Abstract
An efficient six-step synthesis of bicyclo[4.4.1]undecane-2,7-dione was elaborated.
Key steps include an enantioselective oxazaborolidine-catalyzed borane reduction (CBS
reduction) of 2,3,4,6,7,8-hexahydronaphthalene-1,5-dione to the corresponding diol,
and a subsequent (syn-diastereoselective) cyclopropanation. Oxidation then gives tricyclo[4.4.1.01,6]undecane-2,7-dione (>99% ee) which on treatment with two equivalents of samarium(II)
iodide undergoes cleavage of the central cyclopropane bond to yield the target compound
without any loss of stereochemical information.
Key words
asymmetric synthesis - chirality - cyclopropane - fragmentation - samarium diiodide