Pyrimidine Derivatives and Related Compounds. XLIV. Thermolysis of 6-Azido-1, 3-dimethyluracil to a Pyrimido [5, 4-g] pteridine Derivative

Abstract

Thermolysis of 6-azido-1, 3-dimethyluracil (1) in formamide gave 1, 3, 6, 8-tetramethylpyrimido [5, 4-g] pteridine-2, 4, 5, 7 (1H, 3H, 6H, 8H)-tetrone (3), while the same reaction in N, N-dimethylformamide (DMF) gave 3-(5-amino-1, 3-dimethyluracil-6-yl)-4, 6-dimethyl-[1, 2, 3] triazolo [4, 5-d] pyrimidine-5, 7 (4H, 6H)-dione (4), which was converted into 3 in refluxing formamide. Compound 4 was also obtained by the treatment of 1 with 4, 6-dimethyl [1, 2, 3] triazolo [4, 5-d] pyrimidine-5, 7 (4H, 6H)-dione (5) in refluxing DMF. The mechanism of these reactions is discussed.