Synthesis of hexahydroquinoline derivatives in the presence of Fe₃O₄@SiO₂@RF–SO₃H nanocatalyst at 40 °C under solvent-free condition^a.

Entry	R	Time	Yieldb (%)	MP	Ref.
1	H	15	95	285–286	286 (ref. 12)
2	4-CH3	18	92	290–292	294–295 (ref. 12)
3	4-OCH3	20	91	290–291	289–293 (ref. 12)
4	2-OCH3	21	91	288–289	—
5	2-OH	22	90	290–291	—
6	4-Isopropyl	20	93	289–290	—
7	4-NO2	12	98	280–292	290–293 (ref. 12)
8	3-NO2	13	97	282–284	282–283 (ref. 12)
9	4-CN	13	97	287–290	—
10	4-Cl	14	92	289–291	290–291 (ref. 10)
11	2,4-Cl	13	94	290–293	—
12	4-Br	13	92	296–298	295–296 (ref. 10)
13	3-Br	12	91	292–294	293–294 (ref. 12)

^aReaction conditions: benzaldehyde (1 mmol), dimedone (1 mmol), malononitrile (1 mmol), ammonium acetate (1 mmol) and Fe₃O₄@SiO₂@RF–SO₃H nanocatalyst (0.9 mol%).

^bIsolated yields.