Synthesis, Characterization, and Reactivity of Novel 6H-1,3,5-Oxathiazine S,S-Dioxides. -S,S-Dioxides (II) are prepared from oxathiazines (I) by oxidation with an excess of m-chloroperbenzoic acid. Further heating of dioxides (II) in the presence of silica gel gives the corresponding carboxamides (III). Some other related reactions are also reported and a possible reaction mechanism is discussed. -(ISLAM, M. R.; TAKIKAWA, Y.; LIM*, K. T.; J. Heterocycl. Chem. 51 (2014) 3, 604-609, http://dx.