Index Catalog // ScholarsArchive@OSU

Cis-2,5-diaminobicyclo[2.2.2]octane : a novel C₂-symmetric scaffold for asymmetric catalysis

Creator:: Shaw, Subrata
Abstract:: This thesis describes the development of a new enantioselective synthetic method employing chiral cis-2,5-diaminobicyclo[2.2.2]octane-based organometallic catalysts. The significance of this new method to organic synthesis is illustrated with preparation of enantioenriched products that are transformed to important pharmaceutical agents. Chapter 1 provides a brief historical overview of asymmetric catalysis, especially...
Resource Type:: Dissertation

Alkylation studies on Hagemann's ester: an approach to the synthesis of the trisporic acids

Creator:: Sung, Wing Lam
Abstract:: Sequential alkylation of Hagemann's ester with methyl and methallyl halides has been studied. Treatment of Hagemann's ester with methyl iodide and sodium ethoxide gave a mixture of 21 and 25 in a ratio of 4:1. Alkylation of 21 with methallyl chloride and potassium t-butoxide afforded a mixture of 37 and...
Resource Type:: Masters Thesis

The synthesis of nonactic acid

Creator:: Arco, Manuel Jose
Abstract:: Alkylation of propylene oxide with 2-lithiofuran gave alcohol I, which was smoothly converted to acetylfuran II. hydrogenation of II over rhodium on charcoal followed by Jones' oxidation afforded ketone III. Further transformation into IV was accomplished via a Wittig reaction followed by saponification with methanolic sodium hydroxide. Hydroboration of the...
Resource Type:: Dissertation

Approaches to the synthesis of polyketides. Vermiculine

Creator:: Kirkemo, Curtis Lee
Abstract:: An approach to the generation of polyketides was investigated, which involved ozonolysis of 6, 7 cyclopenteno -1> 4, 5, 8 -tetrahydromethoxy- 3-methylnaphthalene (26), to produce what is believed to be polyketide 27. Compound 26 was formed by the following sequence: Die ls -Alder addition of 1, 2 -dim.ethylenecyclopentane and 2...
Resource Type:: Dissertation

Approaches to the synthesis of penicillin

Creator:: Furuta, Takuya
Abstract:: Several approaches to the synthesis of penicillin from 2-iminothioazolidine 50, from 2-thiothiazolidine 66 and by photocyclization of 77 and 78 were investigated. 2-Iminothiazolidine 50 was prepared from dibromoester 45 by the action of benzylamine followed by treatment of aziridine 46 with potassium or ammonium thiocyanate. Attempted introduction of a two-carbon...
Resource Type:: Dissertation

The total synthesis of (-)- acorenone B ; Approaches to the synthesis of mycosporin (P 310)

Creator:: Ruppert, John Fredrick
Resource Type:: Dissertation

The synthesis of trisporic acids

Creator:: Prisbylla, Michael Paul
Abstract:: A total synthesis of the fungal hormones, trisporic acids A and B, is described, starting from a -methyltetronic acid 34. A Robinson annelation of 34 with ethyl vinyl ketone affords the lactone 33. Treatment of 33 with N-bromosuccinimide gave 97, which was hydrolyzed to the lactol 103. The reaction of...
Resource Type:: Dissertation

Approaches to the synthesis of trichothecane sesquiterpenes

Creator:: Thomas, James Anthony
Resource Type:: Dissertation

Cyclization of olefinic β-ketoesters. An approach to the synthesis of aplysistatin

Creator:: Skeean, Richard William
Resource Type:: Dissertation

Approaches to the synthesis of methymycin

Creator:: Raghavan, Palaykotai Rajagopalan
Abstract:: Several approaches to the synthesis of methymycin were investigated. Segment A (39), containing functionality corresponding to C-9, 10, and 11 of methynolide was made in six steps from propionaldehyde in an overall yield of 37%. Oxidation of 34 with silver nitrate gave 35 which, upon hydroxylation with hydrogen peroxide, gave...
Resource Type:: Dissertation

The isolation and structure of leptosphaerin : a metabolite of the marine ascomycete, Leptosphaeria oraemaris (Linder) and A synthesis of the marine toxin, 9-isocyanopupukeanane

Creator:: Schiehser, Guy Alan
Abstract:: The ethyl acetate extract of the culture filtrate of the marine Ascomycete, Leptosphaeria oraemaris (Linder) yielded a novel metabolite designated by the common name leptosphaerin. An x-ray crystallographic structure analysis was disproved by the synthesis of 3-acetoxy-S-(1,2-dihydroxyethyl)- 3-pyrrolin-2-one 1, starting with N,N-dibenzylhydroxylamine 47 and D-mannitol 44. Oxidation of 47 followed...
Resource Type:: Dissertation

Intramolecular diels-alder cycloadditions of citraconic and mesaconic esters ; Studies on the synthesis of the northwest and southeast segments of boromycin

Creator:: Sheldon, Bernard Gale
Resource Type:: Dissertation

Part I. The total synthesis of (±)-cinnamodial and related drimane sesquiterpenes; Part II. Photochemical activation of the carboxyl group via N-Acyl-2-thionothiazolidines

Creator:: Burton, Lester Percy Joseph
Resource Type:: Dissertation

Condensation of crotonic and tiglic acids with aldehydes and ketones

Creator:: Johnson, Paul Robert
Resource Type:: Masters Thesis

Phenolic oxidative coupling : an approach to the synthesis of pretazettine

Creator:: Chong, Wesley Kwan Mung
Abstract:: Various hypervalent iodine compounds were evaluated as reagents for intramolecular phenolic oxidative coupling. It was found that phenyliodine(III) bis(trifluoroacetate) was effective for the coupling of the monophenolic substrate 13a to 14a under neutral conditions. Vanadium oxytrifluoride and hypervalent iodine compounds were compared as oxidants for the conversion of 32 to...
Resource Type:: Dissertation

Chiral synthesis of alcohols via asymmetric epoxidation

Creator:: Engebrecht, Jeffrey Ronald
Abstract:: Enantioselective epoxidation of crotyl alcohol, followed by a cuprate mediated methylation, gave a 1:1 mixture of (2S) -3- methyl -1,2- butanediol and (2R,3S)-2-methy1-1,3- butanediol. The latter was separated as its 2,4,6-trimethylbenzenesulfonate derivative and converted via the iodide to the corresponding phosphonium salt. The separated butanediol derivatives were independently transformed to...
Resource Type:: Masters Thesis

Studies on the synthesis of the "northern" and "southern" segments of boromycin and aplasmomycin

Creator:: Kang, Myung Chol
Abstract:: The stereocontrolled synthesis of the southern lactone 17 of boromycin and of the northern segments of both boromycin and aplasmomycin are described. The syntheses begin with enantioselective epoxidation of 3-buten-2-ol (42) to provide the optically active 2(S),3(R) epoxy alcohol 43. The absolute configuration was confirmed by preparing 43 from (-)-2,3-dihydroxybutyric...
Resource Type:: Dissertation

Approaches toward the asymmetric synthesis of pillaromycin A

Creator:: Nolen, Ernest G.
Resource Type:: Dissertation

Chiral synthesis of monic acid C

Creator:: Theramongkol, Parinya
Abstract:: Bromoalkoxylation of dihydropyran with bromine and 1-borneol, followed by dehydrobromination and epoxidation, afforded trans-2-1- bornyloxy-3,4-epoxytetrahydropyran as a major product. This was treated with sodium phenylselenide to give a 1:1 mixture of (2R,3R,4R)- 2-1-bornyloxy-3-hydroxy-4-phenylselenotetrahydropyran and its (2S,3S, 4S) diastereomer. Elimination of the selenoxide, derived from oxidation of the former with hydrogen...
Resource Type:: Dissertation

Synthetic transformations of shikimic acid

Creator:: White, Edward D., III
Abstract:: Four strategies which involve synthetic elaboration of the shikimate nucleus are discussed. Methyl shikimate was differentially protected as the 3,4-0-cyclopentylidene ketal and as the 5- 0- tert- butyldiphenylsilyl ether. The methyl ester was then reduced with diisobutylaluminum hydride and the resulting allylic alcohol was oxidized to aldehyde 47 with pyridinium...
Resource Type:: Masters Thesis

Approaches to the synthesis of the macrolactone pyrrolizidine alkaloids (-)-integerrimine and (+)-usaramine

Creator:: Jayasinghe, Lalith Ratnasiri
Abstract:: A formal total synthesis of the macrolactone pyrolizidine alkaloid (-)-integerrimine (2), from R-(+)-citronellal (93) is described. Aldehyde 93 was converted to exo methylene derivative 94 which was reduced to allylic alcohol 95. The epoxides 96 and 98, obtained in a ratio of 3:1 respectively by Sharp less epoxidation of 95...
Resource Type:: Dissertation

Synthesis of two subunits of avermectin B1a

Creator:: Dantanarayana, Anura Pathmasiri
Abstract:: Avermectins are a group of potent anthelmintic agents produced by Streptomyces avermitilis. They are active at extremely low dosages and are now in commercial use. In this study, the synthesis of two segments of avermectin B[subscript 1a] are described. The synthesis of the hexahydrobenzofuran subunit (segment A) began with the...
Resource Type:: Dissertation

Approaches toward synthesis of the mycosporins

Creator:: Cammack, Janice H.
Abstract:: The mycosporins, formerly called P310's are secondary metabolites of fungi closely associated with fungal reproductive processes that require light. The structurally related iminomycosporins are found in marine plants and animals and may also have functions related to light. In this study, approaches toward the asymmetric synthesis of the mycosporins are...
Resource Type:: Dissertation

Approaches to the total synthesis of verrucarol

Creator:: Hill, David E. (David Edwin) 1954-
Abstract:: Verrucarol is the sesquiterpene portion of a number of macrocyclic di- and triesters of potential medicinal importance. In this study, a novel approach to the synthesis of this fungal metabolite is presented. An A-B-C route was investigated in which C-3 and C-4 of the C-ring were emplaced using a [2+2]...
Resource Type:: Dissertation

Absolute stereochemistry and total synthesis of botryococcene

Creator:: Reddy, Guvvala Nagabhushana
Abstract:: Studies were carried out to determine the absolute stereochemistry of botryococcene (1). The natural product was degraded to two sets of 'y- and 8- valerolactones. All enantiomeric variations of these lactones were synthesized in optically pure form starting from (S)- and (R)-methyloxiranes. 1H NMR correlation of natural and synthetic materials...
Resource Type:: Dissertation

Structural and synthetic studies of higher terpenoids : Part I. The absolute configuration of (-)-botryococcene : Part II. Total synthesis of (±)-2-desoxystemodinone

Creator:: Somers, Todd Charles
Resource Type:: Dissertation

Synthesis of metabolites from the ascomycetes : I. The synthesis and absolute configuration of leptosphaerin : II. Approaches to the synthesis of byssochlamic acid

Creator:: Pallenberg, Alexander J.
Abstract:: Part I. The total synthesis of (+)-leptosphaerin (2), a metabolite of the marine Ascomycete Leptosphaeria Oraemaris (Linder) was achieved, unambiguously establishing both the relative and absolute stereochemistry of this natural product. This synthesis also resolved the long-standing question of which of the isomeric structures 1 or 2 correctly represents the...
Resource Type:: Dissertation

Synthesis of a model of the spiroketal portion of avermectin B

Creator:: Warrier, Ulhas S.
Abstract:: Avermectin Bia is a member of a class of medicinally important natural products known for its potent antiparasitic activity and interesting structural features. In this thesis, synthesis of a model for the spiroketal portion of the avermectins is presented. Oxidation of (S)-2-methylbutanol, followed by a stereoselective chromium mediated reaction with...
Resource Type:: Masters Thesis

Total synthesis of (+)-bourgeanic acid and conformational analysis of its dilactone

Creator:: Johnson, Alan T. (Alan Thomas), 1957-
Resource Type:: Dissertation

Approaches to the synthesis of trichothecenes

Creator:: Kim, No-soo
Resource Type:: Dissertation

The synthesis of macrolactones from [omega]-hydroxyacyl xanthates

Creator:: Akella, Annapoorna
Resource Type:: Masters Thesis

An approach toward the synthesis of euonyminol and cathedulin K- 19

Creator:: Shin, Hyunik
Abstract:: A synthetic approach toward the two major fragments of cathedulin K-19, euonyminol (4) and dimethyl cathate (69), was investigated. Synthesis of dimethyl cathate was accomplished in 3 steps starting from 73. Efforts directed towards the synthesis of euonyminol, a highly oxygenated dihydroagarofuran sesquiterpene, was advanced to a stage in which...
Resource Type:: Dissertation

Synthetic studies on marine natural products : Part 1. Synthesis of the sesquiterpenoid dihydropallescensin D via manganese(III)- mediated carbocyclization. Part 2. Approaches toward the synthesis of prianosin and discorhabdin alkaloids

Creator:: Yager, Kraig M.
Resource Type:: Dissertation

Part I : synthesis of azetidin-2-ones from pyrazolidin-3-ones ; Part II : synthesis of a subunit of the immunosuppressant FK-506

Creator:: Toske, Steven Gerald
Resource Type:: Dissertation

Synthetic studies on marine natural products : I. Stereoselective synthesis of E,Z-1,3-Dienes by tandem nucleophilic addition to a dienylphosphonium salt followed by Wittig reaction. II. Synthesis of cyclopropyl oxylipins by a cation mediated carbocyclization

Creator:: Jensen, Mark S.
Resource Type:: Dissertation

Synthetic studies on alkaloids : part I, an approach toward the synthesis of (̳+)-koumine : part II, an approach toward the synthesis of (̳+)-morphine

Creator:: Stappenbeck, Frank
Resource Type:: Dissertation

Synthetic studies n bioactive natural products. Part I, An approach towards the nootrophic agent huperzine A. Part II, Synthesis of the tricarbonyl subunit of rapamycin

Creator:: Jeffrey, Scott C.
Resource Type:: Dissertation

Synthetic studies on natural products : Part I. The total synthesis of ±-euonyminol and ±-3,4-dideoxymaytol : Part II. The absolute configuration and enantioselective synthesis of curacin A

Creator:: Kim, Tae-Seong
Resource Type:: Dissertation

Synthetic studies on necic acids of pyrrolizidine alkaloids

Creator:: Lee, Nadine Chauyi
Resource Type:: Dissertation

Synthetic studies on the macrolide antibiotic rutamycin B

Creator:: Wang, Shan
Resource Type:: Dissertation

Synthetic approaches to the tricarbonyl subunit of rapamycin

Creator:: LaMunyon, James B.
Abstract:: Rapamycin (5) was isolated in 1975 from the soil bacteria Streptomyces hygroscopicus and its structure was determined from spectroscopic techniques and an x-ray crystallographic analysis. Although it was initially found to exhibit antibiotic activity, it was subsequently shown to possess potent immunosuppressive activity as well. Three approaches to the synthesis...
Resource Type:: Masters Thesis

Synthetic studies of nonadrides

Creator:: Drapela, Nicholas Ernest
Abstract:: An asymmetric approach to the synthesis of byssochlamic acid (1) is described. Regioisomeric enzymatic differentiation is described in the selective hydrolysis of dimethyl ester 30 by porcine liver esterase. Chiral dimethyl ester 42 was prepared by desymmetrization of cyclopentene 34 using porcine liver esterase. A key intramolecular [2+2]cycloaddition-cycloreversion photometathesis of...
Resource Type:: Dissertation

Synthetic studies on alkaloids : part I; asymmetric synthesis of (±) codeine. Formal synthesis of (±) morphine : part II; a unified asymetric approach toward synthesis of polyhydroxylated pyrrolizidine alkaloids, australine and alexine

Creator:: Hrnciar, Peter
Resource Type:: Dissertation

Total synthesis of (-)-7-epicylindrospermopsin

Creator:: Hansen, Joshua D.
Abstract:: The first asymmetric synthesis of (-)-7-epicylindrospermopsin via intramolecular nitrone cycloaddition is described. The synthesis utilized a convergent approach to prepare the cycloaddition precursor 176, which was assembled by condensation of hydroxylamine 175 with aldehyde 145. Hydroxylamine 175 was synthesized from ethylene glycol (166) in seven steps. Aldehyde 145 was completed...
Resource Type:: Dissertation

Studies toward the total synthesis of sanglifehrin A

Creator:: Suttisintong, Khomson
Abstract:: Studies toward synthesis of subunits of sanglifehrin A, an immunosuppressant featuring a highly substituted [5,5]-spirolactam moiety as well as a 22-membered macrocycle are described. The macrolactone contains a peptidic backbone characterized by an unusual [beta]-substituted (S)-piperazic acid and (S)-m-hydroxyphenylalanine units. These studies resulted in the synthesis of advanced intermediate 358...
Resource Type:: Dissertation

Natural product synthesis via cyclobutanes : part I, Asymmetric synthesis of (+)-byssochlamic acid, part II, An approach to the nootropic agent huperzine A

Creator:: Kim, Jungchul
Abstract:: PART I. Asymmetric syntheses of both natural (+)- and nonnatural (-)-byssochlamic acid via a [2+2] photoaddition-cycloreversion strategy are described. X-ray crystallographic analysis of the cyclohexylamine salt 99 showed that the structure of the monomethyl ester 100 from esterase hydrolysis of 44 was originally misassigned as 56. The enantiomeric relationship of...
Resource Type:: Dissertation

Synthesis of marine natural products. part I, Cryptophycins-1, -3, -4, -24, and -29, part II, Polycavernoside A

Creator:: Robarge, Lonnie A.
Resource Type:: Dissertation

Total synthesis of indole alkaloids: pt. 1. Asymmetric synthesis of (-)-ibogamine. pt. 2. An approach toward the synthesis of koumine

Creator:: Choi, Younggi
Abstract:: PART I. The preparation of (-)-ibogamine (1) in fourteen steps from benzoquinone and in 10% overall yield is a powerful illustration of the value of the asymmetric Diels-Alder reaction as a starting point in a multistep synthesis. All four cycloadducts, 70, 77, 84 and 96, obtained with the (S)-BINOL-TiCl₂ complex...
Resource Type:: Dissertation

Studies toward the total synthesis of phorboxazole A

Creator:: Kuntiyong, Punlop
Abstract:: Studies toward the total synthesis of a highly potent cytotoxic marine natural product, phorboxazole A, were conducted and resulted in a route to an advanced intermediate, C4-C32, for this purpose. A key feature of our approach is the stereoselective synthesis of two cis-2,6-disubstituted tetrahydropyrans present in the macrolide portion of...
Resource Type:: Dissertation

Synthesis of furanoeremophilane sesquiterpenoids

Creator:: Shanmugham, Meenakshi Sundaram
Abstract:: Two approaches to the tricyclic core of the furanoeremophilane sesquiterpenoids are described. The first approach entails a projected Diels-Alder/retro Diels-Alder reaction of an acetylenic oxazole 64. Construction of the pivotal aldehyde 67 commenced from ketone 68. The acetyenic moiety was then introduced via a Felkin-Ahn addition of lithiopropyne to aldehyde...
Resource Type:: Dissertation

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