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N
N
O
N
Pd
PS
O
Pd
O
O
O
N
PS
O
52
PS = cross-linked polystyrene
53
Scheme 14.47
Cl
Cl
Pd
Cl
Na
2
PdCl
4
MeOH, rt
N
OH
N
N
O
N
N
N
O
NaH, DMF
S
S
S
54
55
glass/Merrifield resin composite
Scheme 14.48
Cy
Cl
56
(3 mol %)
KF
EtOH/H
2
O (5:1)
80 °C, 24 h
Cl
Ph
P
Pd
Q-phos
+ PhB(OH)
2
Cy
Cl
Q-phos =
t
-Bu
2
PC
5
H
4
FeC
5
Ph
5
56
89%
Scheme 14.49
n
n
O
(AcO)
2
Pd
O
(
NH
4
)
2
S
2
O
8
, TMEDA
SDS, HCl
Pd(OAc)
2
Pd(OAc)
2
O
N
N
N
N
N
N
O
N
O
O
N
O
O
N
O
Pd
(OAc)
2
57
58
59
Scheme 14.50
could be coordinated. The resulting material was effective for Suzuki coup-
lings of aryl bromides in water-ethanol (1 : 1). No palladium leaching was
observed in water-ethanol or a range of organic solvents. Tunable catalyst
systems can be generated by coordinating ligands to fiber-supported pal-
ladium complexes.
154
FibreCats with a supported dicyclohexylphenylphos-
phine ligand modified by sterically demanding, electron-rich ligands, such
as tri-tert-butylphosphine, provided high activity for Suzuki coupling of aryl
chlorides in water-ethanol (5 : 1) at 80 1C (Scheme 14.49). No palladium
leaching (
o
0.01 ppm) was observed in these reactions.
Palladium supported on network polymer 58 formed by free
radical polymerization of 2,4,6-triallyloxytriazine (57) catalyzes the Heck,
Sonogashira and Suzuki couplings of aryl iodides and bromides in aqueous
solvents (Scheme 14.50).
155
The recyclability of polymeric catalyst 59 was
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