Synthesis of the Nonribosomal Peptide Phevalin and Analogs.

Phevalin, a cyclic nonribosomal peptide produced by Staphylococcus aureus, has intriguing biological properties. A synthetic route to access phevalin and similar pyrazinone natural products tyrvalin, leuvalin, phileucin, and a few synthetic analogs is described. The reaction sequence involves a one-pot carbamate deprotection/imine formation/aerobic oxidation to form the pyrazinone-containing products.