Comparison of activity of some heterogeneous solid acid catalysts for the synthesis of substituted coumarins.

Entry	Catalyst	Catalyst (mol%)	T (°C)	Time (min)	Yield (%)	References
1	Fe3O4-DABCO	1	100	40	93	30
2	γ-Fe3O4@HAp–Ag	10	80	20	95	31
3	Fe3O4@SiO2@PrSO3H	2	130	25	96	32
4	CMK-15-SO3H	3	130	20	95	33
5	Random pore carbon-SO3H	7	130	60	90	34
6	Fe3O4@SiO2@EtSO3H	75	90	90	93	35
7	SnClx–SiO2	5	120	35	90	36
8	SBA-15-Ph-Pr–SO3H	7	130	60	90	36
9	ZrW2	20	12	120	94	37
10	SnW2	20	120	120	88	37
11	Nanosponge MFI zeolite	0.5	130	120	94	38
12	TiZnO	10	110	180	85	39
13	Fe3O4@Boehmite–NH2–CoII	6.6	90	30	95	40
14	SCCMNPs	6.5	120	20	98	29