The base-catalysed cyclisation of phenyl N-(2-hydroxybenzyl)-N-methylcarbamates is concerted
作者:Vojeslav Štěrba、Oldřich Hrabík、Jaromír Kaválek、Jaromír Mindl、Andrew Williams
DOI:10.1039/b209323p
日期:2003.1.13
The kinetics of the cyclisation in aqueous solution of phenyl-(2-hydroxybenzyl)-N-methylcarbamates to 3-methyl- 3,4-dihydrobenzo[e][1,3]oxazin-2-ones and phenolate ions fit the rate law: kobs = kc/(1 + [H3O+]/Ka) The values of kc and pKa fit Brønsted equations against the pKa's of the corresponding free phenols but the system does not conform to the reactivity-selectivity hypothesis. The values of
苯基-(2-羟基苄基)-N-甲基氨基甲酸酯在水溶液中环化为3-甲基-3,4-二氢苯并[e] [1,3]恶嗪-2-酮和酚酸根离子的动力学符合速率定律:kobs = kc /(1 + [H3O +] / Ka)kc和pKa的值使Brønsted方程与相应的游离酚的pKa相符,但该系统不符合反应性-选择性假设。根据以下公式,Brønsted参数beta Y和beta X的值随Y和X的变化而变化:beta X = -0.179pKaHY + 0.87 beta Y = -0.179pKaHX + 2.30 Cordes-Thornton叉的幅度和符号-相互作用系数pXY(-0.179)排除了涉及四面体中间体的逐步机理,并且与一致的位移机理一致。