Chemistry Reference
In-Depth Information
Br
Ph
Me
C
6
H
4
-4-Me
C
6
H
4
-4-Me
Me
C
6
H
4
-4-Me
C
6
H
4
-4-Me
H
N
N
N
O
O
Pr
Pr
2BF
4
O
2BF
4
C
6
H
4
-4-Me
C
6
H
4
-4-Me
O
O
N
N
N
C
6
H
4
-4-Me
C
6
H
4
-4-Me
Me
Me
Ph
125a
125b
124
CF
3
R
Br
N
Et
3
B
r
H
N
2X
N
O
CF
3
O
O
N
N
R
F
NEt
3
O
F
N
126
R=
127
128
F
O
O
O
O
O
O
O
O
O
O
O
O
O
O
129
Figure 8A.8.
O
O
124
(10 mol %)
CsOH, H
2
O
CH
2
Cl
2
, -78
OAc O
Ph
R
OMe
CO
2
t
Bu
N
O
t
Bu
+
R
OMe
°
C
Ph
CPh
2
N
R=Ph,4-NO
2
-Ph, 4-MeO-Ph,
2-thienyl, 2-pyridinyl
Up to 92% yield
Up to 97 ee
Scheme 8A.66.
[135,136]. Subsequently, a variety of chiral PTCs such as
125
,
126
,
127
,
128
, and
129
were
employed in the conjugate addition of enolates to Michael acceptors (Fig. 8A.8).
Cinchonidine - derived catalyst
124
[137] also effi ciently promoted the asymmetric
synthesis of 4-alkylidene glutamic acid derivatives under phase-transfer conditions with
up to 97% ee (Scheme 8A.66).
