- Synthesis of (S)-(+)-enantiomers of food-relevant (n-5)-monoenoic and saturated anteiso-fatty acids by a Wittig reaction
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We developed an enantioselective synthesis for the food-relevant anteiso-fatty acids a15:0, a16:0, and a17:0. Different (carboxyalkyl)triphenylphosphonium bromide salts were coupled with (S)-3-methylpentanal in a Wittig reaction. Mixtures of the obtained cis-/trans-isomers were separated by Ag+-HPLC to give the novel cis-isomers of (S)-(+)-a15:1n-5, (S)-(+)-a16:1n-5, and (S)-(+)-a17:1n-5. Hydrogenation of the monoenoic products led to (S)-(+)-a15:0, (S)-(+)-a16:0, and (S)-(+)-a17:0, which are essential for the assessment of the bioactivity of tests with standards of anteiso-fatty acids.
- Thurnhofer, Saskia,Vetter, Walter
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p. 1140 - 1145
(2007/10/03)
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- Alkylation of alkenes: Ethylaluminum sesquichloride-mediated hydro-alkyl additions with alkyl chloroformates and di-tert-butylpyrocarbonate
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A general method for the hydro-alkyl addition to the nonactivated C=C double bond of alkenes using alkyl chloroformates (primary, secondary), 12, and di-tert-butylpyrocarbonate, 52, mediated by ethylaluminum sesquichloride (Et3Al2Cl3) has been developed. Reaction of 12 and 52, respectively, with Et3Al2Cl3 gives an alkyl cation which is added to the alkene; hydride transfer to the adduct carbenium ion or, if applicable, 1,2-H shift followed by hydride transfer from Et3Al2Cl3 to the rearranged adduct carbenium ion gives the saturated addition product. The reaction has been applied to 1-alkenes, 2-methyl-1-alkenes, internal double bonds, and to three cyclic alkenes. Special interest has been focused on alkylations of unsaturated fatty compounds, such as oleic acid (2), which are important renewable feedstocks. 2-Methylalkanes, 3-methylalkanes, 2,4-dimethylalkanes, 2,3-dimethylalkanes, 2,2,4-trimethylalkanes, cyclohexylalkanes, and carboxylic acids and esters with the respective branched alkyl chain have been synthesized with good to moderate yields.
- Biermann, Ursula,Metzger, Juergen O.
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p. 10319 - 10330
(2007/10/03)
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- Anticancer effects of specific branched-chain fatty acids and related production process
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A group of specific branched-chain fatty acids, with significant anticancer effects on human and animals; methods of making using either chemical synthesis or biosynthesis methods; and methods of treating cancer.
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- Friedel-Crafts alkylation of alkenes: Ethylaluminum sesquichloride induced alkylations with alkyl chloroformates
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The formal addition of propane to nonactivated double bonds can be achieved with isopropyl chloroformate (2) in the presence of Et3Al2Cl3. Thus, a 1:1 mixture of 10-isopropyloctadecanoic acid (3) and the 9- regioisomer is formed from oleic acid (1). The reaction may also be carried out with 1-alkenes by the addition of triethylsilane as a hydride donor.
- Biermann, Ursula,Metzger, Juergen O.
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p. 3675 - 3677
(2007/10/03)
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- 1-O-(13-Methyl-1-Z-tetradecenyl)-2-O-(13-methyltetradecanoyl)-glycero-3-phospho-ethanolamine, a Plasmalogen from Myxococcus stipitatus
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The structure of 1-O-(13-methyl-1-Z-tetradecenyl)-2-O-(13-methyltetradecanoyl)-glycero-3-phospho-ethanolamine isolated from Myxococcus stipitatus has been elucidated. 1H and 13C NMR as well as mass spectral data have been accumulated which allow a ready identification and structure elucidation of compounds of this type. - Keywords: Myxobacteria, Myxococcus stipitatus, Phospholipids, Plasmalogen, Structure Elucidation
- Stein, J.,Budzikiewicz, H.
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p. 1017 - 1020
(2007/10/02)
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