The preparation of highly substituted pyridazines via a tethered imine-enamine (TIE) procedure

1,2,4,5-Tetrazines can be converted directly into cyclo-annelated pyridazines via an inverse electron demand Diels-Alder procedure incorporating tethered imine-enamine (TIE) methodology. This methodology provides an improved one-pot preparation of such compounds, eliminating the need for either the preformation of the enamine or a separate aromatisation step, and has been applied to 4 tetrazines producing 11 pyridazines.