Abstract
Tributyl(ethyl)phosphonium oxopentenolate ([P(4442)][Pen]) is an ionic liquid developed to capture CO and has shown ability to catalyze carbonylation reactions in organic chemistry. Carbon-11 ((11)C, t(1/2)=20.4 min) labeled CO is a highly versatile building block for the synthesis of positron emission tomography (PET) radiotracers that are applied for medical imaging. The use of [(11)C]CO is limited by its low solubility in organic solvents. Herein, we report a proof-of-concept study evaluating a new method to prepare (11)C-labeled amides, ureas and carbamates via reaction of [(11)C]CO in [P(4442)][Pen] and applied for fully automated radiosyntheses of Bruton's tyrosine kinase inhibitors, [(11)C]evobrutinib and [(11)C]ibrutinib.