Tz-Thalidomide is a tetrazine tagged Thalidomide (Ligands for E3 Ligase). Tz-Thalidomide has binding affinity for BRD4, with IC50s of 46.25 μM (BRD4-1) and 62.55 μM (BRD4-2). Tz-Thalidomide is a click chemistry reagent, it contains a Tetrazine group that can undergo an inverse electron demand Diels-Alder reaction (iEDDA) with molecules containing TCO groups[1].