ISSN:
1573-9171
Schlagwort(e):
7E,9Z-dodecadienyl acetate
;
1-acetoxy-2E,4Z-heptadiene
;
1-bromo-3E,5E-octadiene
;
ω-tert-butoxyalkylmagnesium chlorides, organocuprate cross-coupling
;
1-tert-butoxy-7E,9Z-dodecadiene, configurational purity
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Chemie und Pharmazie
Notizen:
Abstract 1-Acetoxy-2E,4Z-heptadiene (4) and 1-bromo-3E,5Z-octadiene (5) were obtained with ≥90 and 88–92 % configurational purity, respectively, starting from 2,4-heptadiyn-1-ol or 3,5-octadiyn-1-ol. The Li2CuCl4-catalyzed cross-coupling of the allylic acetate4 with 5tert-butoxypentylmagnesium chloride affords 1-tert-butoxy-7E,9Z-dodecadiene (11) contaminated with ≥25 % of minor stereoisomers in 54–60 % overall yield. Under similar conditions, the homoallylic bromide5 reacts with 4-tert-butoxybutylmagnesium chloride to give in 50–52 % yield another sample of diene11 containing ≤17 % of minor stereoisomers. If the latter coupling is carried out with enyne8 instead of5 followed bycis-hydrogenation of the triple bond in the resulting product, the configurational purity of diene11 is as high as 84.7 % (∼45 % overall yield). The reaction of11 with Ac2O in the presence of FeCl3 leads directly to the target 7E,9Z-dodecadienyl acetate (1) with somewhat lower configurational purity than that of the starting ether11.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00704206
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