Table 1.

Effect of various amounts of catalysts, temperature and solvents in synthesis of pyrazolo[4′,3′:5,6]pyrido[2,3-d]pyrimidines.

Entry	Solvent	Catalyst (mg)	Temp. (˚C)	Time (min.)	Yield (%)
1	–	5	100	40	70
2	–	10	100	15	91
3	–	20	100	35	72
4	–	–	100	120	-
5	–	10	110	20	85
6	–	10	50	60	46
7	–	10	25	70	40
8	EtOH	10	Reflux	45	70
9	DMF	10	100	100	30
10	H2O	10	Reflux	120	–
11	CH3CN	10	Reflux	120	Trace
12	n-Hexane	10	Reflux	120	–
13	CHCl3	10	Reflux	100	35
14	Toluene	10	Reflux	120	–
15	MeOH	10	Reflux	60	60
16	CH2Cl2	10	Reflux	65	35
17	EtOAc	10	Reflux	120	–