N.C.A [11C]CO2 as a safe substitute for phosgene in the carbonylation of primary amines

Article abstract of DOI:10.1002/(SICI)1099-1344(199906)42:6<537::AID-JLCR215>3.0.CO;2-3

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