The ring-closures of homocalycotomine and its 1′- and 2′-methyl-substituted diastereomers 3, 4 and 7, 8 with thionyl chloride or with sulfuryl chloride led to 1,2,3-oxathiazino[4,3-a]isoquinoline derivatives 9-11 and 18, 19 or to 15, 17 and 22, 23, respectively. The relative configurations and the predominant conformations of the cis1-transcis2 conformational equilibrium were studied by means of 1H- and 13C-NMR spectroscopy, with the application of DNOE, 2D HSC and 2D-COSY measurements. In good agreement with the liquid-phase results, the X-ray investigations revealed that 9 and 10 have the cis1, while 18 has the trans-anellated stereostructure.
|Number of pages||7|
|Journal||Journal of the Chemical Society. Perkin Transactions 2|
|Publication status||Published - febr. 1 2000|
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