• Journal of the Korean Chemical Society
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• v.56 no.3
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• pp.328-333
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• 2012

A simple, convenient and practical green synthetic protocol for sodium bisulfite catalyzed multicomponent reaction of ethyl acetoacetate, hydrazine hydrate, malononitrile, and various aldehydes for the synthesis of 6-amino-4-phenyl-3-methyl-2,4-ihydropyrano[2,3-c]pyrazole-5-carbonitriles using ultrasound irradiations in solvent free condition. This method provides the advantage of operational simplicity, shorter reaction time and excellent yields making the protocol environment friendly and economically lucrative.