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Showing 1 to 20 of 324 for “"Enantioselective"”.
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Enantioselective synthesis using bromoacetals.
A brief overview of why it is important to prepare a chiral compound as a specific enantiomer rather than as a racemate is discussed along with several general strategies on how they maybe prepared. The area of research into the preparation of racemic and enantiomerically pure arylpropanoic acids …
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Enantioselective nucleophile-catalyzed cycloadditions
… This is the first report of a catalytic enantioselective synthesis of trisubstituted [beta]-lactones. Two enantioselective phosphine-catalyzed [3+2] cycloadditions of allenoates are detailed in Chapter 2. A method for the asymmetric synthesis of cyclopentenes via a [3+2] cycloaddition of …
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Mechanistic Aspects of Enantioselective Complexation
The effect of differential penetration ("intercalation") of enantiomeric analytes between the strands of synthetic, brush-type liquid chromatographic chiral stationary phases (CSPs) has been investigated. The design and evaluation of a new family of $\pi$-basic CSPs which utilize these …
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Enantioselective Total Synthesis of the Kibdelones
… this fragment was synthesized in an enantioselective fashion from resorcinol. After joining these fragments with sequential Sonogashira reactions a demanding late stage C-H arylation reaction was used to forge the final C-C bond of the natural product. Importantly, this biaryl bond …
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Catalytic, Enantioselective Cyclopropanation of Allylic Alcohols
In mechanistic investigations, spectroscopic examinations and reaction surveys of substrate, reagent, and promoter were combined with solid-state evidence concerning the active form of the catalytically operative species to rationalize many of the observed features and trends of this system. …
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The enantioselective synthesis of C₁₈-sphingosines
Biocatalytic conversion of chlorobenzene to the corresponding homochiral cyclohexadiene cis-diol (113) allows, through careful symmetry-based planning, the stereodivergent synthesis of all sphingosine stereoisomers. This was achieved via the selective preparation of the appropriate diastereomer of …
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Part I. Anionic Acyl Transfer Catalysis;Part II. Enantioselective alcoholysis of Acyl Donors;Part III. Enantioselective N-acylation
… developed four generations of amidine-based enantioselective acyl transfer catalysts(ABCs) and applied them successfully to the kinetic resolution of chiral alcohols. Compared with chiral alcohols, the kinetic resolution of chiral acyl donors is more complicated and far less developed. In my …
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Iridium-Catalyzed Enantioselective Allylation of Alkenyl Boronates
Organoboronic esters are highly functionalizable synthetic intermediates owing to their unique reactivity that allows for pre-complexation with organometallic reagents to form boronates, which can then engage in bimolecular reactions. Furthermore, incorporation of boronic esters into their …
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Lewis base catalyzed enantioselective oxysulfenylation of alkenes
… has been harnessed in the development of an enantioselective oxysulfenylation reaction for unactivated alkenes. The weak Lewis acid N-(phenylthio)-phthalimide can be activated in the presence of a moderate Brønsted acid and chiral Lewis base donors. The resulting complex is a powerful …
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Lewis base catalyzed enantioselective sulfenoamination of alkenes
… Lewis acid has been successfully applied to the enantioselective sulfenoamination of olefins. The unreactive, achiral Lewis acidic sulfenylating agent, N-arylthiophthalimide, is activated by the coordination of a chiral Lewis base, binaphthyl-derived selenophosphoramide, in presence of a Brønsted …
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Development of Catalytic Enantioselective Minisci-type Reactions
… the development of a protocol for the catalytic enantioselective Minisci-type addition of prochiral radicals to heteroarenes through the dual techniques of chiral Brønsted acid catalysis and photocatalysis. The first research section details the initial hypothesis, design and implementation of …
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Studies towards the enantioselective synthesis of (+)-castanospermine
A study has been carried out on the enantioselective total synthesis of the indolizidine alkaloid (+)-castanospermine. The aim was to develop a convergent synthesis based on a C-8/C-8a disconnection. A distinguishing feature of this method is that it is non-carbohydrate-based.
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Progress in transition metal-based enantioselective catalysis
In Chapter 1, the first enantioselective cross-coupling reactions of racemic secondary benzylic halides are described (eq 1). This method was applied to the syntheses of intermediates employed by other groups in the generation of bioactive compounds, e.g., an androgen receptor agonist (1.1) and two …
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Scope of enantioselective reduction of imines with trichlorosilane
… continuing previous successI in the field of enantioselective organocatalytic reduction of imines with trichlorosilane. Syntheses of various precursors (ketones) and substrates (imines) for the reduction reaction and their reduction following the protocol (Scheme A1) are described in this …
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Synthesis of Chiral Surfactants for Enantioselective Organic Synthesis.
<p>The first step of the synthesis of the hydrocarbon-based chiral surfactant <b>(2)</b> involved the methylation of (S)-leucinol to give (2S)-N-hexadecyl-N,N-dimethyl-(1-hydroxy-4-methyl-1-pentyl)-2-ammonium bromide (2.92g, 67%). The chiral surfactant was synthesized by reacting …
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Enantioselective Conjugate Additions to a Hindered Cyclohexenone System
… to carbon nucleophile conjugate additions to enantioselectively generate vicinal quaternary-tertiary stereocenters. Intermolecular conjugate additions were studied extensively but were unfortunately limited in scope. It is hypothesized that steric congestion around the enone from the chiral …
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Synthetic Chiral Stationary Phases in Enantioselective Liquid Chromatography
The occurrence of $\pi - \pi$ face to face and $\pi - \pi$ face to edge interactions on a particular type of chiral stationary phase (CSP) used for chromatographic separations of enantiomers has been studied. Highly polarizable aromatic substituents, such as halogens, have been found to enhance …
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Organoselenium redox-catalyzed, enantioselective syn-difunctionalization of alkenes
… the intersection of these two approaches, enantioselective selenofunctionalization- deselenenylation reactions catalyzed by chiral, enantioenriched organoselenium electrophiles are discussed. The second part of this dissertation describes the development of a catalytic, enantioselective …
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Approaches toward the enantioselective total synthesis of amarogentic
… different, but complementary strategies for the enantioselective synthesis of the secoiridoid core of amarogentin were evaluated. The first is based on the enantioselective desymmetrisation of meso-anhydrides using titanium TADDOLates. 1,2,4,6-Tetrahydrophthalic anhydride was desymmetrised and …
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