Chemistry Reference
In-Depth Information
1) [MCl(cod)]
2
(2 mol % M), L*
HO
O
N
CO
2
Bn
CO
2
Bn
N
CO
2
Bn
CO
2
Bn
+
H
B
N
2) H
2
O
2
, NaOH
N
O
123
124
H
yield
91%
30%
46%
40%
76%
%eeof
124
84 (
R
)
32 (
S
)
54 (
S
)
44 (
R
)
71 (
S
)
L*
M
Rh
Ir
Rh
Ir
Ir
O
PPh
2
105
105
5
5
125
DME
DME
DME
DME
THF
Î50 C, 0.5 h
0 C to rt, 7 h
Î50 C, 0.5 h
rt, 7 h
0 C, 4 h
PPh
2
O
PPh
2
PPh
2
H
(
S
,
S
)-diop (
5
)
L* = (
S
,
S
)-bdpp(
105
)
PPh
2
N
(
R
,
R
)-
125
Scheme 9.26.
Me
H
Me
[RhCl(cod)]
2
(3 mol %), L*
O
H
+
O
H
B
MeO
2
C
B
MeO
2
C
THF, rt
O
O
126
127
128
L*
(
R
)-binap (
85
)
(
S
,
S
)-norphos (
129
)
(
R
)-phanephos (
130
)
yield
96%
86%
89%
%eeof
128
94 (
1S,2R
)
>99 (
1R,2S
)
97 (
1R,2S
)
H
PPh
2
PPh
2
PPh
2
PPh
2
H
L* = (
S
,
S
)-norphos (
129
)
(
R
)-phanephos (
130
)
Scheme 9.27.
O
1) [RhCl(cod)]
2
,(
R
)-binap (
85
)
SO
2
Ph
+
SO
2
Ph
H
B
OH
2) H
2
O
2
,NaOH
O
131
132
, 38% ee
Scheme 9.28.
Pinacolborane as a hydroborating agent in rhodium-catalyzed asymmetric hydrobo-
ration of vinylarene instead of catecholborane has been investigated recently. The reac-
tion of styrene using josiphos ligand with pinacolborane was more enantioselective than
with catecholborane (Scheme 9.29) [68]. In addition, the opposite enantiomer was
obtained by the same catalytic systems except for the hydroborating agents.
