reacts with p-anisic acid (3) exclusively
在基于邻-金属化位点在芳族化学的新值一般方法邻- ,间- ,和对-茴香酸(1 - 3)(方案1)进行说明。通过改变碱,金属化温度和曝光时间,可以将金属化选择性地定向到任何一个邻位。的金属化邻-茴香酸(1)与小号正丁基锂/ TMEDA在THF中在-78℃下在位置adjacente将羧酸只发生。另一方面,通过n -BuLi / t -BuOK观察到区域选择性的逆转。在LTMP为0°C的情况下,间苯二酸的两个指向矢(2)协同作用以直接将金属引入它们之间,而n - BuLi / t- BuOK优先除去位于甲氧基和羧酸酯(H-4)对位的质子。s- BuLi / TMEDA仅在羧酸酯附近与对茴香酸(3)反应。根据这些方法,已开发出通过多种途径难以达到的,具有多种功能的非常简单的甲氧基苯甲酸的途径(表1)。