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United States Department of Agriculture

Agricultural Research Service

Title: Synthesis of Five Conjugated Linoleic Acid Isomers (9-Trans,11-Cis;9-Trans,11-Trans-; 10-Trans,12-Cis-; 10-Cis,12-Cis-; 10-Trans,12-Trans-18:2) Labelled with Four Deuterium Atoms

Authors
item Adlof, Richard
item Walter, Erin

Submitted to: Annual Meeting and Expo of the American Oil Chemists' Society
Publication Type: Abstract Only
Publication Acceptance Date: May 10, 1998
Publication Date: N/A

Technical Abstract: Cis 9, trans 11 and trans 9, trans 11 isomers of conjugated linoleic acid (cis 9, trans 11 octadecadienoic acid) 17,17,18,18 d4 were prepared by an eight step synthesis. The methyl cis/trans 9, trans 11 octadecadienoate 17,17,18,18 d4 (96% d4)isomer pair (46.54) were obtained from the Wittig coupling of trans 2 nonenyltriphenylphosphonium bromide (8,8,9,9-d4) and methyl 9 oxononanoate. To prepare triphenylphosphonium bromide, the tetrahydropyranyl ether of 5 hexyn 1 ol was reduced with deuterium gas/ Wilkinson's catalyst to yield 1 hexanol 5,5,6,6 d4. The alcohol was converted to the iodide (phosphorous pentoxide/phosphoric acid/potassium iodide) and coupled with 2 propyn 1 ol (lithium amide in liquid ammonia) to yield 2-nonyn 1 ol d4. Acetylenic alcohol was reduced with lithium metal in liquid ammonia to yield trans 2 nonen 1 ol d4. Trans alcohol was converted to the bromide (via. triphenylphosphine dibromide) and then converted to the phosphonium salt. To prepare trans 10, cis 12 and cis 10 cis 12 18:2 15,15,16,16 d4 isomer pair (86% d4); 2 pentyn 1 ol was reduced to pentanol 2,2,3,3 d4 with deuterium gas/Wilkinson's catalyst. The alcohol was converted to the iodide and coupled with 2 propyn 1 ol to yield 2 octyn 1 ol d4. Reduction with H2 gas/Lindlar catalyst yielded 2 octen 1 ol d4. Olefinic alcohol was converted to the bromide and then to the phosphonium salt. Wittig coupling of the salt with 10 oxodecanoate yielded 10 trans,12 cis and 10 cis,12 cis 18:2 isomer pairs. Conjugated isomer pairs formed during final Wittig coupling reactions were separated by reversed phase HPLC and silver resin chromatography. Purities were >95% for each geometric isomer. Yields for the 9,11 and 10,12 18:2 isomer pairs was ca. 20% for each isomer.

Last Modified: 10/22/2014
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