New 1,2,3-triazolo[4,5-d] 1,2,4-triazolo[3,4-b]pyridazine derivatives II

New tricyclic 1,2,3-triazolo-1,2,4-triazolo-pyridazine derivatives, bearing a methyl substituent on the 1,2,3-triazole ring, were prepared as potential biological agents. N-Methylation of dimethyl 1,2,3-triazole-4,5-dicarboxylate allowed synthesis of the isomeric 1-methyl-4,7-dihydroxy and 2-methyl-4,7-dihydroxy triazolo-pyridazines 4a and 4b which, by a chlorination reaction, gave the corresponding 1-methyl-4-chloro(6a), 1-methyl-7-chloro- (6b) and 2-methyl-4-chloro- (9) substituted 1,2,3-triazolo-pyridazines. The nucleophilic substitution with hydrazine hydrate and the suitable cyclization to form the 1,2,4-triazole ring, provided the expected tricyclic isomeric derivatives 8a, 8b and 11 respectively. The p-methoxybenzyl substituent, introduced as a leaving group to obtain either v-triazolo-pyridazine or v-triazolo-s-triazolo-pyridazine derivatives unsubstituted on the 1,2,3-triazole ring, appeared inadequate. Some compounds underwent binding assays toward the adenosine A(1) and A(2A) receptors.