First total synthesis of versicotide A, B and C.

The syntheses of versicotides A-C, natural products containing anthranilic acid and NMe-Ala, were achieved by solid phase peptide synthesis on 2-chlorotrityl resin followed by solution phase macrocyclization. Using an oxyma additive, the difficult coupling reactions to the deactivated aromatic amine of o -aminobenzoic acid, were performed in high yield, avoiding anthranilic rearrangements or side reactions.