Facile approach to N,O,S-heteropentacycles via condensation of sterically crowded 3-phenoxazin-3-one with substituted anilines.

A convenient method for the synthesis of a series of 2-(arylamino)-3-phenoxazin-3-ones based on the nucleophilic substitution reaction between sterically crowded 3-phenoxazin-3-one and arylamines performed by short-term heating of the melted reactants at 220-250 °C is described, and the compounds were characterized by means of single-crystal X-ray crystallography, NMR, UV-vis, and IR spectroscopy, as well as cyclic voltammetry. The reaction with -amino-, -hydroxy-, and -mercapto-substituted arylamines widened the scope and provided an access to derivatives of N,O- and N,S-heteropentacyclic quinoxalinophenoxazine, triphenodioxazine and oxazinophenothiazine systems.

A new heteropentacyclic system coupling sterically crowded -benzoquinone with -phenylenediamines.

The reaction between 3,5-di(-butyl)--benzoquinone 1 and -phenylenediamine performed under oxidative conditions that is highly sensitive to the reaction conditions (type of solvent, ratio of reactants, and duration of the reaction) gives rise to various derivatives of a new condensed 10-quinoxalino[3,2,1-]phenoxazin-10-one heteropentacyclic system. The reaction of 1 with -phenyl--phenylenediamine results in the formation of three phenazine-like compounds and, unexpectedly, a derivative of a new spiro[1,3]dioxole-2,2'-furanyl-1-benzo[]imidazole system. The molecular structures of the prepared compounds were authenticated by NMR, mass spectra and X-ray crystallography data.