Bromo-PEG-propionic acid t-butyl ester

Br-PEGn-CH₂CH₂COO-tBu is a heterobifunctional reagent designed for sequential conjugation strategies, enabling nucleophilic substitution (e.g., with thiols or amines) via the bromide group followed by acidic deprotection of the tert-butyl ester for carboxyl-mediated modifications. Its key advantages include orthogonal reactivity for controlled stepwise assembly, tunable spacer length (n), and protection of the carboxyl group during alkylation reactions, though the t-Bu ester requires acidic deprotection and the bromide group is moisture-sensitive.