京都大学 / 0048 / 新制・論文博士 / 博士(薬科学) / 乙第13086号 / 論薬科博第2号 / 新制||薬科||9(附属図書館) / (主査)教授 竹本 佳司, 教授 高須 清誠, 教授 川端 猛夫 / 学位規則第4条第2項該当 / Doctor of Pharmaceutical Sciences / Kyoto University / DFAM

The acetate of 6,6-dimethyl-2-cyclohexen-l-ol was thermally decomposed and the pyrolysis products were characterized. This allylic ester decomposed with difficulty. Under conditions which led to complete decomposition of 3-acetoxcyclo-hexene, 6,6-dimethy-2-cyclohexene-l-ol acetate was virtually unreacted. Complete decomposition of the allylic acetate was achieved at about 600°C. The pyrolysis products consisted mainly of o-xylene, toluene, 5,5-dimethyl-l,3-cyclohexadiene and acetic acid. The aromatic compounds are thought to be formed from the less stable diene. Partial decomposition of ester enriched with deuterium in the 4-position, permitted estimation of the isotope effect, Ku/kD, for the pyrolytic elimination. The value obtained was about 2. Together with other experimental evidence, it indicates that the main mode of decomposition is 1,4-conjugate elimination and that allylic rearrangement, if it occurs at all, is unimportant. / Thesis / Master of Science (MS)

No description available.

No description available.

The field of organic chemistry is divided into many subfields, which include polymer design and synthesis, transition metal catalysis and organocatalysis among a variety of others. Challenges in polymer design and synthesis can be highlighted pointedly in the use of photoresists for lithographic processing. Recent challenges in development of shorter wavelength sources has led to the need to develop new photoresist materials that can be exposed twice without any development steps in between. Two methods for addressing double exposure materials will be presented. Additionally, the areas of catalysis, whether transition metal or organic in nature, are important methods in organic synthesis. The mechanism of the addition of Gilman reagents to enones has been the subject of debate, and efforts to elucidate this mechanism will be presented. Finally, organocatalysis has expanded its scope into a variety of reactions previously only conducted with transition metal catalysts. Work towards an enantioselective allylic amination reaction using organocatalysis as well as absolute stereochemistry of the product will be explored. / text

Palladium is probably the most useful metal in organic syntheses. It has shown great utility in various reactions such as C-C, C-N, C-O bond formation under mild conditions. The presence of abundant amount of palladium-chemistry related literature in the form of books, reviews emphasizes the growing importance of these reagents. Nowadays organopalladium chemistry is being used in various fields such as new methodology development, natural product synthesis, synthesis of polymers. Regio- and stereoselectivity is another facet of Pd catalyzed methodologies which has been extensively utilized in the last decade to obtain enantiopure compounds. The main emphasis of this work is to utilize Pd catalyzed allylic alkylation to synthesize new heterocycles including furans, isoxazolines and new cyclopentane amino-acid analogs in an enantioselective manner. The stereochemical outcome of these reactions is influenced by desymmetrization catalyzed by hydrolytic enzymes namely lipases. Chapter 1 reviews the recent advances in the field of palladium catalyzed synthesis of bicyclic furan analogs and provides a mechanistic explanation for these processes. Chapter 2 describes synthesis of new optically pure isoxazoline-2-oxide and furan analogs using Pd(0) catalyzed intramolecular cyclizations. Starting from a meso-diol, optically pure compounds were prepared without utilizing chiral ligands at any stage of the synthesis. The stereochemical outcome of the product (>99 % ee) was influenced by desymmetrization catalyzed by Pseudomonas cepacia lipase and the stereoselective nature of the palladium catalyzed transformations. Chapter 3 describes Pd(0) catalyzed allylic alkylation of allylic esters using various 1°, 2° nitroalkanes. This reaction resulted in the formation of nitro substituted aldehydes and ketones via an isomerization-alkylation step. The effect of various solvents, catalyst-ligand systems and bases was also studied. The presence of versatile nitro group in these compounds which can be easily converted to a ketone, reduced to amine or transformed into carboxyl group, imines, hydroxylamines, makes them an attractive starting material for various other synthetic compounds. Chapter 4 describes the chemoenzymatic synthesis of L-carbafuranomycin and related cyclopentane amino acids analogs. The synthesis utilizes the hydrolytic enzymes to induce enantioselectivity in the whole process. Out of all the peptidomimetics and related compounds, unnatural amino acids such as bicyclic and carbocyclic amino acids are of valuable interest as they have provided new building blocks for large number of potential drug candidates. The work presented here provides a more general and efficient route to these class of unnatural amino acids.

This thesis deals with the design of ligands for efficientasymmetric catalysis and studies of the conformation of theligands in the catalytically active complexes. All ligandsdeveloped contain chiral oxazoline heterocycles. The conformations of hydroxy- and methoxy-substitutedpyridinooxazolines and bis(oxazolines) during Pd-catalysedallylic alkylations were investigated using crystallography,2D-NMR techniques and DFT calculations. A stabilising OH-Pdinteraction was discovered which might explain the differencein reactivity between the hydroxy- and methoxy-containingligands. The conformational change in the ligands due to thisinteraction may explain the different selectivities observed inthe catalytic reaction. Polymer-bound pyridinooxazolines and bis(oxazolines) weresynthesised and employed in Pd-catalysed allylic alkylationswith results similar to those of monomeric analogues;enantioselectivities up to 95% were obtained. One polymer-boundligand could be re-used several times after removal of Pd(0).The polymer-bound bis(oxazoline) was also used in Zn-catalysedDiels-Alder reactions, but the heterogenised catalyst gavelower selectivities than a monomeric analogue. A series of chiral dendron-containing pyridinooxazolines andbis(oxazolines) were synthesised and evaluated in Pd-catalysedallylic alkylations. The dendrons did not seem to have anyinfluence on the selectivity and little influence on the yieldwhen introduced in the pyridinooxazoline ligands. In thebis(oxazoline) series lower generation dendrimers had a postiveon the selectivity, but the selectivity and the activitydecreased with increasing generation. Crown ether-containing ligands were investigated inpalladium-catalysed alkylations. No evidence of a possibleinteraction between the metal in the crown ether and thenucleophile was discovered. A new type of catalyst, an oxazoline-containing palladacyclewas found to be very active in oxidations of secondary alcoholsto the corresponding aldehydes or ketones. The reactions wereperformed with air as the re-oxidant. Therefore, this is anenviromentally friendly oxidation method. <b>Keywords:</b>asymmetric catalysis, chiral ligand,oxazolines, conformational study, allylic substitution,polymer-bound ligands, dendritic ligands, crown ether,oxidations, palladacycle.

No description available.

<p>This thesis deals with the design of ligands for efficientasymmetric catalysis and studies of the conformation of theligands in the catalytically active complexes. All ligandsdeveloped contain chiral oxazoline heterocycles.</p><p>The conformations of hydroxy- and methoxy-substitutedpyridinooxazolines and bis(oxazolines) during Pd-catalysedallylic alkylations were investigated using crystallography,2D-NMR techniques and DFT calculations. A stabilising OH-Pdinteraction was discovered which might explain the differencein reactivity between the hydroxy- and methoxy-containingligands. The conformational change in the ligands due to thisinteraction may explain the different selectivities observed inthe catalytic reaction.</p><p>Polymer-bound pyridinooxazolines and bis(oxazolines) weresynthesised and employed in Pd-catalysed allylic alkylationswith results similar to those of monomeric analogues;enantioselectivities up to 95% were obtained. One polymer-boundligand could be re-used several times after removal of Pd(0).The polymer-bound bis(oxazoline) was also used in Zn-catalysedDiels-Alder reactions, but the heterogenised catalyst gavelower selectivities than a monomeric analogue.</p><p>A series of chiral dendron-containing pyridinooxazolines andbis(oxazolines) were synthesised and evaluated in Pd-catalysedallylic alkylations. The dendrons did not seem to have anyinfluence on the selectivity and little influence on the yieldwhen introduced in the pyridinooxazoline ligands. In thebis(oxazoline) series lower generation dendrimers had a postiveon the selectivity, but the selectivity and the activitydecreased with increasing generation.</p><p>Crown ether-containing ligands were investigated inpalladium-catalysed alkylations. No evidence of a possibleinteraction between the metal in the crown ether and thenucleophile was discovered.</p><p>A new type of catalyst, an oxazoline-containing palladacyclewas found to be very active in oxidations of secondary alcoholsto the corresponding aldehydes or ketones. The reactions wereperformed with air as the re-oxidant. Therefore, this is anenviromentally friendly oxidation method.</p><p><b>Keywords:</b>asymmetric catalysis, chiral ligand,oxazolines, conformational study, allylic substitution,polymer-bound ligands, dendritic ligands, crown ether,oxidations, palladacycle.</p>

No description available.