Enantiomeric 9,11-Dideoxy-9,11-ethane Analogues of Prostaglandin Endoperoxide

A series of schemes is described for the transformation of (−)-(lS,2S,3S,6R,7R,9R)-10,12-dioxatetracyclo[7.2.1.1^3,6-0^2,7]- tridecan-8-one, prepared via hydrogenation of a Diels–Alder adduct of levoglucosenone and cyclopentadiene, into key products (+)-(1 R,2R,5RS,7S,8S)- and (−)-(1S,2S,5RS,7R,8R)-4-oxatricyclo[6.1.2.0^2,7]undecan-5-ols and subsequently into the title compounds.