Palladacarboxamide Capping Reagents for Carbon Isotope Labeling and Pharmaceutical Diversification

Area of Science:

• Medicinal Chemistry
• Organic Synthesis
• Radiochemistry

Background:

• Radiolabeling is crucial for understanding drug behavior in the body.
• Aryl carboxamides are prevalent in many pharmaceutical agents.
• Efficient methods for introducing isotopes like carbon-14 are needed.

Purpose of the Study:

• To develop a direct and efficient method for carbon-14 labeling of aryl carboxamides.
• To facilitate the synthesis of radiolabeled pharmaceutical compounds.
• To enable late-stage radiolabeling for drug development.

Main Methods:

• Utilized palladium-catalyzed organometallic carboxamide capping reagents.
• Generated near stoichiometric amounts of carbon-14 monoxide (¹⁴CO) from a surrogate.
• Employed Suzuki cross-coupling reactions with boronic acids or esters.

Main Results:

• Achieved direct ¹⁴C-labeling of aryl carboxamides.
• Synthesized structurally diverse, high-value aryl carboxamides.
• Demonstrated late-stage ¹⁴C-incorporation into drug molecules.

Conclusions:

• The developed protocol offers a simple and direct route for carbon isotope labeling.
• Air-stable organometallic complexes facilitate the labeling process.
• The method is readily adaptable for drug discovery and development programs.