Stereoselective synthesis of the epicoccin core.

A short, convergent, and asymmetric synthesis of the epicoccin core was achieved using a phosphite-promoted one-step condensation of a complex proline-type amino acid. Key features of the assembly of this amino acid were a double-bond isomerization/vinylation/ring-closing metathesis strategy as well as an efficient, highly diastereoselective [2 + 2] cycloaddition of a ketene to an enecarbamate, derived from L-pyroglutamic acid.