Chemistry Reference
In-Depth Information
only a small amount of OsO
4
(
<
2% of the total amount) leaching from IL phase to
organic phase [71] .
N
N
N
N
Br
O
O
Ph
MeO
OMe
L-27
1.3.3.6. Asymmetric Fluorination in ILs
Chiral Pd - BINAP complex - catalyzed enan-
tioselecttive fl uorination of β - ketoesters and β-ketophosphonates can be achieved in ILs
(Scheme 1.42). The reactions proceed smoothly to afford the corresponding products in
good yields with ees in most cases [72]. The catalyst can be reused up to 10 times with
slight loss of activity.
O
O
SO
2
Ph
Pd•
L-28
(2.5 mol %)
CO
2
t
Bu
CO
2
t
Bu
Ch
3
+
F
N
Ph
Ph
SO
2
Ph
[C
6
C
1
im][BF
4
], rt, 60 h
F
93% yield, 92% ee
9th: 86% yield, 91% ee
10th: 67% yield, 91% ee
H
3
C
(1.5 equiv)
O
+
+
P
P
P
P
P
P
P(3,5-Me
2
C
6
H
3
)
2
P(3,5-Me
2
C
6
H
3
)
2
Pd
Pd
*
*
*
H
2OTf
-
Pd•
L-28
L-28
Scheme 1.42.
1.3.3.7. Others
There are some more reactions such as asymmetric allylic substitution
[73], asymmetric cyclopropanation [74], asymmetric synthesis of cyanhydrines [75],
asymmetric allylation [76], asymmetric addition of alkynes to imines [77], and asym-
metric hydroamination [78]. These reactions have been investigated in ILs; however,
considering the property, character, and aim of using ILs, reuse of the catalysts should
be further investigated.
1.4. MICROWAVE - ASSISTED CATALYTIC ASYMMETRIC SYNTHESIS
Microwave irradiation has been widely accepted in academic chemical laboratories as
well as pharmaceutical companies. The use of this nonconventional method in chemical
