Synthesis of (–)-Virosaine A
A Concise Enantioselective Total Synthesis of (–)-Virosaine A.
Angew Chem. Int. Ed. 2017;
18 September 2017 (online)
Virosaine A is a highly congested, polycyclic member of the Securinega alkaloid family. In their elegant synthetic approach towards (–)-virosaine A, Gleason and Hughes rely on an epoxide opening to trigger the intramolecular [3+2] cycloaddition proposed in its biosynthesis.
Epoxide opening in oxabicycle F afforded nitrone G, which underwent an intramolecular cycloaddition reaction to give the pentacyclic core structure H. Subsequent alcohol protection and regioselective lithiation/bromination afforded intermediate I, which was converted to (–)-virosaine A by a sequence of five more transformations.