- Novel fatty acid methyl esters from the actinomycete Micromonospora aurantiaca
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The volatiles released by Micromonospora aurantiaca were collected by means of a closed-loop stripping apparatus (CLSA) and analysed by GC-MS. The headspace extracts contained more than 90 compounds from different classes. Fatty acid methyl esters (FAMEs) comprised the major compound class including saturated unbranched, monomethyl and dimethyl branched FAMEs in diverse structural variants: Unbranched, α-branched, γ-branched, (ω-1)-branched, (ω-2)-branched, α-and (ω-1)-branched, γ-and (ω-1)-branched, γ-and (ω-2)-branched, and γ-and (ω-3)-branched FAMEs. FAMEs of the last three types have not been described from natural sources before. The structures for all FAMEs have been suggested based on their mass spectra and on a retention index increment system and verified by the synthesis of key reference compounds. In addition, the structures of two FAMEs, methyl 4,8-dimethyldodecanoate and the ethyl-branched compound methyl 8-ethyl-4-methyldodecanoate were deduced from their mass spectra. Feeding experiments with isotopically labelled [ 2H10]leucine, [2H10]isoleucine, [2H8]valine, [2H5]sodium propionate, and [methyl-2H3]methionine demonstrated that the responsible fatty acid synthase (FAS) can use different branched and unbranched starter units and is able to incorporate methylmalonyl-CoA elongation units for internal methyl branches in various chain positions, while the methyl ester function is derived from S-adenosyl methionine (SAM).
- Dickschat, Jeroen S.,Bruns, Hilke,Riclea, Ramona
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supporting information; experimental part
p. 1697 - 1712
(2012/02/04)
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- Reductive ethylation of homoallyl alcohols with a disubstituted double bond with ethylmagnesium bromide in the presence of titanium(IV) isopropoxide
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Homoallyl and bishomoallyl alcohols with a disubstituted double bond treated with ethylmagnesium bromide in the presence of titanium(IV) isopropoxide are converted into the products of a reductive ethylation of the olefin fragment. Under similar conditions esters of β,γ-unsaturated carboxylic acids undergo a successive cyclopropanation of the ester group and reductive ethylation of the double carbon-carbon bond and yield 1-(3-ethylalkyl)cyclopropanols. The features of the observed reactions are explained in the framework of the carbometallation mechanism of the double carbon-carbon bond by the action of dialkoxytitanacyclopropane reagents. Pleiades Publishing, Inc. 2006.
- Kulinkovich,Shevchuk,Isakov,Prokhorevich
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p. 659 - 664
(2007/10/03)
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- Studies related to fatty acid desaturation. Part I: Preparation of methyl-substituted nonanols, nonyl bromides and total synthesis of new branched oleic acids
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Convenient pathways for the synthesis of seven structurally defined isomers of methyl-nonanols and methyl-nonylbromides are described.These synthons are used to perform Wittig reactions between convenient phosphoranes and aldehydes in order to obtain seven new octadecenoic acids bearing a methyl grouping on carbons 11 to 17. branched nonan-1-ols / branched 1-nonylbromides / Wittig reactions / methyl 9-bromononanoate / methyl 8-formyloctanoate / methyl 11 or 17-methyloctadec-9-enoates
- Genard, S.,Patin, H.
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p. 397 - 406
(2007/10/02)
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- SYNTHESIS OF (Z)- AND (E)-14-METHYL-8-HEXADECEN-1-OLS FROM METHYL (E)-5-METHYL-2,5-HEPTADIENOATE - THE CODIMER OF ISOPRENE AND METHYL ACRYLATE
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1-Bromo-5-methylheptane was obtained from methyl (E)-5-methyl-2,5-heptadienoate - the codimer of isoprene with methyl acrylate.During alkylation with the lithium alcoholate of lithio-8-nonyn-1-ol in the presence of HMPTA it forms 14-methyl-8-hexadecyn-1-ol.Hydrogenation of the latter at a palladium catalyst in the presence of quinoline gives (Z)-14-methyl-8-hexadecen-1-ol, and reduction with lithium aluminium hydride gives (E)-14-methyl-8-hexadecen-1-ol.
- Zakharkin, L. I.,Petrushkina, E. A.
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- SYNTHETIC INVESTIGATIONS INTO INSECT-ATTRACTING SUBSTANCES (SEX ATTRACTANTS). IV. SYNTHESIS OF 14-METHYL-8-cis-HEXADECENAL AND 14-METHYL-8-trans-HEXADECENAL, COMPONENTS OF THE SEX PHEROMONE OF THE DERMESTID BEETLE Trogoderma granarium EVERTS
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14-Methyl-8-hexadecyn-1-ol was obtained by the alkylation of 7-methyl-1-nonyne with heptamethylene chlorohydrin.Its hydrogenation in the presence of colloidal nickel catalyst was used for the synthesis of 14-methyl-8-cis-hexadecen-1-ol, and reduction with lithium aluminum hydride was used for the synthesis of 14-methyl-8-trans-hexadecen-1-ol.Both ethylenic alcohols were converted by oxidation into the corresponding aldehydes, which are the main components of the sex pheromone of the dermestid beetle.
- Kovalev, B. G.,Rastegaeva, V. M.
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