- Structure-Odor Correlations in Homologous Series of Mercaptoalkanols
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To study the influence of molecular structure on the sensory properties of mercaptoalkanols, homologous series of 1-mercaptoalkan-3-ols, 3-mercaptoalkan-1-ols, 2-mercaptoalkan-1-ols, 4-mercaptoalkan-2-ols, 3-mercapto-3-methylalkan-1-ols, 1-mercapto-2-methylalkan-3-ols, 3-mercapto-2-methylalkan-1-ols, and 2-ethyl-3-mercaptoalkan-1-ols were synthesized. Odor thresholds in air and odor qualities were determined, and the results obtained were correlated to the chemical structures. Sensory properties were strongly influenced by steric effects: All homologous series revealed a minimum in odor thresholds between five and seven carbon atoms, and increasing the length of the carbon chain led to an exponential increase in odor thresholds. The olfactory power of the thiols was considerably improved by methyl or ethyl substitution in the α-position to the thiol group as well as by an additional methyl or ethyl group at the mercapto-containing carbon atom. By using comparative molecular similarity indices analysis, a 3D-quantitative structure-activity relationship model could be created, which was able to predict the odor thresholds of mercaptoalkanols in good agreement with the experimental results. Retention indices, NMR data, and mass spectra for 49 mercaptoalkanols, most of them synthetically prepared for the first time, are supplied.
- Polster, Johannes,Schieberle, Peter
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- Aroma extraction dilution analysis of Sauternes wines. Key role of polyfunctional thiols
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The aim of the present work was to investigate Sauternes wine aromas. In all wine extracts, polyfunctional thiols were revealed to have a huge impact. A very strong bacon-petroleum odor emerged at RI = 845 from a CP-Sil5-CB column. Two thiols proved to participate in this perception: 3-methyl-3-sulfanylbutanal and 2-methylfuran-3-thiol. A strong synergetic effect was evidenced between the two compounds. The former, never mentioned before in wines, and not found in the musts of this study, is most probably synthesized during fermentation. 3-Methylbut-2-ene-1-thiol, 3-sulfanylpropyl acetate, 3-sulfanylhexan-1-ol, and 3-sulfanylheptanal also contribute to the global aromas of Sauternes wines. Among other key odorants, the presence of a varietal aroma (α-terpineol), sotolon, fermentation alcohols (3-methylbutan-1-ol and 2-phenylethanol) and esters (ethyl butyrate, ethyl hexanoate, and ethyl isovalerate), carbonyls (trans-non-2-enal and β-damascenone), and wood flavors (guaiacol, vanillin, eugenol, β-methyl-γ-octalactone, and Furaneol) is worth stressing.
- Bailly, Sabine,Jerkovic, Vesna,Marchand-Brynaert, Jacqueline,Collin, Sonia
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- A novel tandem [4++2] cycloaddition-elimination reaction: 2-alkenyl-4,4-dimethyl-1,3-oxathianes as synthetic equivalents for α,β-unsaturated thioaldehydes
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The first tandem cationic [4++2] polar cycloaddition-elimination reaction of 1-thia-1,3-butadienyl cations B with olefins to afford directly 3,4-dihydro-2H-thiopyrans D is described. The cations B were easily accessible by treatment of monothioacetals A, particularly the 2-alkenyl-4,4-dimethyl-1,3-oxathianes 1, with a hard Lewis acid. In this novel reaction, 2-alkenyl-4,4-dimethyl-1,3-oxathianes were utilized as synthetic equivalents for highly reactive α,β-unsaturated thioaldehydes. The effect of geminal dimethyl substituents on the oxathianes 1 and the mechanistic aspect of the reaction are considered. The reaction's asymmetric version was also investigated using a chiral oxathiane 4 derived from (-)-(1R,2R,5R)-2-(1-mercapto-1-methylethyl)-5-methylcyclohexanol. Although the enantioselectivities were moderate, the whole process can be done under odorless conditions.
- Ohsugi, Shin-Ichi,Nishide, Kiyoharu,Node, Manabu
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p. 1859 - 1871
(2007/10/03)
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- Mercapto alcohols and mercaptoalkyl esters
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New compounds having the formula EQU1 wherein R1 represents a hydrocarbon moiety having from 1 to 7 carbontoms, R2 is hydrogen, methyl or ethyl, and R3 is hydrogen, formyl or acetyl. The compounds are useful in the preparation, modification and intensification of a great variety of flavor and perfume compositions.
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