The synthesis of the cyclic antibacterial peptide Kawaguchipeptin B on 11 different DVB cross-linked PS resins

We report the first synthesis of the antibacterial peptide Kawaguchipeptin B. This was carried out on 11 different polystyrene resins ranging from 0.3 to 6.0% DVB cross-linking. The synthesis was accomplished using an Fmoc/tBu/Aloc strategy, with side chain resin attachment and a C-terminal allyl ester group for cyclisation. The syntheses of the linear and cyclic forms of the peptide were monitored and surprisingly showed that synthetic efficiency increased with increasing resin-cross linking.