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Abstract
Single electron oxidative coupling reactions have played a role in organic synthesis for almost two centuries, predating Thomson's discovery of the electron by more than sixty years. These complicated bond-forming systems rely on the interconversion of anions, radicals, cations, and radical ions. Over the last 10-15 years, radical cations and the radicals they convert to have been applied to an expanding number of carbon-heteroatom and carbon-carbon bond-forming reactions. Given the complexity of these systems, full application of these transformations requires a fundamental understanding of the mechanistic impact and importance of the factors involved in a given reaction system. The research presented herein represents a careful mechanistic analysis of the controlling factors that exist in the single electron oxidative coupling of activated olefins, while contributing alternative synthetic strategies that utilize this newly elucidated information for more efficient protocols.
The body of work presented in this dissertation presents the following: 1) investigation of the interplay of solvent, oxidant, and substrate structure established that the rate limiting step of the single electron oxidation of β-dicarbonyls is the solvent-dependent decay of the radical cation; 2) development of a novel CAN-mediated synthesis of tetra-substituted pyrazoles from β-diketones yielded an alternative synthetic pathway to propyl pyrazole triol, an estrogen receptor ligand; and 3) the detailed kinetic and spectroscopic analysis of organo-SOMO activation, an intricate system containing organocatalysis, phase transfer, single electron oxidation, and free radical chemistry provided information necessary to propose a catalytic cycle and optimize the synthetic protocol, decreasing reaction times.
