18F-Fluorination of Unactivated C–H Bonds in Branched Aliphatic Amino Acids: Direct Synthesis of Oncological Positron Emission Tomography Imaging Agents

A mild and selective photocatalytic C–H 18F-fluorination reaction has been developed that provides direct access to 18F-fluorinated amino acids. The biodistribution and uptake of three 18F-labeled leucine analogues via LAT1 mediated transport in several cancer cell lines is reported. Positron emission tomography imaging of mice bearing PC3 (prostate) or U87 (glioma) xenografts using 5-[18F]-fluorohomoleucine showed high tumor uptake and excellent tumor visualization, highlighting the utility of this strategy for rapid tracer discovery for oncology.