Synthesis of (+)-1,3:2,5-Dianhydroviburnitol ((+)-(1R,2R,3S,5R,6S)-4,7-Dioxatricyclo3,6>octan-2-ol)

Article abstract of DOI:10.1002/hlca.19880710604

Epoxidation of (-)-(1R,2R,4R)-2-endo-cyano-7-oxabicyclo<2.2.1>hept-5-en-2-exo-yl acetate ((-)-5) followed by saponification afforded (+)-(1R,4R,5R,6R)-5,6-exo-epoxy-7-oxabicyclo<2.2.1>heptan-2-one ((+)-7).Reduction of (+)-7 with diisobutylaluminium hydride (DIBAH) gave (+)-1,3:2,5-dianhydroviburnitol (= (+)-(1R,2R,3S,4R,6S)-4,7-dioxatricyclo<3.2.1.0^3,6>octan-2-ol; (+)-3).Hydride reductions of (+/-)-7 were less exo-face selective than reductions of bicyclo<2.2.1>heptan-2-one and its derivatives with NaBH4, AlH3, and LiAlH4 probably because of smaller steric hindrance to endo-face hydride attack when C(5) and C(6) of the bicyclo<2.2.1>heptan-2-one are part of an exo oxirane ring.