1,5-Diazido-3-oxapentane

1,5-Diazido-3-oxapentane, provides two azide handles within a flexible, oxygen-containing spacer, enabling modular assembly of bifunctional degraders. Its bifunctionality supports orthogonal conjugation strategies commonly used in targeted protein degradation workflows, facilitating the attachment of ligands under conditions that preserve sensitive binding motifs. The points below describe its structure and practical reactivity considerations in detail.

Structure: The linker is a flexible aliphatic chain featuring an ether oxygen and two terminal azide groups. It contains stable C–C and C–O single bonds, with azide functionality providing reactive N-rich termini. These features contribute to favorable conformational adaptability and compatibility with bioconjugation chemistries used in PROTAC construction.

Reactivity: Azide groups are typically engaged via azide–alkyne cycloaddition (Cu(I)-catalyzed or copper-free strain-promoted variants) or related azide conjugation approaches. For PROTAC synthesis, the linker is commonly used as a coupling intermediate to install one or two functional partners sequentially, leveraging orthogonality between click handles and other protected functionalities. Reactions are generally performed in polar organic or mixed solvent systems under inert atmosphere when required, with catalysts such as Cu(I) salts for classical click or cyclooctyne reagents for copper-free conjugation.