Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
Org Lett. 2020 Jul 17;22(14):5572-5576. doi: 10.1021/acs.orglett.0c01928. Epub 2020 Jul 8.
Intermolecular haloesterification is an important class of transformations. The resulting products are valuable building blocks. However, it is often necessary to use super-stoichiometric amount of acid in order to compensate the low reactivity. Herein, we report a zwitterion-catalyzed intermolecular bromoesterification using acid and olefin in an equimolar ratio. Mechanistic study revealed that the charge pair in the zwitterion works synergistically in activating both NBS and carboxylic acid.
分子间卤酯交换反应是一类重要的转化反应。所得产物是很有价值的构建模块。然而，为了补偿低反应性，通常需要使用超化学计量的酸。在此，我们报道了一种使用酸和烯烃以等摩尔比的两性离子催化的分子间溴酯化反应。机理研究表明，两性离子中的电荷对协同作用，同时活化 NBS 和羧酸。
