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TABLE 10-1. In Vitro Cytotoxicities Against B16BL6 by (10R)- and
(10S)-Corossolin
Compound
GI
50
(mg/mL)
LC
50
(mg/mL)
(10R)-corossolin
0.042
7
(10S)-corossolin
0.77
>
10
the other hand, the epoxides 26 and 27 were prepared easily from a well-known
chiron, (R)-isopropylidene glyceraldehyde. Coupling reactions of 14 with 26 and
27 in parallel, selective reduction of triple bonds and deprotections provided
(10R) and (10S)-corossolin, respectively. It is noteworthy that the toxicity of
(10R)-corossolin against cancer cells B16BL6 in vitro is more potent than that of
(10S)-corossolin (Table 10-1).
A similar convergent synthetic strategy was applied in our synthesis of annona-
cin, using sequential assembly of the three key fragments, aldehyde 29, phospho-
nium 30, and alkyne 14 (Scheme 10-9). In this synthesis, the a,b-unsaturated-g-
lactone unit was constructed after completion of the linear skeleton. A modified
method was applied into the synthesis of segment 3 (Scheme 10-5), in which
the six carbons, as well as two chiral centers from D-glucono-d-lactone, were
all incorporated
into the final target. Therefore, the efficiency of the whole
OMOM
OH
OHC
CO
2
Me
29
L-ascorbic acid
(Vc)
O
CO
2
Me
PPh
3
Br
O
O
( )
3
O
28
30
OMOM
OMOM
O
CO
2
Me
( )
4
CO
2
Me
O
O
31
32
O
CO
2
Me
PPh
3
, I
2
1. LiHMDS
Scheme 10-5
O
O
20
5
O
O
Im
∆
O
2. Pd, H
2
O
O
33
3
OH
OH
32
O
C
12
H
25
15
20
14
O
10
4
HO
HO
O
annonacin
Scheme 10-9. Total synthesis of annoancin by Wu et al.
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