- Structure-odor correlations in homologous series of alkanethiols and attempts to predict odor thresholds by 3d-qsar studies
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Homologous series of alkane-1-thiols, alkane-2-thiols, alkane-3-thiols, 2-methylalkane-1-thiols, 2-methylalkane-3-thiols, 2-methylalkane-2-thiols, and alkane-1,??-dithiols were synthesized to study the influence of structural changes on odor qualities and odor thresholds. In particular, the odor thresholds were strongly influenced by steric effects: In all homologous series a minimum was observed for thiols with five to seven carbon atoms, whereas increasing the chain length led to an exponential increase in the odor threshold. Tertiary alkanethiols revealed clearly lower odor thresholds than found for primary or secondary thiols, whereas neither a second mercapto group in the molecule nor an additional methyl substitution lowered the threshold. To investigate the impact of the SH group, odor thresholds and odor qualities of thiols were compared to those of the corresponding alcohols and (methylthio)alkanes. Replacement of the SH group by an OH group as well as S-methylation of the thiols significantly increased the odor thresholds. By using comparative molecular field analysis, a 3D quantitative structure-activity relationship model was created, which was able to simulate the odor thresholds of alkanethiols in good agreement with the experimental results. NMR and mass spectrometric data for 46 sulfur-containing compounds are additionally supplied.
- Polster, Johannes,Schieberle, Peter
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p. 1419 - 1432
(2015/03/05)
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- Metathesis-mediated synthesis of (R)-10-Methyl-2-tridecanone, the southern corn rootworm pheromone
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(R)-10-Methyl-2-tridecanone, the female sex pheromone of the southern corn rootworm (Diabrotica undecimpunctata howardi Barber), was synthesized in 9 steps from methyl (S)-3-hydroxy-2-methylpropanoate in a 15.7% overall yield. Olefin cross metathesis between (R)-6-methyl-1-nonene and 5-hexen-2-one employing Grubbs' first-generation catalyst was the key step of the synthesis.
- Shikichi, Yasumasa,Moriy, Kenji
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experimental part
p. 407 - 409
(2012/08/13)
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- Regio- and stereochemical study of sex pheromone of pine sawfly; Diprion nipponica
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Regio- and stereoisomers of 1,2,ω-trimethyldecyl propionate (ω = 5-9) were prepared from stereochemically pure chiral building blocks as sex pheromone candidates of a pine sawfly; Diprion nipponica. Among the synthesized candidates, (1S,2R,8S)-1,2,8-trimethyldecyl propionate was found to be the sex pheromone of D. nipponica, based on compatibility of its GC-MS data with that of the extract of females, and its significantly high pheromone activity in a field bioassay. The field bioassay of the synthesized compounds also revealed that (1S,2R,SR)-1,2,8-trimethyldecyl propionate, (1S,2R,7S)-1,2,7-trimethyldecyl propionate, and (1S,2R,6S)-1,2,6-trimethyldecyl propionate could attract male sawflies to some extent as pheromone mimics.
- Tai, Akira,Syouno, Emi,Tanaka, Kazuki,Fujita, Morifumi,Sugimura, Takashi,Higashiura, Yasutomo,Kakizaki, Masashi,Hara, Hideho,Naito, Tikahiko
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p. 111 - 121
(2007/10/03)
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- Pheromone Synthesis, CLXVII. - Synthesis of All of the Eight Stereoisomers of Methyl 2,6,10-Trimethyltridecanoate, the Male-produced Pheromone of the Stink Bugs, Euschistus heros and E. obscurus
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All of the eight possible stereoisomers of methyl 2,6,10-trimethyltridecanoate (1), the male-produced attractant pheromone of the South American soybean pest, Euschistus heros, and that of E. obscurus, are synthesized by starting from the enantiomers of citronellol (2) and methyl 3-hydroxy-2-methylpropanoate (9). - Key Words: Euschistus heros / Euschistus obscurus / Pheromones / Stink bugs / Sulfones, alkylation of / Tridecanoate, methyl 2,6,10-trimethyl-
- Mori, Kenji,Murata, Noriaki
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p. 1153 - 1160
(2007/10/02)
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- Stereochemistry of Aliphatic Carbocations, 14. Alkyl Shifts from Secondary to Primary Carbon Atoms
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Alkyl shifts from secondary to primary carbon atoms have been induced by the nitrous acid deamination of suitable amines (4, 22, 39, 51); they include sequential rearrangements (-CH3,CH3 and -CH3,H).Predominant although incomplete inversion at the migration origin has been observed (Me 70percent, Et 62-64percent, nPr 65percent, iPr 64percent, tBu 55percent).Our results require the intervention of open secondary carbocations which may be preceded by less stable bridged intermediates.
- Kirmse, Wolfgang,Guenther, Bernd-Rainer,Knist, Johannes,Kratz, Sigrid,Loosen, Karin,et al.
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p. 2127 - 2139
(2007/10/02)
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