Inverse Diels-Alder Proline-Catalyzed Route to 1,2,4,5-Tetrazines

Significance

The well-known inverse electron demand Diels-Alder reaction of ketones with 1,2,4,5-tetrazines using solid support anchored l -proline organocatalysis is reported. The normal mechanism via enamine cycloaddition to the tetra­zine followed by elimination and recovery of the proline catalyst is proposed. The scope of the reaction was modestly tested for the ketone component but is clearly based on commercially available tetrazine derivatives.