Comparison of MNPs@CNF@ATSM–Co(ii) with reported catalysts for the synthesis of highly substituted piperidine derivatives^a.

Entry	Catalyst (mol%)	Solvent	Time (h)	Temp. (°C)	Yield (%)	Ref.
1	BF3·SiO2	MeOH	—	65	—	27
2	Ph3CCl	MeOH	5	50	79	18
3	Tartaric acid	MeOH	14	RT	79	25
4	ZrOCl2·8H2O	EtOH	3.5	Reflux	80	27
5	ZrCl4	EtOH	9	RT	90	28
6	BDMS	EtOH	3	RT	75	45
7	Bi(NO3)3·5H2O	EtOH	12	RT	81	46
8	p-TsOH·H2O	EtOH	10	RT	78	20
9	TBATB	EtOH	24	RT	74	47
10	InCl3	CH3CN	24	RT	60	31
11	Ascorbic acid	EtOH	11	RT	86	48
12	I2	MeOH	8	RT	81	49
13	Glutamic acid	EtOH	7	RT	89	50
14	MNPs@CNF@ATSM–Co(ii)	EtOH	2	40	94	This work

^aBased on the three-component reaction of benzaldehyde (2 mmol), aniline (2 mmol), and methyl acetoacetate (1 mmol).