Investigation of Trimethylenemethane Cyclopentyl-Annulations as a Strategy to Obtain a Functionalized Angular Triquinane Skeleton.

The angular triquinane carbocyclic ring system is a component of many natural products found in numerous terrestrial and marine plants. A strategy for the synthesis of functionalized angular triquinanes utilizing two trimethylenemethane (TMM)-based [3+2] cycloaddition reactions is presented. This synthetic strategy employs the intermolecular dyil-trapping reaction to give eventual access to the bicyclo[3.3.0]oct-1-en-3-one system. A subsequent [3+2] cycloaddition with a TMM equivalent provides the angular triquinane carbocyclic framework.