The bromination of 2,4,6-trimethylaniline (I) with Br2 in aqueous HCl gives 3-bromo-2,4,6-trimethyl-aniline (II), which is then condensed with nitrilotriacetic acid (III) by means of pyridine and acetic anhydride.
The title pyranodipyrimidine derivative is prepared by cyclization of 4-nitrobenzylidene bis-thiobarbituric acid pyridine salt (I) employing either trifluoroacetic anhydride at 30-40 C or in lower yields with acetic anhydride at 70-80 C. The cyclization of is also carried out in the presence of POCl3/P2O5 in refluxing chloroform.