Electrochemical [¹¹C]CO₂ to [¹¹C]CO conversion for PET imaging

Area of Science:

• Radiochemistry
• Organic Synthesis
• Electrochemistry

Background:

• Carbon-11 (¹¹C) radiotracers are crucial in Positron Emission Tomography (PET) imaging.
• Efficient synthesis of ¹¹C-labeled compounds requires reliable methods for producing key precursors like carbon-11 carbon monoxide (¹¹C]CO).
• Existing methods for [¹¹C]CO generation can be inefficient or require harsh conditions.

Purpose of the Study:

• To develop a novel electrochemical method for generating [¹¹C]CO from readily available [¹¹C]CO₂.
• To optimize the reaction conditions for high yield and purity of [¹¹C]CO.
• To demonstrate the utility of the generated [¹¹C]CO in synthesizing a downstream radiolabeled molecule.

Main Methods:

• Electrochemical reduction of [¹¹C]CO₂ using Ni(cyclam) and Zn(cyclen complexes.
• Optimization of reaction parameters such as potential, solvent, and catalyst loading.
• Subsequent reaction of produced [¹¹C]CO with N-benzylbenzamide precursor.

Main Results:

• Successful generation of [¹¹C]CO from [¹¹C]CO₂ with yields up to 10%.
• High radiochemical purity (RCP) of >98% for the synthesized [¹¹C]N-benzylbenzamide.
• Demonstration of mild reaction conditions for the entire process.

Conclusions:

• The developed electrochemical methodology provides an efficient route to [¹¹C]CO from [¹¹C]CO₂.
• This method offers a valuable tool for the synthesis of ¹¹C-labeled PET tracers.
• The high RCP of the final product highlights the potential of this approach for clinical applications.