Synthesis and Properties of 1,5‐Dimethyltricyclo[3.3.0.0^2,8]octane‐ and 1,5‐Dimethyltetracyclo[3.3.0.0^2,80^4,6]octane Derivatives

Abstract

Abstract The synthesis of 1,5‐dimethyltricyclo[3.3.0.0 2,8 ]octane‐3,7‐dione ( 2 ), 1,5‐dimethyltetracyclo[3.3.0.0 2,8 0 4,6 ]‐octane‐3,7‐dione ( 3 ), the corresponding dienes 5 and 6 as well as the mixed enones 13 – 15 is reported. Using He( I ) photoelectron spectroscopy (PE) as a tool, a considerable interaction between the n orbitals on the O‐atoms and the σ frame in 2 and 3 as well as of the double bonds in 5 and 6 and the σ frame is found. These interactions are also traced back by the electronic absorption spectra of these compounds. The molecular structures of 2 and 3 have been investigated by X‐ray analysis.