Table 3.

Synthesis of pyrazolo[4′,3′:5,6]pyrido[2,3-d]pyrimidine-5,7(6H)-dionein the presence of various catalysts under ultrasonic irradiation.

Entry	Catalyst	(mol%)	Time (min)	Yield (%)
1	FeCl3	10	120	25
2	[PVI-SO3H]FeCl56	10	120	48
3	Fe3O4	10 mg	120	Trace
4	NH4NO3	10	120	Trace
5	SSA57,58	10 mg	120	35
6	Nano-SB-[PSIM]Cl59	10 mg	120	Trace
7	NaHSO4	10	120	–
8	GTBSA60	10	120	55
9	SBA-15/(CH2)3 N(CH2PO3H2)261	10 mg	120	35
10	[Py-SO3H]Cl62	10	120	35
11	p-TSA	10	120	25
12	Et3N	10	120	–
13	MIL-100(Cr)/NHEtN(CH2PO3H2)263	10 mg	120	63
14	APVPB64	10 mg	120	40
15	MHMHPA65	10	120	55
16	GTMPA66	10	120	40
17	Co(NO3)3·6H2O	10	120	36
18	H2BDC-NH2	10	120	42
19	Fe3O4@Co(BDC)-NH2	10 mg	50	72a

^aThis work.