Total Synthesis of the Nematicidal Cyclododecapeptide Omphalotin A by Using Racemization-Free Triphosgene-Mediated Couplings in the Solid Phase

Racemization-free coupling of Fmoc-N-methyl amino acids on a solid support is quantitative with a new triphosgene-activation method. With this method, the total synthesis of the nematicidal cyclododecapeptide omphalotin A (see picture) was accomplished, which because of its high content of N-methyl amino acids had not yet been accessible.