Biomedical Engineering Reference
In-Depth Information
O
( )
8
O
1)
CO
2
H
N
H
O
O
OH
17
(10 mol%), 4°C
O
O
+
H
H
OH
2)
NaBH
4
,
MeOH, 0°C
77%
Me
Me
34
(ee = 96%)
anti
:
syn
= 6.2:1
33
23
p
-MeOC
6
H
4
CH(OMe)
2
PPTS, benzene, 80°C
recrystallization
64%
Me
OTIPS
PMBO
OH
PMP
O
Me
13
Me
7
O
O
13
10
TIPSO
O
12
Me
7
10
11
PMBO
OTr
OTIPS
Me
OH
37
36
35
(ee = 99%,
anti
only)
OH
Me
16
NH
Organocatalytic
aldol
13
Me
OTIPS
OH
Me
11
HO
O
16
7
13
3
Me
TIPSO
O
OMe
7
11
N
HO
OTr
O
α
-Aminoxylation
O
32
Cytotrienin A
(
31
)
SCHEME 6.7
Synthesis of the C7-C16 unit of cytotrienin A.
acetal followed by recrystallization afforded
in a diastereo- and enantiomerically
pure form. Elongation of the C14-C16 moiety and oxidative ring opening of the furan
ring finally furnished the desired C7-C16 unit
35
32
[12].
6.2.2. Mannich Reaction
The Mannich reaction is a carbon-carbon bond forming reaction between an
enolizable carbonyl group and an imine, giving access to
b
-amino carbonyl
compounds. Since the first example of a proline-mediated asymmetric Mannich
reaction reported by List in 2000 [13], the organocatalytic asymmetric Mannich
reaction has been investigated by several research groups [4]. Thus, proline was
found to be an efficient organocatalyst for the synthesis of
b
-amino alcohols such as
38
(Scheme 6.8) [14].
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