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Anion Relay Cyclopropanation and Aryl Vinyl Cyclopropane Cope Rearrangements By Anion Relay Cyclopropanation and Aryl Vinyl Cyclopropane Cope Rearrangements By Kevin Michael Allegre B.Sc., The University of Kansas, 2013 Submitted to the graduate degree program in Chemistry and the Graduate Faculty of the University of Kansas in partial fulfillment of the requirements for the degree of Doctor of Philosophy. Chair: Jon A. Tunge Paul R. Hanson Helena Malinakova Michael Rubin Ryan A. Altman Date Defended: 18 July 2019 The dissertation committee for Kevin M. Allegre certifies that this is the approved version of the following dissertation: Anion Relay Cyclopropanation and Aryl Vinyl Cyclopropane Cope Rearrangements Chair: Jon A. Tunge Date Approved: 24 July 2019 ii Abstract Kevin M. Allegre and Jon A. Tunge Department of Chemistry, July 2019 University of Kansas Anion Relay Chemistry is a powerful tool for the rapid development of molecular complexity in an operationally simple manner. Much of the work in this field has been pioneered and developed by the Smith group, whose work has primarily focused on silicon and phosphorus Brook rearrangements to effect anion relay. Presented herein is the development of a retro-Claisen condensation protocol to effect anion relay in the synthesis of vinyl cyclopropanes, and subsequent aromatic Cope rearrangement of those vinyl cyclopropanes. This protocol provides a supplementary method of anion relay utilizing readily accessible nucleophiles, which obviates the need for synthesis of alkyl silanes or phosphines as starting materials. Chapter 1 is a review of anion relay chemistry, which focuses on through-space anion relay over 3 or more bonds. It covers both new developments and applications to total synthesis of through-space anion relay more than three bonds since the field was last reviewed by Smith in 2008. Chapter 2 begins with an overview of retro-Claisen activation of allylic alcohols and its application to decarboxylative and deacylative allylation reactions (DcA and DaA). This synopsis is followed by an overview of a novel anion relay cyclopropanation accomplished through a retro- Claisen activation of a nascent allylic alcohol following an initial Tsuji-Trost allylation between a carbon nucleophile and a vinyl epoxide. This reaction constitutes the latest example of retro- Claisen activation of allylic alcohols presented by our group, and a novel application of anion relay chemistry. Of note is that the anion relay is accomplished without a Brook rearrangement, iii obviating the necessity to synthesize alkyl silanes or phosphonates. Furthermore, it is an example of [1,6]-anion relay, examples of which are much less common than [1,2]-and [1,4]-anion relay. In chapter 3, aromatic vinyl cyclopropane Cope rearrangements are reviewed. This review is followed by a description of the aromatic Cope rearrangement of the vinyl cyclopropanes made using the methodologies outlined in Chapter 2. While divinyl cyclopropane Cope rearrangements are common and facile at room temperature, aryl vinyl cyclopropane Cope rearrangements are much less common, tend to require forcing conditions such as high temperatures and usually further require rigorously stereodefined starting materials to take advantage of the cyclopropane strain release to drive dearomatization. The reaction described in this document features a dynamic equilibrium of aryl vinyl cyclopropane diastereomers prior to Cope rearrangement, allowing the difficult Cope rearrangement to be accomplished even without stereodefined starting materials. iv Acknowledgements I would like to thank Dr. Jon Tunge for his profound influence on my life as a chemist and as a human. Without his fostering, I would not have been able accomplish the works described in this dissertation. He taught me to learn, how to think, and how to grow professionally. From Jon, I learned not to apologize, but to improve; refining oneself as one refines a chemical process. I would like to thank my committee members; Dr. Helena Malinakova for the knowledge I gained in her organometallic chemistry class, Dr. Ryan Altman for his words of encouragement over the years. Dr. Michael Rubin has always given me excellent advice. I appreciate the lessons I learned in his class, as well as through his example and his advice over the years. Dr. Paul Hanson I admire for his curiosity and his passion. He has always fostered a sense of wonder and excitement in chemistry in myself and my fellow students. I would like to thank my parents for moral and financial support. It’s difficult to express my gratitude in text, as much of what I have gained from them is intangible and abstract, but they obviously have crafted me to a large extent into the person that I am today and are doing the same now for my own children. I wish to thank them for their constant faith in me and for believing in me even betting on my success has not always seemed logical. Furthermore, I would like to thank my wife, Jamie Allegre, for her constant support and encouragement throughout my career. Without the support of her strength and character, the task of completing graduate school would have proved impossible. As a parent, my highest priority in life is supporting my children and fostering their happiness. While the endeavor of pursuing a PhD began with this goal in mind, my efforts would have been in vain without Jamie. v I would like to thank Gertrude Marsi for the financial support provided by the KUEA fund established in her and Dr. Kenneth Marsi’s honor. Other financial support for this work was received from National Science Foundation grant no. CHE-1465172, and the Kansas Bioscience Authority Rising Star Program. vi Contents Abstract ........................................................................................................................................... iii Abbreviations .................................................................................................................................. ix Chapter 1: Review of Anion Relay Chemistry ................................................................................. 1 § 1.1 Introduction ..................................................................................................................................... 2 1.1.1– Types of Anion Relay .................................................................................................................. 2 1.1.2 – Through-Space Anion Relay ...................................................................................................... 3 § 1.2 Recent Developments in Through-Space [1, > 2]-Anion Relay ........................................................ 5 1.2.1 – Through-Space [1,3]-Anion Relay.............................................................................................. 5 1.2.2 – Through-Space [1,4]-Anion Relay.............................................................................................. 7 1.2.3 – Through-Space [1,5]-Anion Relay............................................................................................ 19 § 1.3 Recent Applications of ARC to Total Synthesis .............................................................................. 23 1.3.1 – Type I [1,4]-Brook Rearrangements ........................................................................................ 23 1.3.2 – Type II [1,4]-Brook Rearrangements ....................................................................................... 27 1.3.3 – Total Syntheses Employing both Type I and Type II [1,4]-Brook Rearrangements ................. 30 § 1.4 Conclusion ...................................................................................................................................... 34 § 1.5 References ...................................................................................................................................... 34 Chapter 2: Synthesis of Vinylcyclopropanes via Type I Anion Relay ............................................ 41 §2.1 Introduction .................................................................................................................................... 42 §2.2 Background ..................................................................................................................................... 43 2.2.1 – Retro-Claisen Activation of Allyl Alcohols ............................................................................... 43 2.2.2 – Intramolecular Pd-catalyzed Cyclopropanation ...................................................................... 49 §2.3 Synthesis of Vinylcyclopropanes via Anion Relay Chemistry .......................................................... 53 2.3.1 – Reaction Optimization ............................................................................................................ 53 2.3.2 – Reaction Scope ........................................................................................................................ 58 2.3.3 – Mechanistic Considerations .................................................................................................... 64 §2.4 Utilization of Cyclopropanes ........................................................................................................... 65 §2.5 Attempts at Asymmetric Cyclopropanation ................................................................................... 68 §2.6 Conclusion ....................................................................................................................................... 71 2.4.1 – Potential Future Directions ....................................................................................................
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