Synthetic Studies Relating to the Structure of Senoxydene. A Sequential Annulation Approach to Angular Triquinane Construction Capable of Varied Tetramethyl Substitution Patterns

Article abstract of DOI:10.1021/jo00355a019

A totally stereocontrolled route to the sesquiterpene known as senoxydene is described.The key phases of the synthesis involve a thermal ene reaction to set stereochemistry while constructing the diquinane segment and a vinylsilane-mediated annulation to elaborate the third, unsaturated five-membered ring.Our findings have disclosed that the natural product has been incorrectly formulated.In an attempt to broaden the scope of this methodology while simultaneously assessing 1H NMR spectral parameters of this group of triquinanes, the positional isomer 20 and 21 were also prepared.The synthetic schemes paralleled that developed earlier.Neither 20 nor 21 proved to be senoxydene.The proton magnetic resonance spectra of all known angular triquinanes are tabulated and discussed as appropriate.The ordering of chemical shifts for natural senoxydene shows them to be atypical for this class of compounds.Close agreement is, however, noted with Δ^9,12-capnellene, suggesting that senoxydene may be a linear triquinane.A definitive reinvestigation of its structure is in order.