Intramolecular Cyclopentene Annulation. 3. Synthesis and Carbon-13 Nuclear Magnetic Resonance Spectroscopy of Bicyclic Cyclopentene Lactones as Potential Perhydroazulene and/or Monoterpene Synthons

Article abstract of DOI:10.1021/jo00168a010

The internal cyclopropanation of several diversely substituted dienic diazo esters is described.Thermolysis of the resulting vinylcyclopropanes yielded cyclopentene-annulated lactones in good yields.Depending on the choice of the dienyl unit, either guaiane or pseudoguaiane substitution patterns of the cyclopentene portion were obtained.Stereochemical assignments based on 13C NMR data are provided for all of these lactones.Subsequent transformations of the bicyclic lactones to differentially functionalized cyclopentenes are described.The potential of these synthons in the synthesis of perhydroazulene sesquiterpenes and several monoterpene cyclopentanoid natural products is addressed.