Chemistry Reference
In-Depth Information
Br
[Rh(PPh
3
)
3
Cl] (5 mol%)
Cs
2
CO
3
(1.7 equiv)
toluene, reflux, N
2
,20h
O
OH
R
1
+
OH
Me
R
1
OP
i
Pr
2
R
2
R
1
O
Me
R
2
1.5 equiv
15 mol%
R
2
phenol
phosphinite
product (yield)
O
Me
OH
Me
OH
Me
OP
i
Pr
2
Me
Me
Me
Me
Me
Me
Me
96%
Me
O
OH
OP
i
Pr
2
O
OH
Me
OH
71%
23%
Scheme 12.58 Rh-catalyzed ortho-arylation of phenols.
OH
OH
R
1
R
1
Ar
R
2
R
2
base
ArX
OP
i
Pr
2
OP
i
Pr
2
R
1
R
1
Ar
L
n
Rh
III
X
Ar
L
n
Rh
I
R
2
R
2
base
HX
i
Pr
2
P
Rh
I
L
n
Ar
O
P
i
Pr
2
O
R
1
Rh
II I
L
n
R
1
Ar
R
2
R
2
Figure 12.16 Proposed mechanism of Rh-catalyzed ortho-arylation of phenols.
described by Rawal and co-workers,
16
where electrophilic palladation dic-
tated the regioselective outcome of the reaction. Oi et al.'s method involves a
five-membered metallacycle intermediate for which only ortho-arylated
products could be obtained.
Chlorophosphines were also found to be ecient ligands for this reaction
(Scheme 12.61).
89
Search WWH ::
Custom Search