Syntheses of Pyrazole Derivatives. VII

Abstract

A remarkable antipyretic and analgetic action was observed with various C-methyl-7-aminopyrazolo [1, 5-a] pyrimidine derivatives, and thus C-alkyl and C-phenyl substituted 7-aminopyrazolo [1, 5-a] pyrimidine and also 3-bromo derivatives were synthesized.The corresponding 7-aminopyrazolo [1, 5-a] pyrimidine (XIII-XXIV) were prepared from 5-aminopyrazoles by the condensation with β-ketonitriles (I-VIII) in the presence of acidic catalysts. Bromination of XIII-XXIV proceeded to give 3-bromo derivatives (XXV-XXX), only when C-3 was not occupied. On the other hand, bromination of 5-aminopyrazoles gave 4-bromo derivatives (XXXI-XXXIII), which were condensed with pyrimidine to give 7-aminopyrazole [1, 5-a] pyrimidien and it became clear that bromination was taken place at C-3.