Antituberculous compounds. XXVIII. Synthesis of pyrazolopyridines

Abstract

Abstract In a previous paper it was reported that N′‐alkyl derivative of isonicotinic acid hydrazide (INH) was more active against tuberele bacilli than the acyl derivative containing the same number of carbon atoms. The authors subsequently reported that the pyrido[2, 3‐ d ]pyridazine was closely related to the acyl derivative of INH except that the terminal carbonyl group was cyclized to the pyridine nucleus, therefore these derivatives were not effective against tubercle bacilli; however, pyridopyridazine, which is similar to the alkyl derivatives of INH, will be more effective against tubercle bacilli. According to the similar expectation, some pyrazolopyridines were prepared.