The first diastereoselective synthesis of natural fungal metabolite (+)-andytriol 1, the proposed biosynthetic precursor of varioxirane, was accomplished in nine linear steps from 2,3-O-isopropylidene-d-ribose. A biomimetic Katsuki–Sharpless epoxidation was then applied to construct the oxirane ring of the varioxiranes. The absolute configuration of the target molecule (+)-1 was for the first time