Optimization of reaction conditions for synthesis of 3,3,3,6,6-pentamethyl-9-phenyl-3,4,5,6,7,9-hexahydro -1H-3,5-xanthene-1,8(2H)-dione.

Entry	Solvent	Catalyst (mol%)	Temp. (°C)	Time (min)	Yielda (%)
1	EtOH : H2O	0.5	45	15	90
2	H2O	0.5	45	20	85
3	EtOH	0.5	45	10	96
4	MeOH	0.5	45	10	85
5	CH3CN	0.5	45	60	70
6	EtOAC	0.5	45	75	65
7	CHCl3	0.5	45	45	85
8	Neat	0.5	45	45	60
9	EtOH	—	45	10	Trace
10	EtOH	1	45	10	95
11	EtOH	1.5	45	10	90
12	EtOH	0.5	—	60	55
13	EtOH	0.5	55	10	90
14	EtOH	0.5	65	10	85
15	EtOH	0.5	45	20	96
16	EtOH	0.5	45	40	92
17	EtOH	0.5	45	60	85
18	EtOH	0.5b	45	60	0
19	EtOH	0.5c	45	60	0
20	EtOH	0.5d	45	30	70

^aReaction conditions: benzaldehyde (1 mmol) and dimedone (2 mmol). The catalyst was prepared by using 0.5 mol% of catalyst as explained in the Experimental section.

^bReaction was performed in the presence of Fe₃O₄ as the catalyst.

^cReaction was performed in the presence of Fe₃O₄@NFC as the catalyst.

^dReaction was performed in the presence of Fe₃O₄@NFC@NNS-Mn(iii) as the catalyst.