Finally, comparing the 4-C and 5-C piperazinyl tethering vectors of AB3029 and AB3030 , respectively, with their closest aniline tethered matched pairs 23 and 26, respectively, we see that the piperazinyl tethered compounds were on average ~3-fold weaker at degrading the BET proteins than their respective aniline tethered matched pairs. Encouragingly however, 31 and 32 did show a 2.9 to 3.7-fold weaker degradation of CRBN compared with 23 and 27, respectively (Table ). It is important to note that 31 and 32