(R,S)-anti-1-Amino-2-[18F]Fluorocyclopentyl-1-carboxylic Acid: Synthesis from Racemic 2-Benzyloxycyclopentanone and Biological Evaluation for Brain Tumor Imaging with Positron Emission Tomography

(R,S)-anti-1-Amino-2-fluorocyclopentyl-1-carboxylic acid (2-FACPC, 4b) was radiolabeled in 39% yield starting from cyclic sulfamidate 12. The 9L gliosarcoma cells assays showed that 4b is mainly a substrate for the L-type amino acid transport with some affinity to the A-type. In rats bearing 9L gliosarcoma tumors, 4b displayed high tumor to brain ratio (10:1) at 120 min after injection. FACPC is an attractive candidate for imaging brain tumors with PET, and its isolated enantiomers are under investigation.