The synthesis of pyrano[2,3-c]pyrazoles catalyzed by [Fe₃O₄@SiO₂-Schiff base-Cu^(II)] complex.

Entry	Aldehyde	Product	Time (min)	Yielda,b (%)	Melting point (°C)
					Measured	Literature
1			10	98	243–245	243–-245 (ref. 38)
2			12	98	234–236	234–236 (ref. 38)
3			15	96	230–231	229–230 (ref. 39)
4			20	94	238–240	237–240 (ref. 40)
5			30	93	195–197	196–198 (ref. 40)
6			15	97	181–183	180–182 (ref. 38)
7			25	96	221–222	221–222 (ref. 41)
8			20	95	207–209	207–209 (ref. 38)
9			35	94	172–174	172–174 (ref. 42)
10			30	91	209–211	209–211 (ref. 38)
11			45	88	246–248	246–248 (ref. 43)
12			55	90	235–237	235–237 (ref. 41)
13			35	92	221–223	222–224 (ref. 38)
14			70	87	209–211	209–211 (ref. 44)
15			70	87	227–228	227–228 (ref. 41)
16			20	87	182–184	182–183 (ref. 45)
17			75	88	218–220	218–219 (ref. 41)
18			10	99	250–251	250–251 (ref. 46)
19			45	90	229–231	228–230 (ref. 47)
20			75	89	214–215	215–216 (ref. 41)
21			65	86	223–224	222–224 (ref. 47)

^aIsolated yield.

^bConditions: ethyl acetoacetate (1 mmol), hydrazine hydrate (1 mmol) arylaldehyde (1 mmol), malononitrile (1 mmol), [Fe₃O₄@SiO₂-Schiff base-Cu^(II)] (12 mg) in water solvent (3 mL) at reflux conditions.