Molecular complexity from aromatics: a novel, stereoselective route to tricyclo[5.2.2.0(1,5)]undecenones, tricyclo[6.2.2.0(1,6)]dodecenones, and [n.3.3]propellanes.

A general stereoselective route to functionalized and substituted tricyclo [5.2.2.0(1,5)]undecenones, tricyclo[6.2.2.0(1,6)]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[5.2.2.0(1,5)]undecenones and tricyclo[6.2.2.0(1,6)]dodecenones endowed with a beta,gamma-enone chromophore. Photochemical reaction of the tricyclic chromophoric systems followed by reductive cleavage provided an efficient entry into propellanes.