One-Pot, Four-Component Synthesis of Pyrano[2,3-c]pyrazoles Catalyzed by Vanadium Oxo Pyridinoporphyrazine

Tetrapyridinoporphyrazines are derivatives of phthalocyanines which have pyridine rings insteadof outerbenzene rings [1]. Porphyrazines containing metal ions such as Zn(II), Ni(II),Cu(II) are strongly stabile. This situation is very important for the application this macrocycliccomplexes as a stable catalyst in organic reactions. Pyrazole derivetives are the significantkind of heterocyclic compounds that feature in several pharmaceutical targets and naturalproducts of medicinal interest. Dihydropyrano[2,3-c]pyrazole derivatives have showed a widevariety of biological activities counting anticancer, antimicrobial, anti-inflammatory, insecticidal,and molluscicidal activities. In continuation of our efforts to synthesize of novel catalysts[2] and multicomponent reactions we wish to report the synthesis of vanadium-oxotetrapyridinoporphyrazine [VO(TPPA)] as an efficient catalyst for the synthesis of dihydropyrano[2,3-c]pyrazole through the condensation reaction of aryl aldehydes, ethyl acetoacetate,malononitrile, and phenyl hydrazine under solvent free condition at 60 °C (Fig. 1).