Complex Polyfluoride Additives in Fmoc-Amino Acid Fluoride Coupling Processes. Enhanced Reactivity and Avoidance of Stereomutation†
journal contributionposted on 2003-03-05, 00:00 authored by Louis A. Carpino, Dumitru Ionescu, Ayman El-Faham, Michael Beyermann, Peter Henklein, Christiane Hanay, Holger Wenschuh, Michael Bienert
Isolated Fmoc amino acid fluorides have previously been shown to be among the most efficient reagents for peptide bond formation. Now, it has been found that anionic, polyhydrogen fluoride additives are capable of diverting many of the classical peptide coupling processes to acid fluoride couplings. Examples include the use of N-HBTU or N-HATU and the carbodiimide technique. As HF-containing species, these additives provide a more suitable medium for the coupling of systems that are sensitive to loss of configuration at the reactive carboxyl function.