作者:R. N. Krasikova、O. F. Kuznetsova、O. S. Fedorova、I. K. Mosevich、V. I. Maleev、Yu. N. Belokon、T. F. Savel’eva、A. S. Sagiyan、S. A. Dadayan、A. A. Petrosyan
DOI:10.1134/s1066362207050128
日期:2007.10
A new procedure was suggested for asymmetric synthesis of of 6-[F-18] fluoro-3,4-L-dihydroxyphenylalanine (6-F-18-L-FDOPA), an important radiotracer for studies of the dopaminergic system by positron emission tomography (PET). The key step of the synthesis is stochiometric asymmetric alkylation of chiral Ni(II) complexes using 3,4-methylenedioxy-6-[F-18] fluorobenzyl bromide as alkylating agent. A series of Ni(II) complexes containing various substituents in the benzyl group were tested. The highest enantiomeric purity of 6-F-18-L-FDOPA was attained with the complex derived from (S)-N-(2-benzoylphenyl)-1-(3,4-dichlorobenzyl) pyrrolidine-2-carboxamide, Ni-DCBPB-Gly, under mild alkylation conditions (CH2Cl2, 40 degrees C, potassium tert-butylate as base). Such conditions are favorable from the viewpoint of synthesis automation. The radiochemical yield of 6-F-18-L-FDOPA corrected for the radioactive decay was 10-15% at a synthesis time of 120 min, including purification by semipreparative HPLC. The radiochemical and chemical purity of the product exceeded 99%, and the enantiomeric purity was as high as 95%, meeting the requirements for using 6-F-18-L-FDOPA in PET practice.