• Login
    View Item 
    •   Home
    • Graduate Theses, Dissertations and Projects
    • Queen's Graduate Theses and Dissertations
    • View Item
    •   Home
    • Graduate Theses, Dissertations and Projects
    • Queen's Graduate Theses and Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Rhodium-Catalyzed Allylic Alkylation of Enolates and Homoenolates: Enantioselective Construction of α- and β-Stereogenic Carbonyl Compounds

    Thumbnail
    View/Open
    Thesis Document (6.950Mb)
    Author
    Wright, Timothy
    Metadata
    Show full item record
    Abstract
    The asymmetric alkylation of enolates is a particularly versatile method for the construction of -stereogenic carbonyl motifs, which are ubiquitous in synthetic chemistry. Over the past several decades, the focus has shifted to the development of new catalytic methods that depart from classical stoichiometric stereoinduction strategies (eg. chiral auxiliary). In this way, the enantioselective alkylation of prochiral enolates greatly improves the step- and redox-economy of this process, in addition to enhancing the scope and selectivity of these reactions. The following thesis outlines some of our efforts in this area, in which we have recently developed an enantioselective rhodium-catalyzed allylic alkylation reaction with unstabilized enolates and related nucleophiles. The thesis is divided into three chapters, including a comprehensive literature review that highlights the current state-of-the-art methods, followed by two research chapters that detail the development, scope and mechanistic aspects of two novel “enolate” alkylation processes.

    Chapter 1 commences with a brief introduction to enolate alkylation, which is followed by a detailed analysis of the historical development and modern approaches for catalytic enantioselective enolate alkylation. The review is divided into two major subsections; namely, the reactions of cyclic and acyclic enolates will be treated separately, thus delineating the significant achievements in each area.

    Chapter 2 highlights our development of the enantioselective rhodium-catalyzed allylic alkylation of prochiral aldehyde enolates. This chapter opens with a summary of the related organocatalytic methods that employ enamine nucleophiles to construct α-stereogenic aldehydes. In this regard, the limitations with these methods set the stage for the development an alternative approach involving unstabilized aldehyde enolates. Hence, we have utilized an enantioselective rhodium-catalyzed allylic alkylation reaction to enable the construction of acyclic quaternary stereogenic centers from α-aryl aldehyde pronucleophiles.

    Chapter 3 illustrates the enantioselective rhodium-catalyzed allylic alkylation of a homoenolate nucleophile. After a brief introduction on homoenolate alkylation; namely, the use of heteroatom-stabilized allylic anions as synthetic homoenolate equivalents, our development of a catalytic enantioselective variant of this process is discussed. To this end, we have shown that lithiated unsaturated α-amino nitriles deliver β-stereogenic carbonyls via regioselective allylic alkylation followed by in situ hydrolysis of the cyanoenamine intermediates.
    URI for this record
    http://hdl.handle.net/1974/27466
    Collections
    • Department of Chemistry Graduate Theses
    • Queen's Graduate Theses and Dissertations
    Request an alternative format
    If you require this document in an alternate, accessible format, please contact the Queen's Adaptive Technology Centre

    DSpace software copyright © 2002-2015  DuraSpace
    Contact Us
    Theme by 
    Atmire NV
     

     

    Browse

    All of QSpaceCommunities & CollectionsPublished DatesAuthorsTitlesSubjectsTypesThis CollectionPublished DatesAuthorsTitlesSubjectsTypes

    My Account

    LoginRegister

    Statistics

    View Usage StatisticsView Google Analytics Statistics

    DSpace software copyright © 2002-2015  DuraSpace
    Contact Us
    Theme by 
    Atmire NV