Stereoisomeric Analysis of 6,10,14-Trimethylpentadecan-2-ol and the Corresponding Ketone in Wing Extracts from African Bicyclus Butterfly Species
Gas chromatography (GC) and mass spectrometry (MS) were used to determine the stereoisomeric compositions of 6,10,14-trimethylpentadecan-2-ol and 6,10,14-trimethylpentadecan-2-one in wing extracts from 17 Bicyclus butterfly species from different regions of Africa. All samples were purified using solid phase extraction (SPE). Since some species contained both alcohol and ketone, these were separated and the ketone was reduced to the alcohol before analysis as either (R)-trans-chrysanthemoyl or (S)-2-acetoxypropionyl esters. A novel asymmetric synthesis was developed for a reference mixture of (2R/S,6S,10R)-6,10,14-trimethylpentadecan-2-ol with known composition of the eight stereoisomers. The mixture then was used as the (R)-trans-chrysanthemoyl esters to correlate each of the eight gas chromatographic peaks to a specific stereoisomer of the extracted wing compounds. Seven butterfly species showed (2R,6R,10R)-configuration of the alcohol, four species contained minute amounts of alcohol too small to determine the stereochemistry, nine species showed (6R,10R)-configuration of the ketone, and one species contained minute amounts of ketone too small to determine the stereochemistry. No other stereoisomers of alcohol or ketone could be detected in the extracts, and the quantities of the compounds in the wing extracts varied from 5 to 900 ng per sample for each species.
Oxidative Transformations of Polyprenols
Oxidative transformationsinvolving the hydroxylsand ω-methylsof polyprenolsisolated from birch greenery (7-9 isoprene units in the chain) were used to produce α,ω-diols, diesters, aldehydoalcohols, and hydroxyacids. The products are of interest as potential anti-inflammatory, antiulcer, hepatoprotective, and cardio-active preparations.
Enantioselective Gas Chromatography
Gas chromatography (GC) is an attractive alternative for the direct separation of volatile and thermally stabile enantiomers. In addition to the high efficiency and the “universal” and sensitive detection GC also offers an unique advantage, i.e., a possibility to separate enantiomers that can interact with the chiral stationary phase (CSP) via van der Waals' forces only. In this article the state of the art is reviewed with special emphasis on cyclodextrin based CSPs. In addition, the applicability as well as the choice of chiral stationary phases are addressed. © 1996 John Wiley & Sons, Inc.