Total Synthesis of (-)-L-755,807: Establishment of Relative and Absolute Configurations

The first total synthesis of (-)-L-755,807 and its three stereoisomers was achieved by our Horner-Wadsworth-Emmons reaction for stereoselective formation of trisubstituted olefins, highly diastereoselective Darzens condensation to construct the epoxy-γ-lactam ring, and late-stage coupling of the ring and side-chain segments for efficient convergent synthesis. This synthesis shows that the originally proposed structure of natural (-)-L-755,807 was incorrect and establishes its relative and absolute configurations.