PT - JOURNAL ARTICLE AU - Naka, Sadahiro AU - Miyake, Yoshinori AU - Kanai, Yasukazu AU - Oota, Yoichiro AU - Kato, Hiroki AU - Shimosegawa, Eku AU - Kirihata, Mitsunori AU - Hatazawa, Jun TI - A novel method for synthesis of 4-Borono-2-[<sup>18</sup>F]fluoro-L-phenylalanine DP - 2014 May 01 TA - Journal of Nuclear Medicine PG - 1164--1164 VI - 55 IP - supplement 1 4099 - http://jnm.snmjournals.org/content/55/supplement_1/1164.short 4100 - http://jnm.snmjournals.org/content/55/supplement_1/1164.full SO - J Nucl Med2014 May 01; 55 AB - 1164 Objectives 4-Borono-2-[18F]fluoro-L-phenylalanine ([18F]FBPA) has been generally prepared according to the method described by Ishiwata et al. (Appl Radiat Isot 1991), in order to study tissue accumulation before boron neutron capture therapy where 4-borono-L-phenylalanine (BPA) is given intravenously as a carrier of 10B to tumor tissue. However, fluorination of BPA with [18F]acetylhypofluorite ([18F]AcOF) in trifluoroacetic acid (TFA), is insufficient for clinical use because of low radiochemical yield (RCY) (20-35%; decay corrected on the based on [18F]AcOF). We devised a novel synthesis of [18F]FBPA in order to improve the RCY. Methods [18F]AcOF was bubbled into CHCl3 (2 mL) containing N-tert-butoxycarbonyl-BPA tert-butyl ester (N-Boc-BPA(OBut) (42 mg) for 5 min at room temperature (rt). After removal of CHCl3, the residue was dissolved in TFA (1 mL) and stirred for 5 min at rt. The RCY of [18F]FBPA were measured by thin layer chromatography with CHCl3/MeOH/AcOH (3/2/1) as eluent. Results The protic solvents such as TFA have been generally used as reaction field for the directly aromatic fluorination with [18F]AcOF. However, it is known that the solvents provide significantly [18F]labeled byproducts in fluorination with [18F]AcOF. Whereas, the aprotic solvent has been hardly used in the aromatic fluorination with [18F]AcOF. We selected CHCl3 which is an aprotic solvent as reaction field and N-Boc-BPA(OBut) as a novel precursor. [18F]FBPA was prepared by fluorination of N-Boc-BPA(OBut) with [18F]AcOF in CHCl3, followed by removal of Boc and But groups with TFA. The RCY based on [18F]AcOF was approximately 80% and was 2-4 times higher than that (20-35%) by the method previously employed. Conclusions The present finding suggested that a novel synthesis of [18F]FBPA may enable increment of the number of cases examined in [18F]FBPA-PET.