Synthesis, hydrolysis reactions and conformational study of 2-substituted 3,5-diamino-4-nitroso-2H-1,2,6-thiadiazine 1,1-dioxides

Abstract

The 2-substituted 3,5-diamino-4-nitroso-2H-1,2,6-thiadiazine 1,1-dioxides are present in solution as a mixture of two rotational conformers of the nitroso group that are stabilized by hydrogen bonds with the amino groups in positions 3 and 5. The stability of these conformations has been studied using ¹H, ¹³C and ¹⁵N NMR spectroscopy, as well as molecular orbital ab initio calculations. In addition, hydrolysis reactions of these compounds have been carried out affording 5-amino-4-hydroxyimino-3-oxo-3,4-dihydro-2H-1,2,6-thiadiazine 1,1-dioxides and 4-amino-3-oxo-2,3-dihydro-1,2,5-thiadiazole 1,1-dioxides.