A Facile Radiolabeling of [¹⁸F]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 ¹⁸F-ligand, [¹⁸F]­2 ([¹⁸F]­FDPA), is radiolabeled in high yield and high specific activity based on our spirocyclic iodonium ylide (SCIDY) strategy. [¹⁸F]­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).