Fused 1,2‐dithioles. IV. Synthesis and reactions of 1,2‐dithiole <i>s</i>‐oxides

Abstract

Abstract 1,2‐Dithiolopyrrolones and their heterologues of type 1 are resonance stabilized systems displaying a high dipole moment. Upon oxidation with organic peracids compounds 2 , 5 , 15a, 16a, 20a and 25a gave the corresponding S (2)‐oxides and, depending on substituents, in some cases the S (2)‐ and S (1)‐dioxides. The S (2)‐monoxides showed a proclivity to disproportionation and were easily reduced to dithioles with symme trical dimethylhydrazine. From S (2)‐oxides and several primary amines bicyclic isothiazole‐ S ‐oxides were obtained ( S/N ‐exchange reaction). From the N ‐unsubstituted isothiazole S ‐oxide 10e the N ‐hydroxyisothiazole 9d was synthesized by an aza‐Pummerer‐type rearrangement. The assumption is made that S (2)‐oxides may be biologically important as active metabolites of pyrrothines and analogues of type 1 in their action as antibacterials and antimycobacterials.