Propargyl-PEG3-amine

Propargyl-PEG3-amine is a PEG-based linker bearing a terminal propargyl group and a primary amine, making it well suited for modular PROTAC assembly where orthogonal conjugation handles are required. Its polyethylene glycol segment supports aqueous solubility and flexible spatial presentation of warhead and E3 ligase ligands, while the reactive alkyne enables efficient click-type coupling strategies. The following sections describe its structural features and practical reactivity considerations in PROTAC linker chemistry.

Structure: The molecule contains a polyethylene glycol chain providing ether-rich, flexible connectivity, terminated by a propargyl (terminal alkyne) functionality and a primary amine. Key bond types include C–C within the propargyl fragment and C–N and C–O bonds within the PEG and amine linkage, supporting hydrophilic behavior.

Reactivity: The terminal alkyne can participate in copper-catalyzed azide–alkyne cycloaddition for forming stable triazole linkages to complementary azide-bearing partners under standard click conditions. The primary amine can be used for amide-bond formation or other nucleophilic acyl substitutions when reacted with activated carboxylic acid derivatives. Typical PROTAC synthesis employs polar organic solvents or aqueous mixtures, with coupling reagents and base selection guided by the electrophile and desired chemoselectivity.