FUNCTIONALIZATION AND UTILITY OF BRIDGING ETHERS IN THE TRANSFORMATIONS OF BICYCLO[5.4.0]UNDECANES

Studies detail the formation and utility of bridged ethers of bicyclo[ 5.4.0]undecanes as a means for stereocontrolled functionalization as d escribed in a survey of conjugate additions, reductions, and oxidative cyclizations. The intramolecular dipolar cycloaddition of 3-oxidopyry lium ylides affords a facile preparation of the starting trans-fused b icyclo[5.4.0]undecenone 1. Efficient methods toward highly oxygenated bicycloundecanes are described via the highly selective reductive clea vage of 12-oxatricyclo[6.3.1.0(1,6)]dodecanes such as 20 and 21. Reclo sure of the era-bridge was examined. Vanadium-catalyzed oxidative recl osure of 24 led exclusively to the novel 2-oxatricyclo[5.4.1.0(3,8)]do decane system 31.