Figure 3.

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, c) enantioselectively synthesised (4R,5S,6S)-11c (Scheme 5), d) enantioselectively synthesised (4S,5R,6S)-11d (Scheme 5), e) coinjection of a) and epimerisation products of (4R,5S,6S)-11c (Scheme 6), and f) coinjection of a) and epimerisation products of (4S,5R,6S)-11d (Scheme 6). 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. For comparison, the relative proportions of the eight stereoisomers obtained by synthesis according to Scheme 4 are indicated by the red curve in e) and f).