Sodium cyclamate-catalyzed expeditious and sustainable synthesis of 6-amino-5-cyano-3-methyl-4-aryl-1,4-dihydropyrano[2,3-c]pyrazoles

Pyrano[2,3-c]pyrazoles represent an important class of fused heterocyclic ring systems largely present in natural and synthetic organic compounds.1 Several pyrano[2,3-c]pyrazole derivatives have been reported and they shows numerous biological properties, such as anti-inflammatory, analgesic, anti-bacterial, anticancer, vasodilator, antioxidant, antifungal, anti-microbial, inhibitory on human Chk1 kinase, antimalarial, hypoglycemic, hypotensive, insecticidal and molluscicidal activities.2 They also find the applications in biodegradable agrochemicals and pharmaceutical ingredients.3 Herein, we report an efficient synthesis of 6-amino-5-cyano-3-methyl-4-aryl-1,4-dihydropyrano[2,3-c]pyrazoles (5a-n) via four-component cyclocondensation of substituted benzaldehydes (1a-n), hydrazine hydrate (2), malononitrile (3), and ethyl acetoacetate (4) at 50 °C in the presence of catalytic amounts of an organocatalyst sodium cyclamate in water as medium. The structure of synthesized heterocycles characterized using melting points, 1H and 13C NMR and IR spectroscopic data

Keywords:

Aryl aldehyde , Green synthesis , Pyrano[2 , 3-c]pyrazole , Sodium cyclamate