Synthesis of the C-C fragment of the archazolids by complex -homodimer cross metathesis.

A synthesis of the C-C fragment of the archazolids is described featuring a complex cross-metathesis coupling reaction between a -homodimer (prepared by silyl-tethered ring-closing metathesis) and the -terminal triene containing "eastern domain" of the archazolid natural products. This cross-metathesis was only successful when using the - as opposed to the monomer or -homodimer, with the -dimer added batchwise to minimize -isomerization. The product was obtained in an optimized 78% yield using the Hoveyda-Grubbs catalyst at 50 °C in toluene.