Sökning: "chiral Lewis acid"

Visar resultat 1 - 5 av 18 avhandlingar innehållade orden chiral Lewis acid.

  1. 1. Lewis acid Mediated Aza-Diels-Alder Reactions and Asymmetric Alkylations of 2H-azirines

    Författare :Erik Risberg; KTH; []
    Nyckelord :Enantioselective; diastereoselective; vinyl azide; 2H-azirines; aziridines; Lewis acid; chiral ligand; chiral auxiliary organolithiums Diels-Alder reaction alkyl radicals triethylborane.;

    Sammanfattning : This thesis describes the use of 2H-azirines, three-membered unsaturatednitrogen-containing heterocycles, as reactive intermediates ina number of Lewis acid promoted alkylations and Diels-Alderreactions providing synthetically useful aziridines. In order to carry out this investigation a new generalprocedure for the ring closure of vinyl azides, forming theresultant 3-substituted-2H-azirines, was developed applying low boiling solventsin closed reaction vessels at elevated temperatures. LÄS MER

  3. 2. New Methods for Chiral Cyanohydrin Synthesis

    Författare :Erica Wingstrand; Christina Moberg; Benjamin List; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; acyl cyanides; asymmetric synthesis; biocatalysis; cyanide; cyanohydrins; dual activation; enzymes; high-throughput screening; Lewis acid; Lewis base; metal catalysis; minor enantiomer recycling; salen; titanium; Chemistry; Kemi;

    Sammanfattning : This thesis deals with method development in asymmetric catalysis and specifically syntheses of enantioenriched O-functionalized cyanohydrins. The first part describes the development of a method for the synthesis of O‑alkoxycarbonylated and O-acylated cyanohydrins. LÄS MER

  4. 3. Efficient Synthesis and Analysis of Chiral Cyanohydrins

    Författare :Stina Lundgren; Christina Moberg; Ben Feringa; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; asymmetric catalysis; cyanohydrins; microreactor; polymersupported catalyst; ketonitriles; titanium; lanthanide; Lewis acid; Lewis base; Organic chemistry; Organisk kemi;

    Sammanfattning : This thesis deals with the development of new methods for efficient synthesis and analysis in asymmetric catalysis. It focuses on the preparation of chiral cyanohydrins by enantioselective addition of cyanide to prochiral aldehydes. LÄS MER

  5. 4. Impact of Secondary Interactions in Asymmetric Catalysis

    Författare :Anders Frölander; Christina Moberg; Gerard van Koten; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; asymmetric catalysis; secondary interaction; hydrogen bond; chiral ligand; allylic alkylation; hydrosilylation; cyanation; pymox; box; PHOX; pybox; palladium; iridium; rhodium; Lewis acid; Lewis base; Organic chemistry; Organisk kemi;

    Sammanfattning : This thesis deals with secondary interactions in asymmetric catalysis and their impact on the outcome of catalytic reactions. The first part revolves around the metal-catalyzed asymmetric allylic alkylation reaction and how interactions within the catalyst affect the stereochemistry. LÄS MER

  7. 5. Lewis Acid Mediated [2,3]-Sigmatropic Rearrangement of Allylic Ammonium Ylides

    Författare :Jan Blid; KTH; []
    Nyckelord :Sigmatropic rearrangement; Lewis acid; Ammonium ylide; NMR spectroscopy; Density functional calculations;

    Sammanfattning : This thesis describes a Lewis acid mediated[2,3]-sigmatropic rearrangement of various allylic ammoniumylides. Several Lewis acids are investigated and BBr3 and BF3are established to be the Lewis acids providing the highestconversion of the starting allylic amines. LÄS MER