Chiral compounds of essential oils XIX. 4‐methyl‐5‐decanolide: Chirospecific analysis, structure and properties of the stereoisomers

Abstract

Racemic mixtures of synthetic cis‐ or trans‐4‐methyl‐5‐decanolide were separated by enantioselective high performance liquid chromatography with Chiraspher‐RT to yield all four stereoisomers as enantiopure compounds of distinct odour activities. In order to elucidate stereochemical features the isolated stereoisomers were reduced to their corresponding 4‐methyl‐1,5‐decandiols by reductive ester cleavage with lithium aluminium hydride. Absolute configurations were derived from proton nuclear magnetic resonance studies of diastereomeric di‐(R)‐2′‐methoxy‐2′‐trifluoromethylphenylacetic acid esters of these 1,5‐diols. Using enantioselective multidimensional capillary gas chromatography (column combination SE 52/heptakis‐(2,3‐di‐O‐methyl‐6‐O‐tert butyldimethylsilyl)‐β‐cyclodextrin), the direct enantioselective analysis of all four lactone stereoisomers was achieved. The application of this method to the scent of living, white flowering orchids (Aerangis confusa) proves cis‐(4S)‐methyl‐(5S)‐decanolide as the unique and genuine stereoisomer of Aerangis lactone.

Stereoisomeric pattern of lilac aldehyde in Silene latifolia, a plant involved in a nursery pollination system

“…Kaiser and Nussbaumer, 1990;Borg-Karlson et al, 1994, 1996Bartschat et al, 1995), though it is known to play a role at least in specialised pollination systems (Ayasse et al, 2003). From electrophysiological studies it is known that insects differently respond to different enantiomers of a specific compound (e.g.…”

The Asymmetric Hetero‐Diels–Alder Reaction in the Syntheses of Biologically Relevant Compounds

“…Aerangis lactones are fragrances extracted from the white orchid Aerangis confusa, and their enantioselective synthesis is of high relevance as different enantiomers smell differently. [43] Scheme 8. Synthesis of bolivianine (49) through a Diels-Alder/intramolecular hetero-Diels-Alder cascade reaction.…”

Can food quality be enhanced by chromatography?

“…With the help of enantiospecific capillary GC many flavours like that of butter with its content of enantiomeric y(8)-lactones [6] or new flavours like the odour of orchids [7] or of passionfruits like maracuja [8] can now be characterized. This plays an important role in quality control in the aroma industry.…”