Intramolecular cyclopropanation of glycals: studies toward the synthesis of canadensolide, sporothriolide, and xylobovide

reaction: see text] The first examples of copper-catalyzed intramolecular cyclopropanations of glycal-derived diazoacetates are reported. The new cyclopropanes are converted into advanced intermediates for the synthesis of bislactone natural products. Synthetic highlights include the selective monodeprotection of a di-tert-butylsilylene ether and a zinc-mediated ring opening cascade reaction.