The synthetic routes for peptide SA-A1 and SA-A2 followed the previously described total synthesis of Sanguinamide A. Briefly, the thiazole containing building block was synthesized with a Boc-protecting group on the primary amine. Next, the linear peptide was assembled on chlorotrityl chloride resin ending with the thiazole building block followed by TFA treatment to cleave the peptide and simultaneously remove the N-terminal Boc group. The peptide was then efficiently cyclized in solution using HBTU as the coupling reagent. Peptide SA-A3 which was assembled completely in linear form followed by mild cleavage from the resin using hexafluoroisopropanol as a weak acid to maintain trityl protection of the cysteine residue. The peptide was then cyclized using PyBOP as the amide forming reagent followed solvent removal and treatment with TFA and scavengers to provide the final deprotected peptide.