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R
3
I
[Rh( coe)
2
Cl]
2
(5 mol%)
PCy
3
(40 mol%)
Et
3
N(4 equiv)
THF,150 °C, 6h
R
1
N
R
1
N
+
X
X
R
2
R
2
n
n
R
3
2equiv
N
O
N
OMe
N
N
N
73%
a
56%
78%
coe = cyclooctene;
a
135 °C, 18h
Scheme 12.62 Rh-catalyzed arylation of heteroarenes.
eoc
Cl
coe
Rh
Rh
coe
eoc
Cl
CH
3
CH
3
PCy
3
+
HI
N
N
Ph
Cy
3
P
N
N
Rh
Cy
3
P
Cl
CH
3
+
I
-
PCy
3
CH
3
N
Cy
3
P
Rh
Cl
C
l
N
H
PCy
3
Rh
PCy
3
H
Ph
-PCy
3
PCy
3
CH
3
PCy
3
PCy
3
N
CH
3
Rh
Cl
PCy
3
N
H
Cl
Rh
I
H
Ph
PhI
Figure 12.17 Proposed mechanism of Rh-catalyzed arylation of heteroarenes.
Br
[Rh(coe)
2
Cl]
2
(5 mol%)
i
Pr
2
i
BuN (3 equ iv)
dichlorobenzene
MW (250 °C), 40 min
N
N
+
N
N
Cy
81%
P
30 mol%
Scheme 12.63 Microwave-assisted Rh-catalyzed arylation of heteroarenes.
Bergman and co-workers also developed a microwave-assisted protocol
with wider substrate scope and where by-product formation could be sup-
pressed (Scheme 12.63).
91
Sames and co-workers reported an Rh-catalyzed C2 arylation of indoles
having a free NH using [Rh(coe)
2
Cl
2
]
2
in the presence of electron-deficient
phosphine ligands.
92
Although indoles with anilide groups were compatible,
no reaction was observed with 7-azaindole (Scheme 12.64).
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