Asymmetric allylboration for the synthesis of β-hydroxy-δ-lactone unit of statin drug analogs

Acrylic esters of homoallylic alcohols prepared in 92–96% ee via the asymmetric allylboration of appropriate aldehydes with B-allyldiisopinocampheylborane, upon ring-closing metathesis in the presence of 10 mol% of Grubbsʹ catalyst provided the corresponding 6-substituted dihydropyran-2-ones. These were diastereoselectively epoxidized and regioselectively reduced to furnish optically pure analogs of statin drugs. This procedure allows for the development of a combinatorial library of analogs of these drugs.