Reactions of tetrachloropyridazine with aliphatic nitrogen nucleophiles

(Chemical Equation Presented) Nucleophilic aromatic substitution reactions of tetrachloropyridazine with a series of aliphatic primary and secondary amines led selectively to products arising from replacement of chlorine at the 4-position in all cases. The structures of the products were unambiguously confirmed by X-ray crystallography. Substitution occurs at the most activated site para to ring nitrogen, despite the possible steric hindrance to substitution by adjacent chlorine atoms, reflecting the activating influence of ring nitrogen meta to the site of attack. N,N′-Dimethylethylene diamine gave a mixture of [6,6] ring fused products following initial substitution at the 4-position.