Synthesis of Propellane-Type 5/5/6-Tricyclic System via Tandem-Metathesis: A New Approach to Quadranoid Skeleton

We disclose a useful synthetic study to prepare a propellane-type 5/5/6-tricyclic system which is present in diquinane-based natural products such as quadrone, terrecyclic acid A, terrecyclol, etc. The present methodology involves LDA-mediated regio- and stereoselective allylation, and tandem-metathesis as key steps. The target molecules were assembled in just two steps starting from a readily available building block, 3β-vinyl-tricyclic ketone, which is prepared from endo-dicyclopentadiene-1-one. All the compounds prepared here are characterized by NMR data analysis and/or chemical methods. The synthetic studies demonstrated here are useful in the synthesis of quadronoid type of natural products.