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Browsing by Author "Moore, Jennifer Lynn, author"

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    The Stetter reaction: scope and mechanistic investigation
    (Colorado State University. Libraries, 2009) Moore, Jennifer Lynn, author; Rovis, Tomislov, advisor
    Since the isolation and characterization of stable imidazolinylidene carbenes by Arduengo in 1991, chemists have been increasingly fascinated by their potential as modifying ligands on transition metals. However, it was not until Ukai demonstrated the efficacy in the benzoin reaction that the use of stable nucleophilic carbenes as catalysts was used for organic transformations. The last 10 years in particular have seen a tremendous explosion of interest in this area, with new reactivity manifolds having been developed across a range of reaction subtypes. The highly enantioselective intramolecular Stetter reaction has been expanded to include the formation of tetrasubstituted stereocenters. The reaction is mild, general, and tolerates aromatic, aliphatic, sulfur, oxygen, and nitrogen tethering of aldehyde and Michael acceptor. The current substrate scope includes compounds with varying electronics and sterics. A mechanistic investigation into the intramolecular Stetter reaction has been conducted. The rate law of the reaction was determined and coupled with kinetic isotope effects, competition experiments and calculations to suggest that proton transfer is rate determining. These results provide the foundation for future development of better catalysts and expansion of substrate scope. The inherent tunability of nucleophilic carbenes as catalysts promises great latitude in overcoming issues associated with functional group compatibility, turnover frequency, turnover number and, naturally, expansion of substrate type. This suggests that nucleophilic carbene catalysts will likely remain useful tools in organic synthesis for the foreseeable future.