Hexafluoroacetone as a protecting and activating reagent: Synthesis of new types of fluoro-substituted α-amino, α-hydroxy and α-mercapto acids

Starting from (S)-aspartic, (S)-malic, (S)-citramalic and (S,R)-thiomalic acid, new types of 4,4-difluoro-substituted α-amino-, α-hydroxy- and α-mercaptopentanoic acids have been synthesized, applying hexafluoroacetone as protecting and activating reagent. The new partially fluorinated α-functionalized carboxylic acids represent interesting monomers for peptide and depsipeptide modification and for rational design and elucidation of secondary structure.