Studies with Polyfunctionally Substituted Heterocycles: New Synthesis of Pyrido[5′,4′:2,3][1,3,4]oxadiazolo[3,2-a]pyridine; Pyridazine; 1,3,4-Oxadiazole; and Pyrazolo[1,5-a]Pyrimidine Derivatives

Article abstract of DOI:10.1002/jccs.199800099

Cyanoacetohydrazide 1a reacts with 2-arylhydrazoketons 2a,b and 3a,b in refluxing ethanol to yield pyrido[5′,4′:2,3][1,3,4]oxadiazolo[3,2-a]pyridine and pyridazine derivatives; in the absence of solvent pyrazolo[1,5-a]pyrimidine derivatives were obtained.