Fluorine-Flanked Congested Sites: Minimal, Though Perceptible Buttressing Effects on the Proton Mobility of Arenes
作者:Christophe Heiss、Frédéric Leroux、Manfred Schlosser
DOI:10.1002/ejoc.200500552
日期:2005.12
(2,6-Difluorophenyl)trimethylsilane, -triethylsilane and -triisopropylsilane undergo sec-butyllithium-mediated metalation at the 3- and 4-position (ortho and meta relative to the halogen) in ratios of 99.6:0.4, 98:2 and 95:5, resp. The steric pressure transmitted by the fluorine atoms can be increased if the trialkylsilyl group is locked up on the other side by a relatively voluminous substituent.
(2,6-二氟苯基)三甲基硅烷、-三乙基硅烷和-三异丙基硅烷在 3-位和 4-位(相对于卤素的邻位和间位)以 99.6:0.4、98:2 和 95 的比例进行仲丁基锂介导的金属化:5,分别。如果三烷基甲硅烷基被相对较大的取代基锁定在另一侧,则可以增加由氟原子传递的空间压力。而(2,6-二氟苯基)三乙基硅烷在4-位和5-位脱质子下以99.4:0.6的比例被2,2,6,6-四甲基哌啶锂攻击,qorthoq/qmetaq金属化比例变为84 :16 当(2-溴-6-氟苯基)三乙基硅烷作为底物时。[在 SciFinder (R) 上]