Derivatives of condensed pyrimidine,pyrazine, and pyridine systems

Pyrazinothiazines and the corresponding 3-hydroxy-3,4-dihydroquinoxalinothiazines, which are dehydrated to quinoxalinothiazines under the influence of acidic agents, are formed in the reaction of 2-mercapto-3-amino-5,6-dimethylpyrazine and 2-mercapto-3-aminoquinoxalines with - or -chloroacetoacetic esters in the presence of an equimolar amount of alkali. The IR, UV, and PMR spectra are presented.See [1] for communication XXXIV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 695–697, May, 1977.