Radiosynthesis of novel N-¹⁸ F-labeled ¹⁸ F-FHex-α-l-Glu and ¹⁸ F-FHex-β-Glu

N-¹⁸ F-labeled amino acids are important substitutes for new positron emission tomography (PET) imaging tracers complementing the deficiency of ¹⁸ F-fluorodeoxyglucose (¹⁸ F-FDG). In this work, two novel N-6-¹⁸ F-alkyl amino acid imaging agents, ¹⁸ F-FHex-α-l-Glu and ¹⁸ F-FHex-β-Glu, were designed and synthesized as potential probes for PET imaging of tumors. ¹⁸ F-FHex-α-l-Glu was synthesized using the precursor 6 from ¹⁸ F-F^- with the yield of 16 ± 4% (n = 5, uncorrected) within about 50 minutes. The specific activity was 14.5 GBq/μmol, and the radiochemical purity was more than 95%. ¹⁸ F-FHex-β-Glu was synthesized using the precursor 12 based on ¹⁸ F-F^- with the yield of 11 ± 3% (n = 3, uncorrected) in about 60 minutes. The specific activity was 9.1 GBq/μmol, and the radiochemical purity was more than 95%.