Effects of various catalysts on the synthesis of 4a^a.

Entry	Catalyst	Conditions	Yieldb (%)
1	Fe3O4	EtOH/reflux	50
2	SiO2@Fe3O4	EtOH/reflux	40
3	GPTMS@SiO2@Fe3O4	EtOH/reflux	Trace
4	Mesalamine	Grinding, r.t.	71c
5	Mesalamine/GPTMS@SiO2@Fe3O4	Grinding, r.t.	95

^aReaction conditions: benzaldehyde (1 mmol), dimedone (1 mmol), malononitrile (1 mmol), catalysts (0.07 g), under different conditions.

^bIsolated pure yield.

^c0.1 g catalyst was used.