Chemistry Reference
In-Depth Information
N
R
N
LLA
3
(5-10 mol %)
CH
2
Cl
2
, -40°C
R
CHO
N
2
CHCO
2
t-
Bu
+
CHO
t-
BuO
2
C
9 examples
43-82% yield
80-94% ee
N
Me
CHO
LLA
3
(5 mol %)
CH
2
Cl
2
, -40°C
Me
N
+
N
2
CHCO
2
Et
CHO
EtO
2
C
53% yield, 95% ee
Br
N
H
O
H
HO
2
C
Me
O
Manzacidin A
Scheme 3.17.
M
O
O
O
N
N
Re
M
M
O
O
O
O
O
M
Re
O
O
OAr
HBM
4
: Re = La, M = Pd
HBM
1
: Re = Y, M = Li
HBM
2
: Re = Dy, M = Li
HBM
3
: Re = La, M = Li
Figure 3.3.
high enantioselectivity. Detailed mechanistic studies revealed that a catalytic amount of
acetone cyanohydrin was effective as an initiator to accelerate the initiation step (Scheme
3.19 ).
Recently, the Shibasaki group developed a new HBM complex
4
and applied this
catalyst for
anti
-selective nitroaldol reactions [34]. Furthermore, the utility of this meth-
