NCA [C-11]CO2 as a safe substitute for phosgene in the carbonylation of primary amines

An efficient one-pot synthesis of [C-11]ureas and [C-11]isocyanates via deh ydration of intermediately formed carbamate salts is described as a general alternative to their formation via [C-11]phosgene. After optimization of t he reaction parameters, in-target produced n.c.a. [C-11]CO2 can be used for labelling in a one pot reaction within a very short reaction time of 10 mi nutes resulting in good radiochemical yields. The developed method has been applied to the C-11-carbonylation of aniline, benzyl- and phenethylamine a nd 1,2-diaminobenzene yielding the appropriate n.c.a. [C-11]ureas in about 65, 85, 25 and 70% radiochemical yield (RCY), respectively. The presented r eaction sequence can be handled easily and safely and lends itself to simpl e automation.