Nano-ZnO Catalyzed Multicomponent One-Pot Synthesis of Novel Spiro(indoline-pyranodioxine) Derivatives

Table 3

Optimization of the ZnO nanoparticle catalyzed model reaction for synthesis of 7′-amino-2′2′-dimethyl-2,4′-dioxo-1,2-dihydrospiro[indoline-3,5′-pyrano[2,3-d][1′,3′]dioxine]-6′-carbonitrile (4a).

Entry	Catalyst (mg)	Yield (%)
1	No catalyst	—
2	10	80
3	15	81
4	20	83
5	25	86
6	30	89

Amount of Reactants: Meldrum acid (1.0 mmol), isatin (1.0 mmol), malononitrile (1.0 mmol), and absolute ethanol (15 mL).