Abstract：
In order to preserve the environment from harmful organic solvents, a synthesis of coumarin derivatives was performed in deep eutectic solvents, which are considered as \"green\" due to their characteristics.
Choline chloride based deep eutectic solvents (DESs) were employed, both as solvents and as catalysts, in the synthesis of coumarin derivatives via Knoevenagel condensation. In order to find the best DES for coumarin synthesis, 20 DESs were tested for the reaction of salicylaldehyde and dimethyl malonate at 80 °C.
Among the twenty tested deep eutectic solvents only five were adequate for this kind of synthesis. The best DES for this reaction was found to be the one composed of choline chloride:urea (1:2). Most coumarin compounds were obtained in good to excellent yield. Compounds 1g, 2g and 2p should be pointed out due to their yields of 85, 88 and 98 %, respectively. 3-Acetylcoumarins 5a, 5c, 5d, 5e, 5f and 5g were synthesized under ultrasound irradiation and were also obtained in excellent yields of 90, 95, 98, 93, 94 and 85 %, respectively.
Series of coumarin derivatives were successfully synthesized, either in choline chloide:urea DES at 80 °C or in ultrasound-assisted reaction, from different salicylaldehydes and active methylene compounds. These \"green\" methods were found to be very effective in Knoevenagel condensation, while DES was recycled for several cycles without any significant influence on the product yield.
Choline chloride based deep eutectic solvents (DESs) were employed, both as solvents and as catalysts, in the synthesis of coumarin derivatives via Knoevenagel condensation. In order to find the best DES for coumarin synthesis, 20 DESs were tested for the reaction of salicylaldehyde and dimethyl malonate at 80 °C.
Among the twenty tested deep eutectic solvents only five were adequate for this kind of synthesis. The best DES for this reaction was found to be the one composed of choline chloride:urea (1:2). Most coumarin compounds were obtained in good to excellent yield. Compounds 1g, 2g and 2p should be pointed out due to their yields of 85, 88 and 98 %, respectively. 3-Acetylcoumarins 5a, 5c, 5d, 5e, 5f and 5g were synthesized under ultrasound irradiation and were also obtained in excellent yields of 90, 95, 98, 93, 94 and 85 %, respectively.
Series of coumarin derivatives were successfully synthesized, either in choline chloide:urea DES at 80 °C or in ultrasound-assisted reaction, from different salicylaldehydes and active methylene compounds. These \"green\" methods were found to be very effective in Knoevenagel condensation, while DES was recycled for several cycles without any significant influence on the product yield.
摘要：
为了保护环境免受有害有机溶剂的影响，香豆素衍生物的合成是在低共熔溶剂中进行的，由于它们的特性，它们被认为是“绿色”。
使用氯化胆碱基深共晶溶剂(DESs)，作为溶剂和催化剂，在通过Knoevenagel缩合合成香豆素衍生物中。为了找到用于香豆素合成的最佳DES，在80°C下测试20种DES的水杨醛和丙二酸二甲酯的反应。
在20种测试的深共晶溶剂中,只有5种适合于这种合成。发现该反应的最佳DES是由氯化胆碱：尿素（1：2）组成的DES。大多数香豆素化合物以良好至优异的产率获得。化合物1g,2g和2p应该指出，由于它们的产率为85％、88％和98％，分别。3-乙酰香豆素5a,5c,5d,5e,5f和5g在超声照射下合成，并以90、95、98、93、94和85％的优异产率获得，分别。
成功合成了一系列香豆素衍生物，在胆碱氯化物中：80°C的尿素DES或在超声辅助反应中，来自不同的水杨醛和活性亚甲基化合物。发现这些“绿色”方法在Knoevenagel冷凝中非常有效，而DES循环了几个周期，对产品产量没有任何显著影响。
使用氯化胆碱基深共晶溶剂(DESs)，作为溶剂和催化剂，在通过Knoevenagel缩合合成香豆素衍生物中。为了找到用于香豆素合成的最佳DES，在80°C下测试20种DES的水杨醛和丙二酸二甲酯的反应。
在20种测试的深共晶溶剂中,只有5种适合于这种合成。发现该反应的最佳DES是由氯化胆碱：尿素（1：2）组成的DES。大多数香豆素化合物以良好至优异的产率获得。化合物1g,2g和2p应该指出，由于它们的产率为85％、88％和98％，分别。3-乙酰香豆素5a,5c,5d,5e,5f和5g在超声照射下合成，并以90、95、98、93、94和85％的优异产率获得，分别。
成功合成了一系列香豆素衍生物，在胆碱氯化物中：80°C的尿素DES或在超声辅助反应中，来自不同的水杨醛和活性亚甲基化合物。发现这些“绿色”方法在Knoevenagel冷凝中非常有效，而DES循环了几个周期，对产品产量没有任何显著影响。
