The first synthesis of a functionalized tricyclicskeleton of vinigrol is described. The key stepinvolved an anionic oxy-Cope rearrangement of bicyclic allylic alcohol18, readily prepared by highlystereoselective addition of vinyl magnesium chloride to the hydroxyenone 15b. Introduction ofthe tertiary hydroxy group at carbon 8a was achieved by an unexpectedhydration of 30 with aqueoustrifluoroacetic acid.