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H
Ph
Pd(OAc)
2
(10 mol%),
Benzoquinone, K
2
HPO
4
Ag
2
CO
3
(1equiv)
t
BuOH,100°C,3h
O
Me
Me
Me
+
OH
B
OH
Ph
R
R
Me
O
O
O
Scheme 12.46 b-Arylation of aliphatic acids (Pd
II
/Pd
0
cycle).
Ar
Ar
Ar
H
Pd(OAc)
2
(10 mol%)
NaOAc, K
2
HPO
4
Ag
2
CO
3
(1equiv)
t
BuOH,130°C,3h
Me
Me
OH
OH
OH
+
Ar-I
+
R
R
R
O
O
O
Scheme 12.47 b-Arylation by using Ar-I (Pd
II
/Pd
IV
cycle).
R
1
Y
Y
R
1
R
2
Cat. Pd(OAc)
2
,ligand
R
2
X
H
substrate
reaction condition
yield (%)
product
Pd(OAc)
2
(10 mol%),
(
t
Bu
3
PH)BF
4
(20 mol%),
K
2
CO
3
(1.3 equiv),
DMF, 140 °C, 5h
Me CO
2
Et
Me
CO
2
Et
60%
N
N
H
Cl
Me
Me
Pd(OAc)
2
(5 mol%),
(Cyp
3
PH)BF
4
(20 mol%),
K
2
CO
3
(2 equiv),
DMF, 140 °C, 4h
NC
NC
79%
H
Cl
Pd(OAc)
2
(5 mol%),
(Cy
3
PH)BF
4
(10 mol%),
Cs
2
CO
3
(1.1 equiv),
PivOH (30 mol%)
mesitylene, 140 °C, 16h
O
O
64%
O
2
N
Cl
H
O
2
N
CO
2
Me
Pd(OAc)
2
(5 mol%),
(Cy
3
PH)BF
4
(10 mol%),
Cs
2
CO
3
(1.1 equiv),
PivOH (30 mol%)
mesitylene, 140 °C, 16h
CO
2
Me
Me
N
N
Me
Me
88%
Me
N
N
Cl
H
Pd(OAc)
2
(5 mol%),
(Cy
3
PH)BF
4
(10 mol%),
Cs
2
CO
3
(1.1 equiv),
PivOH (30 mol%)
mesitylene, 140 °C, 16h
O
O
CF
3
89%
CF
3
Me
Me
Cl
H
Scheme 12.48
Synthesis of four- and five-membered ring through C
sp
3
-H arylation.
Fagnou and co-workers reported Pd-catalyzed intramolecular direct -H
arylation with an aryl or heteroaryl halide, leading to the formation of
valuable four- or five-membered ring compounds such as cyclobutarenes,
indanes, indolines, dihydrobenzofuran and indanones (Scheme 12.48).
75,76
In cases where more than one C
sp
3
-H bond can react, the arylation occurred
regioselectively on the primary C-H bond. On substrates with more than one
primary C-H bond, the regioselectivity trends correlated with the size of
palladacycle intermediate, with five-membered rings favored over six- and
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