Nucleophilic aromatic substitutions on 4,5-dicyanopyridazine. Part 2: Nitrogen nucleophiles

As previously reported with pyrrole and indole C-nucleophiles, 4,5-dicyanopyridazine (DCP) showed remarkable reactivity as a heterocyclic electrophile at the C-4 carbon toward amino nucleophiles. Aminocyanopyridazines, the formal SNAr2 products, have been easily synthesized in satisfactory yields through the facile substitution of a CN group of DCP, that behaves as leaving group. Operating in different solvents, the best results were generally obtained with a medium polar solvent, such as THF. The introduction of amino functionalities into the pyridazine system allows a desymmetrization of the starting material and opens the way to further synthetic elaborations.