218
M. Rueping, E. Sugiono
Table 3 Scope of the first enantioselective Brønsted acid catalyzed transfer
hydrogenation of quinolines
Entry
10
R
t[h]
Yield [%] a
ee [%] b
1
a
phenyl
12
92
97
2
b
2-F-Phenyl
30
93
98
3
c
2 - C H 3 -Phenyl
48
54 c
91
4
d
2,4-(CH 3 )-Phenyl
60
65 d
97
5
e
2-naphthyl
12
93
>99
6
f
3-Br-Phenyl
18
92
98
7
g
4-(CF 3 )-Phenyl
30
91
>99
8
h
1 , 1 -biphenyl-4-yl
12
91
>99
9
i
4 - C H 3 O-phenyl
12
90 e
98
10
j
2-furyl
12
93
91
11
k
choromethyl
12
91 e
88
12
I
n-butyl
12
91
87
13
m
n-pentyl
12
88
90
14
n
2-phenylethyl
12
90
90
15
o
12
94 e
91
16
p
12
95 e
90
a Isolated yields of 10 after chromatography
b Enantioselectivities were determined by HPLC analysis
c 45% recovered starting material
d 5mol% catalyst
e 1mol% catalyst