Acid-PEG3-t-butyl ester is a PEG linker containing a t-butyl protected carboxyl group with a terminal carboxylic acid. The terminal carboxylic acid can react with primary amine groups in the presence of activators (e.g. EDC, or HATU) to form a stable amide bond. The hydrophilic PEG spacer increases solubility in aqueous media. The t-butyl protected carboxyl group can be deprotected under acidic conditions.
Acid-PEG3-C2-Boc is a PEG- and Alkyl/ether-based PROTAC linker can be used in the synthesis of PROTACs for the degradation of EGFR and inhibition of mTOR[1][2].
[1] Nathanael Gray, et al. Bifunctional molecules for degradation of egfr and methods of use. WO2017185036A1.
[2] Christopher Semko, et al. Rapamycin analogs as mtor inhibitors. WO 2018204416 A1.