- New syntheses of 1,7-dimethylnonyl propanoate, the western corn rootworm pheromone, in four different ways via cross metathesis, alkylation and coupling reactionsss
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A mixture of the four stereoisomers of 1,7-dimethylnonyl propanoate, the female sex pheromone of the western corn rootworm (Diabrotica virgifera virgifera LeConte), was synthesized in four different ways by employing one of the following four reactions as the key step: (i) cross metathesis using the Grubbs I catalyst, (ii) cross metathesis using the Grubbs II catalyst, (iii) alkylation of an alkynide anion, and (iv) Grignard coupling in the presence of dilithium tetrachlorocuprate. Although the cross metathesis approaches enabled two short syntheses (4 or 6 steps) of the pheromone to be achieved, the cheapest and most efficient synthesis was possible via Grignard coupling to give the desired pheromone in a 40% overall yield based on 2-methyl-1-butanol (8 steps).
- Mori, Kenji
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experimental part
p. 595 - 600
(2011/04/23)
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- Novel Caprolactones from a Marine Streptomycete
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Two new caprolactones, (R)-10-methyl-6-undecanolide (1) and (6R,10S)-10-methyl-6-dodecanolide (2), were identified in the lipid extract of a marine streptomycete (isolate B6007). Their structures were proposed on the basis of GC-MS experiments and proved by synthesis. The absolute configuration of the compounds was established by comparison of the natural and synthetic stereoisomers using chiral gas chromatography. These caprolactones show a moderate phytotoxicity and a promising activity against cancer cells with concomitant low general cytotoxicity.
- Stritzke, Katja,Schulz, Stefan,Laatsch, Hartmut,Helmke, Elisabeth,Beil, Winfried
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p. 395 - 401
(2007/10/03)
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- 48. Ferroelectric Liquid Crystals Part 2 Chiral Phenyl Benzoates Incorporating a trans-1,4-Disubstituted Cyclohexane Ring
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About forty novel phenyl benzoates also incorporating a trans-1,4-disubstituted cyclohexane ring and a chiral centre have been prepared.The dependence of the liquid-crystal transition temperatures of this new class of compounds on lateral substituents, diverse central linkages, chain lengths, and position of the chiral centre has been studied systematically.The synthesis and liquid-crystal transition temperatures of these new compounds are described in detail.
- Kelly, Stephen M.,Buchecker, Richard
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p. 451 - 460
(2007/10/02)
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- SYNTHESIS AND BIOLOGICAL ACTIVITY OF BOTH (E)- AND (Z)-ISOMERS OF OPTICALLY PURE (S)-14-METHYL-8-HEXADECENAL (TROGODERMAL), THE ANTIPODES OF THE PHEROMONE OF THE KHAPRA BEETLE
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Both (E)- and (Z)-isomers of (S)-14-methyl-8-hexadecenal (trogodermal) were synthesized from 100percent optically pure (R)-(+)-citronellic acid.These antipodes of the khapra beetle pheromone were 1/500 to 1/1000 times as active as the natural (R)-pheromone.Determination of the optical purities of citronellic acid and related compounds was achieved by hplc method.Warning was made not to forget the measurement of density in expressing the optical rotation of a neat liquid as D (neat).
- Mori, K.,Kuwahara, S.,Levinson, H. Z.,Levinson, A. R.
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p. 2291 - 2297
(2007/10/02)
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- Alkoxybenzylidene-aminobenzonitriles
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Liquid crystal cells containing mixtures of cholesteric optically active p-alkoxybenzylidene-p'-aminobenzonitrile compounds with nematic liquid crystal compounds form cholesteric liquid crystals which change to the nematic stage upon application of an ele
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