Second-generation difluorinated cyclooctynes for copper-free click chemistry

Area of Science:

• Chemical Biology
• Organic Chemistry
• Biotechnology

Background:

• 1,3-dipolar cycloaddition reactions, particularly with azides and alkynes, are crucial for site-selective biomolecule labeling.
• Copper-catalyzed click chemistry, while effective, is limited in biological applications due to metal toxicity.
• Previous work introduced difluorinated cyclooctyne (DIFO) reagents for copper-free click chemistry in living systems.

Purpose of the Study:

• To develop novel, synthetically tractable difluorinated cyclooctyne (DIFO) reagents for copper-free click chemistry.
• To assess the reactivity and utility of these new DIFO analogues in biological labeling and imaging.

Main Methods:

• Synthesis of a new class of difluorinated cyclooctyne (DIFO) analogues.
• Evaluation of the reaction kinetics of DIFO reagents with azides in a copper-free [3 + 2] cycloaddition.
• Application of the DIFO reagents for imaging glycans on live cells.

Main Results:

• A novel series of DIFO reagents were synthesized with improved tractability.
• The new DIFO analogues exhibited rapid [3 + 2] cycloaddition rates comparable to the parent compound.
• Successful imaging of glycans on live cells was achieved using the second-generation DIFO reagents.

Conclusions:

• Second-generation DIFO reagents provide a more accessible platform for copper-free click chemistry.
• These reagents maintain high reactivity, enabling efficient bioorthogonal labeling and imaging in living systems.
• The expanded utility of these DIFO compounds will facilitate broader adoption of copper-free click chemistry by biologists.