Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 30 of 68
Full-Text Articles in Entire DC Network
1,4-Biradicals In Intermolecular Photocycloaddition Reactions Of Cyclic Enones With Alkenes, And, 1,4-Biradicals In Intramolecular Photocycloaddition Reactions Of Cyclic Enones With Alkenes, David Jack Maradyn
Digitized Theses
The irradiation of cyclic enones with ultraviolet light in the presence of alkenes results in the formation of cyclobutane adducts possessing head-to-head and/or head-to-tail regiochemistry. The long-accepted Corey-de Mayo mechanism predicts that the regiochemistry of the cyclobutane adducts is controlled by the relative orientation of the enone and alkene in an exciplex intermediate. Weedon and co-workers have demonstrated that partitioning of 1,4-biradical intermediates between starting material and cyclobutane products controls the product regiochemistry in the intermolecular photocycloaddition reactions of 2-cyclopentenones with alkenes.;These earlier results have been extended. The 1,4-biradical intermediates formed in the photocycloaddition reactions of 2-cyclohexenone with alkenes, in …
Aspects Of Reactions Of Sulfonyl Compounds With Nucleophiles, Manjinder Singh Gill
Aspects Of Reactions Of Sulfonyl Compounds With Nucleophiles, Manjinder Singh Gill
Digitized Theses
This thesis describes four topics in organic sulfur chemistry involving reactions of sulfonyl compounds with nucleophiles. In the first chapter the reactions of aromatic sulfonyl chlorides with amines in aqueous media were studied. The observed pH-yield profiles pointed strongly to the involvement at high pH of third-order processes leading to the sulfonamides. A new term {dollar}(k\sb{lcub}\rm NOH{rcub}){dollar} was introduced in the rate expression (eq 9) and the calculated pH-yield profiles from eq 10 gave a good agreement with experimental data. The increased value of rate constants with alkyl chain size of the amine, suggested aggregation of reactants due to hydrophobic …
Part I 2+2 Photocycloaddition Reactions Of N-Acylindoles With Alkenes Part Ii Photochemical Reactions In Supercritical Carbon Dioxide, Islet Brian Des
Part I 2+2 Photocycloaddition Reactions Of N-Acylindoles With Alkenes Part Ii Photochemical Reactions In Supercritical Carbon Dioxide, Islet Brian Des
Digitized Theses
Part I. Irradiation of 2-methyl, 3-methyl and 2,3-dimethyl substituted N-acylindoles in the presence of alkenes results in the formation of {dollar}\lbrack{dollar}2+2{dollar}\rbrack{dollar} cycloadducts which contain cyclobutane rings. The regiochemistry of the major product in all cases examined was found to be the result of initial bond formation from the 2-position of the N-acylindole to the less substituted terminus of the alkene. The quantum yield of cycloadduct formation was determined for the photocycloaddition reaction of the N-benzoyl derivatives with methyl acrylate and for the N-carboethoxy derivatives with 2-methylpropene. The reaction efficiency was found to be dependent on two factors. The first of …
Marcus Theory Applied To Acetal Cleavage And Aldol Reactions, Jonathan Arthur Barker
Marcus Theory Applied To Acetal Cleavage And Aldol Reactions, Jonathan Arthur Barker
Digitized Theses
The acid catalyzed and uncatalyzed hydrolysis of the acetal 2,2-dimethoxypropane (DMOP) and the ortho ester trimethylorthoacetate (TMOA) have been studied in aqueous solution at 25{dollar}\sp\circ{dollar}C. Theoretical and experimental evidence have been found for a base catalyzed E2 mechanism of DMOP hydrolysis proceeding through an enol ether. This mechanism is neither predicted nor observed for TMOA hydrolysis. The specific acid catalyzed and uncatalyzed rate constants for hydrolysis are for DMOP k{dollar}\rm\sb{lcub}H+{rcub}=(2.5\pm0.3)\times10\sp3\ M\sp{lcub}-1{rcub}s\sp{lcub}-1{rcub},\ k\sb w=(3.6\pm0.2)\times10\sp{lcub}-8{rcub}\ s\sp{lcub}-1{rcub},\ k\sb{lcub}OH-,E2{rcub}=(2.8\pm0.4)\times10\sp{lcub}-8{rcub}\ M\sp{lcub}-1{rcub}s\sp{lcub}-1{rcub},\ and\ for\ TMOA\ k\sb{lcub}H+{rcub}=(2.05\pm0.12)\times10\sp4\ M\sp{lcub}-1{rcub}s\sp{lcub}-1{rcub},\ k\sb w=(3.7\pm0.3)\times10\sp{lcub}-6{rcub}\ s\sp{lcub}-1{rcub}.{dollar} General acid catalysis was observed for TMOA with four general acids. From the Bronsted plot, {dollar}\alpha=0.76\pm0.05.{dollar} …
Intramolecular Aldol Condensation Reactions And Transacetalization Equilibria, Junan Guo
Intramolecular Aldol Condensation Reactions And Transacetalization Equilibria, Junan Guo
Digitized Theses
Part I. Intramolecular aldol condensation reactions. The detailed kinetics and equilibrium for the intramolecular aldol condensation reaction of 2,5-hexanedione, 2, 6-heptanedione, 1-phenyl-1, 5-hexanedione and 5-oxohexanal were studied and correlated in terms of Marcus theory. All the reactions, with the readily explained exception of the intramolecular aldol addition of 5-oxohexanal, gave us approximately constant intrinsic barriers: 14.49 {dollar}\pm{dollar} 0.82 kcal/mol for the intramolecular aldol addition step and 13.99 {dollar}\pm{dollar} 0.74 kcal/mol for the subsequent dehydration step, which are also in excellent agreement with the intrinsic barriers found for intermolecular aldol condensation reactions.{dollar}\sp{lcub}16{rcub}{dollar} This means that Marcus theory is applicable to intramolecular …
Part I 2+2 Photocycloaddition Reactions Of Cyclic Enones With Alkenes Part Ii Photochemical Reactions In Supercritical Fluids, David Andrew
Part I 2+2 Photocycloaddition Reactions Of Cyclic Enones With Alkenes Part Ii Photochemical Reactions In Supercritical Fluids, David Andrew
Digitized Theses
Part I. The irradiation of 2-cyclopentenone with ultraviolet light in the presence of alkenes results in the formation of 2+2 cycloadducts which contain cyclobutane rings. According to the Corey-de Mayo mechanism, the regiochemistry of the cyclobutane products is controlled by the relative orientation of the alkene and the cyclic enone in an exciplex intermediate which precedes the formation 1,4-biradicals along the reaction pathway.;The biradicals formed in the photocycloaddition reactions of 2-cyclopentenone, 2-methyl-2-cyclopentenone and 3-methyl-2-cyclopentenone with various alkenes were trapped as stable compounds by H{dollar}\sb2{dollar}Se. By determining the structures and relative yields of the trapped products, the structures and relative rates …
Oxidative Addition As A New Route To Organometallic Polymers And Dendrimers, Sudhir Achar
Oxidative Addition As A New Route To Organometallic Polymers And Dendrimers, Sudhir Achar
Digitized Theses
This thesis describes new routes to organometallic polymers and dendrimers employing an oxidative addition method. The new complexes {dollar}\lbrack\rm PtMe\sb2(NN)\rbrack{dollar} 1, (1b: (NN) = 4,4{dollar}\sp\prime{dollar}-di-tert-butyl-2,2{dollar}\sp\prime{dollar}-bipyridine; 1c: (NN) = 4,4{dollar}\sp\prime{dollar}-dimethyl-2,2{dollar}\sp\prime{dollar}-bipyridine; 1d: (NN) = 4-vinyl-4{dollar}\sp\prime{dollar}-methyl-2,2{dollar}\sp\prime{dollar}-bipyridine) were shown to be useful precursors to polymers. {dollar}\{lcub}{dollar}Note 1a: (NN)= 2,2{dollar}\sp\prime{dollar}-bipyridine{dollar}\{rcub}{dollar}.;The oxidative addition of organic halides (R-X) to 1 gave {dollar}\lbrack\rm PtXMe\sb2R(NN)\rbrack{dollar} {dollar}\rm\{lcub} (NN)\sb{lcub}1a{rcub}{dollar}: R-X = methyl 2-(bromomethyl)acrylate; 2-(bromomethyl)acrylic acid; 2-bromoethyl methacrylate; methyl bromoacetate; ethyl bromoacetate; bromoacetic acid; bromoacetonitrile and bromoacetamide. {dollar}\rm (NN)\sb{lcub}1b{rcub}{dollar}: (R-X) = 2-bromoethyl methacrylate and vinyl bromoacetate. {dollar}\rm (NN)\sb{lcub}1d{rcub}{dollar}: vinyl bromoacetate; 2-bromoethyl methacrylate; acryloyl chloride and vinylbenzyl chloride{dollar}\{rcub}{dollar}.;The free radical polymerization of the …
Beta-Enolization In Bicyclic Ketones, David James Muir
Beta-Enolization In Bicyclic Ketones, David James Muir
Digitized Theses
A variety of bicyclic ketones was prepared and under strongly basic conditions (t-BuOK/t-BuOH/185{dollar}\sp\circ{dollar}C) their behaviour with respect to {dollar}\beta{dollar}-enolization was examined. Several new compounds were produced upon such treatment; these were identified on the basis of their {dollar}\rm\sp{lcub}13{rcub}Cmr{dollar} and {dollar}\rm\sp1Hmr{dollar} spectra.;3,3-Dimethylbicyclo (3.2.2) nonan-2-one slowly rearranged to 3,3-dimethylbicyclo (3.3.1) nonan-2-one, and the latter was stable. Similarly, 3,3-dimethylbicyclo (3.2.2) non-6-en-2-one rearranged to 3,3-dimethylbicyclo (3.3.1) non-6-en-2-one, which was not stable. Experiments with 3,3-dimethylbicyclo (3.3.1) non-6-en-2-one revealed that it was converted into five compounds. The major product, 2,2-dimethyl-4,5,6,7-tetra-hydrindan-1-one, arose from a {dollar}\beta{dollar}-enolate rearrangement. However, this enone underwent slow reduction to cis- and trans-8,8-dimethylbicyclo (4.3.0) …
Rate And Equilibrium Constants Of Useful Reactions, Jinqiao Lu
Rate And Equilibrium Constants Of Useful Reactions, Jinqiao Lu
Digitized Theses
Part I. The halogenation of propiophenone has been reported to give rise to benzoic acid and acetic acid. It was discovered that under some conditions, the major product of the chlorination of propiophenone is 2-phenylglyceric acid, and that this appears to be a general reaction. 1-Phenyl-1,2-propanedione and 3-chloro-1-phenyl-1,2-propanedione have been proven to be the key intermediates on the chlorination path leading to 2-phenylglyceric acid. The migratory aptitudes of substituted methides ({dollar}\sp-{dollar}CH{dollar}\sb2{dollar}X) are also reported.;Part II. For the classical Michael reaction, the forward addition rate is second order overall, first order in the concentration of methyl cinnamate and first order in …
Tetramesitylgermasilene: Synthesis And Reactivity Of A Germanium-Silicon Double Bond, Jeffrey A. Cooke
Tetramesitylgermasilene: Synthesis And Reactivity Of A Germanium-Silicon Double Bond, Jeffrey A. Cooke
Digitized Theses
This thesis describes the synthesis of tetramesitylgermasilene (Mesityl=2,4,6-trimethylphenyl), the first example of a compound containing a germanium-silicon double bond, from hexamesitylsiladigermirane, the first compound containing a three-membered ring composed of two germanium atoms and one silicon atom. The synthesis can be effected both thermochemically and photochemically; however, the germasilene can only be characterized in solution at {dollar}{lcub}-78{rcub}\sp\circ{dollar}C.;In addition, a remarkable 1,2-mesityl rearrangement of the germasilene to form a silylgermylene is reported, with discussion describing a similar rearrangement found in tetramesityldigermene, a compound containing a germanium-germanium double bond. Finally, the thesis details initial investigations into the reactivity of the germasilene with …
Evidence For A Continuum Model Of Diffusion In Lipid Bilayer Membranes: Synthesis And Studies Of Macrocyclic Polyamides In Monolayer And Lipid Bilayer Systems, Patricia Alison Paprica
Evidence For A Continuum Model Of Diffusion In Lipid Bilayer Membranes: Synthesis And Studies Of Macrocyclic Polyamides In Monolayer And Lipid Bilayer Systems, Patricia Alison Paprica
Digitized Theses
This research project is directed towards establishing the relationship between the surface areas of intermediately sized molecules (50-300A{dollar}\sp2{dollar}) and their lateral diffusion coefficients in lipid bilayer membranes. Synthetic methods were developed to allow for the preparation of two series of macrocyclic polyamide amphiphiles, with and without fluorescent nitrobenzoxadiazole (NBD) labels, using macrocyclic polyamine aza-crown ethers as starting materials.;The geometry of the macrocyclic polyamides were determined using variable temperature NMR, which has indicated that both the C(O)-N bond and NBD-N bond in the smallest, labelled macrocyclic polyamide exhibit partial double bond character. As a consequence of this restricted bond rotation, both …
Mechanistic And Synthetic Investigations In Sulfonyl Chemistry And Acyl Transfer, Zhen Rong Guo
Mechanistic And Synthetic Investigations In Sulfonyl Chemistry And Acyl Transfer, Zhen Rong Guo
Digitized Theses
This thesis contains three chapters dealing with the organic chemistry of sulfonyl and carbonyl compounds. The first chapter describes the synthesis and rate studies of a series of {dollar}\beta{dollar}-methoxy sulfones and their unsubstituted parent compounds designed to test some basic ideas of the nature of the electronic effects of substituents in saturated systems. The substrates were designed to illustrate the effect of the change of the H{dollar}\sb\alpha{dollar}-C{dollar}\sb\alpha{dollar}-C{dollar}\sb\beta{dollar}-O dihedral angle on the rate of base-promoted H-D exchange reaction. The presence of a {dollar}\beta{dollar}-methoxy group affected the H-D exchange rates by factors varying from a few hundred to greater than ten thousands. …
Ph Optimization Of Nucleophilic Reactions And Mechanisms Of Reactions Of Sulfonyl Chlorides, Joe Ying Lam
Ph Optimization Of Nucleophilic Reactions And Mechanisms Of Reactions Of Sulfonyl Chlorides, Joe Ying Lam
Digitized Theses
This thesis consists of four chapters all involving the chemistry of sulfonyl chlorides in water.;Chapter 1 describes the mechanisms of the reactions of alkanesulfonyl chlorides with water with and without added nucleophiles. Evidence is provided that the hydrolysis of alkanesulfonyl chlorides proceeds (a) at low pH, by S{dollar}\sb{lcub}\rm N{rcub}{dollar}2-S attack of water, (b) at intermediate pH, by rate determining attack of hydroxide anion to form sulfene which is then trapped by water, and (c) at high pH, by way of sulfene both formed and trapped by hydroxide anion. Among the following pathways observed in the reaction of alkanesulfonyl chlorides with …
Radiotracers For The Angiotensin System, Vincenzo Quiquero
Radiotracers For The Angiotensin System, Vincenzo Quiquero
Digitized Theses
Angiotensin converting enzyme (ACE), a dipeptidyl carboxypeptidase, is one of the enzyme components of the renin-angiotensin-aldosterone system. ACE is responsible for the production of angiotensin II, a potent vasoconstrictor, and for the inactivation of the potent vasodepressor peptide bradykinin. The enzyme is a vascular endothelial component of many tissues (i.e. lungs, kidney, preoptic region of brain) and has been shown to be localized on the lumenal surface of the vascular endothelium. Diseases involving granuloma (i.e. sarcoidosis, silicosis, asbestosis) are known to change the distribution of ACE and to cause hypertension. A radiolabelled pharmaceutical which binds with ACE could permit the …
Synthetic Applications Of The Photochemical Cycloaddition Reactions Of N-Acylindoles And Conformational Studies Of The Cycloadducts, Boke Zhang
Digitized Theses
The ability of a series of nitrogen-substituents to activate the cycloaddition photochemistry of indoles has been examined; the N-substituents were chosen in order to enable their removal following cycloaddition under mild neutral, acidic or basic conditions. N-substituted indoles, 17, 12 and 104c-g, were prepared in which the N-substituent is COPh, CO{dollar}\sb2{dollar}Et, CO{dollar}\sb2{dollar}CH{dollar}\sb2{dollar}CH{dollar}\sb2{dollar}SiMe{dollar}\sb3{dollar}, CO{dollar}\sb2{dollar}CH{dollar}\sb2{dollar}CH{dollar}\sb2{dollar}CN, CO{dollar}\sb2{dollar}Bu{dollar}\sp{lcub}\rm t{rcub}{dollar}, CO{dollar}\sb2{dollar}Ph, and CO{dollar}\sb2{dollar}CH{dollar}\sb2{dollar}Ph, respectively.;The silylethoxycarbonyl group of photoadducts derived from 104c can be removed by treatment of the adduct with fluoride ion in dichloromethane, the tert-butyloxycarbonyl group of adducts derived from 104e by treatment with trifluoroacetic acid at room temperature; the benzyloxycarbonyl group of adducts …
Nucleophilic Reactions Of Sulfonyl And Carbonyl Compounds, Darryl Frederick Klassen
Nucleophilic Reactions Of Sulfonyl And Carbonyl Compounds, Darryl Frederick Klassen
Digitized Theses
This thesis contains topics in organic sulfur chemistry and general physical organic chemistry. In the first chapter a pH rate profile (log {dollar}k\sb{lcub}\rm obs{rcub}{dollar} vs pH) was determined for the hydrolysis of ethylene sulfone (1) over the pH range from 4 to 11.5 at 75{dollar}\sp\circ{dollar}C. The rate constant {dollar}k\sb{lcub}\rm obs{rcub}{dollar} was found to be of the form {dollar}k\sb{lcub}\rm obs{rcub}{dollar} = {dollar}k\sb{lcub}\rm w{rcub}{dollar} + {dollar}k\sb{lcub}\rm OH{rcub}{dollar} (OH{dollar}\sp-{dollar}) where {dollar}k\sb{lcub}\rm w{rcub}{dollar} = (8.71 {dollar}\pm{dollar} 1.38) {dollar}\times{dollar} 10{dollar}\sp{lcub}-5{rcub}{dollar} s{dollar}\sp{lcub}-1{rcub}{dollar} and {dollar}k\sb{lcub}\rm OH{rcub}{dollar} = (2.98 {dollar}\pm{dollar} 0.89) {dollar}\times{dollar} 10{dollar}\sp{lcub}-2{rcub}{dollar} M{dollar}\sp{lcub}-1{rcub}{dollar}s{dollar}\sp{lcub}-1{rcub}{dollar}. In the pH region that corresponds to the uncatalyed hydrolysis ({dollar}k\sb{lcub}\rm w{rcub}{dollar}, pH 4 …
In Search Of An Alternative Route To Germasilenes: The Synthesis And Chemistry Of (Halosilyl)Germanes, Umesh Ramji Parshotam
In Search Of An Alternative Route To Germasilenes: The Synthesis And Chemistry Of (Halosilyl)Germanes, Umesh Ramji Parshotam
Digitized Theses
This thesis describes attempts to prepare a germasilene, a compound containing a germanium-silicon double bond, by either a {dollar}\beta{dollar}-elimination reaction or a reductive elimination reaction.;The precursor, Mes{dollar}\sb2{dollar}HGeSiClMes{dollar}\sb2{dollar}, 1, (Mes = 2,4,6-trimethylphenyl) was prepared by the addition of Mes{dollar}\sb2{dollar}HGeLi to Mes{dollar}\sb2{dollar}SiCl{dollar}\sb2{dollar} in THF in excellent yield. We examined the effect of changing the nature of the solvent, leaving group, base and ligands on the reaction between 1 and base.;Mes{dollar}\sb2{dollar}ClGeSiClMes{dollar}\sb2,{dollar} 29, and Mes{dollar}\sb2{dollar}BrGeSiClMes{dollar}\sb2{dollar}, 30, prepared by the chlorination and bromination of 1 respectively, were treated with lithium naphthalenide (LiNp) in an attempt to prepare Mes{dollar}\sb2{dollar}Ge = SiMes{dollar}\sb2{dollar} by a reductive elimination reaction. …
Part I Photochemical Deconjugation Reactions Of 3-Alkyl-2-Cyclohexenones Part Ii Biradicals In 2+2 Photocycloaddition Reactions Of 2-Cyclopentenone, Andreas Rudolph
Part I Photochemical Deconjugation Reactions Of 3-Alkyl-2-Cyclohexenones Part Ii Biradicals In 2+2 Photocycloaddition Reactions Of 2-Cyclopentenone, Andreas Rudolph
Digitized Theses
Part I. Ultraviolet irradiation of 3-methyl-2-cyclohexenones leads to the formation of the deconjugated exocyclic isomers in low quantum yields. The reaction proceeds via the triplet excited state of the enone but the mechanism has not been determined satisfactorily. Part I of this thesis describes evidence for acid catalysis of the reaction. The presence of small quantities of carboxylic acid greatly enhances the quantum yield of the deconjugation reaction. The proposal of the intermediacy of a carbocation was supported by the detection of products derived from addition to the conjugate base of the acid to the carbocation. In addition, the presence …
Oxidative Addition Reactions Of Dimethylplatinum(Ii) Complexes, Khin Than Aye
Oxidative Addition Reactions Of Dimethylplatinum(Ii) Complexes, Khin Than Aye
Digitized Theses
This work deals with synthesis, characterization and reaction mechanisms in studies of the oxidative addition of organic compounds to dimethyl(1,10-phenanthroline)-platinum(II), (PtMe{dollar}\sb2{dollar}(NN)). The organic compounds studied include lactones, epoxides, alkylpalladium(IV) complexes, alkyl halides including a coumarin derivative, and diphenyl diselenide and diphenyl disulphide. A particularly detailed study has been made of the oxidative addition of the C-O bonds of a {dollar}\beta{dollar}-lactone and of epoxides.;The oxidative addition of propiolactone to the platinum(II) complex to give a platina(IV)lactone, (PtMe{dollar}\sb2\{lcub}{dollar}CH{dollar}\sb2{dollar}CH{dollar}\sb2{dollar}C(O)O{dollar}\{rcub}{dollar} (NN)), (NN = 2,2{dollar}\sp\prime{dollar}-bipyridine or 1,10-phenanthroline) is reported. The structure is determined by both NMR and X-ray crystallography. The oxidative addition of propiolactone to …
Bioreductive Alkylating Agents As Probes For Tissue Hypoxia, Paul A. Culbert
Bioreductive Alkylating Agents As Probes For Tissue Hypoxia, Paul A. Culbert
Digitized Theses
The research discussed in the following thesis falls under the general categories of organic chemistry and radiochemistry and the application of these disciplines to the development of imaging agents and labelling techniques for the branch of Nuclear Medicine involving single photon emitting radionuclides. The thesis is made up of three sections; one dealing with the synthesis, labelling and biological testing of a series of radioiodinated 2-nitrobenzyl alcohol derivatives as potential probes for tissue hypoxia; a second chapter dealing with the synthesis, labelling and biological testing of 1-(4- ({dollar}\sp{lcub}123{rcub}{dollar}I) -iodophenyl-2,6,7-trioxabicyclo- (2.2.2) octane as a potential imaging agent for the GABA{dollar}\sb{lcub}\rm A{rcub}{dollar} …
Studies In Organic Synthesis: I Demethylation Of Methyl Enol Ethers And Methyl Aryl Ethers Ii Toward Sexiphenylene Iii Toward A New Method For Vinylcyclopropanation, Jeffrey Robert Walker
Studies In Organic Synthesis: I Demethylation Of Methyl Enol Ethers And Methyl Aryl Ethers Ii Toward Sexiphenylene Iii Toward A New Method For Vinylcyclopropanation, Jeffrey Robert Walker
Digitized Theses
Cycloseychellene, a tetracyclic sesquiterpene, has been a synthetic target of our group for some time and earlier work had ended with the preparation of a methyl enol ether intermediate. A possible pathway for the completion of this total synthesis had, as its key step, an intramolecular Prins (ene) reaction. Studies were conducted in order to examine possible methods for the formation of the enolate which this approach required. The possible use of a silyl enol ether, as the enolate precursor, was examined in a model study, but the preparation of the enol ether was not successful. In addition, model studies …
Intermolecular And Intramolecular Photocycloaddition Reactions Of Cyclopentenone And N-Acylindoles, David L. Oldroyd
Intermolecular And Intramolecular Photocycloaddition Reactions Of Cyclopentenone And N-Acylindoles, David L. Oldroyd
Digitized Theses
Aspects of the photochemistry of N-acylindoles in which the indole nitrogen is part of an amide or urethane group have been studied. It has been found that the chemical fate of the N-acylindole excited state can be controlled by appropriate choice of wavelength, solvent, concentration, excited state multiplicity and structure of the acyl substituent.;Irradiation of N-benzoylindole or N-ethoxycarbonylindole with ultra-violet light in the presence of cyclopentene gives a mixture of (2+2) cycloadducts and rearranged photo-Fries products. The quantum yields of formation of the photo-Fries products were found to be wavelength dependent and, especially in the case of N-benzoylindole, highly solvent …
Part~I~Photoenolization Of Alpha,Beta-Unsaturated Ketones Part~Ii~Photochemical Studies Of Some N-Aroyl Substituted Indoles, David F. Wong
Part~I~Photoenolization Of Alpha,Beta-Unsaturated Ketones Part~Ii~Photochemical Studies Of Some N-Aroyl Substituted Indoles, David F. Wong
Digitized Theses
Part I. Ultra-violet light irradiation of {dollar}\alpha{dollar},{dollar}\beta{dollar}-unsaturated ketones possessing a {dollar}\gamma{dollar}-hydrogen as well as a {dollar}\gamma{dollar}-alkyl substituent results in isomerization to their {dollar}\beta{dollar},{dollar}\gamma{dollar}-unsaturated isomers. The process occurs by an intramolecular {dollar}\gamma{dollar}-hydrogen abstraction by the excited carbonyl to generate a dienol intermediate. The deconjugation reaction is not efficient for {dollar}\alpha{dollar},{dollar}\beta{dollar}-unsaturated ketones which do not possess a {dollar}\gamma{dollar}-alkyl substituent; this is because thermal 1,5-hydrogen transfer in the dienol intermediate gives back starting ketone efficiently. Part I of this thesis describes a procedure for trapping dienols generated photochemically from several {dollar}\gamma{dollar}-unsubstituted {dollar}\alpha{dollar},{dollar}\beta{dollar}-unsaturated ketones. The trap used is chlorotrimethylsilane in the presence of a …
Part I N-Acylindole 2+2 Photocycloaddition Reactions Part Ii Enone 2+2 Photocycloaddition Reactions, David J. Hastings
Part I N-Acylindole 2+2 Photocycloaddition Reactions Part Ii Enone 2+2 Photocycloaddition Reactions, David J. Hastings
Digitized Theses
Part I. Ultra-violet irradiation of N-acylindoles in the presence of alkenes results in the formation of 2+2 photocycloadducts containing a cyclobutane ring derived from the bonding of the alkene termini to the 2 and 3-positions of the indole. The reaction proceeds via the triplet excited state of the N-acylindole with a quantum yield of product formation which is much less than that of the quantum yield for intersystem crossing. The reaction's inefficiency is explained by the existence of 1,4-biradical intermediates which can undergo cleavage to yield ground state starting materials in competition with ring closure to give the observed photocycloadducts. …
Stereoelectronic Effects, Mechanism, And Synthesis In Sulfonyl Chemistry, Rajendra Rathore
Stereoelectronic Effects, Mechanism, And Synthesis In Sulfonyl Chemistry, Rajendra Rathore
Digitized Theses
ABSTRACT HAS BEEN ARCHIVED 09/17/93;
Surface Photochemistry: Semiconductor Mediated Reactions, Anthony Montague Draper
Surface Photochemistry: Semiconductor Mediated Reactions, Anthony Montague Draper
Digitized Theses
The semiconductor photoinduced valence isomerizations of several strained saturated hydrocarbons were investigated. Particularly, the radical cation rearrangements of quadricyclane and bishomocubane on ZnO and CdS were explored with respect to various experimental conditions; solvent, light intensity, temperature and presence of oxygen. A kinetic treatment of the data obtained revealed that bimolecular processes at the surface may occur by two routes: reaction between two adsorbed species, the Langmuir-Hinshelwood model and reaction of an adsorbed molecule with a molecule in solution, an Eley-Rideal type process. Unimolecular reaction at the surface was adequately described by only considering adsorbed substances. The square root relationship …
Part I Total Synthesis Of (+,-)-Hirsutene Part Ii Photochemical And Photophysical Properties Of N-Benzoylindoles, Bimsara Wijesekara Disanayaka
Part I Total Synthesis Of (+,-)-Hirsutene Part Ii Photochemical And Photophysical Properties Of N-Benzoylindoles, Bimsara Wijesekara Disanayaka
Digitized Theses
Part One. The synthesis of polycyclic compounds usually requires various synthetic approaches to construct the required carbon skeletons. This thesis describes a sequence which leads to the preparation of the tricylo (6.3.0.{dollar}0\sp{lcub}2,6{rcub}{dollar}) undecane skeleton found in a number of physiological fungal metabolites. The key steps in this sequence are photochemical cycloaddition of the enol of 5,5-dimethylcyclohexane-1,3-dione to a cyclopentene, followed by intramolecular reductive coupling of the dione with a low valence titanium compound. A formal synthesis of the fungal metabolite hirsutene is described using this procedure. The route involves the photochemical (2+2) cycloaddition of 5,5-dimethylcyclohexane-1,3-dione to 2-methyl-2-cyclopentenol, followed by the …
Synthesis And Mechanism In Organic Sulfonyl Chemistry, Kishan Chand Khemani
Synthesis And Mechanism In Organic Sulfonyl Chemistry, Kishan Chand Khemani
Digitized Theses
This thesis describes four topics in synthesis and mechanism of reactions of certain organo-sulfonyl compounds. The first describes the reaction of thiirane-1,1-dioxide with hydroxide ion. Notwithstanding an earlier report, it was found that the major product of this reaction was ethanesulfonate anion, substituted analogues of which have occasionally been observed as products of certain Ramberg-Backlund reactions. It is proposed that the reaction proceeds via a penta-coordinated sulfur intermediate formed by the attack of hydroxide ion at the sulfonyl function of thiirane-1,1-dioxide.;In the second study, use of {dollar}\sp{lcub}18{rcub}{dollar}O labels and kinetics led to the conclusion that hydrolysis of 2-hydroxyethanesulfonyl chloride to …
Work Towards The Total Synthesis Of Patchouli Alcohol And Approaches To Cycloseychellene, Murray Douglas Bailey
Work Towards The Total Synthesis Of Patchouli Alcohol And Approaches To Cycloseychellene, Murray Douglas Bailey
Digitized Theses
The synthesis of polycyclic compounds usually requires numerous synthetic operations in order to construct the desired carbon skeletons. A simple procedure termed a bicycloannulation allows for the generation of one of these ring systems in one synthetic operation. The tricyclo 3.2.1.0('2,7) octane ring system incorporates a two carbon bridge cross a cyclohexane ring which includes at one end a cyclopropane ring. This tricyclic carbon skeleton is a highlighting feature of a number of terpenoids, including the sesquiterpene cycloseychellene. Beginning with a substituted cyclohexenone, the bicycloannulation allows for the construction of all but one of the rings in this tetracyclic sesquiterpene. …
Synthetic And Mechanistic Features Of Base-Catalyzed Homoenolization And Homoketonization, Arthur Jonas Ragauskas
Synthetic And Mechanistic Features Of Base-Catalyzed Homoenolization And Homoketonization, Arthur Jonas Ragauskas
Digitized Theses
The behavior of a variety of homoenolate anions generated either by hydrolysis of polycyclic ethers (homoketonization) or by base-catalyzed hydrogen abstraction from polycyclic ketones (homoenolization) has been investigated.;A series of polycyclic derivatives of cyclopropanol were prepared and the base-catalyzed ketonization of the corresponding cyclopropoxides was examined to establish the regio- and stereochemistry of the ring cleavage. The examples derived from 2.2.1 and 2.2.2 ketones, by Simmons-Smith cyclopropanation of their silyl enol ethers, were found to undergo ring expansion preferentially while less-strained analogs gave the (alpha)-methyl derivatives of the initial ketone. In all cases of ring expansion, the cleavage proceeds with …