Biomedical Engineering Reference
In-Depth Information
O
O
OH
O
organocatalysis
R
1
+
R
1
H
H
H
R
2
R
2
OH
O
OH
O
Me
Catalyst:
Product:
H
H
CO
2
H
H
Me
Me
2
13
14
80%, ee = 99%
anti
:
syn
= 4:1
87%, ee = 99%
anti
:
syn
= 14:1
OH
O
OH
O
H
H
Me
TIPSO
OTIPS
15
16
81%, ee = 99%
anti
:
syn
= 3:1
92%, ee = 95%
anti
:
syn
= 4:1
O
OH
Catalyst:
( )
8
Product:
O
88%, ee = 99%
anti
:
syn
= >20:1
(after NaBH
4
reduction)
OH
Me
CO
2
H
N
H
17
18
SCHEME 6.4
Proline and its derivative-catalyzed cross-aldol reaction of aldehydes.
the six-membered hemiacetal
in a highly diastereoselective manner (Scheme 6.6).
The latter was then converted in a few steps first to the corresponding ketone
29
30
, via
deoxygenation at the C6 position, and then to the desired sugar
20
[10].
) is a 21-membered ring lactam that exhibits a potent
apoptosis-inducing activity on HL-60 cells (Scheme 6.7) [11]. Hayashi et al. recently
reported the synthesis of the C7-C16 unit
Cytotrienin A (
31
of cytotrienin A, where the C11 and C12
stereogenic centers were introduced through a proline-mediated aldol reaction Ref. 12.
32
Mukaiyama
aldol
Me
OH
Me
OH
MeO
OTIPS
MeO
OH
CCl
3
HN
O
O
Me
Organocatalytic
aldol
O
O
Me
Organocatalytic
aldol
H
Me
Sugar moiety
20
5
Me
2
OTBS
O
H
OH
Me
MeO
O
O
5
9
Me
2
CO
2
Me
Me
O
Cl
H
OMe
O
H
9
Callipeltoside C (
19
)
C1-C9 unit
21
FIGURE 6.1
Synthetic analysis of callipeltoside C.
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