Abstract
The thermal cyclization of 4-amino-6-methylamino- (3) and 4, 6-bis (methylamino) -5-phenylazopyrimidines (4) to adenine (10) and its N6-methyl derivative is described. Compound 3 was synthesized by reaction of phenylazomalononitrile (2) with N-methylformamide and ammonia. Compound 4 was synthesized from 2, formamide, methylamine and its hydrochloride. These compounds were also obtained by methylation of 4, 6-diamino-5-phenylazopyrimidines, followed by rearrangement in methanolic dimethylamine. Heating 4 at 250-260°C afforded 6-methylaminopurine (12) together with a small amount of 8-anilino-6-methylaminopurine (13). Similarly, refluxing 3 in Dowtherm A yielded 10 and 8-anilinoadenine (11).
