Page 17 - Volume 3, Issue 2, July 2010
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© Benaki Phytopathological Institute
Mosquito oviposition aggregation pheromone
47
1,3-oxathiane, was converted by Ko and Eliel
(1986) into (–)-(5
R
,6
S
)-6-acetoxy-5-hexade-
canolide in a highly diastereoselective fash-
ion (Figure 24).
The construction of the carbon skele-
ton was accomplished by Grignard addi-
tion of 5-pentenylmagnesium bromide to
α
-benzyloxy aldehyde
65
. Mitsunobu inver-
sion at C6, ozonization, oxidation and finally
lactonization smoothly led to (5
R
,6
S
)-6-ben-
zyloxyhexadecanolide. Deprotection of the
benzyl group and acetylation of hydroxy
lactone afforded the target compound
1a
(
8
steps, 36% yield
).
(–)-(5
R
,6
S
)-6-acetoxy-5-hexadecano-
lide has also been targeted by Machiya
et
al.
(1985). Machiya’s approach commenced
from isopropylidene-
L
-glyceraldehyde (Fig-
ure 25) in which the nucleophilic addition
of Grignard reagent involved the diastereo-
face-differentiating process as the key step
affording an alcohol, which was smoothly
transformed in five steps to aldehydes
69
and
70
. Those aldehydes were a chromato-
Figure 25
Figure 24
