Synthesis and 19F NMR parameters of a perfluoro-tert-butoxy tagged L-DOPA analogue

The robust multistep synthesis of a perfluoro-tert-butoxy (PFTB) tagged analogue of the non-proteinogenic amino acid 3,4-dihydroxy-L-phenylalanine (L-DOPA) via diastereoselective benzylation of Oppolzer's sultam glycinate was developed. The new compound is characterized by a flexible alkoxy linker connecting PFTB to the biochemically and pharmacologically relevant L-DOPA scaffold, which facilitates the free motion of the fluorinated moiety. Therefore, the nine chemically equivalent fluorine atoms give rise to an intense and sharp F NMR singlet signal that is easily detected in an aqueous environment. In addition, the kinetics of F NMR relaxation processes in blood solution fit the requirements for the potential use of the new compound as a probe in F magnetic resonance imaging applications in translational clinical field.