The Synthesis of 7-Substituted-2,3-dihydropyrido [4,3-d]pyridazine-1,4-diones and 1,4-Dioxo-7-substituted-1,2,3,4-tetrahydropyrido[4,3-d]pyridazine 6-Oxides from Methyl Ketones.

A general four-step transformation of alkyl, cycloalkyl, aryl, and heteroaryl methyl ketones via 3-(dimethylamino)-1-substituted-prop-2-en-1-ones, followed by microwave [2+2] cycloaddition of dimethyl acetylenedicarboxylate, cyclization of (2E,3E)-2-[(dimethylamino)methylene]-3-(2-substituted)succinates with ammonia or hydroxylamine hydrochloride into 2-substituted-pyridine-4,5-dicarboxylates and their N-oxides and final cyclization with hydrazine hydrate into of 7-substituted-2,3-dihydropyrido[3,4-d]pyridazine-1,4-diones and 1,4-dioxo-7-substituted-1,2,3,4-tetrahydropyrido[4,3-d]pyridazine 6-oxides is shown.