Propargyl-PEG6-NHS ester

Propargyl-PEG6-NHS ester is a PEG-based bifunctional linker designed for efficient conjugation in PROTAC workflows, enabling stable attachment of targeting ligands through amide formation while preserving a terminal alkyne handle for subsequent click-type coupling. Its flexible polyethylene glycol scaffold enhances solubility and reduces steric interference, supporting robust synthesis of modular PROTAC constructs. The detailed Structure and Reactivity parameters are provided below.

Structure: The linker comprises a polyethylene glycol chain terminated with a propargyl group and an N-hydroxysuccinimide ester. It features an NHS-activated carboxylate for amide bond formation and a terminal alkyne for orthogonal bioorthogonal coupling. The ether-rich PEG backbone imparts flexibility and hydrophilicity.

Reactivity: The NHS ester reacts with primary amines under mildly basic aqueous or mixed solvent conditions to form stable amide linkages, typically proceeding via nucleophilic acyl substitution. For PROTAC assembly, the terminal alkyne can be used in copper-catalyzed azide–alkyne cycloaddition or related alkyne coupling strategies, using appropriate catalysts and solvent systems compatible with sensitive ligands.