Chiral compounds of essential oils XXI: (E, Z)-2,3-dihydrofarnesals—chirospecific analysis and structure elucidation of the stereoisomers
✍ Scribed by Dietmar Bartschat; Claudia Kuntzsch; Martin Heil; Anette Schittrigkeit; Katja Schumacher; Martin Mang; Armin Mosandl; Roman Kaiser
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 124 KB
- Volume
- 8
- Category
- Article
- ISSN
- 0958-0344
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✦ Synopsis
A synthetic racemic mixture of (E,Z)-2,3-dihydrofarnesal was oxidized to the corresponding carboxylic acids and converted to diastereomeric (S)-phenylglycinyl amides which were separated by high performance liquid chromatography. Reductive amide cleavage yielded the enantiopure aldehydes. Absolute configurations were derived from proton nuclear magnetic resonance spectroscopy studies of the diastereomeric amides or from enantioselective analysis of 4-methylhexanoic acid as a product of deoxygenation and oxidative decomposition of the corresponding enantiopure dihydrofarnesols. Using enantioselective multidimensional capillary gas chromatography (column combination PS 268/heptakis-(2,3-di-O-acetyl-6-O-tert-butyldimethylsilyl)--cyclodextrin) the direct enantioselective analysis of all four stereoisomers was achieved. The application of this method to the scent of orchids (Aerides jarckianum) and to the blossom fragrance of Citrus limon proves that genuine (E)-2,3-dihydrofarnesal has an enantiomeric distribution in the range of 85:15 in favour of the (3S)-enantiomer.