Experimental and computational studies of theoretically significiant alkenes
The concept of a novel type of homoconjugation, henceforth referred to as columnar homoconjugation, is introduced. A new class of organic molecules which is expected to exhibit such interaction is devised; for this series, the name "columnene" is coined. Molecular Orbital calculations (Huckel, MNDO, and/or ab initio) for a series of columnenes as well as cyclic allenes, cyclicbutatrienes, and trans cyclic alkenes olefins are reported. These calculations lead to the prediction that alkene moieties easily withstand slight twisting and bending destabilization. Synthetic strategies towards columnenes are developed and are categorized by two approaches: butatriene and bisallyl synthetic equivalent approaches. The utility of the butatriene synthetic equivalent approach for the synthesis of benzocyclobutenes is demonstrated. The first synthesis of 1,2,3-cyclononatriene, inspired by the results of MO calculations, is reported; the molecule is further characterized by complexation with Wilkinson's catalyst.