[4 + 2] Cycloaddition of in Situ Generated 1,2-Diaza-1,3-dienes with Simple Olefins: Facile Approaches to Tetrahydro­pyridazines

A catalyst-free [4 + 2] annulation process between in situ generated 1,2-diaza-1,3-butadienes and simple olefins has been developed. Under mild conditions, the reactions afforded 1,4,5,6-tetrahydro­pyridazines, which feature a wide range of bioactive compounds, with high yields (up to 99% yield).