Table 2.

Optimization of the reaction condition for the synthesis of 2-amino-3-cyano-4H-chromene catalyzed by Fe₃O₄@UiO@DAS.

Entry	Cat. (mg)	Temp	Solv	Time (h)	Yielda (%)
1	–	Reflux	H2O	6	18
2	–	Reflux	EtOH	6	21
3	–	Reflux	H2O:EtOH (5:1)	6	29
4	–	Reflux	THF	6	Trace
5	4,4′-Diamino-2,2′-stilbenedisulfonic acid 3 mg	Reflux	H2O:EtOH (5:1)	6	73
6	MNP@MPS 3 mg	Reflux	H2O:EtOH (5:1)	6	32
7	MNP@MPS@PAA 3 mg	Reflux	H2O:EtOH (5:1)	6	45
8	Fe3O4@UiO-66-NH2 3 mg	Reflux	H2O:EtOH (5:1)	6	32
9	Fe3O4@UiO@DAS 5 mg	Ambient	Solvent-free	6	Trace
10	Fe3O4@UiO@DAS 5 mg	80	Solvent-free	6	57
11	Fe3O4@UiO@DAS 5 mg	Reflux	H2O:EtOH (5:1)	6	65
12	Fe3O4@UiO@DAS 5 mg	Reflux	H2O:EtOH (5:1)	3	65
13	Fe3O4@UiO@DAS 5 mg	Reflux	H2O:EtOH (5:1)	0.5	65
14	Fe3O4@UiO@DAS 10 mg	Reflux	H2O:EtOH (5:1)	0.5	83
15	Fe3O4@UiO@DAS 13 mg	Reflux	H2O:EtOH (5:1)	0.5	94
16	Fe3O4@UiO@DAS 15 mg	Reflux	H2O:EtOH (5:1)	0.5	94

Reaction conditions: Benzaldehyde (1a, 1 mmol), malononitrile (2, 1.1 mmol), and 4-hydroxy-6-methyl-2H-pyran-2-one (3a, 1 mmol) in the presence of Fe₃O₄@UiO@DAS and 2 ml of water–ethanol (5:1) as a green solvent.

Significant values are in [bold].

^aIsolated yields.