Stereoselective Total Synthesis of Marine Cyclodepsipeptide Calcaripeptides A–C

The first stereoselective total syntheses of marine cyclodepsipeptides, calcaripeptides A-C, have been accomplished. Emphasis was given particularly in identification of an efficient strategy for the macrocyclization. The notable features of our synthesis include Evans alkylation, Crimmins syn-aldol, Crimmins acetate aldol, Wittig olefination, and Shiina macrolactonization reactions. An anomaly in the (1)H NMR of the proposed calcaripeptide B has been amended during this synthetic study.