Gohier Frédéric, Castanet Anne-Sophie, Mortier Jacques
Université du Maine and CNRS, Unité de chimie organique moléculaire et macromoléculaire (UMR 6011), Faculté des sciences, avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France.
J Org Chem. 2005 Feb 18;70(4):1501-4. doi: 10.1021/jo0483365.
[reaction: see text] By treatment with s-BuLi, s-BuLi/TMEDA, or t-BuLi at approximately -78 degrees C, 4-fluoro- and 4-chlorobenzoic acids (1a,b) are metalated preferentially in the position adjacent to the carboxylate. A complete reversal in regioselectivity is observed for 1a when treated with LTMP; a sequential process involving a rapid intraaggregate lithiation through a quasi dianion complex "QUADAC" is postulated to explain the unusual reactivity of Me(2)S(2) and I(2).
[反应:见正文] 在约-78℃下用仲丁基锂、仲丁基锂/四甲基乙二胺或叔丁基锂处理时,4-氟苯甲酸和4-氯苯甲酸(1a、b)优先在与羧酸盐相邻的位置发生金属化。用LDA处理1a时,区域选择性完全反转;推测一个涉及通过准双负离子络合物“QUADAC”进行快速聚集内锂化的连续过程来解释二甲基二硫和碘的异常反应性。