A summary of solvent-free pyrano[2,3-c]pyrazoles and spiropyrano[2,3-c] pyrazoles synthesis.

Product	Reactants	Catalyst	Solvent	Method employed	Reaction time	Yield	Ref.
Pyrano[2,3-c]pyrazoles	Four-component system: hydrazine hydrate, ethyl acetoacetate, aldehyde/ketone, and malononitrile	Per-6-amino-β-cyclodextrin	Solvent-free	Room temperature mixing	1–2 min	90–99%	Kanagaraj et al.102
4H-Pyrano[2,3-c]pyrazoles	Four-component system: aldehydes, malononitrile, ethyl acetoacetate, and hydrazine monohydrate	[bmim]OH ionic liquid	Solvent-free	Heating (50–60 °C)	5–10 min	81–91%	Khurana and Chaudhary103
Biologically active substituted pyranopyrazoles	Four-component system: aromatic aldehydes, ethyl acetoacetate, hydrazine hydrate, malononitrile	[(CH2)4SO3HMIM][HSO4]	Solvent-free	Room temperature stirring	30 min	80–90%	J. Ebrahimi et al.104
Pyrano[2,3-c]pyrazoles	Three-component system: aldehyde, ethyl cyanoacetate, and pyrazolone	Nd-Salen immobilized mesoporous silica (NdSM)	Solvent-free	Heating (70 °C)	10–20 min	78–92%	A. Rather et al.105
Pyranopyrazole derivatives	Four-component system: aromatic aldehyde, phenylhydrazine, ethyl acetoacetate, malononitrile	β-Cyclodextrin/epichlorohydrin (β-CD/EP)	Solvent-free	Heating (100 °C)	20–60 min	65–94%	J. Nasab et al.106
Pyrano[2,3-c]pyrazoles	Four-component system: ethyl acetoacetate, hydrazine hydrate, malononitrile, and aryl aldehydes	CoCuFe2O4 magnetic nanocrystals	Solvent-free	Room temperature stirring	40–45 min	89–92%	Dadaei and Naeimi107
Pyrano[2,3-c]pyrazoles	Four-component system: malononitrile, ethyl acetoacetate, phenyl hydrazine hydrate, and substituted aldehydes	Fe3O4@SiO2@Si(OEt)(CH2)3@melamine@TC@Cu(OAc)2	Solvent-free	Room temperature stirring	7–15 min	63–92%	Soleimani et al.108
Pyrano[2,3-c]pyrazoles	Four-component system: malononitrile, ethyl acetoacetate, hydrazine hydrate, and substituted aldehydes	CuSnO3:SiO2	Solvent-free	Heating (60 °C)	10 min	90–98%	S. L. Sangle et al.109
Pyrano[2,3-c]pyrazoles	Four-component system: malononitrile, ethyl acetoacetate, hydrazine hydrate, and substituted aldehydes	Nitrogen-doped graphene oxide (NGO)	Solvent-free (physical grinding)	Room temperature mixing	2 min	48–99%	S. Ganesan et al.110
Dihydropyrano[2,3-c]pyrazoles	Three-component system: methyl arenes, 3-methyl pyrazolone, and malononitrile	Urea hydrogen peroxide	Solvent-free (physical grinding)	Room temperature mixing	15–25 min	80–88%	P. Verma et al.111
Pyrano[2,3-c]pyrazoles	Four-component system: malononitrile, ethyl acetoacetate, hydrazine hydrate, and substituted aldehydes	NMPyTs (ionic liquid; boiled at 120 °C)	Solvent-free (physical grinding)	Room temperature mixing	10 min	80–95%	Amol V. Sapkal et al.112