Enantioselective\nCycloaddition of <i>in Situ</i> Formed aza-Dienes and Vinyl\nDiazo Compounds for the Synthesis of\nOptically Enriched and Diazo Containing Tetrahydropyridazine

A copper catalyzed enantioselective\nformal aza-Diels–Alder\nreaction of <i>in situ</i> formed 1,2-diaza-1,3-dienes from\nα-halohydrazones and vinyl diazo compounds was described. The\nprotocol provides a variety of optically enriched diazo-containing\ntetrahydropyridazines in moderate yields and with up to excellent\nenantioselectivities. The present methodologies utilize chiral oxazolines\nas the chiral ligands for asymmetric catalysis and feature mild reaction\nconditions, readily available substrates, and broad substrate scope.