54
X. Feng et al.
Table 2.17 Hydrogenation of 2-quinolinecarboxylates 44
N
COOR'
N
H
COOR'
R
R
H 2
B(C 6 F 5 ) 3
44
45
entry product
yield (%)
1
45a
N
H
COOMe
94
2
45b
N
H
COOMe
Me
99
3
45c
N
H
COOMe
F
99
4
45d
N
H
COOMe
F
F
92
5
45e
N
H
COO
i Pr
99
N
COOMe
N
H
∗
COOMe
Cy 3 P, H 2
45a
82% conv.
14% ee
44a
chiral diene 9e
HB(C 6 F 5 ) 2
Scheme 2.13 Asymmetric hydrogenation of 2-quinolinecarboxylate 44a
Ph
Ph
HB(p-C 6 F 4 H) 2
Ph
Ph
(Hp-C 6 F 4 ) 2 B
B(p-C 6 F 4 H) 2
46
47
Scheme 2.14 Synthesis of bisborane 47 from chiral spiro[4.4]diene 46