34
X. Feng et al.
Table 2.2 Catalytic asymmetric hydrogenation of imines
Ar
R
N
Ph
Ar
R
HN
Ph
HB(C 6 F 5 ) 2 10 (2.5-10 mol %)
9i (1.25-5 mol %)
H 2 (20 bar), rt
3
5
Entry product
yield (%) ee (%)
1
5a
Ph
Me
NHPh
98
78
2
5b
Me
NHPh
BnO
91
89
3
5c
Me
NHPh
F 3 C
97
85
4
5d
Me
NHPh
MeO
91
80
5
5e
95
85
6
5f
NHPh
96
79
7
5g
PhHN
63
88
8
5h
Et
NHPh
i PrO
93
78
∗ ∗
Me
NHPh
O
N
I
Me
Me
Me
N
B(C 6 F 5 ) 2
Me
Me
Me
N
H
B(C 6 F 5 ) 2
Me
Me
Me
1. -78 °C to rt
2. -78 °C to rt
(R)-11
(S)-12
(S)-13
H 2 (2 bar)
toluene, rt, 1 min
C6D6, 80 °C, 15 min
H
n BuLi
B(C 6 F 5 ) 2 Cl
Scheme 2.5 Synthesis of Catalyst (S)-13