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Showing 1 to 20 of 85 for “"diols"”.
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Synthesis of pyrrolizidine diols via azide-diene cycloadditions
… formal stereospecific syntheses of pyrrolizidinediols 8, 9, 10, and 11. The possibility of asymmetric induction was also investigated, and was realized in the microbial reduction of only one of the enantiomers of alcohol ill protected as ester 248, providing potential access to either …
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Vanadium-Catalyzed Aerobic Oxidation of Diols and Lignin Models/Extracts
… of cellulose-derived substrates (e.g., diols). Two trialkoxyamine oxovanadium(V) complexes bearing a triethoxyamine and tris[2-(3,5-di-tert-butyl-phenoxy)methyl]amine ligand respectively, selectively cleaved the C-C bond in 1,2-diols with excellent rates and using air as the only …
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Reactivity studies of arene-cis-diols in cycloadditions and potassium permanganate oxidations: synthesis of the corresponding arene-trans-diols and an approach to the synthesis of (+)-pancratistatin
… novel cycloaddition chemistry of the arene-cis-diols (7) were investigated. It was found that permanganate oxidation of arene-cis-diols yielded a mixture of 2 products, (157a) and (157b) in low yield. The influence of the C1-substituent on the outcome of the reaction was found to be a complex …
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The synthesis of amino- and deutero- sugars from halo-cyclohexadiene-cis-diols
A versatile method for the preparation of 2-amino-2-deoxy-, 3-amino-3-deoxy-, 4- amino-4-deoxy-, and 5-amino-5-deoxy-sugars from noncarbohydrate precursors, halobenzenes 1 (Figure 1), has been developed. See: Figure 1: Aminosugar Targets from Halobenzenes This methodology has also been applied to …
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Utilization of Biomass Derived Furans in Value-Added Organics and Heterogeneous Oxorhenium Catalysts for Deoxydehydration of Diols
… were studied for deoxydehydration of vicinal diols, a reaction relevant to the conversion of biomass derived sugars.</p> <p>A cationic oxorhenium(V) oxazoline was studied for the catalytic condensation of diols or epoxides with aldehydes. Here, reactions were done under neat conditions and …
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The origin of remarkable chromatographic differences in novel azulenyl-1,5-diols and synthesis and use of phosphinine and phosphabarrelene ligands for asymmetric catalysis.
… diastereomers, a series of such azulene 1,5-diols were prepared. Every pair of diastereomers was especially well separated, and X-ray crystallography revealed a conformational explanation of the large differences in mobility. The separation of the diol enantiomers was then studied on two …
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I. Palladium-catalyzed anti-Markovnikov oxidative amination of olefins II. Catalytic deracemization of axially chiral diols III. Three component carboamination of electron deficient alkenes
… converting a wide array of axially chiral aryl diols into racemic samples including 3,3’- and 6,6’-substituted derivatives of BINOL with varying steric and electronic properties. Development of this work is ongoing in our lab, with identification of general resolution agents and more active …
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Catalytic Activity of Molybdenum-Dioxo Complexes
… deoxydehydration (DODH), the net reduction of diols and polyols into alkenes and dienes. Catalyst design involved variations on dioxomolybdenum(VI) supported by a dianionic meridional pincer ligand. Rational substrate scope was explored using aliphatic diols, aromatic diols, and biomass derived …
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Kinetics and mechanisms of oxidation of organic and inorganic substrates by transition metal oxo complexes
… these reactions, undergo ring-opening to the 1,2-diols. A concerted mechanism that involves external nucleophilic attack of the olefin on the peroxy oxygen has been proposed;The kinetics and the mechanisms of oxidations of 1,2-diols, phenols and H2O2 by the pentaaquaoxochromium(IV) ion, CrO2+ were …
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Synthesis and cytotoxity of oxysterols:studies on the A,B ring polyoxygenated sterols
… of four diastereomerically pure cholest-4-en-3,6-diols was developed. Epoxidation on these cholest-4-en-3,6-diols showed that an allyl group exerts an auxiliary role in producing products with desired configuration in syntheses of the eight diastereomerically pure 45-epoxycholestane-3,6-diols. …
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Low-temperature vinylcyclopropane rearrangement in the total synthesis of (-) - specionin
… oxidation of arenes to the corresponding cis-diols has been shown to be a convenient source of optically pure diols which can be used as synthons in asymmetric synthesis of complex, highly oxygenated molecules. The utility of such synthons has been demonstrated by the total synthesis of (-)- …
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Asymmetric synthesis involving silicon
… active, synthetically useful, silylated diols (17 pairs) have been prepared by asymmetric dihydroxylation of the corresponding allyl and vinylsilanes using Sharpless catalysts. Chiral analysis of these silyl diols was carried out by <sup>1</sup>H NMR methods in the presence of …
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The development of organic peroxide mediated oxidations
… processes: a method to selective synthesis anti-diols directly from commercially available alkene starting materials and an organocatalytic sulfoxidation procedure using diketones as catalysts.;Chapter 1 describes a novel metal-free method for the one-pot anti-dihydroxylation of alkenes to form …
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Studies on the stereo- and regiochemistry of [4+2] cycloaddition of nitroso compounds to chiral halobenzenediols. Total synthesis of lycoricidine
… been converted to the corresponding cis-arenediols by a microbial oxidation with the bacterium Pseudomonas putida strain 39- D. Enantiomerically pure cis-diols were obtained from chloro- and bromobenzene. The acetonides of these two diols have been utilized as useful synthons in the …
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Rapid Synthesis, Characterization, and Catalytic Function of Rhodium(III) and Iridium(III) Chloro-bridged Dimers
… for oxidative lactonization of 1,4- and 1,5-diols. Oxidative lactonization of 1,4-butanediol to afford γ-butyrolactone proceeded selectively and efficiently using [(η5-Me4C5R)IrCl]2(μ2-Cl)2 as the catalyst. Several R substituents were tested to assess electronic substituent effects. The most …
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Oxocarbenium Ion and Alkene Metathesis Strategies for the Synthesis of Complex Cyclohexanes
… cyclohexanes and tetrahydropyrans with cis 3,4-diols. To expand the scope of the OCC methodology, the goal was to evaluate the OCCs on non-cyclic oxocarbenium ions derived from mixed thioacetal precursors. Chapter two describes reactions with alkene nucleophiles. In particular, the OCC on an …
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Nanoparticles as strengthening agents in polymer systems
… acid and phenyl boronic acid complexes of 1,2-diols [HOCMe2CMe2OH, cis-C6H 10(OH)2, trans-C6H10(OH) 2, o-C6H4(OH)2], 1,3-diols (neol-H2), monosaccharides (L-fucose, mannose and galactose) and disaccharides (celloboise and sucrose) it is found that the guaran polymer is cross-linked via a borate …
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Design and synthesis of ring D modified steroidal hormones
… led to the formation of the corresponding 16,17-diols, which gave the derived 14β-compounds on glycol cleavage. Furthermore, under acidic conditions the 16,17-diols were found to undergo high yield 16(17 --> l7¹)abeo rearrangements, to afford 14,16-etheno compounds.
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Studies on stereospecific diketopiperazine oxidation and applications to the synthesis of complex epidithiodiketopiperazines
… and the configurational stability of the product diols. An example of a subsequent thiolation was then demonstrated to proceed under retention of stereochemistry, in contrast to the stereoinvertive thiolations previously observed in several total syntheses. The data is supported by computational …
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Approaches towards C-10-hydroxylated analogues of narciclasine
… involves the use of homochiral cyclohexadiene diols, products of the biocatalytic transformation of aromatic compounds, as precursors to ring C, and of highly oxygenated aromatic molecules to construct ring A. The document also reports a detailed account of the protocols studied for the …
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