Chemistry Reference
In-Depth Information
Pd(OAc)
2
(10 mol%)
Ac-IIe-OH (10 mol%)
BQ, KHCO
3
Ag
2
CO
3
,
t
-amylOH
110 °C
H
3
C
R
1
CH
3
R
2
R
1
O
R
2
Ar BF
3
K
OH
OH
OH
o
r
+
R
H
3
C
H
R
O
O
Ar BPin
Ar
O
H
Ac-Ile-OH
Scheme 12.16 Coupling of substituted phenylacetic acids with Ar-BF
3
K/Ar-BX
2
.
COOK
O
R
1
R
2
H
NHAc
O
[O]
n-2
Pd
II
AcOH
OAc
[O]
n
C-H cleavage
BQ
reoxidation
OK
R
O
Pd
II
Pd
0
Ln
AcHN
O
R
1
O
reductive
elimination
transmetallation
Ar
BX
3
K
OK
R
COOK
O
R
KBX
4
PdII
Ar
Ar
L
Figure 12.6 Proposed mechanism for Pd-catalyzed carboxylic
acid-directed
arylation.
Me
Me
Pd (OAc)
2
(5 mol%) , [Ph
2
I]BF
4
(1.15 equiv)
AcOH, 100 °C , 12h
N
N
88 %
O
O
Me
O
N
N
N
N
N
Me
O
58 %
75 %
83 %
49 %
Scheme 12.17 Pd-catalyzed ortho-arylation using [Ph
2
I]BF
4
.
In 2005, Sanford and co-workers reported the Pd-catalyzed ortho-arylation
of 2-arylpyridines using an electrophilic arylating agent, [Ar-I-Ar]BF
4
(Scheme 12.17).
32
Different types of N-heterocycles such as quinolines,
oxazolidinones, pyrrolidinones and benzodiazepines were successfully
arylated by this method. To show the functional group compatibility,
[Mes-I-Ar]BF
4
was used as arylating reagent, where the mesityl group was
found to facilitate the aryl transfer process due to steric reasons.
Search WWH ::
Custom Search