At elevated temperature (refluxing THF) prenyl anion adds regio- and enantioselectively to aldehyde 1 when a chiral, borneol-derived ligand is present. This reaction is the key stepin the first totalsynthesis of the monoterpene (-)-rosiridol (retrosynthesis is shown on the right). In addition, the absolute configuration of this natural product has been assigned conclusively. M=Zn, R=tBuMe2 Si.