Total Synthesis of Halicylindramide A

A rapid and efficient Fmoc solid-phase synthesis of halicylindramide A is described. The strategy comprises resin attachment of the first amino acid via the side chain of aspartic acid, stepwise solid-phase synthesis of the linear peptide analog up to the cysteine residue, on-resin head-to-tail cyclization and linear peptide synthesis of the N-terminal region, and finally cysteine oxidation and formylation. The stereochemistry of the halicylindramide A was confirmed by comparison of NMR and RP-HPLC data with the natural molecule. A distinctive conformational change was observed from the CD spectra of the halicylindramide A in sodium dodecyl sulfate.