Synthesis, reactions, and antimicrobial activity of some novel pyrazolo[3,4‐d]pyrimidine, pyrazolo[4,3‐e][1,2,4]triazolo[1,5‐c]pyrimidine, and pyrazolo[4,3‐e][1,2,4]triazolo[3,4‐c]pyrimidine derivatives

Abstract Treatment of N ‐phenyl‐substituted benzenecarbo‐hydrazonoyl chlorides 1a ‐ d with malononitrile in sodium ethoxide solution gave 5‐amino‐4‐cyanopyrazole derivatives 2 ‐ 5 . Compounds 2 ‐ 5 were converted to formidate derivatives 6 ‐ 9 upon treatment with TEOF in acetic anhydride. The reaction of the latter products 6 ‐ 9 with hydrazine hydrate gave imino‐amino derivatives 10 ‐ 13 , which was converted to hydrazino derivatives 14 ‐ 17 by refluxing with hydrazine hydrate. Hydrazino as well as imino‐amino derivatives undergo condensation, cyclization, and cycloaddition reactions to give pyrazolo[3,4‐ d ]pyrimidine 18 ‐ 21 , pyrazolo[4,3‐ e ][1,2,4]triazolo‐[3,4‐ c ]pyrimidine 22 ‐ 27 , and pyrazolo[3′,4′:4,5]pyrimido[1,6‐ b ][1,2,4]triazine 42 ‐ 44 derivatives. Antimicrobial studies are performed using two Gram‐positive bacteria and two Gram‐negative bacteria. Data indicated that compounds 5 , 28D , 29B , and 31D are exploring elevated antibacterial effects against all strains tested. Compound 28D is the most promising antibacterial agent against the delicate bacterial strain Bacillus subtilis and Pseudomonas aeruginosa with high effectiveness (low minimum inhibitory concentration [MIC] value) 40 and 60 μg/mL, respectively.