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

Table 4

Comparison of catalytic activity of ZnO nanoparticles in the synthesis of compound 5e by conventional (Δ) heating method and stirring at 25°C.

Entry	Conditions	Types of catalysts	Reaction time (hrs/min.)	Yield (%)
	Stirring (25°C)	No catalyst	8 hrs	Traces
	Stirring (25°C)	Nano-ZnO	60 min	89
	Δ	No catalyst	6 hrs	Traces
	Δ	Nano-ZnO	40 min	55