Abstract
The reaction of the hydrazide of 6,7-diphenyltetrazolo[1,5-b]pyridazine-8-carboxylic acid 3 with aromatic aldehydes gave 8-arylidenecarbohydrazide derivatives. The reaction of 3 with methanesulfonyl chloride, benzenesulfonyl chloride, phenyl and benzylisothiocyanate afforded the corresponding N-substitute derivatives. The reaction of 3 with potassium ethylxanthate gave 5-(6,7-diphenyltetrazolo[1,5-b]pyridazin4-yl)-1,3,4-oxadiazole-2-thione 7. The alkylation of this product in an alkaline medium proceeds at the sulfur atom, while the aminomethylation and acylation proceed at the nitrogen atom. Compound 3 was also reacted with N-aminothiosemicarbazide to give 5-(6,7-diphenyltetrazolo[1,5-b]pyridazin-8 yl)4-amino-1,2,4-triazole-3-thione 11.