Towards a one-pot synthesis of ¹¹C-amides via copper(I) catalyzed [¹¹C]CO₂ fixation

Synthesis of 11 C-amides has been hindered by the lack of versatile synthetic methods capable of directly and easily converting [ 11 C]CO 2 into 11 C-amides without conversion of [ 11 C]CO 2 into [ 11 C]CO. Herein, we explore an alternative one-pot synthesis of 11 C-amides using a metal catalyst via the addition of boronic acids/esters to [ 11 C]isocyanates generated in situ from primary amines and [ 11 C]CO 2 . A proof-of-concept for synthesizing [ 11 C]benzanilide directly from [ 11 C]CO 2 using organoboronic esters and tributylphosphoranylidines using copper(I) catalysis was demonstrated. We successfully utilized this novel method for the radiosynthesis of [ 11 C]benzanilide, in RCC of 12%. Further development of this methodology will be needed for wider application in the radiolabeling of 11 C PET radiotracers. Identification of catalyst capable of aiding the transmetallation step while not impeding [ 11 C]CO 2 fixation are likely needed for wider application of this methodology.