Carbon-11 carboxylation of terminal alkynes with [ 11 C]CO 2 .

A copper-catalyzed radiosynthesis of carbon-11 radiolabelled carboxylic acids was developed by reacting terminal alkynes and cyclotron-produced carbon-11 carbon dioxide ([11 C]CO2 ) in the presecence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). A small library of 11 C-labelled propiolic acid derivatives were obtained with a total synthesis time of 15 minutes from end of bombardment (EOB) with a (non-isolated) radiochemical yield ranging from 7% to 28%.