SYNTHESES AND HPLC SEPARATION OF CHIRAL 1 ,3,4-THIADIAZINES AND 1,3,4-SELENADIAZINES

The reaction of 4-isopropylthiosemicarbazide and 4-alkyl(aryl)-2-methy l-thiosemicarbazide and -selenosemicarbazides, respectively, with alph a-halogenketones gives 1,3,4-thiadiazines and 1,3,4-selenadiazines. Th e titel compounds undergo, in the presence of acids or bases, ring con traction with extrusion of sulphur and selenium, respectively, and for mation of pyrazoles. Studies in this work are reported analytical HPLC separations of chiral 1,3,4-thiadiazines and 1,3,4-selenadiazines, re spectively, on different chiral stationary phases (CSP). The influence of various charged and uncharged modifiers in the mobile phase on the chromatographic resolution is discussed.