Hydroxy-PEG-acetic acid t-butyl ester

Hydroxy-PEG-acetic acid t-butyl ester is a heterobifunctional reagent featuring a hydroxyl group and a protected tert-butyl ester, primarily used as an intermediate in multi-step organic synthesis where the ester requires subsequent acidic deprotection to a carboxylic acid for conjugation. Its key advantages include orthogonal reactivity for sequential modifications, tunable spacer length (n), and protection of the carboxyl group during synthetic steps, though deprotection is necessary for final functionalization.