Nano-Pd/Chitosan Composite: An Extremely Effective Catalyst to the Synthesis of Pyrazolyl Analogues through Suzuki–Miyaura Cross-Coupling Reactions in an Aqueous Medium

Table 1

^aReaction condition and screening of the nano-Pd/chitosan catalyst.

Entries	Solvents	Bases	Temperatures (°C)	Times (h)	Yields^b (%)
1	Dioxane	Na2CO3	80	2	35
2	EtOH	Na2CO3	80	2	41
3	CH3CN	Na2CO3	100	2	55
4	Toluene	Na2CO3	80	2	30
5	DMF	Na2CO3	100	2	60
6	H2O	Na 2 CO 3	60	1	85
7	H2O	K2CO3	60	1	65
8	H2O	Cs2CO3	60	1	57
9	H2O	Et2NH	60	1	48
10	H 2 O	Na 2 CO 3	50	1	76
11	H 2 O	Na 2 CO 3	40	1	72

^aCompound 1:1.0 mmol, 4-cyano-3-methoxyphenylboronic acid:1.5 mmol, Na₂CO₃: 2.0 mmol, nano-pd/chitosan: 0.02 mol %, water: 5 mL, 60°C in pressure vessel tube 1 h; ^bisolated and recrystallized yield. The bold values represent maximum yield of the product.