Synthesis of Trifluoromethyl‐Substituted Proline Analogues as 19F NMR Labels for Peptides in the Polyproline II Conformation

As good as a Pro: Another CF3-substituted amino acid, CF3MePro (see structure), has been added to the arsenal of 19F NMR labels; it is particularly suited for the study of proline-rich peptides. This amino acid was carefully designed and chosen from other synthesized isomers, according to strict selection criteria, as the most stable, nonracemizable, conformationally restricted, and compatible with solid-phase peptide-synthesis protocols.