Hexafluoroacetone as protecting and activating reagent: New routes to amino, hydroxy, and mercapto acids and their application for peptide and glyco- and depsipeptide modification

A critical overview is given of the synthetic potential of hexafluoroacetone (HFA) as bidentate reagent for the synthesis of new monomers to peptide, depsipeptide and glycopeptide. Topics covered are as follows: reaction of HFA with α-functionalized carboxylic acids; derivation/deprotection of HFA-amino, HFA-hydroxy and HFA-mercapto acids; site-selective derivation of α-functionalized dicarboxylic acids; ω-isocyanates from α-functionalized, ω-dicarboxylic acids; ω-diazoketones from α-functionalized dicarboxylic acids; further site-selective transformations of side-chain carboxy groups; and transformations of HFA-amino acids including the NH function.