Advances in Palladium-Catalyzed Allylation, Propargylation, and 1,3-Dienylation of Acetonitrile Pronucleophiles
Issue Date
2016-08-31Author
Locascio, Theresa M.
Publisher
University of Kansas
Format
410 pages
Type
Dissertation
Degree Level
Ph.D.
Discipline
Chemistry
Rights
Copyright held by the author.
Metadata
Show full item recordAbstract
Presented herein is the development and application of palladium-catalyzed methods for allylation, propargylation and 1,3-dienylation of acetonitrile pronucleophiles. The developed methods focus on optimizing both atom- and step-economy during product formation thus resulting in a minimal production of waste. Further, ligand-controlled regiodivergent strategies are also presented which provide efficient access to various functionalities through a change in reaction mechanism controlled by the denticity of the coordinating ligand. In regards to the developed methods for the propargylation and 1,3-dienylation of acetonitrile pronucleophiles, the presented work provides access to these functionalities using propargylic electrophiles that were rarely observed using previously known methods. In chapter 1, a brief review of commonly employed propargylation methods is presented which often occur under harsh reaction conditions or result in a large amount of byproduct formation. Further, few exceedingly difficult palladium-catalyzed propargylation strategies are also reported that overcome the large bias for the allenyl isomer or products arising from dinucleophilic addition. Alternatively, in chapter 2, we present our ligand-controlled regiodivergent strategy for the propargylation and 1,3-dienylation of acetonitrile pronucleophiles. Specifically, we report the first palladium-catalyzed coupling of a butadiene synthon to generate 1,3-dienylated products. Further, each method provides significant advantages over commonly employed strategies to access such functionalities such as optimizing step-economy and avoiding the necessity for prefunctionalized starting materials. In chapter 3 of this dissertation, we present our ongoing efforts to expand the substrate scope of the developed regiodivergent method to nitriles possessing a pKa 17. To achieve this goal, decarboxylative cross-coupling is employed to access the reactive intermediate in situ via irreversible decarboxylation thus generating CO2 as the only byproduct. Once again, selective propargylation or 1,3-dienylation is ligand-controlled and can occur though changing the ligand from monodentate to bidentate, respectively. Lastly, in chapter 4 we present a method for the in situ activation of allylic alcohols using CO2 for the allylation of nitroalkanes, nitriles, and aldehydes. The developed method provides several advantages over commonly employed allylation strategies: (a) avoids the pre-activation of allylic electrophiles for successful cross-coupling, (b) avoids the use of additives for allylic alcohol activation, and (c) generates base in situ for pronucleophile activation thus providing an atom-economic alternative for allylic cross-coupling.
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