Synthesis and characterization of tetramethylene-syn-sesterbicyclo[2.2.2]octene

The synthesis of syn-sesterbicyclo[2.2.2]octene () bilaterally grafted by an exocyclic s-cis-butadiene moiety is achieved from 1,8,9,10-tetrachloro-11,11-dimethoxy-endo-tricyclo[6.2.1.02,7]undeca-3,5,9-triene () employing repetitive Diels–Alder cycloadditions between 1,3-cyclohexadiene, generated from p-benzoquinone, and diethyl fumarate or maleic anhydride as the exocyclic butadienyl equivalent, followed by subsequent transformation to the conjugated diene moieties. In comparison with the corresponding sesquibicyclo[2.2.2]octene , the 1H NMR demonstrates the anisotropic shielding effect operating within the three parallel laticyclic double bonds. However, the UV absorption of shows less effect by the increase of laticyclic conjugated ethylene units.