通过将催化胺,N-甲基咪唑和N,N,N',N'-四甲基乙二胺(TMEDA)结合在一起,已开发出一种有效的方法,用于在水中作为溶剂在酰氯和醇之间进行酯化。通过使用pH调节剂将pH值保持在11.5左右,可以防止酸氯和/或酯类的分解并促进缩合,从而完成当前的Schotten-Baumann型反应。催化剂的选择(0.1当量)至关重要:N-甲基咪唑和TMEDA的组合使用具有显着的协同作用。催化胺具有两个不同的作用:(i)N-甲基咪唑与酰氯形成高反应性的铵中间体,并且(ii)TMEDA充当有效的HCl粘合剂。仔细的1 H NMR监测研究合理地支持了这些中间体的生产。在酰氯和伯胺或仲胺之间也实现了相关的酰胺形成,伯胺或仲胺包括较少的亲核或水溶性胺,例如2-(或4-)氯苯胺,Weinreb N-甲氧基胺和2,2-二甲氧基乙胺。
Acid liability of allylic esters: use of methallyl esters as acid-labile protecting groups for car☐ylic acids
作者:Christopher R. Schmid
DOI:10.1016/s0040-4039(00)77708-2
日期:1992.2
Substituted allylic esters are cleaved in refluxing 90% formic acid to afford car☐ylicacids. The scope and generality of the reaction is investigated, and several examples using methallyl esters as an acid-labile protecting group for car☐ylicacids are presented.
Iridium-catalyzed oxidative esterification reaction of aliphatic aldehydes and olefinic alcohols with precoordination of the double bond of alcohols to iridium
作者:Syun-ichi Kiyooka、Mahuyu Ueno、Eri Ishii
DOI:10.1016/j.tetlet.2005.04.093
日期:2005.7
A novel iridium-catalyzed oxidative esterification reaction of aliphaticaldehydes and olefinic alcohols in toluene was found under mild conditions of [IrCl(cod)]2 (5 mol %) in combination with K2CO3 (10 mol %) at rt.
发现在室温下[IrCl(cod)] 2(5 mol%)和K 2 CO 3(10 mol%)的温和条件下,一种新型的铱催化的脂肪族醛和烯烃醇在甲苯中的铱催化氧化酯化反应。
[IrCl(cod)]2-catalyzed direct oxidative esterification of aldehydes with alcohols
[IrCl(cod)](2) catalyzed the oxidative esteritication of a variety of aldehydes with methanol as a solvent in combination with K2CO3 under mild conditions (rt, 12 h). The oxidative esterification reaction of aliphatic aldehydes also took place with olefinic alcohols as reagents in toluene under similar conditions. (c) 2007 Elsevier Ltd. All rights reserved.