Bis(2,5-dioxopyrrolidin-1-yl) 16-(3-(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)propanoyl)-4,7,10,13,19,22,25,28-octaoxa-16-azahentriacontane-1,31-dioate

This PROTAC linker is a bis-activated diimide-type scaffold designed to connect two functional partners through robust amide-forming chemistry. Its lactam-derived carbonyl framework supports efficient coupling under standard peptide-linker conditions, enabling systematic variation of linker length and geometry for targeted protein degradation workflows. The molecule’s bifunctional reactivity makes it particularly useful for assembling PROTACs where controlled conjugation is required; detailed structural and reactivity considerations follow below.

Structure: The linker contains two lactam carbonyl units and multiple ether oxygens within a poly(ethylene glycol)-like backbone, providing conformational flexibility. It also features an amide-forming diimide character and a terminal ester motif that can be converted to nucleophile-reactive intermediates. Overall, it combines polar ether segments with electrophilic carbonyl functionality.

Reactivity: Suitable PROTAC construction typically relies on nucleophilic acyl substitution and amide bond formation from activated carbonyl groups. Coupling is commonly performed using amine or aminoacid-derived nucleophiles under mildly basic conditions, with carbodiimide or related peptide-coupling strategies where appropriate for converting ester/acid functionalities into amide linkages. Polar aprotic solvents such as DMF or DMSO are often used to promote solubility and reaction efficiency, while temperature and stoichiometry are optimized to minimize hydrolysis of activated intermediates.