Synthetic and mechanistic investigations of superelectrophilic reactions
Boblak, Kenneth Nicholas
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This dissertation describes various intramolecular cyclizations promoted by superacid. The first chapter deals with the formation of N-heterocyclic indenes. In these reactions protonated N-heterocyclic rings are shown to enhance the reactivity of the carboxonium electrophile for the cyclodehydration of various ketones. The second chapter explores an unusual regioelectronic effect that controls whether Markovnikov or conjugate addition takes place across a double bond. The addition facilitated by superacid depends on the position of olefin functionality on N-heterocyclic olefinic derivatives. The final chapter investigates highly stable superelectrophilic systems and the trapping of their carbocations to highly functionalized fluorenes. This study includes the direct observation of dicationic and tricationic reactive intermediates in magic acid media via low temperature, nuclear magnetic resonance spectroscopy. The superelectrophilic cores promote charge-charge repulsion enhancing anti-aromaticity of the polycyclic-fluorene protons.