Propargyl-PEG2-Tos

Propargyl-PEG2-Tos is a PEG-based PROTAC linker featuring a terminal alkyne handle and a tosylate leaving group, enabling efficient, modular assembly of targeted protein degraders. Its ether-rich PEG segment promotes solubility and conformational flexibility, while the activated tosylate facilitates nucleophilic substitution to install diverse warheads. The propargyl functionality further supports orthogonal “click” coupling strategies. Detailed structural and reactivity considerations are provided below.

Structure: The linker combines an ether-containing PEG scaffold with a tosylate (tosyl) ester and a terminal propargyl (alkyne) group. It contains aromatic sulfonate functionality, ether linkages, and a carbon–carbon triple bond, providing a balance of polarity, flexibility, and orthogonal reactive sites for PROTAC synthesis.

Reactivity: The tosylate moiety is designed for nucleophilic substitution under conditions commonly used for alkyl tosylates, where suitable nucleophiles (e.g., amines or oxygen nucleophiles) displace the tosylate to form a new C–X bond. The terminal alkyne can be engaged in copper-catalyzed azide–alkyne cycloaddition or related alkyne coupling workflows. Typical synthesis uses polar aprotic solvents and base to promote substitution, with copper catalysts and appropriate ligands for click reactions when applicable.