NOVEL SYNTHESIS OF PYRIDOPYRIDAZINE, PYRROLOPYRIDAZINE AND SOME PYRIDAZINE DERIVATIVES

1,6-dihydro-4-methyl-6-oxopyridazin-3-carboxylates (1) react with hydr azine hydrate in ethanol to give the corresponding hydrazide (2). Comp ounds 2 gave the carboazides 3 upon treatment with nitrous acid. The c arboazides (3) react with different alcohols, different amines and hyd razine hydrate to give the corresponding carbamate, substituted urea, and semicarbazide derivatives 5-7, respectively. Also compound 3 when refluxed in xylene gave pyrrolopyridazine (4). Compound 1 reacts with aromatic aldehydes to give styryl derivative 8 which upon refluxing wi th hydrazine hydrate gave the corresponding hydrazide (9) which underg oes cyclization to pyridopyridazine (10) upon treatment with Cu2Cl2.