Tesi: "Synthesis"

1

Coates, Helen Margaret. "Synthetic studies towards stemofoline synthesis". Thesis, University of Southampton, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238730.

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2

Nimkar, Sandeep Krishnaji. "Studies in asymmetric synthesis: Development of new synthetic methods for syntheses of natural products". Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186538.

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The research, to be discussed in three chapters, involves the development of new synthetic methods which are applicable to the total synthesis of many natural products. Chapter 1: As a part of a program to synthesize new auxiliary agents for asymmetric synthesis, we have prepared a structurally rigid acetal from norbornene in three chemical steps. This enantiomerically pure acetal has been used for resolution of racemic α-hydroxy esters and might be applied as a chiral auxiliary for diastereoselective reactions. Chapter 2: The Calicheamicin and Esperamicin antibiotics have shown remarkable biological activity as site-specific cleaving agents of double stranded DNA. The oligosaccharide portion of these molecules plays an important role in the site specificity. We have developed synthetic methodologies that allow synthesis of the deoxyaminosugar components of these antibiotics and can be extended to synthesize unnatural amino sugars for structure-activity studies. Chapter 3: Enantiomerically pure cyclopropyl ketones, which are available via chiral ketals, are very useful for syntheses and diastereoselective manipulations of common and large rings. This method has been extended to introduce up to four contiguous chiral centers in a common ring. This extension could be useful for the syntheses of complex natural products.

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3

Hale, Joshua G. "Biomimetic motion synthesis for synthetic humanoids". Thesis, University of Glasgow, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270966.

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4

Liu, Yunqi. "Synthetic approaches toward natural product synthesis". Diss., The University of Arizona, 1995. http://hdl.handle.net/10150/187050.

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Abstract (sommario):

1,2-Dithiolan-3-one-1-oxide exists in antihumor antibiotic leinamycin and can cause DNA cleavage in the presence of thiols. Diastereoselective synthesis of this unique ring system has been achieved by low temperature oxidation of the corresponding 1,2-dithiolan-3-ones with 3,3-dimethyldioxirane. 5-Methyl-1,2-dithiolan-3-one-1-oxides were synthesized by oxidation of 5-methyl-1,2-dithiolan-3-one with 3,3-dimethyldioxirane. Eu(fod)₃ and C₆D₆ induced proton chemical shift studies showed that the major isomer in the product has a trans sulfoxide relative to the 5-methyl group. Low temperature oxidation of 4-substituted-amino-5,5-dimethyl-1,2-dithiolan-3-ones by 3,3-dimethyldioxirane preferentially led to the corresponding trans-1,2-dithiolan-3-one-1-oxides. This assignment was made on the basis of a X-ray crystallographic structure study. Formation of azlactones as well as 1,2-dithiolan-3-one-1,1-dioxide were also observed when some substituted 1,2-dithiolan-3-ones were oxidized by 3,3-ditnethyldioxirane. Three 2,2-dimethyl-1,3-dithian-4-ones were synthesized by SnCl₄ mediated condensation of β-mercaptothioacids and acetone. Oxidation of 2,2,6-trimethyl-1,3-dithian-4-one with Ce(IV) did not give 1,2-dithiolan-3-one or 1,2-dithiolan-3-one-1-oxides as anticipated; 1,3-dithian-5-en-4-one was detected as the product instead. Synthetic approaches toward loline were explored. Intramolecular photoaddition of bicyclic olefinic N-nitrosamine did not give the desired product. An epoxide approach did not furnish loline due to unsuccessful epoxide ring opening by azide ion. In the urea approach, the tertiary nitrogen of the bicyclic urea preferentially undergoes a transannular iodocyclization. The same results were obtained by halocyclizing bis-silylimidate or mono-silylimidate of the bicyclic urea.

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5

Vong, Binh G. "Synthetic studies of lateriflorone and synthesis of seco-lateriflorone : stereoselective total synthesis of ( - )-Borrelidin /". Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2004. http://wwwlib.umi.com/cr/ucsd/fullcit?p3142455.

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6

Stewart, Mark Richard. "The design and synthesis of synthetic receptors". Thesis, University of Leeds, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.400852.

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7

Swenson, Helen Rachel. "Studies in synthetic peptides and heterocyclic synthesis". Thesis, University of Edinburgh, 1999. http://hdl.handle.net/1842/13061.

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Abstract (sommario):

The following work documents three studies undertaken using solid phase synthesis techniques. Interaction of the zinc metalloprotease, endothelin converting enzyme-1(ECE-1), with its peptidic natural substrate big endothelum-1 has been investigated via an SAR study, using solid phase peptide synthesis (SPPS). Truncated forms of the substrate had been previously reported to inhibit ECE-1, this was confirmed however the big ET-1 analogues were shown to be substrates for the enzyme. A short study of the substrate specificity of ECE-1 was carried out. The synthesis of vast libraries of peptides using combinational synthesis has been used to accelerate the drug discovery process. Purification of these mixtures has not been previously attempted. 17-Tetrabenzo [a,c,g,i]fluoroeneyhethoxycarbonyl (Tbfmcc) developed for use with single peptides of proteins, has been used to achieve facile purification of five peptide libraries synthesised using SP. The methodology was fully optimised for the efficient separation of the desired library members from all impurities by exploiting the affinity of TBfmoc for carbon. A potential small molecule inhibitor of the zinc metalloenzyme, farnesyl transferase (FTase), was designed. The efficient solution phase synthesis of this novel structure is reported its adaptation to solid phase synthesis is described, with the view to using multiple parallel synthesis techniques to synthesise a range of analogous.

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8

Scott, Felicia Yi Xia. "Controlled Hybrid Material Synthesis using Synthetic Biology". Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/86147.

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The concept of creating a hybrid material is motivated by the development of an improved product with acquired properties by amalgamation of components with specific desirable traits. These new attributes can range from improvements upon existing properties, such as strength and durability, to the acquisition of new abilities, such as magnetism and conductivity. Currently, the concept of an organic-inorganic hybrid material typically describes the integration of an inorganic polymer with organically derived proteins. By building on this idea and applying the advanced technologies available today, it is possible to combine living and nonliving components to synthesize functional materials possessing unique abilities of living cells such as self-healing, evolvability, and adaptability. Furthermore, artificial gene regulation, achievable through synthetic biology, allows for an additional dimension of the control of hybrid material function. Here, I genetically engineer E. coli with a tightly controlled artificial protein construct, allowing for inducible expression of different amounts of the surface anchored protein by addition of varying concentrations of L-arabinose. The presence of the surface protein allows the cells to bind nonliving nanoparticle substrates, effectively turning the cells into living crosslinkers. By using the living crosslinker, I was able to successfully synthesize a robust, macroscale living-nonliving hybrid material with magnetic characteristics. Furthermore, by varying the particle size and inducer concentration, the resulting material exhibited alterations in structure and function. Finally, I was able to manipulate material kinetics within a PDMS channel by applying fluctuating magnetic fields and demonstrate material durability. These results demonstrate the ability to manipulate synthesis of living-nonliving hybrid materials, which demonstrate the potential for use in promising applications in areas such as environmental monitoring and micromachining. Additionally, this work serves as a foundational step toward the integration of synthetic biology with tissue engineering by exploiting the possibility of controlling material properties with genetic engineering.
Ph. D.

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9

Kim, Charles. "Synthetic studies toward the synthesis of norrisolide /". Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2002. http://wwwlib.umi.com/cr/ucsd/fullcit?p3055785.

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10

Phillips, Andrew. "Studies towards the total synthesis of patellazole B". Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/269364.

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Abstract (sommario):

The patellazoles are a family of marine polyketide natural products first isolated from Lissoclinum patella in 1988 by both the Moore and Ireland groups. They exhibit significant cytotoxicity against the HCT 116 human colon tumour cells. To date however, their full 3D stereostructure have yet to be elucidated, which has hindered their development as potential drugs, and hampered full investigation into their biological mechanism of action and has deterred total synthesis efforts. This thesis describes synthetic efforts towards Patellazole B, which exhibits the highest potency of the three main congeners. To fully elucidate the structure and renew interest in the patellazoles as anticancer compounds, we have developed a flexible and modular synthesis that aims to define the unknown stereocentres within the pertinent region and allow for rapid fragment union. Compound 36 has been chosen as an initial target for NMR comparison studies. The synthesis of all eight diastereomers of this macrocycle should aid determination of the four unknown stereocentres. Chapter 2 describes the synthesis of the C1–C12 fragment, focusing on the configuring of the C5 methyl stereocentre and the construction of the C7-C10 stereotetrad via a boron-mediated anti aldol with an in-situ reduction. In the third chapter, the synthesis of the C13-C19 fragment is outlined. A boron-mediated glycolate aldol has been used to install the C16-C17 anti stereochemistry and a substrate-controlled reduction at C15 delivered the hydroxyl with high diastereoselectivity. Studies into the C¬17¬ methylation are also described. Chapter 4 describes the synthesis of one possible diastereomer of the C20-C25 fragment, as a template for the preparation of the other 7 possible diastereomers. The route therefore employs only catalyst based control methods to install the three stereocentres, utilising a Sharpless asymmetric epoxidation and Evans aldol to construct the stereotriad. The 22R, 23S, 24S diastereomer has been initially chosen to investigate the later chemistry. Chapter 5 contains discussion of the ongoing work investigating fragment union and formation of the macrocycle. A Heck coupling reaction has been employed to construct the C19-C20 bond and a Suzuki coupling reaction has been developed to facilitate the C12-C13 bond formation. These two cross couplings have delivered the C1 - C25 fragment, 360, the final compound reported in this thesis, which is three steps away from the completed macrocycle and six from compound 36. The experimental procedures and spectroscopic characterisation of the synthesised intermediates can be found in Chapter 6 and the Appendix.

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11

Shinde, P. D. "Design and synthesis of combretastatin A-4 analogues, synthesis of terrein and synthetic studies towards kodaistatin". Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2004. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2899.

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12

Rivas, Fatima R. "Synthetic studies towards the total synthesis of norzoanthamine". Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2006. http://wwwlib.umi.com/cr/ucsd/fullcit?p3221252.

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Abstract (sommario):

Thesis (Ph. D.)--University of California, San Diego, 2006.
Title from first page of PDF file (viewed September 8, 2006). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.

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13

Rahn, Volker Siegfried. "Synthetic studies towards the total synthesis of (-)-alstonerine". Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401724.

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14

Wild, Mark. "Synthetic studies towards the synthesis of spongistatin 1". Thesis, Bangor University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310863.

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15

Zha, Huiyan, e 查慧艳. "Design, synthesis and characterization of synthetic ion transporters". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hdl.handle.net/10722/206532.

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In recent decades, small molecules have been widely applied to the generation of functional ion transporters. Major discoveries disclosed in this thesis include a self-assembled chloride-dependent potassium channel candidate, a physiological chloride and bicarbonate dual-transporter, and a series of efficient synthetic ion transporters. In nature, K+ channels play an important role in Ca2+ signaling, volume regulation, secretion, proliferation, and migration. The extracellular K+ concentration (4 mM) is about 40 times lower than the intracellular K+ concentration (160 mM). The opening of K+ channels consequently generates an efflux of positive charge, which hyperpolarizes or repolarizes the cellular membrane. In this research, by using fluorescence assays, NMR and patch clamp experiments, compound ZHY-CM23 was found to self-assemble into a chloride-dependent K+ selective channel mediating K+ transport across lipid bilayers and cell membranes. In addition, the synthetic K+ channel formed by ZHY-CM23 was found to be capable of generating and modulating the membrane potential of liposomes and to significantly hyperpolarize the resting membrane potential of HEK 293 cells. This finding provides new insight into developing drugs for the treatment of severe human diseases caused by K+ channel malfunction, such as arrhythmia, neurological disorders and autoimmune diseases. Cystic fibrosis is a chronic recessive disease resulting from the loss of function mutations in the gene encoding of the cystic fibrosis transmembrane conductance regulator (CFTR), a member of the ABC family of membrane transporters. Recent findings reveal that restoring bicarbonate transport might be useful for the treatments of the underlying defect in cystic fibrosis. On the basis of fluorescence assays, NMR and short circuit current experiments, the small molecule ZHY-CM11 has been discovered to not only act as a bicarbonate transporter in lipid membranes, but also to induce chloride-dependent bicarbonate secretion in cultured calu-3 epithelia. It is a promising lead compound to be developed for the treatment of cystic fibrosis and other diseases related to chloride and bicarbonate transport defects. Through structural modifications on the bioactive ion channels and the transporters ZHY-CM23 and ZHY-CM11, some valuable information on the structure-activity relationship has been obtained, and a series of potentially biologically applicable synthetic ion transporters have been discovered.
published_or_final_version
Chemistry
Doctoral
Doctor of Philosophy

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16

Viseux, Eddy Michel Elie. "Synthetic studies towards a total synthesis of roseophilin". Thesis, University of Sussex, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420509.

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17

Charles, Mark David. "Synthetic studies toward a total synthesis of morphine". Thesis, University of Sussex, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272077.

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18

Turvill, Michael W. "The synthesis of natural and synthetic colouring materials". Thesis, University of Nottingham, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280103.

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19

Wang, Shouming. "Synthetic methodology and synthesis using #alpha#,#beta#-epoxyaldehydes". Thesis, University of Salford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328053.

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20

Scott, Richard. "Synthetic approaches towards the synthesis of phorbol esters". Thesis, University of Reading, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314251.

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21

Scott, Karen Ann. "Synthetic studies related to the synthesis of vincristine". Thesis, University of Strathclyde, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367067.

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22

Foot, Jonathan Stuart. "New synthetic methodology and antiviral natural product synthesis". Thesis, University of York, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.412621.

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23

Spoors, Paul Grant. "New synthetic approaches towards the synthesis of morphine". Thesis, University of Southampton, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.330148.

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24

Thom, Catriona. "Synthetic methods directed towards the synthesis of rapamycin". Thesis, University of Southampton, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241117.

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25

Tang, Andrew. "Synthetic methodology towards the synthesis of sesquiterpene lactones". Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612321.

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26

Clark, Jonathan. "New synthetic methods towards the synthesis of taxanes". Thesis, University of Leicester, 1994. http://hdl.handle.net/2381/34051.

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Abstract (sommario):

This thesis is a continuation of previous work done in the Jenkins group to produce taxanes from glucose. The reactions investigated by R. Bonnert and J. Howarth are improved upon to enable the large scale synthesis of the diol (1). After the successful protection of (1) with two tert-butyldiphenylsilyl protecting groups the benzylidene ring was opened by bromination with N-bromosuccinimide. This compound then underwent fragmentation with zinc metal to open the acetal ring and yield the highly functionalised key intermediate chiral cyclohexane (2). This aldehyde was then reduced with sodium borohydride and protected with a triethylsilyl group. The alkene side chain underwent ozonolysis cleanly followed by the addition of lithium-2,2,3,3-tetramethyl-bromocyclopropane. The cyclopropane addition was improved upon by the addition of cerium trichloride. Compounds (3) were isolated from this reaction and a series of studies were done to test the viability of these compounds to undergo further reactions, in particular to rearrange to give dienes. Compounds with bromine in were found to rearrange and those with chlorine in did not. It is believed that most of this work was done with compounds containing chlorine, although at the time this was not realised. Detailed spectroscopic studies verified the stereostructures as those desired for taxanes at the key chiral centres. Alternative sugar routes were also considered and this work gave rise to a new Robinson reaction on a carbohydrate, to give compound (4). Unfortunately this compound was found to have the wrong stereostructure for the synthesis of taxanes from it.

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27

Chen, Yong. "Synthetic Studies on Total Synthesis of Azaspiracid-3". The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1385895424.

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28

Cafiero, Lauren. "New synthetic applications of trichloromethyl carbinols in synthesis". Thesis, [Tuscaloosa, Ala. : University of Alabama Libraries], 2009. http://purl.lib.ua.edu/112.

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29

Singh, R. "Carbohydrate functionalized synthetic elastomers: synthesis, characterization and applications". Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2010. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/3739.

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30

O'Riordan, Timothy Jeremiah Cornelius. "Synthesis of the pyrrolidinone core of oxazolomycin A". Thesis, University of Oxford, 2009. http://ora.ox.ac.uk/objects/uuid:298746d3-69df-47b9-8a83-7949df1c94dc.

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Abstract (sommario):

This thesis describes the development of synthetic strategies towards the densely functionalised pyrrolidinone core of the polyene β-lactone-γ-lactam antibiotic oxazolomycin A. Chapter 1 The oxazolomycins The oxazolomycins, a unique class of biologically active molecules containing a spiro-fused β-lactone-γ-lactam ring system are introduced. The isolation, structural elucidation and biological properties of the oxazolomycins as well as those of the structurally related inthomycins are reviewed. Chapter 2 Previous syntheses The two total syntheses of neooxazolomycin and the synthetic approaches to the pyrrolidinone core of oxazolomycin A and KSM-2690 B are evaluated. Chapter 3 Project aims An outline of the synthetic strategy employed in this project and details of the novel retrosynthesis of the pyrrolidinone core of oxazolomycin A are discussed. Chapter 4 Synthetic studies towards the pyrrolidinone core of oxazolomycin A The synthetic studies carried out towards the pyrrolidinone core of oxazolomycin A are described in detail. The preparation of an advanced intermediate containing the five chiral centres, four of which are contiguous, was achieved in twenty steps as a single diastereomer and as a single enantiomer. Chapter 5 Synthetic studies towards the middle fragment of oxazolomycin A A novel synthetic approach to the diene fragment contained in oxazolomycin A is reported. The formal synthesis of a dienyl iodide, in four fewer steps than previously reported was accomplished. Chapter 6 Conclusions and future work A summary of the synthetic work reported in this thesis and proposals for future study are presented. Chapter 7 Experimental Full experimental procedures and characterisation of compounds are reported. Chapter 8 References A complete list of citations employed in the previous seven chapters is provided.

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31

Källström, Jan Eddy Adolf. "Synthesis studies towards daphlongeranine B". Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:638685a8-da64-488b-b65d-ba9a2111d4fb.

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Abstract (sommario):

This thesis describes the development of a synthetic route towards daphlongeranine B, an alkaloid isolated from the fruits of Daphniphyllum longeracemosum, by utilising an intramolecular Michael addition to form its unique tricyclic core. Chapter 1 gives a general introduction to the family of Daphniphyllum alkaloids together with some recent examples, from the literature, illustrating some synthetic attempts towards structurally similar alkaloids. This chapter also features our retrosynthetic analysis of daphlongeranine B. Chapter 2 details the synthesis of the model spirocyclic enone 72 which was the vital building block needed to investigate the key intramolecular Michael addition. This key reaction was then successfully validated and access to the unique tricyclic core 64 of daphlongeranine B was made possible. Chapter 3 expands the scope of the key intramolecular Michael addition step. This chapter first describes a synthetic route to the Î2-substituted spirocyclic enone 112 and subsequently validates the key intramolecular Michael addition step to give the tricyclic core 138 of daphlongeranine B. Chapter 4 details a synthetic route towards the spirocyclic fragment 141 by utilising a Baker's yeast reduction and a tandem addition/cyclisation reaction.

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32

Pearson, Jem M. "Hydrogen-bonding motifs for non-covalent synthesis". Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:f0630898-35b4-4c74-bc31-dfd252c2ee26.

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Abstract (sommario):

This work describes the design and synthesis of a set of four organic molecules that are intended to hydrogen-bond to each other in a pairwise manner. The four hydrogen-bonding units, termed ‘A’, ‘B’, ‘C’ and ‘D’, when placed in solution together, are designed so that A binds only to B, and C binds only to D. Each unit does not bind to itself, nor to either of the other two units to which binding is not intended. For example, A binds to B, but not to A, C, or D. Each unit contains an array of four hydrogen-bonds for strong binding to its partner, is designed to be as rigid as possible, as non-tautomeric as possible, and utilises a staggered non-symmetrical architecture. Of the four intended compounds, three were successfully synthesised (A, B and D). Units B and D were soluble in CDCl₃, but Unit A was not. Therefore, the design and synthesis of Unit A was amended, and two variants of Unit A that are both soluble in CDCl₃ were successfully synthesised. ¹H NMR binding experiments were performed between Unit B and each of the two variants of Unit A. Their binding behaviour was described. A binding constant could not be calculated because the units did not bind in a 1:1 fashion.

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33

Chi, Xiang-yong. "A Sythetic Study of a Cyclic Siloxydiyne and its Iron Carbonyl Complex". Thesis, University of North Texas, 1989. https://digital.library.unt.edu/ark:/67531/metadc500871/.

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The synthetic studies include the synthesis of the cyclic siloxydiyne, 3,3,5,5,8,8,10,10-octamethyl-4,9-dioxa-3,5,8,10-tetrasilacyclodeca-1,6- diyne [VI] and its novel iron carbonyl complex. In the preparation of [VI] by HBr promoted condensation of bis (methoxydimethylsilyl) acetylene, a minor product, a cyclic trimer was always formed along with the major product [VI]. No evidence of an equilibrium between the trimerization product and the dimerization product was found. Compound [VI] can react with iron carbonyl reagents to produce a novel binuclear iron complex of trimethylenemethane [VII] in very low yield either in a thermal or photo-reaction. The key step proposed by us in the formation of [VII] is a I,2-silyl shift in a complexed bis (silyl) acetylene to form a vinylidene intermediate. Experiments aimed at isolating this intermediate were not successful.

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34

Sherlock, Jay T. "Synthesis". Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/34055.

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Abstract (sommario):

This thesis is an investigation of place. The project is a vehicle which informs how the variables of site and program can be developed into place. Through the production of tangible work the architect may verify whether the creation of place is successful. The analysis of this outcome can enhance and reinforce the architect's position.
Master of Architecture

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35

Olbrich, Martin. "Synthesis of C2-tritwistane, synthetic and theoretical studies toward polytwistane and syntheses of twistanamines as potentential antiviral agents". Diss., Ludwig-Maximilians-Universität München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:19-181658.

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36

Blum, Janna Karen. "Broadening the enyzme-catalyzed synthesis of semi-synthetic antibiotics". Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39528.

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Abstract (sommario):

An alpha-amino ester hydrolase (AEH) applicable to synthesis of semi-synthetic antibiotics was cloned from the genomic DNA of Xanthomonas campestris pv. campestris sp. strain ATCC 33913. AEHs catalyze the synthesis and hydrolysis of alpha-amino beta-lactam antibiotics. The enzyme was characterized for thermodynamic and kinetic parameters. The enzyme shows optimal ampicillin hydrolytic activity at 25C and pH 6.8. The AEH enzymes have been shown to have excellent synthetic capability. Additionally, we demonstrated the first fully aqueous enzymatic one-pot synthesis of ampicillin direct from the natural product penicillin G eliminating the isolation of the intermediate 6-APA. Lastly, to improve the thermostability of the AEH a modified structure-guided consensus model of seven homologous enzymes was generated along with analysis of the B-factors from the available crystal structures of the known AEH from Xanthomonas citri. Our best variant, which is a quadruple mutant, E143H/A275P/N186D/V622I, which has a T_50_30, the temperature at which the half-life is 30 minutes, of 34C and 1.3-fold activity compared to wild-type. Overall, we have successfully improved the understanding of the AEH class of enzymes and applied a novel cascade application, demonstrating AEHs unique applicability in the synthesis of beta-lactam antibiotics. The improved thermostability will further improve the industrial relevance of AEHs.

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37

Kundu, Kousik. "Synthesis of highly functionalized diazoacetoacetates and their synthetic applications". College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/4103.

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Abstract (sommario):

Thesis (Ph. D.)--University of Maryland, College Park, 2006.
Thesis research directed by: Chemistry. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

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38

Sreekumar, Sanil. "Synthetic studies towards the total synthesis of lancifodilactone G". Thesis, University of Liverpool, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.569566.

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This thesis presents our studies towards the first total synthesis of the novel anti- HIV agent lancifodilactone G, which has a highly unusual aliphatic enol. The first chapter provides a survey of architecturally diverse nortriterpenoids that were isolated from the Schisandraceae family. A proposed biosynthetic pathway for lancifodilactone G and closely related natural products provides a rationale for the formation of the consecutive 7/8/5 fused carbo cycles that are unique to Schisandra nortriterpenoids. Chapter 1 goes on to outline the reported strategies to access the core of lancifodilactone G and concludes with a retrosynthetic analysis proposed by the Evans group, which includes a biosynthetically inspired single-pot polycyclisation reaction. Chapter 2 describes the highly stereocontrolled synthesis of the eastern fragment (F-G rings) using transition metal-mediated Pauson-Khand reaction. This chapter also reviews the metal-mediated diastereoselective Pauson-Khand reaction directed by the stereogenic centre at C2, with the ample illustration to total synthesis. Attempted strategies for the assembly of the bicyclic cyclopentanone motif via a dienyl Pauson-Khand reaction of silicon- and oxygen- tethered diene-enes are presented. The failure of these strategies at different stages of the synthesis resulted in the exploration of a classical Pauson-Khand approach, which successfully furnished the eastern fragment. Finally, a second-generation synthesis is described which provided the fully functionalised eastern fragment with improved efficiency and overall yield. Chapter 3 discusses the successful synthesis of the western fragment (B-C rings) using a diastereoselective [4+3] cycloaddition strategy. Attempted strategies for the synthesis of the key 2,3-disubstituted furan derivative are presented, which was achieved via a hetero Pauson- Khand reaction. This chapter includes a brief account of the classical [4+3] cycloaddition reactions of furans using an in situ generated oxyallyl cation and also employing vinyl carbenoids in the metal-catalysed version. The review also highlights the application of the [4+ 3] cycloaddition reaction in the expeditious assembly of functionalised 7-membered rings that occur in a number of important biologically active natural products. The third chapter goes on to describe the application of these cycloaddition reactions in the synthesis of the fully functionalised western fragment of Lancifodilactone G. Chapter 4 describes a model study aimed at expediting the synthesis of the western fragment using a rhodium-catalysed allylic substitution reaction. A brief mechanistic discussion on unique aspects of the allylic alkylation reaction is illustrated. Chapter 4 concludes by outlining the coupling strategy for eastern and western fragments and the end game studies for the completion of the synthesis of lancifodilactone G.

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39

Welsh, Emma Jane. "Asymmetric synthesis of aphanorphine and synthetic approaches toward dictyoxetane". Thesis, University of Birmingham, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.446335.

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40

Dunn, Stephen Henry. "Total synthesis of norsegoline : synthetic approaches to the cystodytins". Thesis, University of East Anglia, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238806.

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41

Crawford, Claire Frances. "Synthetic studies towards a total synthesis of hemibrevetoxin B". Thesis, University of Leeds, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435783.

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42

Pearson, David James. "Synthetic studies towards the total synthesis of popolohuanone E". Thesis, University of Sheffield, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267117.

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43

Shen, Yue. "Design, synthesis and characterization of the synthetic yeast genome". Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/33182.

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With the rapid development of DNA synthesis technologies, synthetic biology has made tremendous progress in the past 15 years, in particular for synthetic genomics. Synthetic genomics is a nascent field of synthetic biology, which aims to design new biological systems/organisms to satisfy human needs. Conventional synthetic biology focuses on the redesign, construction and modeling of biological parts, pathways or genomes that do not exist in nature, while synthetic genomics encompasses technologies that allow the generation of chemically synthesized larger parts of genomes or whole genomes, with simultaneous redesign of an organism's genetic material. Synthetic genomics is painting a blueprint for a new era of biology and holds great potential for a multitude of applications, such as pharmaceuticals, biofuels and rapid generation of vaccines against emerging diseases. Chapter One gives an introduction of the current state of the art and challenges of synthetic genomics and the objectives of this study. Chapter Two demonstrates the design and construction strategy of two megabase-long synthetic yeast chromosomes, SynII and SynVII. Chapter Three describes the full characterization of SynII and SynVII. Chapter Four introduces the SCRaMbLE (Synthetic Chromosome Rearrangement and Modification by LoxPsym-mediated Evolution) system and its application in SynII and SynVII. Taken together, this work demonstrates the utility of synthetic yeast for understanding biological systems and its potential for industrial applications.

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44

Oswald, Magalie Florence. "Novel synthetic methodologies for the synthesis of heterocyclic rings". Thesis, University of Sussex, 2010. http://sro.sussex.ac.uk/id/eprint/2348/.

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Part 1. Synthesis of Stereodefined Heterocyclic Rings. We wish to report the development of novel methodology for the synthesis of stereodefined heterocyclic rings, which could be used for the synthesis of natural products containing for example tetrahydrofuran motifs, such as members of the pamamycin family. Due to their ambivalent properties, organoaluminium reagents can easily react with acetals by transfering an alkyl group after prior coordination with the substrates. This work has led to the development of a novel cascade reaction. It involves the reaction of acetals with trialkylaluminium reagents, which is followed by a cyclisation reaction, generating consequently tetrahydrofuran or tetrahydropyran rings. In addition, investigation towards the synthesis of pyrrolidines was also carried out. Part 2. Investigation and Development of a Novel Cascade Reaction. The Bergman cycloaromatisation reaction is based on the formation of a biradical intermediate species and has been, over the years, a constant source of inspiration for scientists. Continued efforts over the last 40 years permitted, among other things, a better understanding of the mode of action of the enediyne antibiotics, a class of natural compounds with exceptional biological activities. The Parsons group recently developed a novel cyclisation reaction, which also generates a biradical species, and which could, after being trapped with a suitable alkene, lead to the formation of tricyclic molecules containing heterocyclic cores. As a result, we wish to further investigate this novel reaction and develop a tandem reaction, involving this reaction combined with a Diels-Alder reaction in order to generate pentacyclic molecules, in one synthetic operation, and from an acyclic precursor.

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45

Vassilaras, Plousia E. "Alternative Synthetic Methodologies for the Synthesis of Organosilicon Compounds". Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1310150433.

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46

Audic, Alexandre. "Synthetic studies towards the total synthesis of hexacyclinic acid". Thesis, University of Glasgow, 2016. http://theses.gla.ac.uk/7790/.

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In the first chapter of this thesis, published works found in the literature about hexacyclinic acid and FR182877 are reported and commented. A quick summary of the previous work done in the Prunet group is also described. In the second and third chapter, a more detailed account of the work undertaken during this PhD was given. Firstly, syntheses of two ABC tricycles incorporating tert-butyl and (trimethylsilyl)ethyl esters were undertaken. These syntheses include two key steps previously developed in the group, a diastereoselective Michael addition and a Snider cyclisation. Multiple conditions for the hydrolysis of the esters were attempted but none of them gave the desired product. The main part of this work is focused on the synthesis of a CDEF model and in particular about the development of the key step, the formation of a nine-membered ring. Several DEF fragments were synthesised in short synthetic sequences and as single isomers. Six different synthetic pathways were developed in total and a novel method, a Michael/elimination reaction, was found to be a very efficient way to close the desired medium-size ring. From the nine-membered ring, regioselective reduction and palladiumcatalysed allylic substitution led to the formation of the CDF tricycle. Final steps of the synthesis were fruitless and led only to decomposition. A synthesis of a chiral C-ring was also developed during this PhD. II Finally, another project was undertaken, not related to hexacyclinic acid. Methodology developed in the group for the diastereoselective formation of trisubstituted alkenes employing a temporary silicon-tethered ring-closing metathesis was extended to homoallylic alcohols. The first steps of the method were similar to the previous methodology but the end-game had to be modified in favour of an oxidation/reduction sequence to successfully obtain the desired products with the correct geometry. In the fourth chapter, procedures and analytical data for the synthesised compounds previously described are reported.

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47

Lau, Shing Hing. "Organic synthesis : taming chemistry using enabling technologies". Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/273347.

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This thesis describes the application of flow chemistry to discovery and development of medicinal compound synthesis and new chemical methodologies respectively. It is divided into three distinct sections. The first section addresses a brief introduction to flow chemistry, highlighting the advantages and challenges that have been faced in the past and present and also the outlook to the future. The second section reports the integration of machine-assisted methods with batch processes to produce two medicinal compounds, a precursor to the sacubitril and OZ439 respectively. In the respect to the precursor to sacubritil, a flow-batch integrated synthesis is developed to provide the desired product in 54% yield over 7 steps from commercially available 4-iodophenyl. In particular, a tube-in-tube gas flow reactor was employed in three gas-liquid reactions without the need for installing a costly highpressure autoclave. These gas-lquid reactions were an ethylene Heck coupling reaction, an anti-Markovnikov Wacker oxidation and a rhodium-catalysed stereoselective hydrogenation respectively. In addition, a diastereoselective Reformatsky-type carbethoxyallylation using zinc metal was also highlighted in this synthesis to install an important stereocentre. A new antimalarial agent, OZ439 containing a trioxolane unit as the main structural feature, has the unique property of providing a single-dose cure for malaria in humans and has recently completed phase IIb trials. A machine-enabled process for the preparation of OZ439 was developed in 33% overall yield over 5 steps without the need of column chromatography purification. This preparation features a selective continuous hydrogrenation, Griesbaum ozonlysis and a Zn-catalysed amide reduction in the present of triethoxylsilane. The third section contains the development of two new methodologies of diazo compounds with organoboron compounds. The first methodology involves an in situ generation of transient allylic boronic species by reacting TMSCHN2 and E-vinyl boronic acids in flow, followed by subsequent trapping with a range of aldehydes (15 examples, 55-97% yield) and on a large scale (10 mmol) to provide homoallylic alcohols with high diastereoselectivity (>20:1 dr confirmed by 1H NMR). This multicomponent metal-free reaction could also be applied under batch conditions (20 further examples, 60-82% yield). The second methodology involves the preparation of an organodimetallic compound, α-trimethylsilyl benzylboronic acid pinacol esters, by reacting TMSCHN2 and phenylboronic anhydrides (21 examples, 60-91% yield), and the development of their applications as bifunctional building blocks to complex structures.

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48

Foley, Michael Andrew. "1-Acyldihydropyridones as Synthetic Intermediates". DigitalCommons@USU, 1988. https://digitalcommons.usu.edu/etd/7180.

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The most efficient and stereoselective total synthesis of (+/-) lausbine II to date has been achieved. The key steps in this are the copper-mediated conjugate addition reaction of the Grignard reagent of 1-bromo-4-chlorobutane to a dihydropyridone and a stereoselective reduction of a quinolizidinone. Methodology has been developed for the convenient synthesis of 1-acyl-2-substituted-1,2,5,6-tetrahydropyridines. This was accomplished by adding novel alkylzinc iodides to the 1-acyliminium ion derived from Nphenoxycarbonyl-4-methoxy-1, 2, 3, 4-tetrahydropyridine.

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49

Wu, Boshen. "Synthesis of taurospongin A and other biologically active natural products". Thesis, University of Oxford, 2017. http://ora.ox.ac.uk/objects/uuid:37a34bc4-efb4-4a6b-9d44-a3ad1c8ae0be.

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This thesis firstly describes a synthesis of the natural product taurospongin A, a potent DNA polymerase beta inhibitor. Sharpless asymmetric dihydroxylation on olefin E-1.60 followed by selective deoxygenation at C(2) via Barton‒McCombie reaction delivers the desired C(1)–C(10) carboxylic acid core. Subsequent esterification of the C(1)–C(10) fragment with C(1′)–C(25′) fatty acid furnishes the natural product in 13.5% yield. The structure of an unnamed natural product 2.14 isolated in 1974 is proven to be misassigned by previous studies within the Robertson group. As described in this thesis, two proposed structures A and B are obtained via total synthesis in order to reveal the identity of the natural product. A synthesis of key intermediate spirocycles 2.148 and 2.158 with desired trans- diol moiety is described by a dihydroxylation reaction on an electron deficient gamma-keto unsaturated acid with subsequent spirocyclisation reaction. Finally, methodology for generating high-value synthetic intermediates by an asymmetric, one-pot enzymatic di/polycarbonyl reduction is described. The concept of such methodology is first proven by the synthesis of (3R)-hydroxybutyl (3R)-hydroxybutanoate 3.20. This thesis then describes substrate scope studies and corresponding stereochemical proof to provide more information about this methodology.

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50

Murphy, James P. "Synthesis of azabicyclic intermediates for alkaloid synthesis". Thesis, Queen's University Belfast, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394528.

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