Synthesis of [F-18]-1-amino-3-fluorocyclobutane-1-carboxylic acid (FACBC):A PET tracer for tumor delineation

Fluorine-18 labeled 1-amino-3-fluorocyclobutane-1-carboxylic acid (FACBC), a new tumor-avid amino acid, was synthesized for positron emission tomograp hy. [F-18]FACBC was prepared with high specific activity by nucleophilic di splacement with an overall radiochemical yield of 12% (EOB). Synthesis of t he triflate precursor was accomplished in nine steps starting from the reac tion of benzyl bromide with epichlorohydrin which gave 1-chloro-2-benzyloxy -3-brompropane. A key step involves conversion of 3-benzyloxy-cyclobutane-1 ,1-dicarboxylate diamide to a mixture of diastereomeric 2-benzyloxycyclobut ane hydantoins.