Investigations on the synthesis and properties of new derivatives of pyrido[3,2-e]-1,3-thiazino[3,2-a]-s-triazine

It has been found that the condensation of esters of 3H-2-imino-7-methyl-4-oxopyrido3,2-e]-1,3-thiazine-5- and -6-carboxylic acids (I, II) with formaldehyde and primary amines affords the corresponding derivatives of a new heterocyclic system pyrido3,2-e]-1,3-thiazino 3,2-a]-s-triazine (IX-XXIV).