(S)-Thalidomide-piperazine-pyrimidine-piperazine-C2-O-CH2-COO-C(CH3)3 is a conjugate of E3 ligase ligand and linker , consisting of Thalidomide and the corresponding Linker. (S)-Thalidomide-piperazine-pyrimidine-piperazine-C2-O-CH2-COO-C(CH3)3 can serve as a Cereblon ligand to recruit CRBN protein and serve as a key intermediate for the synthesis of complete PROTAC molecules.