211At and 125I-Labeling of (Hetero)Aryliodonium Ylides: Astatine Wins Again |
| |
Authors: | Dr Clémence Maingueneau Dr Marion Berdal Dr Romain Eychenne Dr Joëlle Gaschet Prof Michel Chérel Dr Jean-François Gestin Dr François Guérard |
| |
Institution: | Université de Nantes, CNRS, Inserm, CRCINA, 44000 Nantes, France |
| |
Abstract: | Despite the growing interest in radioiodine and 211At-labeled radiopharmaceuticals, the search for radiolabeling reactions has been somewhat neglected, resulting in a limited number of available radiosynthetic strategies. Herein we report a comparative study of nucleophilic 125I and 211At-labeling of aryliodonium ylides. Whereas radioiodination efficiency was low, 211At-labeling performed efficiently on a broad scope of precursors. The most activated aryliodonium ylides led rapidly to quantitative reactions at room temperature in acetonitrile. For deactivated precursors, heating up to 90 °C in glyme and addition of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) as radical scavenger appeared essential to avoid precursor degradation and to achieve high radiochemical yields and molar activity. The approach was applied successfully to the preparation of 4-211At]astatophenylalanine (4-APA), an amino acid derivative increasingly studied as radiotherapeutic drug for cancers. This validated aryliodonium ylides as a valuable tool for nucleophilic 211At-labeling and will complement the short but now growing list of available astatination reactions. |
| |
Keywords: | astatine-211 halogenation iodine-125 iodonium ylides radiolabeling |
|
|