Figure 4.

Gas chromatographic analysis of 11 on a homochiral stationary phase. a) Synthetic mixture of all eight stereoisomers (Scheme 4), b) headspace extract from D. clavata, and c) – m) pure racemates and enantiomers of 11a–d. Compound (4R,5S,6S)-11c was obtained by enantioselective synthesis (Scheme 5), the pure racemates of 11a–d and the pure enantiomers of 11a, 11b and 11d were obtained by chromatographic separation from the synthetic mixture of all eight stereoisomers. The peak labelled with asterisk represents the second main natural product in the headspace extracts from D. clavata, also labelled by asterisk in Figure 1.