Tetrahydropyrido[d]pyridazinones—promising scaffolds for drug discovery

An approach to the synthesis of all possible tetrahydropyrido[d]pyridazinones has been developed. The method relies on the catalytic hydrogenation of the corresponding aromatic counterparts, which were obtained by cyclization of the relevant dibromomethyl-substituted pyridinecarboxylates with hydrazine. The synthetic schemes include 4–5 steps starting from commercially available materials. The tetrahydropyrido[d]pyridazinone scaffolds are combinations of a saturated heterocycle (piperidine) and a privileged aromatic heterocycle (pyridazinone); hence they are promising starting points for the design in medicinal chemistry.