Amino-PEG5-t-butyl ester

This Amino-PEG5-t-butyl ester linker is designed for modular PROTAC synthesis, providing a flexible polyethylene glycol spacer that can enhance solubility and enable efficient conjugation between a ligand and an E3-recruiting moiety. Its protected carboxyl functionality supports controlled coupling strategies while maintaining chemical compatibility across common linker-building workflows. The detailed structural and reactivity characteristics are provided below to guide experimental selection and downstream assembly.

Structure: The linker contains a PEG-based ethylene glycol chain, an amino functional group, and a tert-butyl ester protecting group. It features ether linkages within the PEG segment and an ester linkage at the protected carboxyl site. Overall, it is a polar, flexible scaffold suitable for bioconjugation.

Reactivity: The tert-butyl ester can be selectively deprotected under acid-mediated conditions to reveal a reactive carboxylic acid for amide or ester-forming coupling. The amino group enables nucleophilic acyl substitution or coupling to activated carboxylic acid derivatives. Typical PROTAC linker construction uses standard peptide-coupling chemistries with appropriate bases and coupling reagents, often in polar organic solvents, to form stable amide bonds under mild conditions.