We also designed analogous compounds SIM4 (6), SIM5 (7) and SIM6 (8) composed of the CRBN ligand pomalidomide 4'-alkylC2-amine in place of VHL ligand (Fig. ). We synthesized trivalent PROTACs in nine overall steps from TME, with installation of either VHL or CRBN ligand followed in the final step by the 2:1 coupling of the BET ligand (see