Abstract
This dissertation describes the synthetic utility of tandem addition / C-C bond cleavage reactions of vinylogous acyl triflates. The first chapter provides background into carbon-carbon bond breaking reactions that have been applied in organic synthesis and the preliminary data that allowed for the original work presented here. Chapter 2 explains the significance as well as the prior syntheses of a commercially important moth pheromone, (Z)-6-heneicosen-11-one. The second chapter culminates in the synthesis of the sex attractant through a fragmentation reaction made possible by the direct extension of the initial nucleophile-triggered fragmentation studies to include the use of Grignard reagents. Chapter 3 describes the application of the fragmentation method, coupled to a benzannulation reaction, to afford penta- and hexasubstituted indanes. This two step sequence provides the basis for future work directed toward the synthesis of alcyopterosin A, a known cytotoxic agent with possible biological applications.
The current difficulties pertaining to the treatment of melanoma are discussed in Chapter 4. Recently, an exciting natural product that provides promising activity against this horrible cancer was discovered. Palmerolide A has the ability to kill melanoma cells selectively at low concentrations. The fragmentation method developed in these laboratories provides entry into a key fragment. The Claisen-type condensation reaction of vinylogous acyl triflates was expanded to the synthesis of a novel beta-ketophosphine oxide olefinating reagent, which allowed for the rapid synthesis of the eastern hemisphere (C1-C15) of this exciting natural product. Optimization of the Claisen-type condensation reaction to provide the beta-ketophosphine oxide reagent, led to the optimal reduction of the number of equivalents of the nucleophile. Intrigued by this, these reactions were explored in more detail. The results of this investigation are described in Chapter 5. The reduction in the number of equivalents of nucleophile, a key feature in these reactions, may be attributed to the ability of the phosphorus atom to form of an oxaphosphetane-like intermediate. As a result, new, potentially useful, beta-ketophosphonates were synthesized.
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