An Efficient Four-Component, One-Pot Synthesis of 6-Amino-4-Aryl-3- Methyl-2,4-Dihydropyrano[2,3-C]Pyrazole-5-Carbonitriles Under Phase- Transfer Catalyst

A series of 6-amino-4-aryl-3-methyl-2,4-dihydropyrano[2,3-c]pyrazole-5-carbonitriles (5a–5j) were synthesized by four-component one-pot reaction of methyl acetoacetate (or ethyl acetoacetate), hydrazine hydrate, arylaldehydes and malononitrile in the presence of phase transfer catalyst. A highest yield of product was obtained while using 30 mol % of HDBAC as a catalyst.