Reaction of N-aminopyridinium derivatives. XIII. Syntheses of pyrazolodiazines by cyclization of N-aminodiazinium salts.

Abstract

N-Aminopyridazinium (IV) and N-aminopyrazinium (VI, VIII) derivatives were synthesized by N-amination of pyridazine (III) or pyrazine (V, VII) derivatives with hydroxylamine-O-sulfonic acid. By the reaction of pyrimidine derivatives (IX, XI) with hydroxylamine-O-sulfonic acid, N-aminopyrimidinium derivatives were not obtained, but pyrimidine N-oxide derivatives (X, XII) or 1-amino-4-methyl-6-oxo-1, 6-dihydropyrimidine (XIV, XVI, XVII) were obtained. Therefore, N-aminopyrimidinium derivatives (XXI, XXII, XXIV, and XXVI) were synthesized by N-amination of IX and XI with O-mesitylenesulfonylhydroxylamine. Pyrazolo-diazines (XXVII-XXX, XXXV-XXXVIII) were synthesized by cycloaddition reaction of these N-aminodiazinium derivatives with acetic anhydride and sodium acetate or methyl acetylenecarboxylate. Pyrazolo [1, 5-c] pyrimidine derivatives (XXXVII-XXXVIII), which are different in oriention, were obtained by 1, 3-dipolar cycloaddition reaction of XXI and XXIV with methyl acetylenecarboxylate.