Effects of 4-hydroxypyrazolo(3,4-d)pyrimidine upon the catabolism of purines by various tissues of the rat and upon the rate of growth of Morris 5123-C hepatoma

A facile environment-friendly one-pot two-step regioselective synthetic strategy for 3,7-diarylpyrazolo[1,5-a]pyrimidines related to zaleplon and 3,6-diarylpyrazolo[1,5-a]pyrimidine-7-amines assisted by KHSO₄ in aqueous media

3-Aminopyrazoles required for the synthesis of pyrazolo[1,5-a]pyrimidines were obtained by the reaction of enaminonitriles with hydrazine hydrate. The resulting aminopyrazoles are reacted with formylated acetophenones under reflux at [Formula: see text] assisted by KHSO[Formula: see text] in aqueous media to form regioselectively 3,7-diarylpyrazolo[1,5-a]pyrimidines and 3,6-diarylpyrazolo[1,5-a]pyrimidine-7-amines. X-ray crystallography of selected compounds 5b and 7i further confirmed the regioselective formation of these products.

Reactions of 3-aminopyrazole derivatives with cyanothioacetamide and its derivatives: Synthesis and reactions of several new pyrazole and pyrazole[3,2-b]pyrimidine derivatives

Thiocarboxamidocinnamonitrile derivatives2 a-f reacted with 3-aminopyrazole derivatives3 a-c to give the pyrazole[3,2-b]pyrimidine derivatives6 a-p. Compounds6 a-p were used as starting material for syntheses of several heterocylic coompounds. Dehydrogenation of6 gave pyrazole[3,2-b]pyrimidines10 a-d while its reaction with diethyl oxalate gave11. Reactions of6 with formic acid gave pyrazolopyrimidines17 a-j, and pyrazolopyrimidopyrimidinoes18 a-j.