STEREOSTRUCTURE OF PYRROLIDINO[1,2-E]-4H-2,4-DIMETHYL-1,3,5-DITHIAZINE

A bicyclic dithiazine with the estimated structure of pyrrolidino[1,2-e]-4H-2,4-dimethyl-1,3,5-dithiazine (I) was synthesized from ethanal, hydrogen sulfide, and 4-aminobutanal. The steric configuration of the structure was confirmed as 2R,4R,8S or its mirror image by an X-ray crystal structure analysis, which is the first determination of the most stable conformation of the dithiazine compounds. All of the spectral data and the KI value on a capillary column for synthesized I coincided well with those of the natural product. Almost every chemical shift in H-1 and C-13 NMR was also clearly assigned, in consideration of the results from the 2D-COSY method and the X-ray crystal structure analysis.