Abstract
Abstract This thesis describes an investigation into the use of the cross conjugated □-keto ester system as a promoter in an intramolecular polyene cyclization reaction for the construction of [4.4.4] propellanes. The polyene cyclization precursor 76 was readily synthesized starting from malononitrile. As such, two-fold alkylation of malononitrile yielded dinitrile 66 which was subsequently reductively alkylated, using a procedure developed in our laboratories, to give acetal 73. Enone 51 was then achieved from acetal 73 via a reaction sequence of reduction (73□74), hydrolysis (74□69), and aldol condensation (69□51). Carbomethoxylation of enone 51 was followed by a dehydrogenation reaction to give cross conjugated □-keto ester 76. In the presence of zinc iodide, enone 76 was found to undergo a facile intramolecular polyene cyclization reaction to afford bicyclic iodide 79, an advance intermediate in our investigations, in a highly regio- and stereoselective manner. In an analogous fashion to the above-mentioned synthetic sequence, dienone 88 was also synthesized. Upon exposure to zinc chloride, however, phenol 96 was the only isolated product, apparently due to a [3,3]-sigmatropic rearrangement process. The details leading to the above described results are discussed in this thesis.