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CHO
R
X=Cl
(1:1)
R'
Pd(OAc)
2
(1 mol%)
SIMes.HCl (2 mol%)
CHO
X
+
R
R'
Cs
2
CO
3
, dioxane, 80°C
R
X=Br,I
X=Br
(1:2)
CHO
R'
R'
CHO
N
CHO
CHO
COMe
COMe
92%
85%
88%
OMe
CHO
CHO
N
COMe
CHO
MeOC
COMe
92%
87%
56%
Scheme 4.44 Direct arylation of (hetero)aromatic aldehydes using an in situ-
generated catalytic system.
Y
[Pd(IPr)(OAc)
2
(H
2
O)]
(
69
)
(1 - 3 mol%)
Z
Y
Z
IPr .H C l (1 - 3 m ol%)
K
2
CO
3
, DMA, 130°C
H
Cl
NN
O
NMs
AcO
Pd
OAc
OH
2
91%
82 %
84 %
OMe
OMe
[Pd(IPr)(OAc)
2
(H
2
O)]
69
N
H
F
3
C
89%
92 %
Scheme 4.45
Intramolecular direct arylation using [Pd(IPr)(OAc)
2
(H
2
O)].
In 2005, Sames and co-workers investigated the reactivity of Pd-NHC
systems in the direct arylation of N-containing heterocycles. First, they
showed the beneficial effect of using IMes instead of PPh
3
for the selective
C3 arylation of indole.
145
Higher yields and selectivities were observed in
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