Search for dissertations about: "desymmetrization"

Showing result 1 - 5 of 8 swedish dissertations containing the word desymmetrization.

2. 1. Controlling the Reactivity and Selectivity in Iridium- and Rhodium-Catalyzed Asymmetric Hydrogenation

   Author : Haibo Wu; Pher Andersson; Virginie Ratovelomanana-Vidal; Stockholms universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Asymmetric hydrogenation; Cascade reaction; Kinetic resolution; Desymmetrization; Dearomatization; Total synthesis; Heterogeneous catalysis; organisk kemi; Organic Chemistry;

   Abstract : The work presented in this thesis is mainly focused on the development of iridium- or rhodium-catalyzed asymmetric hydrogenation featuring a number of practical concepts including cascade reaction, kinetic resolution, desymmetrization, and dearomatization. The protocols rely on gaining control of the reactivity among different olefins or olefin precursor as well as maintaining chemo- and stereo-selectivity in the hydrogenation. READ MORE

4. 2. Methods for Asymmetric Olefination Reactions; Development and Application to Natural Product Synthesis

   Author : Daniel Strand; Tobias Rein; Viresh Rawal; KTH; []
   Keywords : 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;

   Abstract : 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. READ MORE

5. 3. General Protocols for the Preparation of Tröger's Base Analogues and Molecular Recognition by Designed Tröger's Base Receptors

   Author : Jacob Jensen; Centrum för analys och syntes; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Organic chemistry; Organisk kemi; non-covalent bonds.; molecular recognition; desymmetrization; metal-mediated reactions; Tröger s base; synthetic protocols;

   Abstract : 2,8-Dihalo substituted analogues of Tröger’s base were prepared via the Tröger’s base condensation reaction. These compounds were used as synthetic intermediates for the preparation of otherwise inaccessible functionalized Tröger’s base analogues. READ MORE

6. 4. Synthesis and Applications of P-chirogenic Phosphine Boranes

   Author : Magnus Johansson; Chalmers tekniska högskola; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; cytisine; gold I catalysis lipase; P-chirogenic; desymmetrization; phosphine; enantioselective cyclopropanation. enantioselective deprotonation; chirality; asymmetric synthesis; borane;

   Abstract : AbstractThis thesis reports the independent synthesis of both enantiomers of P-chirogenic phosphine ligands and the building blocks thereof, which are suitable for parallel synthesis efforts and for the generation of more diverse libraries of P-chirogenic compound. The use of P-chirogenic phosphine boranes in transition metal-catalyzed reactions, such as palladium-catalyzed allylic alkylation and amination, is also described. READ MORE

7. 5. Asymmetric Formation and Isomerization of Three-Membered Rings : Catalyst Development and Evaluation

   Author : Sophie Bertilsson; Tobias Rein; Uppsala universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Chemistry; allylic alcohol; α-amino acid derivative; aza-Diels-Alder reaction; aziridination; cyclopropanation; desymmetrization; epoxide rearrangement; kinetic resolution; lithium amide; rhodium-carboxylate; Kemi; Chemistry; Kemi; organisk kemi; Organic Chemistry;

   Abstract : Enantiopure α-amino acid derivatives were prepared using a protocol which allows for highly controlled regio- and chemoselectivity in the hydrogenation/ hydrogenolysis of aza-Diels-Alder adducts. One of the resulting α-amino esters, (1S,3R,4R)-2-azabicyclo[2.2.1]heptane-3-carboxylic acid ethyl ester, was utilized further as a catalyst precursor. READ MORE