Aim and Objective: 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.

Materials and Methods: 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.

Results: 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.

Conclusion: 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.

目的和目的：为了保护环境免受有害有机溶剂的侵害，在深共熔溶剂中合成了香豆素衍生物，由于其特性，香豆素衍生物被认为是“绿色”的。

材料和方法：在通过Knoevenagel缩合合成香豆素衍生物中，使用氯化胆碱基深共熔溶剂（DESs）作为溶剂和催化剂。为了找到最适合香豆素合成的DES，在80°C下测试了20种DES对水杨醛和丙二酸二甲酯的反应。

结果：在二十种经过测试的深共熔溶剂中，只有五种足以进行这种合成。发现用于该反应的最佳DES是由氯化胆碱：脲（1∶2）组成的DES。大多数香豆素化合物均以良好至极好的收率获得。应指出化合物1g，2g和2p的产率分别为85％，88％和98％。在超声辐射下合成3-乙酰香豆素5a，5c，5d，5e，5f和5g，并且分别以90％，95％，98％，93％，94％和85％的优异产率获得。

结论：在不同的水杨醛和活性亚甲基化合物中，在80℃的胆碱氯化物：脲DES中或在超声辅助反应中，成功合成了一系列香豆素衍生物。发现这些“绿色”方法在Knoevenagel缩合中非常有效，而DES循环使用了多个循环，而对产品收率没有任何重大影响。