Chemistry Reference
In-Depth Information
O
O
Catalyst
Conditions
CO
2
t
-Bu
CO
2
t
-Bu
PhCH
2
Br
+
*
Ph
24
25
Ph
OH
HO
Ph
26
(1 mol %)
K
2
CO
3
Toluene
0°C
44%, 50% ee (
R
)
1d
(5 mol %)
K
2
CO
3
Toluene
rt
97%, 46% ee (
S
)
-
Br
OH
O
NH
HN
O
+
N
N
H
-
Br
26
1d
+
PPh
3
Ar
-
5f
(1 mol %)
CsOH·H
2
O
Toluene
-40°C
94%, 97% ee (
S
)
CF
3
Br
+
Ar =
N
CF
3
Ar
(
S
,
S
)-
5f
Scheme 2C.13.
Ar
O
O
O
4
(15 mol %)
CO
2
Et
27
CO
2
Et
+
ArF
Ar
+
CsOH
Toluene-CHCl
3
(9:1)
-20°C
CO
2
Et
28
29
O
2
N
NO
2
4c
: 90%,
28
/
29
= 1.0:1
racemic for
28
: 89%,
28
/
29
= 16:1
80% ee
for
28
Ar =
-
X
4d
+
H
N
OR
4c
(R = Bn, X = Br)
4d
(R = Bz, X = Cl)
N
Scheme 2C.14.
Jørgensen and others developed the catalytic, regio- and enantioselective nucleo-
philic aromatic substitution reaction between activated aromatic compounds and
1,3-dicarbonyl compounds under phase-transfer conditions. Interestingly, examination
on the addition of 2,4-dinitrofl uorobenzene to 2-carboethoxycyclopentanone
27
revealed
that the use of
O
- benzoylated cinchonidine - derived catalyst
4d
was crucial for obtaining
C
- arylated product
28
predominantly with high enantioselectivity (Scheme 2C.14 ) [35] .
