A green and one-pot synthesis of a library of 1,4-dihydropyrano[2,3-c]-pyrazole-5-carbonitrile derivatives using thiourea dioxide (TUD) as an efficient and reusable organocatalyst
作者:Rajesh H. Vekariya、Kinjal D. Patel、Hitesh D. Patel
DOI:10.1007/s11164-015-2308-7
日期:2016.5
The efficacy of thiourea dioxide (TUD) as an efficient, inexpensive, and readily accessible organocatalyst for the synthesis of 1,4-dihydropyrano[2,3-c]-pyrazole-5-carbonitrile derivatives via a four-component reaction of ethyl acetoacetate, hydrazine hydrate, aryl aldehydes, and malononitrile is described. Upon completion of the reaction, the product was isolated by filtration, and the remaining aqueous TUD solution could be reused several times with consistent catalytic activity. High yields, simple work-up process, avoiding the use of organic solvents, short reaction time, and recyclable catalyst are the superior advantages of the present protocol.
本文介绍了二氧化硫脲(TUD)作为一种高效、廉价且易于获得的有机催化剂,通过乙酰乙酸乙酯、水合肼、芳基醛和丙二腈的四组分反应合成 1,4-二氢吡喃并[2,3-c]-吡唑-5-甲腈衍生物的功效。反应完成后,通过过滤分离出产物,剩余的 TUD 水溶液可重复使用多次,并具有稳定的催化活性。产率高、操作过程简单、避免使用有机溶剂、反应时间短以及催化剂可回收利用是本方案的显著优点。