| Abstract
| - Seven new cyclic natural polysulfides 1−7 were identified in extracts of two bacterial Cytophaga strains(CFB-phylum) isolated from biofilms from the North Sea. Their structures are based on mono- and dimeric-cyclization products of 2-methylpropane-1,2-dithiol 8, which was also present in the extract in traceamounts. The structures were deduced by analysis of their mass spectra and confirmed by synthesis. The1H NMR spectra of some these compounds suggested a high flexibility of the trithiepane and tetrathiocanesystems. Therefore, their conformation was further analyzed by DFT calculations and dynamic NMRspectroscopy. While thiepane 4 possesses a twist-chair lowest energy conformation, its isomers 2 and 3adopt a chairlike conformation, as does the tetrathiocane 5. In contrast, tetrathiocane 6 favors again atwisted chair conformation.
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