t-Boc-aminooxy-PEG6-propargyl

t-Boc-aminooxy-PEG6-propargyl is a PEG-based bifunctional linker designed for constructing PROTACs through modular conjugation chemistry. It combines an aminooxy handle for oxime formation with a protected amine motif and a terminal propargyl group for orthogonal click-type coupling, enabling efficient assembly of targeted protein degraders. Its flexible polyethylene glycol spacer can improve solubility and reduce steric constraints around the binding elements. The detailed Structure and Reactivity parameters are provided below.

Structure: The linker contains a polyethylene glycol chain providing conformational flexibility, flanked by an aminooxy functionality and a terminal propargyl (alkyne) group. A tert-butoxycarbonyl protecting group masks the aminooxy-associated reactivity, while the molecule features stable ether linkages and carbon–carbon triple-bond character at the propargyl terminus.

Reactivity: PROTAC assembly typically leverages oxime ligation at the aminooxy site under mildly acidic aqueous or mixed solvent conditions to form an oxime linkage with an appropriate carbonyl partner. The terminal alkyne can then be used in copper-catalyzed azide–alkyne cycloaddition or related alkyne-compatible coupling strategies, using standard Cu(I) generation systems and polar aprotic solvents. Protecting-group stability should be considered during sequential conjugation steps.