Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 25 for “"Atom-economy"”.
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A New Synthesis of enantiopure C-3-substituted Glutamates by Utilization of Ortho Ester protected (S)-Pyroglutamic acid
… to ameliorate the serious drawback of the bad atom-economy in the reaction sequence of previously published silylether-mediated procedures. To meet these requirements, the ortho ester functionality (OBO ester) developed by Corey was introduced. According to the plan of synthesis, the starting …
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Direct Brønsted acid-catalyzed functionalization of benzhydryl alcohols and 2-ethoxytetrahydrofuran using potassium trifluoroborate salts
… yields. This protocol features excellent atom economy since alcohols and organotrifluoroborates react in a 1:1 ratio. Functional group tolerance superior to Lewis acid- and metal-catalyzed approaches was demonstrated. Furthermore, we were able to extend this method to …
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Sintesi e coordinazione di leganti Ciclopentadienilici O-Multifunzionalizzati
… features to the related metal systems. The atom-economy synthetic procedure adopted which consists in the one-step Cyclopentene-oxide ring opening, quantitatitatively affords stereoselective formation of the multi-hydroxyl rac-1,2,4- C5H2[CH(CH2)3CHOH]3 Cpººº ligand1. Rh complexation of …
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Hydrophosphination of Vinylcyclopropane & Quinine for Metal Coordination Chemistry
… (P-C) bond. This method maximizes atom economy, produces minimal by-products and can proceed with or without free radical initiators (highly reactive species with an unpaired electron), using either heat or light. This dissertation focuses on preparing new phosphine ligands through …
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Improving Palladium Catalyzed C–H Activation Methodologies Towards Industrial Applicability
… advantages of this protocol would be improved atom economy, less generated waste and lower cost, i.e. attractive selling points for potential industrial applicability. Taking inspiration from the Wacker Process, promising results came from the combination between Copper, as co-catalyst, and …
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New developments in main group chemistry for application in modern battery technology
… and AlCl3 in THF, this hasshown to be a low atom economic route and instead an alternative method of combining Ph2Mg and half an equivalent of AlCl3 has been shown to yield the same active species but with a higher atom economy. Based on this knowledge, a range of R2Mg species have been …
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Zincative Functionalization of C–H Bonds Using Lithium Amide Zincate Bases
… of valuable functional groups improves atom economy and efficiency. However, field of direct C–H functionalization still has many challenges including regioselectivity, directing group limitations, and often harsh reaction conditions with toxic and rare transition metal catalysts. …
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Lewis Base Promoted Annulations of Allenoates with 1,4-Naphthoquinones
… generating more complex molecules with high atom economy and few byproducts.</p> <p>The development of complex small molecules using easy to obtain starting materials such as 1,4-naphthoquinone is a significant goal of this project. Current research has been focused on cyclizing …
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Application of thermodynamic principles in biocatalytic synthesis of novel nucleoside analogues
… necessitates lengthy routes and results in low atom economy. Nature’s chemistry set, on the other hand, is set up to work with the high density of functional groups of nucleosides. Nucleoside phosphorylases are known to be very regio- and stereospecific enzymes. They are part of the nucleoside …
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Catalytic biomass conversion and upgrading into platform chemicals and liquid fuels
… block. This new upgrading process has 100% atom economy, can be carried out under solvent-free conditions, and produces the C12 DHMF with quantitative selectivity and yield, the hallmarks of a "green" process. More significantly, the C12 DHMF has been transformed catalytically into …
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The development of novel organocatalytic and transition-metal catalysed methodologies for amide bond formation
… within organic chemistry, highly efficient and atom economical approaches enabling the transformation are desired. Traditional methodologies, in which a stoichiometric coupling reagent is utilised, although efficient, have several inherent drawbacks hindering their general applicability, …
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Sustainable strategies for alcohol halogenation
… next to an alcohol often comes at the cost of atom economy. This work is centred on enhancing the efficiency of alcohol activation towards halogenation, with respect to halide waste generation. Though many organocatalytic routes to alcohol halogenation have been developed, these methods often …
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Genetic characterization of Rhodococcus rhodochrous ATCC BAA-870 with emphasis on nitrile hydrolysing enzymes
… allows for high product yields and better atom economy than nonselective chemical methods of performing this reaction, such as acid or base hydrolysis. In order to apply BAA-870 as a nitrile biocatalyst and to mine the organism for biotechnological uses, the genome was sequenced using …
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Rhodium-Catalyzed Enantioselective Desymmetrizations of Oxabicyclic Alkenes and Alkene Difunctionalization via Nickel-Catalyzed Arylcyanation
… developed in the Lautens group are aimed at atom economical bond construction processes that streamline synthesis and minimize waste. The arylcyanation reaction and the asymmetric ring opening (ARO) reaction are two examples of methods developed in our group that embody this design principle. …
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New explorations in visible-light mediated energy and single electron transfer for nitrogen heterocycle synthesis
… might otherwise need high temperatures, poor atom economy or harsh reactants to proceed. This thesis explores the use of visible-light mediated photocatalysis for the synthesis of biologically important nitrogen containing heterocycles, investigating both single electron transfer and energy …
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Diagnosing Band-Mediated Electrochemical Half-Reaction Mechanisms and Identifying the Unique Features Thereof
… reduce volumes of chemical waste by improving atom economy, and enable new means of functionalizing small molecule feedstocks and modifying heavily functionalized biomass feedstocks. Despite the centrality of redox catalysis to both contemporary and future chemistry, a unified understanding of …
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Dirhodium(II,II) paddlewheel complexes conjugated to a polypyridyl tris-amine scaffold: synthesis and application as asdjncaslpre-catalysts in the hydroformylation of 1-octene
… principles such as using renewable feedstocks, atom economy, and catalysis. The use of rhodium-based catalysts for hydroformylation offers greater selectivity and catalytic activity under milder conditions compared to cobalt-based counterparts. Furthermore, the introduction of sterically …
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Palladium and manganese catalysis in C-H activation
… sustainable approach in terms of waste, cost and atom economy. 2-Pyrone and 2-coumarin analogues represent privileged biological scaffolds and possess broad spectrum biological activity. Importantly, there have been limited reports of catalytic methods involving the C-H activation of 2-pyrones and …
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Using Data-Driven Models to Understand Transition Metal Catalyst Energy Landscapes and Metal-Organic Framework Stability
… analogues to these enzymes, often enabling atom-economy, tunability, and selectivity not possible with bulk heterogeneous catalysts. Single-site catalysts with 3d transition-metals can access a range of spin- and oxidation-states. Due to strong oxidation and spin-state dependence on the …
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Biosynthetic engineering for the assembly of better drugs
… is an unnatural isomer of a natural product. The atom economy of microbial synthesis of pharmaceutical intermediates and active ingredients also far exceeds those of conventional schemes. We recently demonstrated the feasibility of this new paradigm for drug discovery by integrating two of the …
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