1,3‐dipolar cycloaddition of diazomethane to azolopyridazines. The synthesis of isomeric 7‐methyl‐7h‐ and 8‐methyl‐8h‐pyrazolo[4,3‐d]azolopyridazmes

1,3-Dipolar cycloadditionof diazomethaneto 6-chloro substituted azolopyridazines 1-4 produces isomeric pairs of 7-methyl-7H- 9-12 and 8-methyl-8H-pyrazolo[4,3-d]azolopyridazines 13-16. The nucleophilic substitutionof chlorine at position 6 affords the corresponding 6-amino 17, 20, 23, 26, 29,32,35 and 38, 6-methoxy 18, 21, 24, 27, 30,33, 36, and 39 and 6-hydrazino derivatives 19, 22, 25, 28, 31, 34, 37, and 40 of these tricyclicsystems.