Catalytic enantioselective synthesis of 18F-fluorinated α-amino acids under phase-transfer conditions using (s)-NOBIN

Abstract We describe a new method for the asymmetric synthesis of [ 18 F]fluorinated aromatic α-amino acids (FAA) under phase transfer conditions using achiral glycine derivative NiPBPGly and (S)- NOBIN as a novel substrate/catalyst pair. The key alkylation step proceeds under mild conditions. Substituted [ 18 F]fluorobenzylbromides were prepared using nucleophilic [ 18 F]fluoride and were used as alkylation agents. Two important FAA, 2-[ 18 F]fluoro-L-tyrosine (2-FTYR) and 6-[ 18 F]fluoro-L-3,4-dihydroxyphenylalanine (6-FDOPA), were synthesized with an ee of 92 and 96%, respectively. The total synthesis time was 110–120 min and radiochemical yields (d.c.) were 25±6% for 2-FTYR and 16±5% for 6-FDOPA.