Inverse-electron-demand diels-alder reactions of condensed pyridazines, part 2. Synthesis of isoquinoline derivatives from pyrido[3,4-d] pyridazines

Article abstract of DOI:10.1016/S0040-4020(01)88258-2

Employment of pyrido[3,4-d]pyridazine derivatives 1, 2, 3 as aza-dienes in inverse-electron-demand Diels-Alder reactions with 1-pyrrolidino-1-cyclopentene or its six-membered homologue, respectively, was found to provide an easy access to the isoquinolines 5, 7, 9, 11, 13, 15 after aromatisation of intermediate mixtures of regioisomeric dihydroisoquinoline derivatives.