The synthesis of 5-substituted-1H-tetrazoles catalyzed by (Fe₃O₄@NFC@NSalophCu)CO₂H^a.

Entry	Aldehyde	Time (min)	Tetrazole	Yieldb (%)	Mp (°C)	TON	TOF	Ref. (lit)
1a		15		97	217–218	242.5	970	60
2b		15		97	258–259	242.5	970	60
3c		15		97	220–221	242.5	970	60
4d		20		90	233–234	225	682	60
5e		10		98	232–233	245	1476	60
6f		15		98	154–156	245	980	60
7g		30		85	220–221	212.5	425	60
8h		10		98	133–134	245	1476	60
9i		15		92	187–189	230	920	53
10j		10		75	214–215	187.5	1130	60

^aReaction conditions: aldehyde (1.0 mmol), hydroxylamine (1.2 mmol), sodium azide (1.5 mmol), catalyst (0.4 mol%), and H₂O (5 mL); 60 °C.

^bIsolated yield.