Base-induced inverse-electron-demand aza-Diels-Alder reaction of azoalkenes and 1,3,5-triazinanes: Facile approaches to tetrahydro-1,2,4-triazines

The base-induced an inverse-electron-demand aza-Diels-Alder reaction of in situ formed 1,2-diaza-1,3-dienes with formaldimines is reported. This protocol features cycloaddition of two in situ generated reactive intermediates and provides a reliable and practical method for the synthesis of tetrahydro-1,2,4-triazine derivatives in synthetically useful yields.