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OMe
MeO
i
-Pr
PCy
2
PCy
2
i
-Pr
LPd
Cl
i
-PrO
O
i
-Pr
N
H
2
i
-Pr
L=BrettPhos
L=RuPhos
BrettPhos
RuPhos
Figure 3.21 Palladacycle catalysts for amination reactions.
Pd(OAc)
2
LiCl, acetone,
rt
then XPhos, rt
83%
toluene, 60 °C
AcO
Pd NH
2
NH
2
Pd NH
2
Cl
L
2
L = XPhos
10
L = SPhos
11
Scheme 3.38 Palladacycle prepared from 2-aminobiphenyl.
F
F
2mol%
10
2eq.K
3
PO
4
Ar
B(OH)2
R
1
R
1
ArX
+
F
F
THF, rt, 30min
F
F
F
i
Pr
N
Me
F
F
F
MeO
S
X=OTf
X=Cl
95 %
95 %
X=OTf
89%
X=Cl
99%
O
n
Bu
F
F
F
F
H
2
N
O
F
F
F
MeO
O
OMe
X=Cl
95%
X=Cl
96%
X=Cl
97%
Scheme 3.39 Coupling of polyfluoroboronic acids to aryl chlorides, bromides and
triflates.
this case forming carbazole and LPd(0). The-second generation palladacycle
was applied in ambient temperature Suzuki-Miyaura coupling reactions.
119
A wide range of (hetero)aryl halides and triflates were used as coupling
partners and excellent functional group tolerance was displayed
(Scheme 3.39). The otherwise unstable polyfluorophenyl and five-membered
2-heterocyclic boronic acids were coupled with a wide range of aryl (pseu-
do)halides, thanks to the milder reaction conditions offered by these cata-
lysts. The rate increase is explained by the fast generation of the catalytically
active species LPd(0) from the palladacycle 10.
Another challenging reaction, namely monoarylation of acetate esters
and aryl methyl ketones, was also carried out successfully using the first-
generation palladacycles.
120
Challenging heteroaryl chloride-heteroaryl
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