A summary of pyrano[2,3-c]pyrazoles and spiropyrano[2,3-c] pyrazoles synthesis using bio-catalysts.

Product	Reactants	Catalyst	Solvent	Method employed	Reaction Time	Yield	Ref.
Spiro[indoline-pyrano[2,3-c]-pyrazole] derivatives	Four-component system: malononitrile, hydrazine hydrate, β-keto ester, and carbonyl compound or isatin	Meglumine	Water/EtOH	Room temperature stirring	25–40 min	85–95%	Guo et al.76
Pyrano[2,3-c]-pyrazole and spiro[indoline-pyrano[2,3-c]-pyrazole] derivatives	Four-component system: hydrazine hydrate, malononitrile, ethyl acetoacetate, and various carbonyl compounds	Bovine serum albumin (BSA)	Water/EtOH	Reflux, heating (45 °C)	45 min	73–96%	Xingtian et al.77
Pyrano-[2,3-c]-pyrazoles	Four-component system: aldehydes, malononitrile, ethyl acetoacetate, and hydrazine hydrate	Lemon peel powder	Ethanol	Room temperature reflux	2–5 h	58–92%	Ghodke et al.78
Dihydropyrano[2,3-c]pyrazoles	Four-component system: aldehydes, malononitrile, ethyl acetoacetate, and hydrazine hydrate	Nano-eggshell/Ti(iv)	Solvent free	Room temperature stirring	8–25 min	62–96%	Dehghani et al.79
Dihydropyrano[2,3-c]pyrazoles	Four-component system: aldehydes, malononitrile, ethyl acetoacetate, and hydrazine hydrate	Aspergillus niger lipase (ANL)	Ethanol	Vigorous stirring, heating (30 °C)	60 min	70–98%	Bora et al.80
Pyrano[2,3-c]-pyrazoles and pyrazolyl4H-chromene derivatives	Four-component system: aldehydes/salicaldehydes, malononitrile, ethyl acetoacetate, and hydrazine hydrate	Bael fruit ash (BFA)	Water	Room temperature stirring	30 min	86–94%	Shinde et al.81