Sökning: "Lewis acid"

Visar resultat 16 - 20 av 69 avhandlingar innehållade orden Lewis acid.

  1. 16. Asymmetric [2,3]-Sigmatropic Rearrangement of Allylic Ammonium Ylides

    Författare :Jan Blid; Peter Somfai; James C. Anderson; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; asymmetric; [2; 3]-sigmatropic rearrangement; allylic amine; ammonium ylide; Lewis acid; enantioselective; boron; phosphazene base; NMR spectroscopy; DFT-calculations; Organic chemistry; Organisk kemi;

    Sammanfattning : The thesis describes the realization of an asymmetric [2,3]-sigmatropic rearrangement of achiral allylic amines. It is divided into two parts; the first part deals with the development of a Lewis acid-mediated [2,3]-sigmatropic rearrangement and the second the asymmetric version thereof. LÄS MER

  3. 17. Lanthanide-mediated C-F Bond Activation Method Development and Mechanistic Investigation

    Författare :Mario Janjetovic; Göteborgs universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; C-F bond activation; fluorine chemistry; lanthanides; single-electron transfer reagent; Lewis acid; chemoselectivity; synthetic method; catalysis;

    Sammanfattning : The use of transition-metals and main-group Lewis acids has proven to be an outstanding source for activation and subsequent functionalization of fluorinated compounds. However, the first is mainly limited to C(sp2)–F bonds which partially are activated by an adjacent heteroatom, and the latter is limited to simple C(sp3)–F bonds due to particularly strong Lewis acid character. LÄS MER

  4. 18. Characterization of Epoxide Hydrolases from Yeast and Potato

    Författare :Lisa Tronstad-Elfström; Mikael Widersten; Michael Arand; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Biochemistry; Epoxide hydrolase; Catalytic residues; Active site; trans-stilbene oxide; Rapid kinetics; Active site tyrosyls; Enzyme mechanism; Lewis acid; X-ray crystallography; Substrate specificity; Unidentified ORF; α β hydrolase fold; Saccharomyces cerevisiae; Biokemi; Biochemistry; Biokemi;

    Sammanfattning : Epoxides are three-membered cyclic ethers formed in the metabolism of foreign substances and as endogenous metabolites. Epoxide hydrolases (EHs) are enzymes that catalyze the hydrolysis of epoxides to yield the corresponding diols. LÄS MER

  5. 19. Development of new Catalytic Methods for the Selective Synthesis of Heterocycles

    Författare :Stalin Reddy Pathi Pati; Nicklas Selander; Masaharu Nakamura; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; catalysis; indium; heterocycles; Lewis acid; multicomponent reactions; furans; alkynes; organisk kemi; Organic Chemistry;

    Sammanfattning : In the field of organic chemistry, the development of new catalytic methods for the synthesis of complex molecules from simple precursors is a top priority. The main focus of this thesis concerns the diastereoselective synthesis of heterocyclic compounds using main group elements as Lewis acid catalysts. LÄS MER

  7. 20. Aspects on the Regio and Stereo Selectivity in the Hydrolsilylation of 1,3-Dienes

    Författare :Magnus Gustafsson; Centrum för analys och syntes; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Metallorganisk kemi; Organometallic chemistry; Organisk kemi; Organic chemistry; Lewis acid; electrophilic ring closure; asymmetric hydrosilylation; reaction conditions; isoprene; regioselectivity; oxygen; Wilkinsons catalyst; 15N-1H-HMQC; 31P; heterobidentate ligands; catalyst; palladium; epoxy-allylsilanes; rhodium complexes; dienes;

    Sammanfattning : This thesis is a summary of four papers concerning various aspects on the transition metal catalysed hydrosilylation of 1,3-dienes. The hydrosilylation reaction is formally an addition of a hydrosilane to an unsaturated system and depending on the reaction conditions, control of stereo-, regio-, and chemo-selectivity can be achieved. LÄS MER