Radiofluorination via [3+2]-nitrone-alkene cycloaddition was studied using the model reaction between (18)F-labeled C-(4-fluorophenyl)-N-phenyl nitrone ([(18)F]1) and substituted maleimides 2a-c. [(18)F]1 was prepared in RCY of 73.6+/-5.8% and radiochemical purity of >95%. Cycloaddition of [(18)F]1 to 2a in toluene at 80 degrees C and in EtOH at 110 degrees C gave the respective isoxazolidine [(18)F]5a in >80% RCY at 10min reaction time. Reaction between [(18)F]1 and 2b, c also went smoothly to afford the respective cycloaddition products in high radiochemical yields.
Zlatopolskiy, B. D., Kandler, R., Mottaghy, F. M., & Neumaier, B. (2012). C-(4-[18F]fluorophenyl)-N-phenyl nitrone: A novel 18F-labeled building block for metal free [3+2]cycloaddition. Applied Radiation and Isotopes, 70(1), 184-192. https://doi.org/10.1016/j.apradiso.2011.09.002