Sökning: "diastereoselectivity"

Visar resultat 6 - 10 av 30 avhandlingar innehållade ordet diastereoselectivity.

  1. 6. 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. 7. Radical Cyclization Approaches to Pyrrolidines

    Författare :Magnus Beşev; Troels Skrydstrup; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Organic chemistry; Radical cyclization; diastereselectivity; pyrrolidine; pyrroline; thiazoline; aziridine; Organisk kemi; Organic chemistry; Organisk kemi; organisk kemi; Organic Chemistry;

    Sammanfattning : Five-membered rings are readily prepared by 5-exo-trig radical cyclization. This thesis is concerned with novel methodology for pyrrolidine synthesis. We have synthesised selenium containing radical precursors from aziridines and α-phenylseleno ketones, and cyclized them to 2,4- and 3,4-disubstituted pyrrolidines. LÄS MER

  4. 8. Synthesis of functionalized allylic, propargylic and allenylic compounds : Selective formation of C–B, C–C, C–CF3 and C-Si bonds

    Författare :Tony Zhao; Kálmán Szabó; Hajime Ito; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; palladium catalysis; allylboration; allenylboration; trifluoromethylation; silylation; copper catalysis; borylation; bimetallic catalysis; organisk kemi; Organic Chemistry;

    Sammanfattning : This thesis is focused on the development of new palladium and copper- mediated reactions for functionalization of alkenes and propargylic alcohol derivatives. The synthetic utility of the 1,2-diborylated butadienes synthesized in one of these processes has also been demonstrated. LÄS MER

  5. 9. Computer-Assisted Organic Synthesis. Addition to Carbonyl Carbons and Aromatic Substitution

    Författare :Ingvar Lagerstedt; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; CAOS; torsional strain; selectivity; aromatic substitution reaction;

    Sammanfattning : This thesis concerns the computer-assisted modelling of additions to ketones and aromatic substitution, and how this modelling can be used within an existing program for synthesis planning. I include a review of existing computer-assisted organic synthesis (CAOS) programs, and discuss how some of these programs deal with knowledge representation. LÄS MER

  7. 10. New Methodologies in Organic Chemistry: Applications to the Synthesis of α-Amino Acids and Natural Products

    Författare :Sebastian Hirner; Peter Somfai; Varinder Aggarwal; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Organic synthesis; 2-Vinylaziridines; 3-Pyrrolines; Ringexpansion; Rearrangement; Anisomycin; Total synthesis; α-Amino acids; Arylglycines; Weinreb amides; α-Arylation; Grignard reagents; Umpolung; Organic chemistry; Organisk kemi;

    Sammanfattning : This thesis deals with the development and application of new synthetic methodology in organic chemistry. The first part describes the development of a new protocol for the synthesis of 3-pyrrolines by means of a microwave-assisted ring-expansion reaction of 2-vinylaziridines. LÄS MER