chapter 2 palladium catalysts in suzuki cross- coupling reaction

could be reused multiple times. The cross-coupling reaction of tolyl boronic acid with
chloropyridines, chloroquinoline, or activated chloroarenes having an electron-
withdrawing group was carried out in toluene, aqueous K3PO4 at 80 °C in the presence
of a polymer-bound PdCl2 catalyst. The resin catalyst was recovered by filtration (Table
3.1, entry 3).
Hu et al. designed and synthesized monophosphine-containing polymer, 25
(Figure 3.5), which was then used for the room-temperature palladium catalyzed
reaction between aryl chlorides and arylboronic acids (Hu et al. 2003).
Sauer and Wang studied palladium complexes anchored on polyethylene-based
supports known as FibreCat catalysts for Suzuki coupling of aryl chlorides, bromides
and iodides under microwave heating conditions. A wide variety of aryl halides were
effectively converted in 10-25 minutes (Wang and Sauer 2004).
Triphenylphosphine based polymer-supported FibreCat precatalysts 26-29
(Figure 3.6) can be used to achieve room-temperature couplings of activated and
inactivated aryl bromides with phenylboronic acid in nearly quantitative conversions
(Colacot et al. 2002).
26
PPh2 Pd
AcO
PPh2 Pd
RCN
Cl
Cl
Me
27
28 29
PPh 2
PPh2 Pd
Cl
Pd
PPh 2
Figure 3.6. Polymer-supported FibreCat precatalysts
HC
CH
O
CH
CH
Ph Ph
In recent years, palladium nanoparticles have also been used as catalysts for
Suzuki reactions. In fact, these particles have characteristically high surface-to-volume
29