Pyridazine derivatives and related compounds, part 8: Synthesis of different heterocycles from 3-hydrazinopyridazine

The reaction of 3-hydrazino-4, 5, 6-triphenylpyridazine 1 with phenylisothiocyanate in ethanol gave thiocarbamoylhydrazine 2 while in butanol gave triazolo{[}4,3-b]pyridazinethione 3. Reaction of 1 with ethyl chloroformate gave ethoxycarbamoylhydrazinopyridazine 5 which upon heating it furnished triazolopyridazine 6. Also, the reaction of 1 with chloroacetylchloride gave triazolopyridazine 7. Reaction of 1 with a number of aromatic aldehydes, D-glucose, and pyruvic acid gave the corresponding hydrazones 9,11. Oxidative cyclization of 9a,b gave triazolo{[}4,3-b]pyridazine 10a,b. On the other hand, reactions of 1 with diethyl oxalate, ethyl acetoacetate, acetylacetone, ethyl cyanoacetate, diacetyl, and with phthalic anhydride are also reported. (c) 2005 Wiley Periodicals, Inc.