Molecular Complexity from Aromatics:  A Novel, Stereoselective Route to Tricyclo[5.2.2.01,5]undecenones, Tricyclo[6.2.2.01,6]Dodecenones, and [n.3.3]Propellanes

A general stereoselective route to functionalized and substituted tricyclo [5.2.2.01,5]undecenones, tricyclo[6.2.2.01,6]dodecenones, and [3.3.3]- and [4.3.3]propellanes from simple aromatic precursors is reported. The methodology involves generation and cycloaddition of annulated cyclohexa-2,4-dienones with various acrylates followed by manipulation of the resulting tricyclic adducts, leading to functionalized tricyclo[5.2.2.01,5]undecenones and tricyclo[6.2.2.01,6]dodecenones endowed with a β,γ-enone chromophore. Photochemical reaction of the tricyclic chromophoric systems followed by reductive cleavage provided an efficient entry into propellanes.