Lithium-halogen exchange has often been used as a route to dehalogenation to form molecules with strained carbon-carbon bonds. We have previously shown that the highly pyramidalized alkene, pentacyclo[4.3.0.02,4.03,8.05,7]non-4-ene (2), may be generated via dehalogenation of 4,5-diiodopentacyclo[4.3.0.02,4.03,8.05,7]nonane (1) with n-butyllithium and t-butyllithium. However, alkyllithium mediated dehalogenation of vicinal diiodide 1 always leads to the formation of alkylithium addition products, even in the presence of a trapping agent such as diphenylisobenzofuran. In order to further study the chemistry and reactivity of this pyramidalized alkene, alternative routes that do not utilize alkyllithiums to generate the pyramidalized double bond must be developed. Electrochemical reduction is an alternative method to conventional dehalogenation routes that offers significant advantages such as low cost, speed, mild conditions, and good functional group tolerance. Indeed, electrochemical reduction represents the most efficient and the cleanest way in which electrons can be added to diiodide to effect dehalogenation. Preliminary studies have been conducted to determine the reduction potential of 1 via cyclic voltammetry. Using decamethylferrocene as an internal reference, TPPA (tris(N,N-tetramethylene)phosphoric acid triamide) as an overcharge protectant, and THF, we have determined the molecule is reduced at -0.85 V.

Synthesis of a pyramidalized alkene via electroreduction

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