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  • Stereoselective synthesis & application of enantioenriched main group α-haloalkyl organometal reagents

    Creator:
    Emerson, Christopher R.
    Abstract:
    Sulfoxide-ligand exchange (SLE) and asymmetric halogen-metal exchange (AHME) processes were separately examined for the enantioselective synthesis of functionalized alpha-haloalkylmetal (carbenoid) reagents. Carbenoids derived from SLE were used to effect stereospecific reagent-controlled homologation (StReCH) of boronic esters and those generated via AHME were engaged in Darzens-type chemistry with aldehydes. Abstract for...
    Resource Type:
    Dissertation
    Full Text:
    ABSTRACT OF THE DISSERTATION OF Christopher R Emerson for the degree of Doctor of Philosophy in

  • Catalytic desymmetrization of D₂d̳-symmertic proprochiral tetrasubstituted biphenyl compounds: a novel approach to the synthesis of axially chiral C₂-symmetric molecules

    Creator:
    Gunderson, Jeremey Tyson
    Abstract:
    Many D2d-symmetric 2,2',6,6'-tetrasubstituted biphenyls are readily prepared via net oxidative dimerization of appropriate 1,3-disubstituted benzenes. Conversion of such proprochiral compounds to useful C2-symmetric chiral biphenyls requires formal replacement of two substituents on opposing aryl ring units with alternate groups. This under exploited desymmetrization tactic has been demonstrated for the generation...
    Resource Type:
    Masters Thesis
    Full Text:
    Abstract approved: Paul R. Blakemore Many D2d-symmetric 2,2',6,6'-tetrasubstituted biphenyls are

  • Atropisomeric 8,8'-biquinolyl derivatives : synthesis, properties and applications

    Creator:
    Milicevic, Selena D.
    Abstract:
    7,7'-Dihydroxy-8,8'-biquinolyl (azaBINOL) was prepared from 7-hydroxyquinoline via N,N-dimethyl O-quinol-7-yl carbamate by directed ortho-metallation followed by FeCl₃-mediated oxidative coupling of the 8-lithioquinoline intermediate. Saponification of the resulting dicarbamate provided crystalline (±)-azaBINOL in 56% overall yield. 6,6'-Bis(dimethylaminocarbonyl)-7,7'-dihydroxy-8,8´-biquinolyl was prepared from the same dicarbamate by a double anionic-Fries rearrangement in 43% yield. 7,7'-Bis(diethylamino-carbonyloxy)-6,6'-diiodo-8,8´-biquinolyl...
    Resource Type:
    Dissertation
    Full Text:
    Paul R. Blakemore 7,7´-Dihydroxy-8,8´-biquinolyl (azaBINOL) was prepared from 7-hydroxyquinoline

  • Total synthesis of sparteine alkaloids from a common tetraoxobispidine intermediate

    Creator:
    Melbardis, John
    Abstract:
    In previous work (Blakemore et al. Org. Lett. 2005, 7, 4721; Heterocycles 2006, 70, 609), successful elaborations of the lupine alkaloids (±)-α-isosparteine (dl-2) and (±)-β-isosparteine (dl-3) were realized from a common tetraoxobispidine precursor, 3,7-diallyl -2,4,6,8-tetraoxo-3,7-diazabicyclo[3.3.1]nonane (93). Herein, the tetraoxobispidine approach to lupine alkaloids was extended to a total synthesis of...
    Resource Type:
    Masters Thesis
    Full Text:
    Tetraoxobispidine Intermediate Abstract approved: Paul R. Blakemore In previous work (Blakemore et al

  • Chain extension of boronic esters with stereo- and regio-defined lithiated oxiranes

    Creator:
    Alwedi, Embarek
    Abstract:
    The stereospecific reagent-controlled homologation (StReCH) of boronic esters with putative lithiooxiranes generated in situ from appropriate precursors via sulfoxide-lithium exchange, tin-lithium exchange, and direct lithiation is described with an emphasis on the first lithiation technique which allows for the regio- and stereo-specific generation of all types of lithiooxirane isomer. Transient...
    Resource Type:
    Dissertation

  • Development of Carbenoid Eliminative Cross-coupling for the Stereocontrolled Synthesis of Trisubstituted Alkenyl Moieties Within Styrenes and 1,3-Dienes

    Creator:
    Tanpure, Subhash D.
    Abstract:
    Traditional approaches for the direct preparation of alkenes are unable to fully control either the stereochemical configuration of the carbon-carbon double bond or else the regiochemistry of the substituents surrounding it. The recently introduced concept of carbenoid eliminative cross-coupling (CEXC) offers a remedy to these deficiencies by providing for a...
    Resource Type:
    Dissertation
    Full Text:
    : ______________________________________________________ Paul R. Blakemore Traditional approaches for the direct preparation of alkenes are

  • Stereospecific Synthesis of Stereotriad Motifs and Alkenes Using Enantioenriched sp³-Hybridized Carbenoids

    Creator:
    Xun, Sun
    Abstract:
    Enantioenriched sp³-hybridized carbenoid reagents CR1R2MX (X = nucleofuge, M = electrofuge) of different types were investigated for the synthesis of polysubstituted alkyl chains by iterative stereospecific reagent-controlled homologation (StReCH) and for the stereospecific connective synthesis of alkenes by eliminative cross-coupling. In the first part, putative enantioenriched α-chloroalkyllithiums (CHRLiCl) were employed...
    Resource Type:
    Dissertation
    Full Text:
    : ______________________________________________________ Paul R. Blakemore Enantioenriched sp3-hybridized carbenoid reagents CR1R2MX (X

  • Stereocontrolled Synthesis of Allenes by Eliminative Cross-Coupling of Carbenoids

    Creator:
    Cao, Yang
    Abstract:
    The bimolecular reaction of two carbenoid species resulting in the formation of a carbon-carbon double bond (pi-system), referred to herein as carbenoid eliminative cross-coupling (CEXC), involves a series of three fundamental steps: (i) ate-complex formation (transmetalation), (ii) 1,2-metalate rearrangement, and (iii) beta-elimination. All three steps are stereospecific and so the...
    Resource Type:
    Dissertation
    Full Text:
    Paul R. Blakemore The bimolecular reaction of two carbenoid species resulting in the formation

  • Synthesis of novel ambifunctional atropisomeric 2,2',6,6'-tetrasubstituted biphenyls and investigation of their properties and organocatalytic activity

    Creator:
    Sephton, Mark Alan
    Abstract:
    Ambifunctional axially chiral 2,2',6,6'-tetrasubstituted biphenyls containing nucleophilic (or basic) functional groups juxtaposed with hydrogen-bond donors were synthesized and their properties studied. Applications for the prepared biaryls as potential organocatalysts for enantioselective carbon-carbon bond forming reactions were examined. Processes investigated included: aldol, Michael, nitroaldol (Henry), and Baylis-Hillman reactions. The novel amidoamine...
    Resource Type:
    Dissertation
    Full Text:
    Activity. Abstract approved: Paul R. Blakemore Ambifunctional axially chiral 2,2

  • Development of Methods for Stereoselective Carbon-Carbon Bond Formation

    Creator:
    Wu, Zhenhua
    Abstract:
    Three distinct methods to achieve the stereoselective synthesis of carbon-carbon bonds were investigated, encompassing: (i) the formation of axially chiral biaryl molecules by enantioselective Suzuki cross-coupling, (ii) the synthesis of α-phenylalkylboronic esters by enantioselective chain extension, and (iii) the stereospecific synthesis of alkenes by eliminative cross-coupling of enantioenriched sp³-hybridized carbenoids....
    Resource Type:
    Dissertation
    Full Text:
    : ______________________________________________________ Paul R. Blakemore Three distinct methods to achieve the stereoselective synthesis of