our search for a new class of HMG-CoA reductase inhibitors, the synthesis of reaction intermediate analogues was investigated. Compound 2, having the C-5 (R) configuration of natural mevinic acids, was prepared in enantiomericallypure form starting from levoglucosan. During this synthesis, an epimerisation of the olefinic intermediate 16 was observed and was found to depend strongly both on the axial