AN ALTERNATIVE ENANTIOSELECTIVE SYNTHESIS OF (-TRICYCLODECADIENONE())

The enantiomerically pure endo-cycloadduct (2) under bar obtained from the thermal Diels-Alder reaction of SR-(1-menthyloxy)-2(5H)-furanone with cyclopentadiene is converted into (+)-tricyclo[5.2.1.0(2,6)]decad i-4,8-en-3-one ((+)-(1) under bar) in a one-pot procedure via ring-ope ning with lithium methyl dimethylphosphonate followed by an intramolec ular Wittig-Horner-Emmons reaction in THF. The use of LiBr as additive in this step is highly beneficial to the formation of (1) under bar. (C) 1997 Published by Elsevier Science Ltd.