Cyclododecatetraene tetraepoxide: highly diastereofacial epoxidation of all-(Z)-1,4,7,10-cyclododecatetraene and selective synthesis of bridged bis-oxocanes

Epoxidation of all-(Z)-1,4,7,10-cyclododecatetraene has been investigated with use of m-CPBA and dimethyldioxirane in anhydrous solvent. The diastereoselectivity of multiple epoxidation steps is complete affording only exo,exo,exo,endo-1,4,7,10-tetraepoxide. To understand this result, the step-by-step epoxidation reaction was investigated and each step was found to be highly regio- and stereoselective. Finally, a Lewis acid-catalyzed ethanolysis or treatment with HBr/KBr of the tetraepoxide gave rearranged diepoxy-oxabicyclo[5.5.1]tridecane (bridged bis-oxocanes) in which eight stereocenters were controlled.