Mal-amido-PEG6-CH2CH2COOPFP ester

This Mal-amido-PEG6-CH2CH2COOPFP ester is a specialized polyethylene glycol-based PROTAC linker designed to connect an amide-bearing module to a reactive ester handle for subsequent conjugation steps. Its ether-rich, flexible scaffold supports favorable linker solubility and conformational adaptability, which can improve productive ternary complex formation in targeted protein degradation workflows. The following sections describe its structure and the practical reaction logic typically used to assemble PROTAC constructs using this linker.

Structure: The linker comprises a PEG chain that provides multiple ether linkages and high conformational flexibility, terminated by an amide-linked “Mal” motif and a carboxylate ester bearing a fluorinated leaving group. It contains amide and ester functional groups, with ether oxygen atoms contributing to polarity and solvation.

Reactivity: The ester functionality is suited for nucleophilic acyl substitution, enabling coupling to amine-containing ligands or PROTAC fragments under mild base-assisted conditions. Typical approaches use polar aprotic solvents and controlled temperature to preserve sensitive groups. Mechanistically, nucleophilic attack on the activated ester carbonyl forms a tetrahedral intermediate followed by leaving-group expulsion, yielding a stable amide linkage that can be carried forward in iterative PROTAC synthesis.