chapter 2 palladium catalysts in suzuki cross- coupling reaction

yield was very low (Table 5.8, entry 1). The use of 2 or 3 g of zeolite has no effect on
the reaction (Table 5.8, entries 2, 3). Nevertheless, presence of 4 g zeolite in the reaction
medium decreased product formation (Table 5. 8, entry 4). We also increased amount of
phenylboronic acid reagent to 2 mmol in the presence of 1g extra amount of zeolite. The
catalyst could not show activity (entry 5). Reaction was repeated in the presence of
NaOEt (entry 6). We increased reaction temperature to 130 ºC (entry 7). They didn’t
work. Finally, moderate yield was obtained by using Fluka reagent (Table 5.8, entry 8).
We concluded that Pd concentration of 0.005% was optimum in the presence of 1g of
zeolite and Fluka reagent for Suzuki reactions of 4-bromoanisole.
Table 5.8. The Optimization of Pd-NaY catalyzed Suzuki reaction of 4-bromoanisole
over the Pd concentration of 0.001 % a
Entry Zeolite (g) Ratio of PhB(OH)2 Conversion% b Yield% b
1 1 1.2 49 33
2 2 1.2 55 33
3 3 1.2 68 31
4 4 1.2 18 18
5 1 2 20 14
6 c 1 1.2 25 8
7 d 1 1.2 41 14
8 e 1 1.2 78 61
a Reaction conditions: 5mmol 4-bromoanisole, 6mmol PhB(OH)2 (Merck), 10mmol Na2CO3,
10mL DMA: water (1:1) under air at 100 ºC. b GC yield. c NaOEt was used as base. d at 130 ºC.
e PhB(OH)2 was supplied from Fluka and amount of all reagents was increased by two.
5.2.2. Pd(NH3)4 2+ -Loaded NaY Type Zeolite Catalyzed Suzuki
Reactions of Aryl Bromides and ArylBoronic Acids
After optimization of reaction conditions, we investigated the substrate scope of
the reaction for a range of aryl bromides with PhB(OH)2 (Table 5.9).
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