Simple and efficient synthesis of highly functionalized cyclohexanes; formal total synthesis of ovalicin and fumagillin

Two chiral cyclohexanes 4 and 6, which are key intermediates for the total synthesis of ovalicin 1 and fumagillin 2, respectively, were synthesized from (2R,3S) 1,2-epoxy-4-penten-3-ol. The key steps involve an efficient construction of divinylalcohol 7 using methallyl Grignard reagent 9c, and an intramolecular olefin metathesis of 7.