Ald-Ph-PEG4-NH-Boc

This PROTAC linker reagent, Ald-Ph-PEG4-NH-Boc, provides a functional handle set that supports modular assembly of bifunctional degraders. Its aldehyde-bearing terminus enables chemoselective conjugation to nucleophilic partners, while the PEG-based spacer and protected amine improve synthetic flexibility and linker solubility in typical organic workflows. The Boc-protected amine further supports stepwise coupling strategies, facilitating rapid optimization of PROTAC architectures. Detailed structural and reactivity considerations are provided below.

Structure: The linker contains an aldehyde functional group conjugated to a phenyl spacer and a poly(ethylene glycol) segment, terminating in a Boc-protected amine. It features an ether-rich PEG chain, aromatic ring connectivity, and a protected carbamate motif, offering enhanced polarity and conformational mobility.

Reactivity: The aldehyde can participate in nucleophilic addition and reversible imine formation, enabling coupling to amine or hydrazine/amine-derived nucleophiles under mild, water-tolerant conditions when compatible with the target chemistry. The Boc group is designed for orthogonal deprotection using standard acid-mediated protocols prior to amide or urea bond formation. Subsequent coupling commonly employs activated carboxylic acid derivatives with base in polar aprotic solvents, following established PROTAC linker assembly principles.