¹⁵N and ¹³C NMR spectroscopy of 1,2,6‐thiadiazine 1,1‐dioxide derivatives and fused systems

Abstract

The natural abundance =N NMR spectra of sulphamide, sixteen 1,2,6-thiadiazine and two 1,2,4,6thiatriazine derivatives, phenylbutazone and antipyrine have been recorded for the first time. The influence of substitnents on nitrogen chemical shifts and the effect of intercalation of SO, and CO groups between two nitrogen atoms are discussed. Prototropic tautomerism was also studied. "CNMR data for some of the l,f,(i-thiadiazine and tbiatriazine derivatives are reported.

Oxidations of 4H‐1,2,6‐Thiadiazines

“…The unsymmetrical 3‐anilino‐5‐methoxythiadiazinone 17 j was more reactive giving complete consumption of the starting material in 20 min but again only an intractable orange solid was obtained (Table 2, entry 6). The oxidation of diaminothiadiazinone 17 k , however, gave an unidentified insoluble solid and not the anticipated 3,5‐diamino‐4 H ‐1,2,6‐thiadiazin‐4‐one 1,1‐dioxide ( 20 k ) [30] . The two substituted 3,5‐dianilino‐thiadiazin‐4‐ones gave good yields of sulfones 20 l and 20 m (Table 2, entries 8 & 9), while with the former, the oxidation prone electron‐rich p ‐methoxy‐phenyl group was notably tolerated.…”

“…The oxidation of diaminothiadiazinone 17 k, however, gave an unidentified insoluble solid and not the anticipated 3,5-diamino-4H-1,2,6-thiadiazin-4-one 1,1-dioxide (20 k). [30] The two substituted 3,5-dianilino-thiadiazin-4-ones gave good yields of sulfones 20 l and 20 m (Table 2, entries 8 & 9), while with the former, the oxidation prone electron-rich p-methoxyphenyl group was notably tolerated. Similarly, the N-methylanilino derivative 17 n gave sulfone 20 n in 67 % yield (Table 2, entry 10).…”