BCN-sulfonamide-PEG2-sulfonamide-N-bis ethanol (compound 71) is a Ligands for Target Protein for PROTAC that contains a sulfonamide linker to increase the solubility of the linker-conjugate. BCN-sulfonamide-PEG2-sulfonamide-N-bis ethanol can be used to synthesize PROTACs with antitumor activity.