Chemistry Reference
In-Depth Information
CH
3
L-24
(11 mol %)
O
O
Cu(OTf)
2
(10 mol %)
+
O
H
3
C
N
O
Solvent, rt
O
N
O
in [C
4
C
1
im][NTf
2
], 20 min 100% conv. 83%
endo
(95% ee)
in CH
2
Cl
2
for 2 h: NR
NTf
2
N
N
O
O
N
N
t
Bu
t
Bu
L-24
Scheme 1.38.
(
R
,
R
)
-L-25
(4 mol %)
O
O
NaClO
[C
4
C
1
im][PF
6
]/CH
2
Cl
2
(1/4)
0°C, 2 h
O
1st: 86% yield, 96% ee
2nd: 73% yield, 90% ee
3rd: 73% yield, 90% ee
4th: 60% yield, 89% ee
5th: 53% yield, 88% ee
H
H
NN
Mn
t
Bu
t
Bu
O
O
Cl
t
Bu
t
Bu
(
R
,
R
)
-L-25
Scheme 1.39.
enhances the catalyst's reactivity, and, moreover, IL and chiral complex can be recycled
up to fi ve times with only slight loss of ee and catalyst activity (Scheme 1.39).
1.3.3.4. Asymmetric Ring Opening of Epoxides in ILs
Cr(salen) complex (Cr •
L - 26)
catalyzes ring opening of epoxides with TMSN
3
in [C
4
C
1
im][PF
6
] and [C
4
C
1
im][OTf] at
room temperature. The catalyst can be recycled up to fi ve times without loss of ee and
can even enhance its activity [65] (Scheme 1.40).
Chiral Co(III)(salen) complex catalyzes hydrolytic kinetic resolution of racemic
epoxides in ILs. Co(II)(salen) complex is oxidized without acetic acid to catalytically
active Co(III)(salen) complex during the reaction, and this oxidation state is stabilized
