Propargyl-PEG4-tetra-Ac-beta-D-glucose

Propargyl-PEG4-tetra-Ac-beta-D-glucose is a PEG-based, carbohydrate-derived PROTAC linker building block designed to connect targeting ligands through a terminal alkyne handle while providing a hydrophilic, conformationally flexible spacer. Its ether-rich PEG segment can improve solubility and reduce steric bias during ternary complex formation, supporting efficient recruitment of target proteins in targeted protein degradation workflows. The structural and reactivity features that enable reliable PROTAC assembly are described in detail below.

Structure: The linker comprises a propargyl-functionalized PEG spacer linked to a tetra-acetylated beta-D-glucose core. It contains an alkyne for bioorthogonal coupling, multiple ether linkages within the PEG chain, and ester groups from acetylated hydroxyls. These features yield a flexible, polar scaffold with modifiable surface polarity.

Reactivity: The terminal alkyne enables copper-catalyzed azide–alkyne cycloaddition with azide-bearing partners; SPAAC is not applicable to this unstrained propargyl group. For CuAAC, typical approaches employ a copper catalyst system with an appropriate ligand, under mild aqueous or mixed-solvent conditions to preserve sensitive targeting ligands. The PEG ether environment and protected carbohydrate esters generally support stable handling during synthesis, with subsequent deprotection possible when required for biological compatibility.