Synthesis and chemistry of some tricyclic cyclopropenes. 3. Tricyclo[3.2.1.02,4]oct-2(4)-ene

The title compound cyclopropene 2 has been synthesized in situ from 2,4- dibromo or -diiodo tricyclo[3.2.1.0 2,4 ]octane via dehalogenation of tert-butyllithium in THF at -78 o 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. Cyclopropene 2 and a previously synthesized cyclopropene 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