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Showing 1 to 20 of 177 for “"Asymmetric Synthesis"”.
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Asymmetric synthesis involving silicon
… silylated diols (17 pairs) have been prepared by asymmetric dihydroxylation of the corresponding allyl and vinylsilanes using Sharpless catalysts. Chiral analysis of these silyl diols was carried out by <sup>1</sup>H NMR methods in the presence of Eu(hfc)<sub>3</sub>. Enantiomeric purity of some …
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Asymmetric synthesis of novel anthracyclinones
The synthesis of novel C9-halogenated anthracyclinones by Lewis acid promoted cyclisations of ortho-methallyl anthraquinonyl chiral dioxanes has been investigated. Tin tetrachloride-N,N-dimethylformamide promoted cyclisation of the dioxane (30) proceeded with excellent stereoselectivity to give an …
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Optimisation of chemoenzymatic processes in asymmetric synthesis
… the optimisation of chemoenzymatic methods in asymmetric synthesis. Modern synthetic organic chemistry has experienced an enormous growth in biocatalytic methodologies; enzymatic transformations and whole cell bioconversions have become generally accepted synthetic tools for asymmetric …
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Asymmetric synthesis of benzylic and heterobenzylic amines
… with 1,3-diphenyl-2-propenyl ethyl carbonate. Asymmetric synthesis of 2-(2-pyridyl)aziridines from chiral 2-pyridineimines bearing a stereogenic center at the nitrogen atom was development. The envisioned route involves the addition of chloromethyllithium to the imine derived from …
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The study of the asymmetric synthesis of lignans
The work in this thesis focuses on the asymmetric synthesis of lignans by approaches such as Diels-Alder reactions, asymmetric alkylation reactions, and intramolecular oxidative coupling reactions. In addition to developing asymmetric synthetic methodologies for chiral lignans, an investigation of …
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Asymmetric synthesis of sultones and sulfonic acid derivatives
… as a chiral auxiliary has been developed. High asymmetric inductions of the alpha-allylations were achieved along with good to excellent yields. In all cases the diastereomerically pure allylated sulfonates could be obtained by recrystallization (de = 98%). Successive acid-catalyzed cleavage of …
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Synthesis of new sulfoximines for asymmetric synthesis and pseudopeptides
… applicability as chiral auxiliaries, ligands in asymmetric catalysis, and building blocks in pseudopeptides. A number of approaches have been investigated for their synthesis, which allows the preparation of various derivatives in a relatively straightforward manner. In order to extend the …
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The asymmetric synthesis of amino acids via electrophilic glycinates
A new asymmetric synthesis of α-monosubstituted-α-amino acids using D- and L-erythro-4-benzy loxycarbonyl-5,6-diphenyl-2,3,5,6-tetrahydro-1,4-oxazin-2-ones 108 as amino acid templates is described. Bromination of 108 with NBS generates the key electrophilic glycinate 132 which couples with a …
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Asymmetric synthesis of (+)-altholactone, a styryllactone from various goniothalamus species
… a RAMP-directed alkylation (ee > 98 %), an asymmetric aldol reaction (ee, de > 98 %) and a selective reduction (de > 96 %). The d-lactone, which is the main motif of the styryllactone family, results from an oxidation/in situ cyclisation sequence and the furanic cycle from an SN2 …
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Asymmetric synthesis of 2-deoxystrptamine analogues as potential RNA ligends
Contains fulltext : 27450.pdf (Publisher’s version ) (Open Access)
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Modular asymmetric synthesis of functionalized azaspirocycles based on the sulfoximine auxiliary
… the development of a more general method for the asymmetric synthesis of azaspirocycles. The synthesis of azaspirocycles involves two synthetic challenges. The first one is the stereoselective construction of the tertiary spiro C-atom bearing a N-atom. The second challenge is the formation of the …
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The Asymmetric Synthesis Of The C1'-C10' Portion of Pamamycin-621A
This thesis describes the synthesis of the C1'-C10' portion 72 of the pamamycin-621A using a cuprate conjugate addition to join enone fragment 52 and organostannane fragment 64a. Fragments 52 and 64a were both synthesized from (S)-methylketene dimer 51.
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Asymmetric synthesis of quaternary hydantoins and spirocyclic pseudoindoxyls via aza-Heck cyclizations
… limited. The various biological activities and synthesis of drugs containing the quaternary hydantoin core will be discussed. This thesis will also discuss the limitations of accessing these important scaffolds and would go on to demonstrate our group’s dedication to utilizing aza-Heck chemistry …
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Asymmetric Synthesis of 1,3-Amino Alcohols and Tropinone Derivatives From Enantiopure Sulfinimines
… The intent of this research is to the develop asymmetric syntheses of piperidine-containing syn and anti 1,3-amino alcohols as well as tropinone and tropane-containing derivatives using sulfinimines (N-sulfinyl imines) as precursors for acid-catalyzed cascade cyclizations. Chiral N-sulfinyl …
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Asymmetric synthesis of trisubstituted isoindolines and tetrahydropalmatine via tandem 1,2-addition-cyclisation
… until now, the cleavage of the auxiliary to synthesise the 1,3-disubstituted isoindolines could not be achieved. The first diastereo- and enantioselective synthesis of 3,4-disubstituted tetrahydro-2-benzazepines in a tandem 1,2-addition/ring closure sequence was attempted. The necessary …
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The asymmetric synthesis of enol phosphates and their application in total synthesis
The synthesis of a wide range of highly valuable enol phosphate products has been carried out. The use of carbon centred magnesium bases, previously developed in the group has allowed the formation of kinetic enol phosphate products under room temperature conditions. By applying specific quench …
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Novel Chiral Diamines and (S)-6-Chloronicotine Derivatives as Catalysts for Asymmetric Synthesis
… pure compounds are highly desirable. Asymmetric synthesis using chiral compounds has become the preferred way to make enantiopure material. For example, selectively synthesizing secondary alcohols that are ubiquitous in natural products and pharmaceuticals can be achieved through the …
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