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Synthesis with citreoviridinoidsBowden, M. C. January 1987 (has links)
No description available.
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Enantioselective synthesis of 2,2,5-Tri- and 2,2,5,5-tetrasubstituted tetrahydrofurans and synthesis of diketopiperazine containing natural productsBenjamin, Noah Meyer 18 February 2013 (has links)
A chiral vinyl sulfoxide has been developed that undergoes highly diastereoselective Diels−Alder cycloadditions with various substituted furans in excellent yield. The cycloadducts can be stereoselectively transformed into tetrasubstituted tetrahydrofurans via ring-opening metathesis/cross-metathesis or oxidative cleavage and refunctionalization.
A partial synthesis of the bioactive diketopiperazine containing natural product gliocladin C was achieved in nine steps, and 13.4% overall yield. The synthesis featured several novel transformations including the construction of the core structure by an elimination and nucleophilic addition sequence, followed by a Lewis acid promoted coupling with indole giving the key quaternary oxindole intermediate. A new protocol for intramolecular reductive coupling of the oxoindole and bis-unsaturated diketopiperazine led to successful construction of the hexacyclic skeleton. / text
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Nonaqueous electrochemical thermodynamicsStafford, Nathan January 1900 (has links)
Thesis (Ph.D.)--University of Nebraska-Lincoln, 2006. / Title from title screen (site viewed April 26, 2007). PDF text: 232 p. : ill. UMI publication number: AAT 3230060. Includes bibliographical references. Also available in microfilm and microfiche formats.
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A study of the addition compounds of titanium tetrabromide and titanium tetraiodide with 1,4-dioxane, tetrahydrofuran, and tetrahydropyran /Rolsten, R. Fred Ç‚q (Robert Fred) January 1955 (has links)
No description available.
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Molecular Dynamics Simulation to Investigate Diffusion Behavior of Polystyrene in Tetrahydrofuran under External Electric FieldHsieh, Ching-Hua 10 July 2001 (has links)
none
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Coupling reactions and separations in propane-organic-aqueous tunable solvent systemsHusain, Zainul Abideen. January 2009 (has links)
Thesis (M. S.)--Chemical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Eckert, Charles; Committee Co-Chair: Liotta, Charles; Committee Member: Meredith, Carson. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Vapor-liquid equilibrium data for tetrahydrofuran and related organicsClark, Lewis William. January 1963 (has links)
Call number: LD2668 .T4 1963 C59 / Master of Science
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Vanadium(V)-katalysierte Oxidationen substituierter Bishomoallylalkohole zur stereoselektiven O-Heterocyclen-Synthese / Vanadium(V)-catalyzed Oxidations of Substituted Bishomoallylic Alcohols for the Stereoselective Synthesis of O-HeterocyclesSchmidt, Philipp January 2002 (has links) (PDF)
In der vorligenden Arbeit wurden Vanadium-abhängige Bromidperoxidase- (VBPO-) Modelle zur stereoselektiven Synthese funktionalisierter O-Heterocyclen entwickelt, die durch Vanadium-katalysierte Oxygenierung von Bishomoallylalkoholen mechanistisch untersucht wurden. Weiterhin wurden Bromcyclisierungen von Bishomoallylalkoholen auf enzymatischem (VBPO), oxidativem und radikalischem Weg für Referenzprodukte einer neuen Variante der Bromcyclisierung durch Vanadium-katalysierte Bromidoxidation durchgeführt. Die Selektivitätsmuster aus den Synthesen ß-hydroxylierter und ß-bromierter Tetrahydrofurane wurden anschließend innerhalb einfacher Naturstoffsynthesen genutzt. Anhand eigener Vorarbeiten wurden neue Vanadium(V)-Komplexe aus Triethoxyvanadat mit tridentaten Schiffbaseliganden, basierend auf Salicylaldehyd und Aminoalkoholen mit strukturell unterschiedlichen Seitenketten in quantitativen Ausbeuten synthetisiert und charakterisiert (51V-NMR, UV und IR). In Test-Cyclisierungen unterschiedlicher Bishomoallylalkohole eignete sich VO(salin)(OEt) mit hohen Umsätzen und guten Regio- wie Stereoselektivitäten am besten. Die relative Geschwindigkeitskonstante (krel = 120±20) der Vanadium-katalysierten Oxidation des Testsystems konnte über Konkurrenzkinetik (Alkenol versus Alken) ermittelt werden und weist deutlich auf eine Bindung des Alkenols an Vanadium während der Oxidation hin. Um die Regio- und Stereoselektivitäten Vanadium-Schiffbase-katalysierter Oxidationen von Bishomoallylalkoholen verstehen zu können, wurden stereochemische Studien anhand des Testsystems durchgeführt. Dessen Oxidation wird demnach im selektivitätsbestimmenden Schritt dem Metallzentrum abgewandt in like-Position bevorzugt gebildet und führt zu dem cis-konfigurierten Tetrahydrofuran als Hauptprodukt. Im Folgenden wurden Vanadium-katalysierte Oxidationen unterschiedlich substituierter bishomoallylischer Alkohole durchgeführt, sämtliche Oxidationen führten regioselektiv zu Tetrahydrofuranen als Hauptprodukte, die Oxygenierung Dimethyl-substituierter Pentenole lieferte durch Substitution an C-1 selektiv cis-konfigurierte Tetrahydrofurane, 2-Substitution führte ebenso wie 3-Substitution zu trans-konfigurierte Oxolanen. Alkohole nicht aktivierter Olefine wurden in der Reihenfolge C-1 ? C-3 mit höherer Selektivität zu trans-konfigurierten Tetrahydrofuranen gebildet. Die Regio- und Stereoselektivitäten der radikalischen Bromcyclisierungen folgen den schon in früheren Arbeiten unserer Arbeitsgruppe aufgestellten Richtlinien (5-exo-trig; 2,5-trans, 2,4-cis und 2,3-trans). Die ionischen Bromcyclisierungen 5,5-dimethylierter Bishomoallyl-alkohole mittels NBS verliefen komplementär zu den Radikal-Cyclisierungen regioselektiv und in Abhängigkeit der Phenylsubstituenten an C-1 - C-3 stereoselektiv zu den 2,5-trans-, 3,5-cis- und 4,5-trans-konfigurierten Tetrahydropyranen. Aus der Bromcyclisierung prochiraler Pentenole in Gegenwart eines Acetonpulvers aus Ascophyllum nodosum (A.n.A.P.) konnte das b-bromierte Tetrahydrofuran racemisch in 87proz. Ausbeute erhalten werden. Ebensowenig führte der Einsatz chiraler Liganden in der Vanadium-katalysierten Oxygenierung prochiraler Penten-1-ole bei guten Ausbeuten (>80%) zu Enantiomeren-angereicherten Tatrahydrofuranen. Innerhalb einfacher Naturstoffsynthesen wurden cis-Pityol, Linalooloxid sowie (-)-epi-Bisabololoxid selektiv unter Standardbedingungen der Vanadium-Schiffbase-katalysierten Oxidationen mit VO(salin)(OEt) und TBHP dargestellt. Die Stereoselektivitäten steigen proportional zu dem Größenunterschied der Substituenten an Position 1 der Bishomoallylalkohole. Abschließend wurde durch Vanadium-katalysierte Bromidoxiadtion mit TBHP eine neue dreistufige Totalsynthese der vier "natürlichen" Muscarin-Isomere ausgearbeitet. Die Gesamtausbeuten dieser Synthesen liegen zwischen 3.0 und 19.9%. / In the present work vanadium dependent bromoperoxidase- (VBPO-) models have been developed for the stereoselective synthesis of functionalized O-heterocycles, that were examined mechanistically by vanadium catalyzed oxygenation of bishomoallylic alcohols. Furthermore bromine cyclizations of pentenols were carried out in an enzymatic (VBPO), oxidative and radical version for reference products of a new variant of the bromine cyclization by vanadium catalyzed bromide oxidation. The selectivity models from these syntheses of ß-hydroxylated and ß-brominated tetrahydrofurans were then used within simple natural product syntheses. By means of own preleminary works new vanadium(V)-complexes were synthesized in quantitative yields from triethyl vanadate and tridentate Schiff-base ligands generated from salicylic aldehyde and amino alcohols with structurally differing side chains, and were characterized spectroscopically (51V-NMR, UV and IR). Cyclizations of different bishomoallylic alcohols indicated that VO(salin)(OEt) was the best among the catalysts tested since it afforded high yields and good regio- and stereoselectivities of oxidation products. The relative rate constant (krel = 120±20) for the vanadium catalyzed oxidation of a test system was determined by competition kinetics (alkenol vs. alkene) and is a clear indication for the coordination of the alkenol at vanadium within the oxidation step. In order to understand the regio- and stereoselectivities of the vanadium Schiff-base catalyzed oxidation of bishomoallylic alcohols stereochemical studies were carried out with the test pentenol. The oxidation of the alkenol double bond has to be the selectivity determining step, proceeding in like-fashion and leading to the cis-configured tetrahydrofuran as main product. Next, vanadium catalyzed oxidations of differently substituted bishomoallylic alcohols were performed, which all led regioselectively to tetrahydrofurans as main products. Oxygenation of 1-substituted pentenols resulted in cis-configured tetrahydrofurans, 2- and 3-substitution led to trans-configured oxolanes. Alcohols with non-activated olefins were converted into trans-substituted tetrahydrofurans with increasing selectivity in the order of C-1- ? C-3-substitution. The regio- and stereoselectivities of the radical bromine cyclization follow the guidelines already set up in former works of our group (5-exo-trig; 2,5-trans, 2,4-cis and 2,3-trans). The ionic bromine cyclizations of 5,5-dimethylated bishomoallylic alcohols by means of NBS ran regioselective complementarily to the radical cyclizations and stereoselective in dependence of the phenyl substituents at C-1 - C-3 to the 2,5-trans-, 3,5-cis- and 4,5-trans-configured tetrahydropyrans. Bromine cyclization of a prochiral pentenol in presence of A.n.A.P. gave rise to the ß-brominated tetrahydrofuran racemically in 87% yield. Even the use of chiral ligands in vanadium catalyzed oxygenation of prochiral pentenols led to no enantiomeric enriched tatrahydrofurans. Within simple natural product syntheses cis-pityol, linalool oxide as well as (-)-epi-bisabololoxid was synthesized selectively under standard conditions of the vanadium Schiff-base catalyzed oxidation with VO(salin)(OEt) and TBHP. The stereoselectivities increased proportionally with the size difference of the substituents in position 1 of bishomoallylic alcohols. Finally a new three-step total synthesis of the four "natural" muscarine isomers was developed by vanadium catalyzed bromide oxiadtion with TBHP. The overall yields of these syntheses range between 3.0 and 19.9%.
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Quantitative determination of emerging contaminants, solvent stabilizers and fullerene nanomaterials, in biological and environmental systems /Isaacson, Carl W. January 1900 (has links)
Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 122-129). Also available on the World Wide Web.
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Studies on organometallic chemistryMartín-Polo, Jesus J. January 1983 (has links)
No description available.
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