A convenient synthesis of coumarin-3-carboxylic acids via Knoevenagel condensation of Meldrum's acid with ortho-hydroxyaryl aldehydes or ketones
作者:Aimin Song、Xiaobing Wang、Kit S Lam
DOI:10.1016/s0040-4039(03)00108-4
日期:2003.2
Coumarin-3-carboxylic acids were obtained in high yields with excellent purity from ortho-hydroxybenzaldehydes and Meldrum's acid after a 2 h reflux in ethanol. The less reactive ketones were first reacted with alcoholic ammonia to form ketimines, which were then condensed with Meldrum's acid to generate 4-alkylcoumarin-3-carboxylic acids in moderate yields.
在乙醇中回流2小时后,从邻羟基苯甲醛和Meldrum酸以高收率获得了香豆素-3-羧酸。反应性较低的酮首先与乙醇氨反应形成酮亚胺,然后与Meldrum's酸缩合以生成中等收率的4-烷基香豆素-3-羧酸。