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dc.contributor.advisorMalinakova, Helena
dc.contributor.authorScheetz, Rachel
dc.date.accessioned2016-01-04T03:20:49Z
dc.date.available2016-01-04T03:20:49Z
dc.date.issued2013-08-31
dc.date.submitted2013
dc.identifier.otherhttp://dissertations.umi.com/ku:12993
dc.identifier.urihttp://hdl.handle.net/1808/19620
dc.description.abstractCarbon-carbon bond-forming processes featuring palladium catalysts play an important role in the synthesis of biologically active organic compounds. In the early 2000s, Canty, Sanford, Ritter and others have focused on studying palladium complexes in the oxidation state Palladium(IV). The PdII-PdIV transformations possess distinct advantages over the traditional catalytic process mediated by palladium in the oxidation states Palladium(0) and Palladium(II). In these transformations, reductive elimination to form new C-C bonds from the PdIV intermediate is expected to occur at a faster rate than &beta-hydride elimination. Overall, the C(sp3)-C(sp3) bond coupling is expected to be favorable. In the past decade, the Malinakova group has been studying the synthesis of unique pallada(II)cycles and exploring their reactivity with different electrophilic organic oxidants. These studies established that allyl halides as well as vinyl and alkynyl iodonium salts are capable of producing PdIV complexes possessing three Pd-C bonds. A stable PdIV complex was isolated, characterized and shown to mediate the formation of a heterocycle. In this Dissertation, the synthesis of various PdIV complexes and studies aimed at explaining the range of fundamental transformations at the PdIV-center beyond reductive elimination are presented. Chapter One discusses a general introduction into Palladium(IV) chemistry which includes a comparison between Pd0-PdII and PdII-PdIV catalytic cycles. This introduction also documents the observed and the proposed advantages of Palladium(IV) complexes in the applications to organic synthesis. Chapter Two constitutes a review of Palladium(IV) complexes in organometallic chemistry with particular emphases on the following themes in Palladium(IV) chemistry: (1) the use of strong oxidants to create various Pd-carbon or Pd-heteroatom bonds; (2) the presence of stabilizing ligands to aid in isolating the PdIV complexes; (3) the overview of known organometallic transformations being mediated by the PdIV-center Chapter Three provides the preliminary studies into the use of diazonium salt oxidants to generate PdIV complexes at low temperatures. The PdIV complexes feature the tripodal tris(pyrazol-1-yl)borate (Tp) ligand as well as two Pd-C(sp3) bonds and the oxidant generates a new Pd-C(sp2) bond. Detailed 1H NMR spectroscopic studies at low temperature provided the evidence of the formation for the (Tp)PdII intermediate via ligand exchange and the formation of the desired PdIV complexes in solution. Chapter Four describes the study of PdIV-mediated C-H activation in an organic oxidant yielding PdIV complexes with multiple Pd-C(sp2/sp3) bonds. Reductive elimination generates a complex heterocycle featuring two new C(sp2)-C(sp3) bonds. Detailed low temperature 1H NMR spectroscopic studies monitor the formation of the PdIV intermediates, give insight into the oxidative addition and C-H activation pathway during the reaction sequence and confirm carbon-carbon bond-formation by establishing the structure of the final organic product. Chapter Five details the synthesis of stable PdIV complexes featuring different auxiliary ligands. These PdIV complexes, which also possess the stabilizing tripodal Tp ligand, are generated in the presence of iodonium salts. The chapter reports our studies on the effect of the electronic properties of auxiliary ligands on the reactivity of the PdIV complex. The studies detailed in the chapter were aimed at exploring the C-H activation in organic substrates induced by the PdIV complexes. However, initial work indicated a limited scope of ligand substitution reactions, which prevented us from realizing the desired C-H activation on the organic substrate. Detailed ligand exchange studies with nucleophiles/additives are described in this chapter.
dc.format.extent264 pages
dc.language.isoen
dc.publisherUniversity of Kansas
dc.rightsCopyright held by the author.
dc.subjectOrganic chemistry
dc.subjectC-H Activation
dc.subjectOxidation
dc.subjectPalladium(IV)
dc.titleExploring New Reaction Pathways Mediated by Palladium(IV) Complexes
dc.typeDissertation
dc.contributor.cmtememberBarybin, Mikhail
dc.contributor.cmtememberJackson, Timothy
dc.contributor.cmtememberTunge, Jon
dc.contributor.cmtememberGegenheimer, Peter
dc.thesis.degreeDisciplineChemistry
dc.thesis.degreeLevelPh.D.
kusw.bibid8086162
dc.rights.accessrightsopenAccess


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