S-acetyl-PEG4-NHBoc

S-acetyl-PEG4-NHBoc is a PEG-based, protected linker designed to support the modular synthesis of PROTACs by providing a flexible hydrophilic spacer and orthogonal functional groups for stepwise conjugation. Its acetyl-protected thioester and Boc-protected amine enable controlled coupling strategies that help preserve bioactive warheads and optimize linker positioning for efficient ternary complex formation. The

Structure: The molecule contains a polyethylene glycol segment that imparts conformational flexibility and aqueous compatibility, connected to a thioester motif and a Boc-protected amine. Key functional groups include an S-acetyl thioester and a carbamate, with stable covalent bonds suitable for orthogonal synthetic transformations.

Reactivity: For PROTAC assembly, the Boc group is typically removed under mild acid conditions to reveal an amine for subsequent amide or urea-forming coupling. The S-acetyl thioester can be used as an acyl-transfer handle or converted to reactive intermediates depending on the target warhead chemistry. Standard peptide-coupling reagents, compatible solvents, and base/acid combinations are selected to maintain thioester integrity until the intended coupling step.