A Facile Radiolabeling of [ 18 F]FDPA via Spirocyclic Iodonium Ylides: Preliminary PET Imaging Studies in Preclinical Models of Neuroinflammation.

A suitable TSPO PET ligand may visualize and quantify neuroinflammation in a living brain. Herein we report a ¹⁸ F-ligand, [ ¹⁸ F]2 ([ ¹⁸ F]FDPA), is radiolabeled in high yield and high specific activity based on our spirocyclic iodonium ylide (SCIDY) strategy. [ ¹⁸ F]2 demonstrated saturable specific binding to TSPO, substantially elevated brain uptake, and slow washout of bound PET signal in the preclinical models of brain neuroinflammation (cerebral ischemia and Alzheimer's disease).