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M
e
Me
O
O
Ph
S
N
S
F
Ph
O
O
F BF
4
F
OTf
N
Me
N
Me
Me
Me
NFSI
49%(p/m=12/1)
70%(p/m=13/1)
81%(p/m=13/1)
Figure 12.8 Effect of different F
+
reagents.
Cl
Cl
Pd catalyst
[Ph
2
I]BF
4
PhNO
2
130 °C, 16h
Ph
Ph
Cl
Me
N
+
Pd
Cl
Me
N
selectivity 71: 1
Cl
Cl
Pd catalyst
Scheme 12.22 Pd-catalyzed site-selective arylation of naphthalene.
N
Cl
reductive
elimination
Ph
[Ph
2
I]X
Pd
oxidative addition
(rate determining step)
X
N
X= Cl or BF
4
PhI
+X
-
+X
-
Ph
Ph
N
Cl
Cl
N
Pd
Pd
X
N
N
coordination
+X
-
Ph
HX
N
Cl
Pd
palladation
X
N
Figure 12.9 Proposed mechanism of
the Pd-catalyzed direct
arylation of
naphthalene.
Also, F
+
reagents played the role of suitable oxidants, which was crucial for
the success of the reaction (Figure 12.8).
In the absence of any directing group, Hickman and Sanford also reported
a site-selective arylation of naphthalenes in 2011 (Scheme 12.22).
36
The
highly selective (50 : 1) a-arylation with [Ph
2
I]BF
4
as the arylating agent was
realized by tuning the structure of the diimine ligand. The proposed
mechanism consists of p-coordination of the naphthalene ring to the Pd
IV
center as the fast step, after the rate-determining oxidation of Pd
II
to Pd
IV
via
oxidative addition (Figure 12.9).
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