Dissertations / Theses: 'Carbenoid use in synthesis'

1

Sheppard, A. "The use of carbenoids in #beta#-lactam synthesis." Thesis, University of Manchester, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380525.

Full text

APA, Harvard, Vancouver, ISO, and other styles

2

Hrytsak, Michael D. "The use of rhodium carbenoid insertion reactions in organic synthesis." Thesis, University of Ottawa (Canada), 1987. http://hdl.handle.net/10393/21296.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Babu, Suresh Dhandayutham. "Part~A. Synthesis of optically active alpha-substituted acids. Part~B. The use of rhodium carbenoid reactions in organic synthesis." Thesis, University of Ottawa (Canada), 1991. http://hdl.handle.net/10393/7955.

Full text

Abstract:

Part A. Chapter 1. The Sharpless epoxidation product from E-4-phenyl-2-butene-1-ol and diethyl D-tartrate was converted into L-($-$)-phenylalanine in three steps. After completion of the above synthesis Sharpless published an extensive study of the synthesis of $\alpha$-amino acids via essentially the same route. Therefore the project was abandoned. Optically active 2-arylpropionic acids such as 2-phenylpropionic acid, 2-napthylpropionic acid, and 2-(4-isobutylphenyl)-propionic acid (Ibuprofen) were synthesized in two steps from Sharpless epoxidation products. Part B. Chapter 2. The synthesis of 4-carboethoxy-4,6-dihydro-thieno (3,4-b) thiophene 5,5-dioxide and 4-phenyl analogue, precursors to thiophene xylylenes, are reported. Attempts to trap the carboethoxy substituted xylylene with electron rich or electron poor dienophiles failed and only dimers were produced. In contrast, the phenyl substituted xylylene gave moderate yields of Diels-Alder adducts in trapping experiments with dienophiles such as dimethylacetylene dicarboxylate, dimethyl fumarate, and benzoquinone. Chapter 3. Several additional examples of a conceptually new route to 1,3-dihydrobenzothiophene-2,2-dioxides from $\alpha$-diazo-$\beta$-sulfonyl esters via a formal rhodium carbenoid insertion into an aromatic C-H bond is reported. Our attempts to extend the scope of this reaction to include insertion into furan derivatives failed. We obtained very unusual furan ring opened products. When the same rhodium carbenoid reactions were carried out with $\alpha$-diazo-$\beta$-ketoamides, 2-hydroxy-3-acetylindole derivatives were formed. Chapter 4. In order to gain insight into the rhodium carbenoid reaction mechanism, the diazo precursors to 1,3-dihydrobenzothiophene-2,2-dioxide, 2-indanone, and 2-tetralone which were mono substituted at the ortho position of the aromatic ring were synthesized and the hydrogen/deuterium isotope effects were measured. The observed isotope effects ranged from 3.3-4.9. Furthermore, deuterium NMR indicated that scrambling had occurred during the cyclization step. These data have been interpreted to show that these rhodium carbenoid reactions should be considered as electrophilic aromatic substitution reactions.

APA, Harvard, Vancouver, ISO, and other styles

4

Bégis, Guillaume. "Studies on the generation and use of functionalised organozinc carbenoids for the synthesis of aminocyclopropanes and related congeners." Thesis, University College London (University of London), 2004. http://discovery.ucl.ac.uk/1446526/.

Full text

Abstract:

The present thesis describes a range of studies on the generation and reactivity of organozinc carbenoid species possessing adjacent nitrogen functionality for the preparation of aminocyclopropanes and related congeners. This thesis opens with two distinct introductory reviews. The first one focuses on the description of the different general methods already available for the synthesis of aminocyclopropanes. The second one is concerned with the generation and reactivity of organozinc carbenoids encountered in the literature. The results and discussion chapter firstly describes the successful generation of an organozinc carbenoid from an acetal moiety contiguous to a nitrogen atom of a simple cyclic amide using a mixture of zinc amalgam and chlorotrimethylsilane. This new organometallic species is found to undergo cyclopropanation reactions with a range of alkenes to yield amidocyclopropanes. Subsequent studies directed towards the design of carbenoid precursors which can lead to the preparation of primary aminocyclopropanes are then discussed. A method for the synthesis of chiral protected aminocyclopropanes in two steps from their corresponding alkenes is described. An investigation of the preparation of N-substituted cyclopropyl amino alcohols and acids is presented. From this study, an N-substituted cyclopropyl glycine derivative is prepared. Finally, this thesis discusses the attempted palladium-catalysed cross-coupling reactions between amino cyclopropylsilanes and aryl iodides and the successful Tamao-Fleming oxidation of the carbon-silicon bond of vicinal amino cyclopropylsilanols to give the corresponding amino cyclopropanols. The thesis terminates with a full description of the experimental procedures used and the compounds prepared.

APA, Harvard, Vancouver, ISO, and other styles

5

Adero, Philip O. "Heterocycle Synthesis via Rhodium (II)-Catalyzed Azido Carbenoid Cyclization." Youngstown State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1348595887.

Full text

APA, Harvard, Vancouver, ISO, and other styles

6

Tuckett, Mark William. "Applications of zirconium chemistry to organic synthesis." Thesis, University of Southampton, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310484.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Main, Calver A. "Novel titanium carbenoid reagents : diversity orientated synthesis of indoles and spirocycles." Thesis, University of Glasgow, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.502007.

Full text

Abstract:

A new synthetic strategy for the preparation of a 96-member library of 2,5-disubstituted indoles involving traceless cleavage from resin is presented. A boronate-bearing titanium alkylidene was prepared and used to convert 8 resin-bound esters into immobilised enol ethers. Cleavage from resin in mild acid with concomitant cyclisation yielded boronate-bearing indoles. Capitalising on the immobilised boronate functionality in enol ethers, Suzuki cross-coupling reactions were performed with 12 aryl iodides to give a 96-member library after cleavage from resin with mild acid, 79 members of the library were confirmed to be 2,5-disubstituted indoles. Also reported is the use of tertiary butyllithium and 2-isopropoxy-4,4,i,5-tetramethyl-l,3,2-dioxaborolane to convert an aiyl bromide into an arylboronate in the presence of a dithiane, with simultaneous reduction of an aryl azide to an amine. In a similar route, we synthesised dithiane for the attempted conversion of resin-bound esters into functionalised 7-azaindoles after cleavage from resin. Further investigation with a different ortho-nitrogen protecting group may yet prove successful.

APA, Harvard, Vancouver, ISO, and other styles

8

Krowiak, Steven A. "Synthesis of cyclic ethers : a tandem carbenoid insertion and ylide rearrangement strategy." Thesis, University of Nottingham, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387858.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Pavlyuk, Oksana M. "Synthesis of Nitrogen-Containing Heterocycles via Carbenoid Insertion/Ring-Closing Metathesis Sequence." Ohio University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1303761092.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Swain, Nigel Alan. "C H insertion approach to the total synthesis of furofuran lignans and their heterocyclic analogues." Thesis, University of Southampton, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288472.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

Grand, Simon Christopher. "The synthesis of carbocyclic nucleoside analogues using rhodium carbenoid C-H insertion reactions." Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367403.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Hodgson, Paul B. "A tandem ylide formation and rearrangement approach to the synthesis of nitrogen heterocycles." Thesis, University of Nottingham, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261172.

Full text

APA, Harvard, Vancouver, ISO, and other styles

13

Fretwell, Mark. "Asymmetric synthesis of cyclic ethers via a tandem carbenoid insertion and ylide rearrangement strategy." Thesis, University of Nottingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324477.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Dossetter, Alexander Graham. "An approach to the total synthesis of neoliacinic acid, a highly oxygenated sesquiterpene lactone." Thesis, University of Nottingham, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243491.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Hansen, K. Emelie. "Synthesis of O-Heterocycles : the [2,3]-sigmatropic rearrangement of transition metal carbenoid-generated allylic oxonium ylides." Thesis, University of Glasgow, 2012. http://theses.gla.ac.uk/3654/.

Full text

Abstract:

In many natural products, heterocycles, such as cyclic ethers, are important features. While there are many different approaches to the formation of these ethers, there are only a few methods available for the synthesis of substituted cyclic ethers with good diastereoselectivity and even less so with good enantioselectivity. The rearrangement of oxonium ylides has proved to be a versatile method for the stereoselective synthesis of cyclic ethers. However, to date, there is no general efficient enantioselective method for the rearrangement of oxonium ylides. This project aimed to develop an enantioselective synthesis of O-heterocycles from chiral copper carbenoids. Screening of various catalysts generated in situ from [Cu(MeCN)4]PF6 and chiral ligands led us to identify a class of ligands, specifically chiral bisoxazoline ligands, that generally resulted in asymmetric induction during the [2,3]-sigmatropic rearrangement of oxonium ylides. Unfortunately, while asymmetric induction was obtained, generally the rearrangement reaction resulted in quite low enantiomeric excess. During the course of this project, iridium-mediated reactions was also investigated. It was found that the catalyst [Ir(COD)Cl]2 could be used for the same transformation as the copper catalysts, which to the best of our knowledge was the first example of the use of an iridium catalyst for the tandem oxonium ylide generation and subsequent [2,3]-sigmatropic rearrangement of diazoketones. As only rather low asymmetric induction was obtained during this transformation, our attention turned towards achieving a greater mechanistic understanding of this reaction, as good mechanistic understanding is essential for enantioselective development. Isotopic labelling of the diazoketone starting materials provided information on the rearrangement products, from which conclusions could be drawn as to the rearrangement mechanism. It was concluded that the rearrangement reactions in question, that take place via copper or iridium carbenoid-mediated reactions, either do not proceed through a free oxonium ylide, but rather through the metal-associated oxonium ylide derivative, or follow a major competing non-ylide route that delivers apparent [2,3]-sigmatropic rearrangement products of oxonium ylides. With regard to rhodium-catalysed reactions, firm conclusions could not be drawn, although there is some suggestion that this reaction also does not proceed solely through the free oxonium ylide pathway. Further investigations of the iridium-catalysed reaction through crossover experiments suggest that the metal-associated oxonium ylide derivative dissociates during the reaction to give an allylic cation and an iridium enolate, which then recombines to give the apparent [2,3]-rearrangement product.

APA, Harvard, Vancouver, ISO, and other styles

16

Zhou, Congying, and 周聰穎. "Ruthenium porphyrins and dirhodium (II, II) carboxylates catalyzed ylide-mediated cycloadditions and carbenoid transfer reactions." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B31046484.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Torssell, Staffan. "Amino Aacohols : stereoselective synthesis and applications in diversity-oriented synthesis." Licentiate thesis, KTH, Chemistry, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-315.

Full text

Abstract:

This thesis is divided into three separate parts with amino alcohols as the common feature. The first part describes the development of a novel three-component approach to the synthesis of α-hydroxy-β-amino esters. Utilizing a highly diastereoselective Rh(II)-catalyzed 1,3-dipolar cycloaddition of carbonyl ylides to various aldimines, syn-α-hydroxy-β-amino esters formed in high yields and excellent diastereoselectivities. This methodology was also applied in a short enantioselective synthesis of the C-13 side-chain of Taxol.

The second part of the thesis describes a total synthesis of D-erythro- Sphingosine based on a cross-metathesis approach to assemble the polar head group and the aliphatic chain.

The last part deals with the application of amino alcohols as scaffolds in a diversity-oriented protocol for the development of libraries of small polycyclic molecules. The design of the libraries is based on the iterative use of two powerful ring-forming reactions; a ring-closing metathesis and an intramolecular Diels-Alder reaction, to simultaneously introduce structural complexity and diversity.

APA, Harvard, Vancouver, ISO, and other styles

18

Torssell, Staffan. "Stereoselective Synthesis of Amino Alcohols : Applications to Natural Product Synthesis." Doctoral thesis, Stockholm : Kemi, Kungliga Tekniska högskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4472.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Winn, Caroline Louise. "Synthesis of sulfur compounds and their use in asymmetric synthesis." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621078.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

Ling, Kenneth B. "Stereoselective cyclopropanations of allylic amines and derivatives." Thesis, University of Oxford, 2009. http://ora.ox.ac.uk/objects/uuid:15907329-15e7-4cbd-ba46-2735ff4129ea.

Full text

Abstract:

This thesis is concerned with the development and application of methods for the stereoselective cyclopropanation of allylic amines and derivatives. Firstly, a highly chemo- and stereoselective cyclopropanation of N,N-dibenzyl-protected allylic amines was developed using the highly reactive Shi’s carbenoid [CF₃CO₂ZnCH₂I]. Subsequent mechanistic studies revealed that the high diastereoselectivity of the reaction was likely to be due to coordination of the amine to the zinc carbenoid reagent. It is then shown that the reaction is general for a wide range of both cyclic and acyclic substrates giving the corresponding cyclopropanes in high yields and diastereoselectivities. Secondly, a novel stereodivergent cyclopropanation of allylic carbamates and amides was developed. It was found that reaction of cyclic allylic carbamates with the Wittig-Furukawa reagent [Zn(CH₂I)₂] typically gives the syn-diastereoisomer in high yields and diastereoselectivities, whilst treatment of the same substrates with Shi’s carbenoid [CF₃CO₂ZnCH₂I] gives the corresponding anti-diastereoisomers in high yields and diastereoselectivities. Mechanistic investigations suggested that reactions with the Wittig-Furukawa reagent proceed via a N-directed intramolecular cyclopropanation step whilst those with Shi’s carbenoid proceed via a sterically directed intermolecular cyclopropanation step. Unsuccessful investigations into an asymmetric variant of the cyclopropanation reaction utilising chiral carbamate protecting groups are then described. Finally, studies towards the total synthesis of the potential anti-obesity therapeutic trans-SCH-A and its epimer cis-SCH-A are described. A stereodivergent route towards the epimeric products was developed through the cyclopropanation of a common allylic carbamate intermediate with either the Wittig-Furukawa reagent or Shi’s carbenoid to give the corresponding trans-2-amino-5-arylbicyclo[3.10]hexane or cis-2-amino-5-arylbicyclo-[3.10]hexane intermediates respectively.

APA, Harvard, Vancouver, ISO, and other styles

21

Yang, Xiaoye. "Synthesis and use of chiral surfactants." [Johnson City, Tenn. : East Tennessee State University], 2001. http://etd-submit.etsu.edu/etd/theses/available/etd-0621101-163829/unrestricted/yangx0702.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Gillon, Karen A. "Scalemic Î² amino alcohols : their synthesis and use in asymmetric synthesis." Thesis, University of Strathclyde, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248481.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Capitta, Francesca. "Use of organocatalysts in stereoselective organic synthesis." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00807093.

Full text

Abstract:

The main topic of thesis is the use of organocatalysis to synthesize cyclobutanones derivatives. Cyclobutanone derivatives are useful molecular building blocks for the construction of complex molecular structures. Surprisingly, however, the use of organocatalysts to functionalize cyclobutanones is rare, especially when the substrate bears substituents. In this thesis, we present the enantioselective transformations and functionalizations of substituted cyclobutanones which employ readily-available amino acids (or derivatives) and thiourea derivatives as organocatalysts. - The first transformation involves the enantioselective aldol reaction between 2-hydroxy-cyclobutanone with a selection of aromatic aldehyde. The results show that the 2-hydroxycyclobutanone is particularly amenable to solvent-free L-threonine-catalyzed direct aldol reactions with reasonable stereocontrol. - After, we synthesized 2,3-disubstituted cyclobutanones through direct aldol reactions involving 3-substituted cyclobutanones and aryl aldehydes catalyzed by N-phenylsulfonyl (S)-proline and via asymmetric nitro-Michael reaction of 3-substituted cyclobutanones and several nitrostyrenes catalyzed by thiourea derivatives. In the first case the relative aldol products were obtained with an unprecedented control of all three contiguous stereocenters in the latter the relatives γ-nitro cyclobutanones were obtained in good yield but in modest enantioselectivity. - The last case concerns the conversion of 3-substituted cyclobutanones into 4-substituted-5-hydroxy-γ-lactam using as electrophile nitrosobenzene and L-proline as catalysts. This reaction involves a ring-expanding O-nitroso-aldol-cyclization domino sequence. The synthetic protocol provides access to the five-membered ring system in good yield, and the formation of two new stereogenic centers is achieved with complete stereochemical control. Thus, the main topic of the first chapter is the organocatalysis, applications of the most common organocatalysts are discussed. The vast majority of organocatalytic reactions use chiral amine as catalysis (asymmetric aminocatalysis). Different types of organocatalysis involve the use of Br¿nsted acids and bases, Lewis acids, hydrogen bond-mediated catalysis, phase transfer and N-heterocyclic carbene catalysis. The second chapter deals with the reactivity of cyclobutanones. High electrophilicity and ring strain make the cyclobutanone and its derivatives a good substrate for ring transformation reactions. Characteristic reactions of functionalized cyclobutanones involve the ring opening, ring contraction and ring expansion reactions. In the third chapter, the synthesis of 2,2-disubstituted cyclobutanones via direct aldol reaction of 2-hydroxycyclobutanone with several aldehydes catalyzed by primary amines is presented. The results show that the 2-hydroxycyclobutanone is particularly amenable to solvent-free L-threonine-catalyzed direct aldol reactions with reasonable stereocontrol. In the fourth chapter we describe the synthesis of 2,3-disubstituted cyclobutanones through direct aldol reactions of 3-substituted cyclobutanones and aryl aldehydes, catalyzed by N-phenylsulfonyl (S)-proline and through asymmetric nitro-Michael reaction of 3-substituted cyclobutanones and several nitrostyrenes, catalyzed by derivatives of thiourea. In this last chapter an organocatalyzed enantioselective desymmetrization reaction of 3-substituted cyclobutanones is presented using nitrosobenzene as an electrophile and proline derivatives as catalysts. This reaction give an original 5-hydroxy-γ-lactam in good yield and with the generation of two new stereogenic centers.

APA, Harvard, Vancouver, ISO, and other styles

24

Davies, Huw John. "Synthesis and use of heterocycles in organocatalysis." Thesis, Cardiff University, 2009. http://orca.cf.ac.uk/54850/.

Full text

Abstract:

This thesis is concerned with two sections: the first deals with the synthesis of quinolinones via a tandem VNS reaction. The second examines the aminocatalysis of the Baylis-Hillman reaction Chapter 1: Provides an overview of aromatic chemistry. Focus is on the separate mechanisms of the substitution of aromatic compounds. An overview of VNS chemistry is also included to provide a basis for the investigations carried out. Chapter 2: Describes the synthesis of a small library of 6/s-rutroaromaric compounds using the VNS reaction. An investigation into the cyclisation of the &w-nitroaromatic compounds to a range of biologically interesting quinolinones is also described. Chapter 3: Introduces the concept of aminocatalysis and gives an overview of recent developments in the field including the Baylis-Hillman reaction, the reaction chosen for asymmetric catalyst development. Chapter 4: Is split into three sections the first describes an interesting solvent effect encountered during the course of the investigation. The second investigates the effect of the structure of secondary amines on the enantioselectivity of the reaction via iminium ion formation. The third section describes the investigation of the structure of Lewis bases on the enantioselectivity of the reaction.

APA, Harvard, Vancouver, ISO, and other styles

25

Bromley, William James. "Synthesis and Use of Novel 1,2,4-Triazines." Thesis, University of York, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.503299.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

Aloui, Mahmoud. "Use of carbohydrates in pseudo-sugar synthesis." Thesis, University of Salford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334027.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Alshammari, Mohammed. "Use of organometallic intermediates in organic synthesis." Thesis, Cardiff University, 2012. http://orca.cf.ac.uk/45471/.

Full text

Abstract:

Chapter One: Chapter one describes a historical overview and the practical consideration of lithiation reactions and highlight of some of the factors that could influence the site of lithiation. It also provides reviews of the directed and side-chain lithiation of substituted aromatics. Chapter Two: Chapter two deals with lithiation of N′-phenethyl-N,N-dimethylurea with three equivalents of t-BuLi in THF at –78 °C followed by reaction with various electrophiles to give side-chain substituted products due to lithiation and substitution at the CH2 next to the phenyl ring (α-lithiation). The 2-lithio isomer can be obtained via Br–Li exchange of 2-bromo derivative using MeLi followed by t-BuLi in THF at –78 °C. The lithium reagents thus obtained react with various electrophiles to give the corresponding 2-substituted derivatives in excellent yields. Lithiation of N′-(3-phenylpropyl)-N,N-dimethylurea takes place on the α-CH2 with t-BuLi at 0 °C. On the other hand, lithiation of N′-(4-phenylbutyl)-N,N-dimethylurea with t-BuLi at 0 °C takes place on one of the methyl groups of the urea unit. Chapter Three: Chapter three includes lithiation of N'-(2-(2-methylphenyl)ethyl)-N,N-dimethylurea with three equivalents of n-BuLi in THF at 0 °C followed by reaction with various electrophiles to give side-chain products in excellent yields due to α-lithiation. Similarly, lithiation of the pivalamide derivative followed by reaction with benzophenone as a representative electrophile gave the corresponding α-substituted product in high yield. Surprisingly, no products resulting from lateral lithiation were observed under the conditions tried, which sharply contrast with the reported results for lateral lithiation of the carbamate derivative. Chapter Four: In this chapter, N-(2-(4-methoxyphenyl)ethyl)amine derivatives are reported to undergo directed ortho-lithiation next to the directing group with n-BuLi at 0 ºC, followed by treatment with various electrophiles, to give high yields of the corresponding substituted products. This contrasts sharply with the earlier results for the α-substitution of the pivaloyl derivative using t-BuLi at a lower temperature. Chapter Five: Chapter five includes variations in the site of lithiation of N-acyl-3-(aminomethyl)pyridine derivatives with different N-substituents using different lithiating reagents. Ring lithiation has been achieved by the use of t-BuLi at -78 °C followed by reaction with various electrophiles to give the corresponding 4-substituted products in high yields. On the other hand, the reaction was regioselective towards the side-chain when LDA was used as the lithium reagent at -20 to 0 °C. A mixture of ring and side-chain substitution products was obtained when n-BuLi was the lithium reagent. Chapter Six: Chapter six investigates the use of various chiral ligands containing different coordinating groups in Matteson homologation. Some stereoselectivity (de = 2-52%) was obtained depending on the type of chiral catalyst used. The best %de (52%) was obtained when Yb(OTf)3 as a Lewis acid and (1R,2R)-1,2-bis((R)-2,2-dimethyl-1,3-dioxolan-4-yl)ethane-1,2-diol as a chiral ligand were used in combination. However, significant %de (46%) could be obtained with the diol chiral ligand in the absence of the Lewis acid, which is very interesting and open windows for further improvement.

APA, Harvard, Vancouver, ISO, and other styles

28

Kuo, David Liang. "The use of camphor in sesquiterpenoid synthesis." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/28847.

Full text

Abstract:

This thesis, entitled "The use of camphor in sesquiter-penoid synthesis", consists of three chapters. Chapter One describes the conversion of (+)-8-bromocamphor (42) into a chiral dimethyl-acetal enolsilyl ether (105) that undergoes facile TiCl₄₋ promoted intramolecular cyclisation to provide tricyclic intermediates (195a,b), which after a series of functional group interconversions and the introduction of the gem-dimethyl group, leads to the first enantiospecific total synthesis of (+)-longiborneol (59) (ca. 13% in 21 steps from ( + )-camphor (26)). Oxidation of (+)-longiborneol (59) provides (+)-longicamphor (83), which was converted into (+)-longi-isoborneol (89) by reduction. Subsequent treatment with of (+)-longiisoborneol (89) with MsCl, 4-DMAP, and pyridine, reveals (+)-longifolene (61) (ca. 52% in 3 steps from (59)). Two other major attempts were also carried out prior to the successful synthesis of (59) and (61). Triene acetates (103a,b) were synthesised (ca. 8% in 10 steps from (+)-camphor (26)), but failed to undergo the intramolecular Diels-Alder reaction. In addition, (+)-campherenone (151) was also prepared (ca. 28% in 9 steps from (+)-camphor (26)), and both (151) and its derivatives (170), and (104) undergo SnCl₄-promoted intermolecular tertiary ∝-alkylation reaction to provide dimers (169a,b). Chapter Two describes two synthetic approaches to albene (221) which involves an intramolecular ene reaction, or an intramolecular free radical cyclisation reaction. A new enantiospecific synthesis route to (+)-β-santalene (259) (ca. 78% in 2 steps from (+)-campherenone (151)) is illustrated, however, (+)-β-santalene failed to undergo the intramolecular ene reaction to provide olefin (261). In addition, bromo-olefin (260) is also prepared (ca. 59% in 14 steps from (+)-camphor (26)), but cyclises in a 6-exo-trig mode in the intramolecular free radical cyclisation reaction to provide methyl ether (331). Chapter Three describes an evaluation of the potential use of (+)-5,6-dehydrocamphor (323) as a chiral synthon in the synthesis of the A,B ring system (cf. 329) of several classes of terpenoid. (+)-5,6-dehydrocamphor (323) was prepared from (-)-endo-3-bromocamphor (41) in two steps, and which is then converted to bicyclic enones (368a,b, 369a,b, 376a,b) by a sequence in which the key reaction was an anionic oxy-Cope rearrangement. Bicyclic enones (368a,b) were converted to tricyclic ketals (385a,b), but attempts to convert this compound to an angularly methylated intermediate (434) were unsuccessful. Furthermore, 1,5-dienols (409a,b), synthesised from (323) in ca. 50% yield, failed to undergo an anionic oxy-Cope rearrangement to provide bicyclic ketones (410a,b). Alternative ways of constructing an angular methyl group into the C(10) position in bicyclic enones (369a,b, or 376a,b) are currently being investigated in our laboratory. In addition, bicyclic ketones (373a,b) could serve as key intermediates in an enantiospecific synthesis of spirodysin (421), and indirectly to the synthesis of furodysin (422), and furodysinin (423). [Formula Omitted]
Science, Faculty of
Chemistry, Department of
Graduate

APA, Harvard, Vancouver, ISO, and other styles

29

Reynoso-Paz, Carolina Beatriz Mariuska. "Synthesis and evaluation of functionalized polymers for use in solid phase organic synthesis /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2002. http://uclibs.org/PID/11984.

Full text

Abstract:

Thesis (Ph. D.)--University of California, Davis, 2003.
Degree granted in Chemistry. Dissertation completed in 2002; degree granted in 2003. Also available via the World Wide Web. (Restricted to UC campuses).

APA, Harvard, Vancouver, ISO, and other styles

30

Youngblood, William Justin. "Synthesis of phthalocyanines for use in electronic materials." NCSU, 2005. http://www.lib.ncsu.edu/theses/available/etd-07082005-113852/.

Full text

Abstract:

This dissertation describes the synthesis of phthalocyanines having specialized structures that provide for electrochemical studies of their fundamental properties and/or for direct preparation of phthalocyanine-based electronic materials. Much of the synthetic effort herein is directed toward the development of a particular class of phthalocyanine, herein referred to as benzimidazoporphyrazines. Benzimidazoporphyrazines are desirable substitutes for typical phthalocyanines in applications requiring phthalocyanine-based materials. The value of benzimidazoporphyrazines is derived from their geometry, which provides four substitution positions at peripheral carbon atoms that lie along the N-N axes of the macrocycles. The modular construction of pigment arrays that include phthalocyanines may be greatly facilitated with the use of benzimidazoporphyrazines. The history of research in benzimidazoporphyrazines is brief, and has not heretofore provided access to benzimidazoporphyrazines bearing substituents that may serve as synthetic handles for modification of the pigments after their formation. This report details the development of synthetic methodology to prepare benzimidazoporphyrazines that bear useful synthetic handles. The synthesis of a set of such pigments is also described. Additionally, the new pigments (and one pigment array) are studied with regard to structural confirmation, as well as by photochemical and electrochemical means.

APA, Harvard, Vancouver, ISO, and other styles

31

Bentley, Paul Anthony. "The use of poly-leucine in stereoselective synthesis." Thesis, University of Liverpool, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366698.

Full text

APA, Harvard, Vancouver, ISO, and other styles

32

Williams, Mark. "Lanthanide alkoxide complexes for use in asymmetric synthesis." Thesis, University of Liverpool, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264785.

Full text

APA, Harvard, Vancouver, ISO, and other styles

33

Singleton, Jamie Andrew. "The use of chiro-inositols in asymmetric synthesis." Laramie, Wyo. : University of Wyoming, 2008. http://proquest.umi.com/pqdweb?did=1679676611&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.

Full text

APA, Harvard, Vancouver, ISO, and other styles

34

Ali, Khan Monika. "Use in synthesis of microbial arene oxidation products." Thesis, University of Bath, 2012. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.558904.

Full text

Abstract:

Abstract This thesis is concerned with microbially derived cis-3,5-cyclohexadiene-1,2- dihydroxy-1-carboxylic acid and its iron tricarbonyl derivatives as precursors for the efficient and practical synthesis of useful products. The opening chapter consists of a review of the biocatalytic cis-dihydroxylation process including its mechanism and applications in synthesis. In a Chapter 2 the utility of cyclohexadiene iron tricarbonyl complexes to date is outlined, with particular focus on their preparation and reactivity. Synthetic routes towards the synthesis of the natural products gabaculine and carbazole alkaloids are described, followed by the preparation of tarniflu and general methods of decomplexation. Chapter 3 presents the synthesis of novel iron tricarbonyl complexes and studies on their reactivity are disclosed. (Figure A.) Chapter 4 describes the formation of a new rearrangement product of the acetonide protected iron tricarbonyl complexes. In order to validate this process, independent studies with labelled compounds have been employed. Following Myers' procedure for microbial oxidation of p-deutero-benzoic acid, quantities of a novel deutero-diol product were successfully prepared and used to elucidate the mechanism of the rearrangement process. (Figure B) In Chapter 5 the formation of the f]5 cyclohexadienyl complexes is discussed followed by the outcome of the nucleophilic addition products. Chapter 7 provides detailed specific and general procedures for the synthesis of the compounds described within this thesis, along with their characterisation data. The appendices provide analytical support to this thesis and list of publications. Each chapter includes a separate discussion of the results and Chapter 6 provides an overall summary and suggestions for possible future work.

APA, Harvard, Vancouver, ISO, and other styles

35

Hutchinson, John Howard. "The use of camphor in natural product synthesis." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25830.

Full text

Abstract:

(+)-9,10-Dibromocamphor 3̲7̲, prepared in three steps from (+)-3-e̲n̲d̲o̲-bromocamphor 1̲5̲a̲, was found to undergo facile ring cleavage to provide the cyclopentanoid ring systems 1̲5̲8̲, 1̲5̲9̲ and 1̲6̲1̲. The bromoacid 1̲5̲9̲ was readily lactonised to provide 1̲6̲0̲ in high yield. The hydroxyacid 1̲6̲1̲ was converted into the hydrindenone 1̲9̲0̲ in three steps and a further six steps were required to complete the total enantiospecific synthesis of (-)-estrone e̲n̲t̲4̲1̲. Studies directed toward the synthesis of vitamin D₃ (2̲1̲3̲) and metabolites have shown that diastereoselective alkylation of lactone 1̲6̲0̲ and ester 2̲8̲3̲ (derived from 1̲6̲1̲) can be accomplished in high yield and with almost complete stereoselectivity. As a result, diol 3̲2̲2̲, representing the structural sub-unit of ring D and side chain of vitamin D₃, has been synthesised. Ring cleavage of the bromoketone 3̲5̲0̲ (derived from 1̲5̲9̲) gave 3̲5̲2̲ which was transformed into the aldehyde 3̲3̲2̲ and the trienols 3̲4̲0̲a̲ and 3̲4̲0̲b̲ to complete a formal synthesis of 3̲2̲7̲a̲, one of the components of the California Red Scale pheromone. Methylation of camphor 1̲0̲ yielded the 3-e̲x̲o̲-methyI derivative 3̲6̲2̲b̲ as the major product. The thermodynamically most stable epimer was found to be 3-e̲n̲d̲o̲-methylcamphor 3̲6̲2̲a̲. In contrast, 3-methylcamphor 3̲6̲2̲a.̲b̲ undergoes preferential endo alkylation. The factors governing these results are discussed. (+)-3- e̲n̲d̲o̲-Bromocamphor 1̲5̲a̲ and (+)-3- e̲n̲d̲o̲-9-dibromocamphor 1̲8̲a̲ were found to rearrange to provide (-)-6- e̲n̲d̲o̲-bromocamphor 1̲7̲2̲ and (-)-6- e̲n̲d̲o̲-9-dibromocamphor 2̲6̲. Dehalogenation of 1̲7̲2̲ provided optically pure (-)-camphor e̲n̲t̲1̲0̲ while dehydrohalogenation gave (+)-5,6-dehydrocamphor 1̲7̲3̲.[formula omitted]
Science, Faculty of
Chemistry, Department of
Graduate

APA, Harvard, Vancouver, ISO, and other styles

36

Jackson, Philip Stephen. "Design and synthesis of solid-supported reagents and their use in multi-step synthesis." Thesis, University of Cambridge, 2002. https://www.repository.cam.ac.uk/handle/1810/251819.

Full text

Abstract:

Solid-supported reagents are being developed as a complementary technique to solid-phase organic synthesis. They offer the advantages of conducting clean chemistry with rapid purification of products and ease of reaction monitoring. This thesis describes the development of a solid-support bisdihydropyran and its use in the resolution of diols and the use of solid-supported reagents in the multi-step synthesis of epothilone B. Also covered is work towards tagged chiral induction reagents for solution-phase reactions with solid phase scavenger purification.

APA, Harvard, Vancouver, ISO, and other styles

37

Nilsson, Camilla. "Dendrimers : Synthesis, Characterization and Use in Thiol-Ene Networks." Doctoral thesis, KTH, Fiber- och polymerteknik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9763.

Full text

Abstract:

Dendrimers are perfectly branched, well-defined macromolecules with a layered structure and a large amount of peripheral end groups. The high functionality in combination with the possibility of dendrimers to adopt a globular shape at high molecular weights, gives them very unique properties.In this work dendrimers up to fifth generation based on 2,2-bis(methylol)propionic acid (bis-MPA) were synthesized with different core structures. The core moieties were chosen in aspects of functionality and flexibility and the impact of the core on the physical and rheological properties was studied. By using the divergent growth approach dendrimers with acetonide, hydroxyl, allyl ether and methacrylate end groups were obtained.The bulk properties of the acetonide- and hydroxyl- terminated dendrimers were investigated with a rheometer. Temperature sweep tests were performed on the acetonide protected dendrimers in a temperature range of -50 up to 120°C at a constant frequency of 1 Hz. It was observed that the glass transition temperature (Tg) increased with increasing generation and that the modulus dropped without a trace of rubbery plateau for lower generations. This lack of rubbery plateau is due to the absence of entanglements between dendrimers. Interestingly, a small rubbery plateau was visible for generation five which implies enhanced interactions between the dendrimers. This behaviour suggests to be strongly influenced by the structural collapse at higher generations. Further, frequency sweep tests were performed on hydroxyl functional dendrimers at different temperatures. The results revealed Newtonian properties for lower generations and shear-thinning behaviour for higher generations at high frequency.Furthermore, this research involves the creation of well-defined thiol-ene networks by incorporation of allyl ether or methacrylate functional dendrimers in thermosets. This was accomplished by using two trithiols of different molecular weights and react them with the enes under UV irradiation. The thiol-methacrylate crosslinking reaction resulted in inhomogeneous films with and residual unsaturations. The thiol-ene films based on allyl ether dendrimers, on the contrary, resulted in homogeneous films with intermolecular couplings between the ene and the thiol being the dominant mode of polymerization.
Dendrimerer är perfekt grenade, väldefinierade molekyler med en struktur indelad i lager och med ett stort antal ändgrupper. Dendrimerer har, på grund av sina många funktionella grupper och sin förmåga att vid höga molekylvikter anta en mer sfärisk struktur, väldigt speciella egenskaper. Dendrimerer upp till femte generation, baserade på 2,2-dimetylolpropan syra (bis-MPA), har syntetiserats med olika typer av kärnstrukturer. Kärnorna valdes med avseende på funktionalitet och flexibilitet, och strukturens påverkan på dendrimerernas fysikaliska och reologiska egenskaper undersöktes. Dendrimerer med acetonid-, hydroxyl-, allyleter- samt metakrylatändgrupper syntetiserades genom att använda en divergent syntesmetod. De hydroxyl- och acetonidfunktionella dendrimerernas reologiska egenskaper i bulk karakteriserades med en reometer. De acetonidskyddade dendrimererna karakteriserades med temperatursvep i ett intervall mellan -50 °C och 120°C och med en konstant frekvens på 1 Hz. Analyserna visade att glastransitionstemperaturen (Tg) ökade med ökande generation och att dendrimerer av lägre generation inte uppvisade någon gummiplatå. Anledningen till detta är att det inte förekommer några kedjeintrasslingar mellan dendrimerer. Dock uppvisar femte generationens dendrimerer liten gummiplatå vilket pekar på ökade interaktioner mellan dem. Detta beteende påverkas av att dendrimerna kollapsar vid höga generationer och att förändringen i strukturen tydligt påverkar interaktionerna. Hydroxylfunktionella dendrimererna karaktäriserades med frekvessvep vid olika temperaturer. Det visade sig att lägre generationer uppvisar Newtonskt beteende medan högre generationer visar sig vara skjuvförtunnande vid höga frekvenser. Som en ytterligare del i detta projekt skapades väldefinierade tiol-en nätverk genom att reagera allyleter och metakrylat-funktionella dendrimerer med två trifunktionella tioler av olika molekylvikt. Reaktionerna initierades med UV-ljus. Tiol-metakrylat filmerna visade på en hög andel homopolymerisation vilket resulterade i inhomogent tvärbundna nätverk med ett stort antal oreagerade grupper. Tiol-allyleter filmerna visade uppvisade däremot homogena nätverk med en liten andel homopolymerisation.
QC 20100831

APA, Harvard, Vancouver, ISO, and other styles

38

Blomberg, Lennart. "Synthesis, coupling and use of oligosaccharides in affinity chromatography." Lund : Organic Chemistry 2, Lund Institute of Technology, Lund University, 1994. http://books.google.com/books?id=-A1rAAAAMAAJ.

Full text

APA, Harvard, Vancouver, ISO, and other styles

39

Chayajarus, Kampanart. "The use of thioglycosides and thionolactones in glycoside synthesis." Thesis, University of Oxford, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.432556.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Moragas, Solà Antoni. "Synthesis and use of highly substituted aziridine 2-carboxylates." Thesis, University of Nottingham, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.594593.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Miller, Neil Derek. "The use of chiral amine oxides in organic synthesis." Thesis, University of Liverpool, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240314.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Ward, Guy Oliver Fairfax. "The use of catalysts and biocatalysts in asymmetric synthesis." Thesis, University of Exeter, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245929.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

Medeiros, Edna Faria de. "The use of pyrylium salts in natural product synthesis." Thesis, University of Essex, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334742.

Full text

APA, Harvard, Vancouver, ISO, and other styles

44

Wright, J. L. "The use of organoselenium-mediated cyclisations in organic synthesis." Thesis, Imperial College London, 1985. http://hdl.handle.net/10044/1/37904.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

Spooner, Julie Elizabeth. "Studies towards the use of sulfones in combinatorial synthesis." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624762.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

Neal, Andrew. "Use of the Claisen rearrangement in natural product synthesis." Thesis, University of St Andrews, 2018. http://hdl.handle.net/10023/16129.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

Voaden, Mark Jonathan. "The use of silicon substituted dienes in organic synthesis." Thesis, University of Manchester, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.702947.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

Durand, Adeline. "Synthesis of oligonucleotide analogues for use in DNA nanostructures." Thesis, University of Southampton, 2010. https://eprints.soton.ac.uk/173975/.

Full text

Abstract:

Thanks to its ability to form duplexes through selective base-pair recognition, DNA is a unique material for orderly self-assembled construction at the nanoscale. To develop a nanotechnology platform on a grid of addressable molecular building blocks using DNA node structures, DNA complexes need to be fixed onto surfaces. To fulfil this requirement on lipid membranes, phosphoramidites monomers modified with a cholesterol moiety and a spacer unit were synthesised. The hydrophobic spacer provides separation between the hydrophobic cholesterol moiety and the phosphate backbone of the DNA strand. For better anchorage of the network to a lipid surface, a hydrophilic spacer was also used to link the cholesterol to the nucleoside. Solution studies demonstrated that the melting temperature (Tm) of the duplex with adjacent cholesterols on each strand is much higher than that of the unmodified duplex. The reliable and highly selective copper(I)-catalysed azide-alkyne 1,3-dipolar cycloadition (CuAAC), the best known example of click chemistry, has proven to be of remarkably broad utility in synthetic chemistry and in nucleic acid chemistry in particular. CuAAC was exploited for the synthesis of a very stable double stranded catenane duplex. The catenane was formed from a single stranded cyclic template and its linear complement, using a third short oligonucleotide (ODN) as a helper for the circularisation of the second ODN. The copper(I)-catalysed cyclisation of oligonucleotides occurred by reaction between their terminal azide and their opposite terminal alkyne, to produce a 1,2,3-triazole linkage between the two reactants. The catenane was characterised by denaturing polyacrylamide gel electrophoresis, UV melting studies and enzyme digestion.

APA, Harvard, Vancouver, ISO, and other styles

49

Samsodien, Mogammad Luqmaan. "Nanoparticles for use in imaging, catalysis and phthalocyanine synthesis." University of the Western Cape, 2018. http://hdl.handle.net/11394/6446.

Full text

Abstract:

Magister Scientiae - MSc (Chemistry)
Nanoscience and nanotechnology are known to be interdisciplinary, crossing and combining various fields and disciplines in pursuit of desirable outcomes. This has brought about applications of nanoscience and nanotechnology in multitudes of industries, spanning from the health, pharmaceutical to industrial industry. Within the health industry, the medical field has seen much advancement through nanoscience and nanotechnology. The importance of finding cures to diseases is top priorities within the medical field, along with advancements in understanding and diagnosing diseases. Due to these outcomes, we see the emergence of imaging techniques playing a crucial role. The work covered in this thesis looks at a prospective luminescent agent applicable in the medical field for bio-imaging, but also at a possible phthalocyanine sensitizer for treatment of cancer through photodynamic therapy. Another area where nanoscience and nanotechnology are found is in industry, where nanoparticles are utilised as catalysts in many synthetic reactions. Highly desirable catalysts in industry are those involved in oxidative reactions where we explore a metal nanoparticle catalyst within this work.

APA, Harvard, Vancouver, ISO, and other styles

50

Donaghey, Jenny E. "Synthesis of semiconducting polymers for use in organic electronics." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/9827.

Full text

Abstract:

A series of novel semiconducting co-polymers based on known, fused aromatic monomers (dibenzosilole, dithienosilole and dithienopyrrole) were synthesized for use in organic field effect transistor (OFET) devices. The fused monomers were copolymerized with triarylamine and thienothiophene units to give a series of six donor polymers. Their electronic energy levels were probed by UV-Vis and photoelectron spectroscopy, and predictions regarding their performance were drawn from this information. Two polymers were tested in OFETs and conclusions were made concerning the relationship between structure and performance. Four donor-acceptor type polymers were synthesized using dithienopyrrole as the electron rich unit. This monomer was copolymerized with benzothiadiazole, difluorobenzothiadiazole, thienopyrrolodione and 1,1’-bithienopyrrolodione. These low band gap polymers were tested as the donor polymer in polymer:fullerene BHJ devices. A novel monomer with long branched alkyl substituents, based on the extended fused-ring system indacenodithiophene (IDT), was synthesized. The nitrogen analogue of this monomer (NIDT) was of interest as its performance could be compared to the carbon and silicon versions of IDT. A route to NIDT was devised and then it was polymerized with four electron poor monomers. The energy levels were estimated by UV-Vis and photoelectron spectroscopy, followed by testing of the materials in OFET and OPV devices. Those with the lowest lying HOMO levels performed best in OPVs. Another series of NIDT containing polymers were synthesized, designed specifically for use in OFET devices. The aim was to produce polymers with highly planar backbones which would form ordered domains and enhance hole transport. An NIDT monomer was synthesized with linear hexadecyl substituents in order to improve π-stacking. The linear NIDT monomer was then copolymerized with thiophene, thienothiophene, thienopyrrolodione and diketopyrrolopyrrole. It was found that the diketopyrrolopyrrole containing polymer, performed best in OFETs and the molecular weight played a large role in how a polymer performed.

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Carbenoid use in synthesis'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles