76
X. Feng et al.
Table 2.35 Asymmetric transfer hydrogenation of 2,3-disubstituted-quinoxalines 72
HB(C 6 F 5 ) 2 10
O
S t Bu
H 2 N
NH 3 ·BH 3 77
76
N
N
R'
R"
N
H
H
N
R'
R"
R
R
36
37
entry product
yield (%) cis/trans ee (%) (trans) ee (%) (cis)
1
37a
N
H
H
N
Me
Ph
78
94/6
-78
2
37b
N
H
H
N
Et
Ph
72
94/6
-84
3
37i
N
H
H
N
Me
S
95
96/4
-77
4
37j
N
H
H
N
Me
Me
84
28/72
99
-5
37k
N
H
H
N
Me
n Pr
72
42/58
98
39
6
37l
N
H
H
N
Me
Bn
76
35/65
97
35
7
37m
N
H
H
N
Et
Et
72
50/50
99
-8
37n
N
H
H
N
78
72/28
93
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