Glycerol mediated green and one-pot synthesis of 6-amino-1,4-dihydropyrano[2,3-c]-pyrazole-5-carbonitriles under catalyst free conditions
A concise, facile and straightforward synthetic protocol has been described for the preparation of 6-amino-1,4-dihydropyrano[2,3-c]-pyrazole-5-carbonitrile derivatives by a one-pot, three-component reaction of ethyl acetoacetate, hydrazine hydrate, aryl aldehydes and malononitrile in glycerol as a green and reusable reaction media under catalyst free condition. The corresponding 6-amino-1,4-dihydropyrano[2,3-c]-pyrazole-5-carbonitriles have been obtained with good to excellent yields (86-92%). This protocol is highly efficient due to its mild reaction conditions, operational simplicity, use of inexpensive, eco-friendly and green reaction media, catalyst-free conditions and absence of toxic organic solvents.
Electrospray mass spectrometry (ESI-MS) was performed using the Advion expression Compact Mass Spectrometer (CMS).