Novel Tetrahydropyridazines by Unusual Aza-Diels-Alder Reaction of Electron-poor 1,2-Diaza-1,3-dienes with Electron-poor Alkenes Under Solvent Free Conditions

1,2-Diaza-1,3-dienes bearing electron-withdrawing groups react with electron-poor alkenes by means of an uncommon aza- Diels-Alder reaction furnishing novel tetrahydropyridazines with high regio- and stereoselectivity. Conducting these cycloadditions in solvent free conditions under thermal conditions the reaction times are significantly reduced, the yields are improved and the stereoselectivity remained unchanged.