Stereoselective synthesis of highly substituted 8-oxabicyclo[3.2.1]octanes and 2,7-dioxatricyclo[4.2.1.03,8]nonanes

The synthesis of new polyhydroxylated 8-oxabicyclo[3.2.1]octanes and 2,7-dioxatricyclo[4.2.1.03,8]nonanes is described. These structures is an interesting synthetic blocks for potential bioactive molecules. The precursor, 3-chloro-8-oxabicyclo[3.2.1]oct-6-ene-2,4-dione was obtained from reaction of tetrachlorocyclopropene with furan, then it was involved in carbonyl groups reduction and double bond oxidation, resulted in the formation of a polyhydroxylated derivatives, differently substituted at C-3 position, with five new stereocenters. Using intramolecular transannular hydroxycyclization, bicyclic epoxy diacetate was transformed into 2,7-dioxatricyclo[4.2.1.03,8]nonane in high yield through an alkoxide intermediate. Compounds thus obtained have a structure close to certain molecules with antitumor and glycosidase inhibitors activity.