2 Frustrated Lewis Pair Catalyzed Asymmetric Reactions
77
Table 2.36 Asymmetric transfer hydrogenations of β-enamino esters 78
HB(C 6 F 5 ) 2 10
O
S t Bu
H 2 N
NH 3 ·BH 3 77
76
Ar
COOR
NH
Ar'
Ar
COOR
NH
Ar'
78
79
entry product
yield (%) ee (%)
1
79a
Ph
COOEt
NH
Ph
67
72
2
79b
Ph
COOEt
NH
N
72
85
3
79c
Ph
COOEt
NH
Bn
76
54
4
79d
Ph
COOEt
NH
MeO
79
80
5
79e
Ph
COOMe
NH
MeO
83
78
6
79f
Ph
COO
n Bu
NH
MeO
82
83
7
79g
Ph
COO
i Pr
NH
MeO
85
85
8
79h
Ph
NH
MeO
O
O
80
84
9
79i
Ph
COO
t Bu
NH
MeO
83
91
10
79j
COO
t Bu
NH
S
MeO
83
80