Study of condensed pyrimidine,pyrazine, and pyridine systems

A new method was developed for the synthesis of pyrimido [5, 4-b][l, 4] oxazin-7-ones by O-alkylation of 5-hydroxy-6-aminopyrimidines with -halo carboxylic acids and subsequent cyclization of the resulting pyrimdyloxyacetic acids in acetic anhydride. The reaction of chloropyrimidooxazinones with hydrazine gives the corresponding hydrazinopyrimidooxazinones, from which the azides were obtained. Unsubstituted pyrimido [5, 4-b][l, 4] oxazin-7-one was synthesized.See [1] for communication XXXIII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 681–685, May, 1976.