ZnO Nanoparticles as an Efficient, Heterogeneous, Reusable, and Ecofriendly Catalyst for Four-Component One-Pot Green Synthesis of Pyranopyrazole Derivatives in Water

Table 2

Screening of catalysts for one-pot condensation of ethyl cyanoacetate, hydrazine hydrate, 4-methoxy benzaldehyde, and methyl acetoacetate.

Entry	Catalyst	Catalyst; (mol %)	Yield; (%)	Time; (min.)
5e	Alum	3	66	110
5e	ZnO nps	9	89	60
5e	Mont K10	7	75	80
5e	P2O5	5	68	110
5e	Acidic alumina	7	63	100
5e	Silica	12	69	100
5e	Mont KSF	7	58	90
5e	Glacial acetic acid	12	60	90

Reaction conditions: hydrazine hydrate (1) (1 mmol), methyl acetoacetate (2) (1 mmol), 4-methoxy benzaldehyde (3) (1 mmol), and ethylcyano acetate (4) (1 mmol) in water (2 mL).