GalNAc-L96-tert-butyl ester is a cleavable PEG ADC linker used in the synthesis of antibody-drug conjugates (ADCs). Amino-Tri-(t-butoxycarbonylethoxymethyl)-methane is also a PEG/Alkyl/ether-based PROTAC linker that can be used in the synthesis of PROTACs.