rdf-syntax-grammar
mods:
  schema location: http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
  title info:
    title: Synthesis and Application of New Ligands Derived from N-Heterocyclic Carbenes, Phosphines and Phosphites for Asymmetric Hydrogenations
  name:
    name part: Khumsubdee, Sakunchai
    role:
      role term: creator
    role:
      role term: author.
  name:
    name part: Burgess, Kevin L.
    name part: 1968-
    role:
      role term: thesis advisor.
  name:
    name part: Texas A & M University
    role:
      role term: degree granting institution.
  type of resource: text
  genre: bibliography
  origin info:
    place:
      place term: txu
    date issued: 2014
    issuance: monographic
  language:
    language term: eng
  physical description:
    form: remote
    extent: 1 online resource.
  abstract: N-Heterocyclic carbene and phosphorus ligands have been synthesized and used for many catalytic reactions including chiral analogs of Crabtree's catalyst for asymmetric hydrogenation. These catalysts have been studied extensively, especially on hydrogenation of "largely unfunctionalized" alkenes, for more than a decade. These substrates, however, could not be easily modified leading to limited applications for organic synthesis. As a result, asymmetric hydrogenations of substrates that have non-coordinating functional groups have gained more attention because the products are chirons that could be used to synthesize many natural products. Even though many chiral analogs of Crabtree's catalysts have been studied, none of these catalysts is perfect. Different catalysts could be suitable for different substrates. This point motivated us to investigate asymmetric hydrogenation of different substrates using our N,carbene Crabtree's catalyst analog; for example, α-methyl-γ-alkyl-γ-amino acid derivatives can be obtained with high stereoselectivities. Moreover, the same point also inspired us to synthesize the new N-heterocyclic carbene ligands to compare the effect on different catalysts that have related structure. Design new ligands to obtain effective catalysts, however, needs high experience and it is possible time consuming with unpredictable outcomes. Using the screening method with mono-chelating phosphorus ligands synthesized from cheap and easily obtained starting materials might be possible solution. However, we cannot rule out the possibility that bi-chelating ligand of the related structure might give better selectivities. Cross metathesis is an easy method that can link two parts together to convert mono-chelating ligand to bi-chelating one. Using metathesis combined with catalysis "metacatalysis" is one method to compare catalytic activity of mono- and bi-dentate ligands. However, the result indicated that most this method was suitable in some cases but not a…
  note: by Sakunchai Khumsubdee.
  note: "Major Subject: Chemistry"
  note: Includes vita.
  note: Doctor of Philosophy Texas A & M University 2013 http://hdl.handle.net/1969.1/151725
  note: Includes bibliographical references.
  note: Text (Dissertation)
  subject:
    topic: Major Chemistry
  subject:
    topic: Asymmetric Hydrogenation
  subject:
    topic: carbenes
  subject:
    topic: iridium
  identifier: http://hdl.handle.net/1969.1/151725
  record info:
    record content source: TXA
    record creation date: 140620
    record change date: 20151206101823.0
    record identifier: in00003436493
    language of cataloging:
      language term: eng