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 1H NMR of the proposed calcaripeptide B has been amended during this
synthetic study.