| Abstract
| - Stereoselective syntheses oftricyclo[5.3.0.03,8]decane 22 andtricyclo[6.3.0.03,9]undecane 26, thebasicskeletons of copaborneol and longiborneol, were achieved by theintramolecular double Michaelreactions of 2-cyclopenten-1-ones 15−17.The substrates were prepared starting withtricyclo[5.2.1.02,6]deca-4,8-dien-3-one (6).The intramolecular double Michael reactions were carriedoutunder three different conditions: TMSCl−Et3N−ZnCl2,TMSI−(TMS)2NH, andBu2BOTf−(TMS)2NH. The framework 26 of longiborneolwas constructed in good yields using the latter tworeagent systems.
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