Table 2.

Optimizing the reaction conditions in the synthesis of pyrazolopyridine 5b^a.

Entry	Catalyst	Catalyst loading (g)	Solvent	Temp (°C)	Yield (%)b
1	_		_	r.t	Trace
2	_		_	80	Trace
3	Fe3O4/Se	0.02	_	r.t	37
4	Fe3O4/Se	0.02	EtOH	r.t	82
5	Fe3O4/Se	0.02	EtOH	80	87
6	Fe3O4/Se	0.02	H2O	r.t	< 41
7	Fe3O4/Se	0.02	H2O	80	< 50
8	Fe3O4/Se	0.02	EtOH	Ultrasonic, r.t	84
9	Fe3O4/Se	0.01	EtOH	80	76
10	Fe3O4/Se	0.03	EtOH	r.t	96
11	Fe3O4/Se	0.04	EtOH	r.t	98
12	Fe3O4	0.03	EtOH	r.t	37
13	Se	0.015	EtOH	r.t	35

^aReaction conditions: ethyl acetoacetate (2 mmol), hydrazine hydrate (2 mmol), 3-nitrobezaldehyde (1 mmol) and ammonium acetate (1 mmol), catalyst (0.03 mg).

^bThe yields relate to the isolated product.