Total Synthesis of Koshidacin A: Payne Rearrangement–Driven Enantioselective Construction of the Side Chain Triol Unit

Koshidacin A is a cyclic tetrapeptide isolated from the Okinawan fungus, Pochonia boninensis FKR‐0564, along with its oxidized form, Koshidacin B. These peptides fall into a series of cyclic tetrapeptides made of three hydrophobic amino acids and a fourth amino acid with a hydrophilic side chain. We report a total synthesis of Koshidacin A, which relies on the asymmetric synthesis of the hydrophilic amino acid from ( S )‐homo‐Garner aldehyde and using a combination of Sharpless asymmetric epoxidation and Payne rearrangement as the key steps.