Sökning: "asymmetric synthesis"

Visar resultat 6 - 10 av 159 avhandlingar innehållade orden asymmetric synthesis.

1. 6. Development and application of new chiral -amino alcohols in synthesis and catalysis : Use of 2-azanorboryl-3-methanols as common intermediates in synthesis and catalysis

   Författare :Pedro Pinho; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Chemistry; Asymmetric synthesis; hetero-Diels-Alder reactions; chiral cyclopentyl-amines; chiral ligands and catalysts; amino alcohols; asymmetric reductions; ruthenium transfer hydrogenation; oxazaborolidines; asymmetric additions; dialkylzinc reagents; Kemi; Chemistry; Kemi; organisk kemi; Organic Chemistry;

   Sammanfattning : The development and application of unnatural amino alcohols,prepared via hetero-Diels-Alder reactions,in synthesis and catalysis is described.The studies are concerned with the [i]scope of the hetero-Diels-Alder reaction and preparation of important intermediates in the synthesis of antiviral agents,[ii ]application of amino alcohols in the ruthenium transfer hydrogenation of ketones,[iii ]use of similar precursors in the in situ generation of oxazaborolidines for reduction of ketones,and [iv] development and application of new chiral auxiliaries for dialkylzinc additions to activated imines, respectively. LÄS MER

3. 7. Asymmetric transformation of ß- and γ-functionalized alcohols : Study of combined ruthenium-catalyzed racemization and enzymatic resolution

   Författare :Annika Träff; Jan-Erling Bäckvall; Reko Leino; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Kinetic resolution; dynamic kinetic resolution; kinetic asymmetric transformation; dynamic kinetic asymmetric transformation; enzyme catalysis; racemization; asymmetric synthesis; chlorohydrin; cyano acetate; amino alcohol; metalloenzyme; bifunctional catalytic system; Organic synthesis; Organisk syntes; organisk kemi; Organic Chemistry;

   Sammanfattning : The major part of this thesis describes the asymmetric synthesis of β- and γ-amino alcohols through the combination of ruthenium catalyzed racemization and enzymatic kinetic resolution. The dynamic kinetic resolution, DKR, protocol for chlorohydrins was improved by employing Bäckvall’s catalyst, which is a base activated racemization catalyst, in combination with Burkholderia cepacia lipase. LÄS MER

4. 8. Synthesis and Evaluation of N,P-Chelating Ligands in Asymmetric Transition-Metal-Catalyzed Reactions : Ir-Catalyzed Asymmetric Hydrogenation and Pd-Catalyzed Asymmetric Intermolecular Heck Reaction

   Författare :Päivi Tolstoy; Pher G. Andersson; Göran Hilmersson; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Asymmetric hydrogenation; Heck reaction; N; P ligand; Iridium; Palladium; Asymmetric catalysis; Alkenes; Fluorine; Diarylmethine stereocenters; Chemistry; Kemi; organisk kemi; Organic Chemistry;

   Sammanfattning : This thesis describes synthesis of new chiral N,P ligands and their evaluation in two types of asymmetric transition-metal catalyzed reactions. The first part of the thesis describes studies in iridium-catalyzed asymmetric hydrogenation. LÄS MER

5. 9. Synthesis of Organoboronic Acids and Applications in Asymmetric Organocatalysis

   Författare :Sybrand Jonker; Kálmán Szabó; Jörg Pietruszka; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Boronic acid; BINOL; allylboration; propargylation; homologation; stereoselective synthesis; asymmetric synthesis; organocatalysis; allylboronic acid; allenylboronic acid; organisk kemi; Organic Chemistry;

   Sammanfattning : Allyl- and allenylboronic acids are valuable reagents in organic synthesis due to their configurational stability and high reactivity. Few allyl- and allenylboronates are commercially available. Therefore, both the preparation and synthetic application of these organoboronic acids are subjects of study. LÄS MER

7. 10. Methods for Asymmetric Olefination Reactions; Development and Application to Natural Product Synthesis

   Författare :Daniel Strand; Tobias Rein; Viresh Rawal; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Antitumor agents; Asymmetric Horner-Wadsworth-Emmons; Desymmetrization; Metal-catalyzed olefination; Mucocin; Palladium-catalyzed allylic substitution; Parallel kinetic resolution; Pyranicin; Pyragonicin; Rhenium; Stereoconvergent synthesis; Stereodivergent synthesis; Stereoselective synthesis; Tetrahydropyran; Wittig reaction; Organic chemistry; Organisk kemi;

   Sammanfattning : This thesis deals with the development and application of methods for asymmetric olefinations, in particular Horner-Wadsworth-Emmons (HWE) reactions, in the synthesis of certain natural products. Relying on asymmetric HWE reactions to access key building blocks, two natu-ral products, pyranicin and pyragonicin, were synthesized from common late intermediates. LÄS MER