Eleuthesides and their analogs: V. Medium- and large-ring lactones based on levoglucosenone

Ozonolysis of the bridging double bond in bicyclic enol ethers obtained by the Michael reaction and subsequent intramolecular etherification afforded chiral decanolides fused to a tetrahydropyran ring. Three-step procedures were developed for the synthesis of chiral lactones with medium and large rings via oxidative cleavage with pyridinium chlorochromate of mixed bicyclic ketals which were prepared by treatment with methanolic HCl of Michael adducts derived from levoglucosenone and cyclopenta-, cyclohexa-, cyclohepta-, and cyclododecanone.