Catalytic activity of the Zr@IL-Fe₃O₄ MNPs in the synthesis of dihydropyrano[3,2-c]chromenes under solvent-free conditions^a.

Entry	Aldehyde	Time (min)	Yieldb (%)	M.P. (obsd) (°C)	M.P. (lit.) (°C)	Product
1		10	96	254–256	255–256 (ref. 45)
2		15	96	257–259	258–260 (ref. 46)
3		15	92	247–249	246–248 (ref. 47)
4		15	95	267–269	266–268 (ref. 48)
5		15	92	248–251	252–254 (ref. 49)
6		20	94	290–292	295–297 (ref. 48)
7		15	92	255–257	258–260 (ref. 38)
8		15	94	258–260	261–262 (ref. 45)
9		15	96	254–256	257–259 (ref. 38)
10		15	92	285–287	289–290 (ref. 48)
11		15	95	259–261	260–262 (ref. 47)
12		20	92	263–265	266–267 (ref. 49)
13		25	90	225–227	222–224 (ref. 45)
14		25	91	252–254	251–253 (ref. 47)
15		25	91	253–255	250–252 (ref. 50)
16		25	91	224–226	227–229 (ref. 51)
17		25	91	252–254	252–253 (ref. 52)

^aReaction conditions: 4-hydroxycoumarin (1 mmol), malononitrile (1.2 mmol), aldehyde (1 mmol), Zr@IL-Fe₃O₄ MNPs (20 mg), solvent-free.

^bThe yields refer to the isolated product.