Preparation of deuterium-labelled methyl linoleate and its geometric isomers from natural seed oils |
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Authors: | R O Adlof H Rakoff E A Emken |
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Affiliation: | (1) U.S, Department of Agriculture, Food Quality and Safety Research, National Center for Agricultural Utilization Research, Agricultural Research Service, 1815 N. University Street, 616O4 Peoria, IL |
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Abstract: | Multi-gram quantities of deuterium-labelled methyl linoleate (methyl cis-9,cis-12-octadecadienoate) and its geometric isomers
are readily synthesized fromCrépis alpina (70–80% cis-9-octadecen-12-ynoic acid) andVernonia galamensis (70–80% 12,13-epoxy-cis-9-octadecenoic acid) seed oils. Methylcis- 9,cis- 12- andtrans- 9,cis- – octadecadienoate-12,13-d2 were prepared by the Lindlar-catalyzed reduction (with D2 gas) of methylcis- 9- and trans-9-octadecen-12-ynoates, respectively. Methyltrans- 9- octadecen-12-ynoate was synthesized by thep-toluene-sulfinic acid-catalyzed isomerization of the corresponding cis isomer. Methylcis- 9fiis- 12., trans- 9fiis- 12;cis- 9,trans- 12- andtrans- 9, frans-12-octadecadienoate-d2, d4 and d6 were prepared by the Wittig coupling (with stereochemical control) of the appropriate d2-, d4- or de-alkyltriphenyl-phosphonium salt with methyl 12-oxo-cis-9- ortrans- 9- dodecenoate (prepared by the para-periodic acid cleavage of methyl 12,13-dihydroxy-cis-9- or trans-9-octadecenoate). Thecis dihydroxy ester was synthesized fromVernonia galamensis seed oil by acetolysis, saponification and then esterification. Thecis dihydroxy ester was isomerized by nitric acid/sodium nitrite to thetrans form and purified by silver resin chromatography. Isotopic purities ranged from 88% (for the d6 isomers) to 99% (for the d2 isomers).
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products not mentioned. |
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Keywords: | Cis andtrans isomers Crepis oilseeds deuterium fatty esters linoleic acid and esters preparation vernolic acid and Vernonia oil Wittig |
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