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@PHDTHESIS{Saladin:59675,
      author       = {Saladin, Sandra},
      othercontributors = {Bolm, Carsten},
      title        = {{E}xploring the reactivity of alpha-triorganylsilyl
                      alpha-diazo esters : {C}-{H} activation, insertion
                      reactions, and rearrangements},
      address      = {Aachen},
      publisher    = {Publikationsserver der RWTH Aachen University},
      reportid     = {RWTH-CONV-208167},
      pages        = {III, 116 S. : graph. Darst.},
      year         = {2004},
      note         = {Aachen, Techn. Hochsch., Diss., 2004},
      abstract     = {The metal-catalyzed reactions of Alpha-triorganylsilyl
                      Alpha-diazo esters have been studied, with an emphasis on:
                      · Dirhodium(II)-catalyzed insertions of
                      Alpha-triorganylsilyl Alpha-diazo esters into activated C-H
                      bonds. · Dirhodium(II)-catalyzed reactions of
                      -triorganylsilyl Alpha-diazo esters with various acyclic and
                      cyclic carbonyl precursors. · The syntheses of
                      Alpha-silyl-substituted Alpha-keto esters, their
                      corresponding hydroxy esters and hydroxy acids, in addition
                      to investigating dirhodium(II)-catalyzed O-H insertion
                      reactions. Insertion of benzyl and ethyl 2-triorganylsilyl
                      2-diazoacetates into activated C-H bonds adjacent to oxygen,
                      such as in tetrahydrofuran, was possible using dirhodium(II)
                      acetate , albeit in moderate yields (up to $50\%$ yield).
                      When the chiral Davies catalyst was used, benzyl
                      2-tetrahydro-2-furanyl-2-trimethylsilylacetate was obtained
                      in $58\%$ ee. Ring expanded products were isolated from the
                      reaction of benzyl Alpha-triorganylsilyl Alpha-diazoacetate
                      with oxetane, attributed to a Stevens rearrangement. The
                      dirhodium(II)-catalyzed reaction of Alpha-triorganylsilyl
                      Alpha-diazoacetates proceeded well with various acyclic and
                      cyclic ketones, affording dioxolanones in up to $98\%$
                      yield. The effect of the structure of the diazo compound on
                      the formation of the dioxolanones was investigated, and
                      various novel silyl-substituted diazo precursors were
                      synthesized for this purpose. A silylated enol ether
                      competes with the formation of a dioxolanone, depending on
                      the electronic and steric properties of the ester
                      functionality. Two routes for the synthesis of
                      Alpha-silyl-substituted Alpha-hydroxy acids were envisioned,
                      comprising dirhodium(II)-catalyzed oxygen transfer and
                      dirhodium(II)-catalyzed O-H insertions. Reactions of
                      Alpha-triorganylsilyl Alpha-diazo esters with propylene
                      oxide afforded 2-silyl-2-oxoacetates in up to $95\%$ yield.
                      These were converted into their corresponding
                      enantiomerically-pure hydroxy acids via reduction using
                      NaBH4, enantiomer separation by preparative HPLC, and
                      palladium-catalyzed hydrogenolytic debenzylation.
                      Alternatively, asymmetric reduction using (R)-Alpine Borane
                      was effective in achieving 2-silyl-2-oxyacetates in up to
                      $91\%$ ee. Various alcohols were effectively inserted into
                      Alpha-triorganylsilyl Alpha-diazo esters, generating
                      2-silyl-2-oxyacetates in up to $97\%$ yield. Insertion of
                      chiral (R)-and (S)-phenylethanols, followed by separation of
                      the diastereomers, and palladium-catalyzed reduction using
                      molecular hydrogen, made it possible to isolate
                      enantiomerically-pure Alpha-silyl-substituted Alpha-hydroxy
                      acids, circumventing the need for preparative HPLC
                      separation. The best diastereomer ratio (dr) of 91:9
                      obtained to date was achieved with
                      (1R,2S,5R)-(-)-8-phenylmenthyl (triethylsilyl)diazoacetate
                      and the novel (S)-tetrakis{[2.2]PCp-4-carboxy}dirhodium(II)
                      catalyst in O-H insertions. Finally, enantomerically-pure
                      Alpha-silyl-substituted Alpha-hydroxy acids were tested as
                      ligands in asymmetric catalysis.},
      keywords     = {Ester (SWD) / Diazoverbindungen (SWD) / Silylgruppe (SWD) /
                      Einschiebungsreaktion (SWD) / Rhodiumkomplexe (SWD) /
                      Katalysator (SWD)},
      cin          = {100000},
      ddc          = {540},
      cid          = {$I:(DE-82)100000_20140620$},
      typ          = {PUB:(DE-HGF)11},
      urn          = {urn:nbn:de:hbz:82-opus-9441},
      url          = {https://publications.rwth-aachen.de/record/59675},
}