SYNTHESIS AND CHEMISTRY OF SOME TRICYCLIC CYCLOPROPENES .3. TRICYCLO[3.2.1.0(2,4)]OCT-2(4)-ENE

The title compound cyclopropene 2 has been synthesized in situ from dibromide 8 and diiodide 9 via dehalogenation of tert-butyllithium in THF at -78-degrees-C. The dihalides were formed in six steps starting with cyclopentadiene and (chloromethyl)maleic anhydride. In the presence of diphenylisobenzofuran (DPIBF) 2 forms a Diels-Alder adduct, most probably 10. Cyclopropene 2 and a previously synthesized cyclopropene 1 were decomposed under these same conditions, only without DPIBF present, to give complex mixtures of products, some of which were characterized as tert-butyl adducts and dimers via the ene reaction of the cyclopropenes.