The conformational behaviour of some dihydro-1,4-thiazines—III

Oxidation of 1, 3, 5, 13 and 14 by either m-chloroperbenzoic acid or sodium periodate gave single sulphoxides, which are assigned the R configuration. The minor sulphoxide formed by sodium periodate oxidation of 4 and the major sulphoxide obtained in the corresponding oxidation of 6 are assigned the S configuration. The conformational properties of the above sulphoxides have been examined by the NMR method; the derivatives show an overwhelming preference to adopt the conformation with the oxide function in the axial environment.