Transformations of 4-Amino-5-cyanopyrimidines. The Synthesis and Transformations of Pyrimido-/4,5-d/Pyrimidines

Several new approaches to the synthesis of pyrimido/4,5- -d/pyrirnidines are described. 5-Cyano-4-(N,N dimethylaminomethyleneamino)- 2-methylthiopyrimidine (2) and 5-cyano-4-ethoxyethyleneamino- 2-methylthiopyirimidine (12) cyclize with hydrazine into 3-amino-4-imino-2-methylthio-3,4-dihydropyrimido/4,5-d/pyrimidine (3) which can be deaminated into 4-amino-2-methylthiopyrimido/ 4,5-d/pyrimidine (4). On the other hand, 5-cyano-4-hydroxyiminomethyleneamino- 2-methylthio- (14) and -2-methoxopyrimidine (15) cyclize thermally into 4-amino-7-methylthio- (16) and 4-amino-7-methoxypyrimido/4,5-d/pyrimidine 3-oxide (17), respectively