Use of Mpc-amino acids in solid phase peptide synthesis leads to improved coupling efficiencies.

The Mpc-group has a somewhat better stability than the Fmoc-group, resists catalytic hydrogenolysis, is highly stable in acidic media and its elimination product does not polymerize spontaneously. In a direct comparison of coupling efficiencies obtained in solid phase peptide syntheses using Mpc- or Fmoc-amino acids it is shown that the use of Mpc-amino acids leads to better coupling efficiencies and, consequently, a more homogeneous peptide. An improved synthesis of Mpc-ONSu and of Mpc-amino acid derivatives is presented.