Optimization of the three-component reaction of 4-hydroxycoumarin (1), 4-chlorobenzaldehyde (2e), and malononitrile (3) under various conditions^a.

Entry	Solvent	Catalyst (mg)	Temp.	Time (min)	Yieldb (%)
1	CH2Cl2	MNPs@Cu/10	Reflux	8	53
2	CH3CN	MNPs@Cu/10	Reflux	8	59
3	toluene	MNPs@Cu/10	Reflux	8	59
4	DMF	MNPs@Cu/10	Reflux	8	63
5	H2O	MNPs@Cu/10	Reflux	8	69
6	EtOH	MNPs@Cu/10	Reflux	8	77
7	Solvent-free	—	90 °C	8	Trace
8	Solvent-free	MNPs@Cu/10	60 °C	8	80
9	Solvent-free	MNPs@Cu/10	80 °C	8	87
10	Solvent-free	MNPs@Cu/10	90 °C	8	95
11	Solvent-free	MNPs@Cu/10	100 °C	8	95
12	Solvent-free	MNPs@Cu/10	110 °C	8	92
13	Solvent-free	MNPs@Cu/5	90 °C	8	64
14	Solvent-free	MNPs@Cu/10	25 °C	8	25
15	Solvent-free	MNPs@Cu/15	90 °C	8	91
16	Solvent-free	MNPs@DETA@piperidine/10	90 °C	20	85
17	Solvent-free	Cu(salal)2/10	90 °C	25	78

^aReaction conditions: 4-hydroxycoumarin (1 mmol), 4-chlorobenzaldehyde (1 mmol), malononitrile (1.1 mmol), and required amount of the catalysts.

^bThe yields refer to the isolated product.