Inverse-electron-demand Diels-Alder reactions of condensed pyridazines, part 1. Synthesis of phthalazine derivatives from pyridazino[4,5-d]pyridazines

Article abstract of DOI:10.1016/S0040-4020(01)86436-X

The 1,4-diarylpyridazino[4,5-d]pyridazine derivatives 1a,b were found to undergo [4+2] cycloaddition reactions with a variety of electron-rich dienophiles like enamines and ketene acetals to afford phthalazine derivatives in good to high yields.