Abstract
Facile one step purine syntheses from phenylazomalonic acid derivatives are described. Adenine, xanthine and guanine were synthesized directly from phenylazomalononitrile, N-(2-cyano-2-phenylazoacetyl) urea and 2-cyano-2-phenylazoacetylguanidine, respectively, by catalytic hydrogenation in formamide in the presence of ammonia (in the latter two the presence of ammonia was not indispensable) in excellent or good yields. Course of the reaction was revealed to involve the initial pyrimidine ring-closure followed by the imidazole ring-closure.
