Catalytic activity of the Zr@IL-Fe₃O₄ MNPs in the synthesis of 4H-benzo-[b]-pyrans under solvent-free conditions^a.

Entry	Aldehyde	Time (min)	Yieldb (%)	M.P. (obsd) (°C)	M.P. (lit.) (°C)	Product
1		17	91	233–235	231–233 (ref. 53)
2		15	96	214–216	212–214 (ref. 54)
3		15	92	227–229	228–229 (ref. 55)
4		15	95	211–212	210–212 (ref. 56)
5		15	92	206–208	207–209 (ref. 57)
6		15	92	182–184	178–180 (ref. 58)
7		15	94	205–207	208–209 (ref. 58)
8		15	95	227–229	228–229 (ref. 58)
9		15	92	226–228	227–230 (ref. 57)
10		15	95	208–210	210–211 (ref. 59)
11		20	92	201–203	203–205 (ref. 58)
12		20	92	182–185	174–177 (ref. 45)
13		25	90	198–200	194–196 (ref. 60)
14		25	91	219–221	223–225 (ref. 61)

^aReaction conditions: dimedone (1 mmol), malononitrile (1.2 mmol), aldehyde (1 mmol), Zr@IL-Fe₃O₄ MNPs (20 mg), solvent-free.

^bThe yields refer to the isolated product.