A facile synthesis of 6-amino-2H, 4H-pyrano[2,3-c]pyrazole-5-carbonitriles in deep eutectic solvent

A convenient synthesis of 6-amino-2H,4H-pyrano[2,3-c]pyrazole-5-carbonitriles has been accomplished by one pot four-component cyclocondensation of aromatic aldehydes (1a-o) malanonitrile (2), ethyl acetoacetate (3), and hydrazine hydrate (4) in freshly prepared deep eutectic solvent, DES (choline chloride:urea). This protocol has afforded corresponding pyrano[2,3-c]pyrazoles in shorter reaction time with high yields, and it avoids the use of typical toxic catalysts and solvents. (C) 2016 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.