Investigation of nitrogen- and sulfur-containing heterocycles

2-Mercapto-3-ureido-6-chloropyridine reacts with the ortho, meta, and para derivatives of phenacyl halides to give 2-phenacylthio-3-ureido-6-chloropyridines, which are readily cyclized to 6-arylpyrido2,3-b]1,4]thiazines regardless of the presence or absence of a substituent in the meta and para positions of the benzene ring.See 1] for communication XXIX.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 798–800, June, 1974.