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Synthetic studies of eupolauridine and eilatin.January 1991 (has links)
by Tat-hung Tong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1991. / Includes bibliographical references. / Chapter I. --- Acknowledgements --- p.(1) / Chapter II. --- List of Nomenclatures --- p.(2) / Chapter III. --- Abstract --- p.(4) / Chapter IV. --- Introduction --- p.(5) / Chapter V. --- Results and Discussion --- p.(12) / Chapter (1) --- Synthetic Strategy --- p.(12) / Chapter (2) --- Preparation of onychine (4) --- p.(13) / Chapter (3) --- Preparation of eupolauridine (1) --- p.(25) / Chapter (4) --- "Preparation of benzo-annulated derivative of eupolauridine : 2,3-benzo-l ,6-diazafluoranthene (9)" --- p.(26) / Chapter (5) --- "NMR data interpretation of 2,3-benzo-4-aza-l-methyl-fluoren-9-one (12) and 2,3-benzo-l,6-diazafluoranthene (9)" --- p.(27) / Chapter (6) --- Synthetic study of eilatin (10) --- p.(32) / Chapter VI. --- Conclusion --- p.(36) / Chapter VII. --- Experimental Section --- p.(37) / Chapter VIII. --- References --- p.(56) / Chapter IX. --- NMR Spectra --- p.(58)
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Syntheses of some nitrogen-bridged (2.2) cyclophanes. / Chemistry of heterocyclic compoundsJanuary 1980 (has links)
by Chan Shau-lung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1980. / Bibliography: leaves 54-56.
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Regiospecific syntheses of polysubstituted furans.January 1997 (has links)
by Ming-Keung Wong. / Submission year appears as 1996. Graduation year on spine miss printed as 1996. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (leaves 75-78). / Acknowledgements --- p.i / Contents --- p.ii / Abstract --- p.v / List of abbreviations --- p.vi / Chapter I. --- Introduction --- p.1 / Chapter I.1 --- Reactions of furan --- p.2 / Chapter I.1.a. --- Electrophilic substitution --- p.2 / Chapter I.1.b. --- Lithiation and alkylation --- p.2 / Chapter I.2. --- Syntheses of furans --- p.3 / Chapter I.3. --- "Syntheses of 2,3-disubstituted furans" --- p.3 / Chapter I.3.a. --- Through C3-substituent-directed lithiation --- p.4 / Chapter I.3.b. --- By molybdenum pentacarbonyl-catalyzed cyclization --- p.5 / Chapter I.3.c. --- By Ag(I) catalyzed cyclization --- p.6 / Chapter I.4. --- Syntheses of rosefuran --- p.6 / Chapter I.4.a. --- Via 2-lithio-3-methylfuran --- p.7 / Chapter I.4.b. --- By Claisen rearrangement --- p.7 / Chapter I.4.c. --- By oxidative decarboxylation with lead tetraacetate --- p.8 / Chapter I.4.d. --- By prenylation of 3-methylbut-2-enolide --- p.8 / Chapter I.4.e. --- Via 3-bromo-2-furylithium --- p.9 / Chapter I.4.f. --- By reaction of α-oxo ketone dithioacetal with dimethylsulfonium methylide --- p.10 / Chapter I.4.g. --- Via allyl alcohol --- p.11 / Chapter I.4.h. --- Via γ-keto aldehyde --- p.11 / Chapter I.4.i. --- By the transformation of 5-oxogeraniol --- p.12 / Chapter I.4.j. --- By base-catalyzed cyclization of alkynoate --- p.13 / Chapter I.4.k. --- Via 3-hydroxyketone cyclization --- p.14 / Chapter I.4.L. --- By [3+2] nitrile oxide cycloaddition --- p.15 / Chapter I.5. --- "Syntheses of 2,4-disubstituted furans" --- p.16 / Chapter I.5.a. --- By electrochemical method --- p.17 / Chapter I.5.b. --- From acyclic reagents --- p.18 / Chapter I.5.c. --- "From 2,3-disubstituted furan" --- p.19 / Chapter I.5.d. --- From p-hydroxy sulfones --- p.20 / Chapter I.6. --- "Syntheses of 2,3,4-trisubstituted furans" --- p.21 / Chapter I.6.a. --- Via tantalum-alkyne complexes --- p.22 / Chapter I.6.b. --- Via intramolecular Diels-Alder reaction of oxazole alcohols --- p.23 / Chapter I.6.c. --- By using unsaturated sulfoxides --- p.24 / Chapter I.7. --- "Syntheses of 2,3,5-trisubstituted furans" --- p.26 / Chapter I.7.a. --- "From α,β-unsaturated ketone" --- p.26 / Chapter I.7.b. --- By palladium catalyzed cyclization --- p.27 / Chapter I.7.c. --- Via base-catalyzed isomerization of alkynyloxiranes --- p.28 / Chapter II. --- Results and Discussion --- p.30 / Chapter II.1 --- "Regiospecific synthesis of 2,3-disubstituted furans" --- p.30 / Chapter II. 1.a. --- "Synthesis of 2,4-bis(trimethylsilyl)furan (137)" --- p.30 / Chapter II.1.b. --- Synthesis of 2-n-hexyl-3-trimethylsilylfuran (140) and 2-benzyl-3-trimethylsilylfuran (143) --- p.35 / Chapter II.1.e. --- "Synthesis of 3-benzyl-2-N-hexylfuran (145) and 2-benzyl-3-[3,4-(methylenedioxy)]benzylfuran (153)" --- p.36 / Chapter II.2. --- Syntheses of rosefuran (4) --- p.40 / Chapter II.2.a. --- "Synthesis of rosefuran (4) from 2,4-bis(trimethylsilyl)furan (137)" --- p.40 / Chapter II.2.b. --- Synthesis of rosefuran (4) from -methyl-4-trimethylsilylfuran (158) --- p.42 / Chapter II.3. --- "Regiospecific synthesis of 2,4-disubstituted furans" --- p.44 / Chapter II.3.a. --- Synthesis of 3-trimethylsilylfuran (163) --- p.44 / Chapter II.3.b. --- Synthesis of tri(2-benzylfuran-4-yl)boroxine (165) --- p.45 / Chapter II.3.C. --- Synthesis of 2-benzyl-4-(p-tolyl)furan (166) and 2-benzyl-4-(trans-2-phenylvinyl)furan (167) --- p.46 / Chapter IL3.d. --- Synthesis of 2-benzyl-4-(trimethylsilylethynyl)furan (169) --- p.47 / Chapter IL3.e. --- "Synthesis of 2,2'-bis(benzyl)-4,4'-bifuran (174)" --- p.50 / Chapter II.4. --- "Regiospecific synthesis of 2,3,4-trisubstituted furan" --- p.51 / Chapter II.5. --- "Regiospecific synthesis of 2,3,5-trisubstituted furan" --- p.53 / Chapter III. --- Conclusion --- p.56 / Chapter IV. --- Experimental Section --- p.57 / Chapter V. --- References --- p.75 / Chapter VI. --- List of spectra --- p.79 / Chapter VII. --- Spectra --- p.81
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Synthesis of a new series of polyhydrocarbon-based dendritic fragments.January 1999 (has links)
by Ka-Fai Ng. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 51-54). / Abstracts in English and Chinese. / Contents --- p.i / Acknowledgments --- p.iii / Abstract --- p.iv / Abbreviations --- p.vi / Chapter Chapter I --- Introduction / Chapter I-1 --- General background of dendrimers --- p.1 / Chapter I-2 --- Synthesis of dendritic molecules --- p.2 / Chapter I-2-1 --- Divergent methods --- p.2 / Chapter I-2-2 --- Convergent methods --- p.4 / Chapter Chapter II --- Functional dendrimers / Chapter II-1 --- Catalytically active dendrimers --- p.8 / Chapter II-2 --- Polyhydrocarbon-based dendrimers --- p.17 / Chapter Chapter III --- Results and Discussion / Chapter III-1 --- Solvent dependence of the rate of Diels-Alder reaction --- p.23 / Chapter III-2 --- Synthesis and characterization of polyhydrocarbon-based dendritic fragments --- p.25 / Chapter III-2-1 --- Architecture of the dendritic fragments --- p.25 / Chapter III-2-2 --- The iterative cycle --- p.27 / Chapter III-2-3 --- Synthesis of GO dendrimer --- p.28 / Chapter III-2-4 --- Construction of G1 dendrimers --- p.29 / Chapter III-2-5 --- Construction of the G2 dendrimers --- p.31 / Chapter III-3 --- Conclusions --- p.36 / Chapter Chapter IV --- Summary --- p.37 / Chapter Chapter V --- Experimental --- p.38 / References --- p.51 / Spectra --- p.55
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Synthesis of metallodendrimers.January 2000 (has links)
by Pui-Shan Fung. / Thesis submitted in: December 1999. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 67-69). / Abstracts in English and Chinese. / Acknowledgments --- p.ii / Abstract --- p.iii / Abbreviations --- p.v / Chapter Chapter I. --- Introduction / Chapter 1. --- General background of dendrimers --- p.1 / Chapter 2. --- Metallodendrimers --- p.4 / Chapter 3. --- Fluorinated dendrimers --- p.12 / Chapter Chapter II. --- Synthesis and characterization / Chapter 1. --- Structure of the dendritic fragments --- p.15 / Chapter 2. --- Synthesis of the terpy-based metallodendrimers --- p.16 / Chapter 3. --- Characterization / Chapter 3.1 --- Characterization of fluorinated dendrimers --- p.31 / Chapter 3.2 --- Characterization of non-fluorinated dendrimers --- p.36 / Chapter Chapter III. --- Redox properties of metallodendrimers / Chapter 1. --- Cyclic voltammetric studies --- p.38 / Chapter 1.1 --- Cyclic voltammograms of fluorinated metallodendrimers --- p.40 / Chapter 1.2 --- Cyclic voltammograms of non-fluorinated metallodendrimers --- p.44 / Chapter Chapter IV. --- Summary --- p.47 / Chapter Chapter V. --- Experimental --- p.49 / References --- p.67 / Spectra --- p.70
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An accelerated approach to the synthesis of dendrimers.January 1999 (has links)
by Vincent Yam-Fat Lau. / Thesis submitted in: November 1998. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 53-57). / Abstract also in Chinese. / Contents --- p.i / Acknowledgments --- p.ii / Publication --- p.iii / Abstract --- p.iv / Abbreviations --- p.vi / Chapter Chapter I. --- Introduction / Chapter 1. --- General background of synthetic chemistry in dendrimers --- p.1 / Chapter 2. --- Accelerated approaches --- p.5 / Chapter Chapter II. --- Synthesis and Characterization / Chapter 1. --- Structure of the dendritic fragments --- p.17 / Chapter 2. --- Synthesis of the dendritic fragments --- p.18 / Chapter 3. --- Characterization --- p.26 / Chapter Chapter III. --- Attempted Synthesis of Electrochemically Active Metallodendrimers / Chapter 1. --- Background --- p.30 / Chapter 2. --- Synthesis of a ferrocene containing spacer for the construction of metallodendrimers containing multiple redox active units --- p.35 / Chapter 3. --- Conclusions --- p.41 / Chapter Chapter IV. --- Summary --- p.42 / Chapter Chapter V. --- Experimental --- p.43 / References --- p.53 / Spectra --- p.58
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Catalytic higher substituted alkenes synthesis via asymmetric hydroalkenylation and diarylphosphonylation. / CUHK electronic theses & dissertations collectionJanuary 2013 (has links)
烯烴是世界上最被廣泛應用的化工原料之一。最近我們通過含氮雜環卡賓鎳氫化物來催化氫化烯化反應,用廉價的單取代簡單烯烴成功合成了更有價值的不對稱1,1-偕二取代烯烴。雖然它們的對映體可以由傳統的手性拆分方法在實驗室中獲得,但卻不太可能實際應用於工業中,從而限制了此新方法的可應用性。因此,本文中我們透過使用烯烴醛耦合反應生成手性含氮雜環卡賓鎳氫化物 [(NHC)NiH]OTf,並以此為催化劑,將其應用在溫和條件下高選擇性的催化不對稱氫化烯化反應。另外,上述烯烴醛耦合反應的副產物 (烯丙基矽醚) 亦可成為基板,通過催化受控的替換反應,最後合成並得出較高取代的烯烴。基於烯丙基磷酸二芳酯為目前在生物學上中一種重要的研究項目,以及其當前製備的困難,我們通過形成碳磷鍵來探索這些烯丙基矽醚的可應用性。故此,在現有的磷碳反應文獻和 Ritter 反應的鼓舞下,我們提供開發烯丙基磷酸二芳酯在溫和條件下的催化製備方法。此方法除可補充現有製備方法的不足外,亦能增加此類化合物有較高的取代基靈活性。 / Alkenes are one of the most versatile chemical feedstock in chemistry. Among the numerous preparative strategies, hydroalkenylation (H.A.) by using N-heterocyclic carbene (NHC)-NiH reported recently by our group represents a novel strategy to access synthetically valuable unsymmetric terminal 1, 1-disubstituted alkenes (DSA) from widely available α-alkenes. Their enantiomers could be obtained by classic chiral resolution methods in laboratory but may not be practical in industry, which limits the applications of this new methodology. As a result, herein we developed a catalytic asymmetric H.A. with high selectivities under mild conditions based on a chiral [(NHC)NiH]OTf catalyst generated in situ from alkene-aldehyde (A.A.) coupling. Since the above A.A. coupling by-product (allyl silyl ethers) is a structural motif potentially amenable for higher alkene catalytic synthesis by a controlled substitution, and because of the current difficulties in the preparation of biologically important allyl diarylhosphonates, we also explore the use of those allyl silyl ethers by means of C-P bond formation. Inspired by both existing phosphonylation literatures and Ritter reaction, we developed a catalytic preparation method for those compounds which complements the existing methods with a high substituent flexibility under milder conditions. / Detailed summary in vernacular field only. / Chan, Chun Wa. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese. / Table of Contents --- p.i / Acknowledgement --- p.iv / Abstract --- p.v / Abstract (Chinese Version) --- p.vi / Abbreviation --- p.vii / Chapter CHAPTER 1 --- IMPORTANCE OF GREENER ALKENE SYNTHESIS AND INTRODUCTION OF NHC AND ITS APPLICATION IN 1,1-DSA SYNTHESIS --- p.1 / Chapter 1.1 --- Synthesis of Higher Alkenes with Different Substitution Patterns from Simple α-Alkene --- p.1 / Chapter 1.2 --- Introduction of NHC --- p.6 / Chapter 1.2.1 --- Electronic Property Comparison --- p.6 / Chapter 1.2.2 --- NHCMetal Complex Stability --- p.8 / Chapter 1.2.3 --- Steric Parameter Comparison --- p.9 / Chapter 1.3 --- Challenges in Using NHC-NiH as Hydroalkenylation (H.A.) Catalyst --- p.10 / Chapter 1.4 --- A New Solution for Catalytic NHC-NiH Based H.A. and 1,1-DSA Preparation --- p.14 / Chapter 1.5 --- Objective and Approach for Asymmetric Cross-H.A. --- p.18 / Chapter CHAPTER 2 --- PRELIMINARY STUDY ON LIGAND STRUCTURALACTIVITY-RELATIONSHIPS (SAR) --- p.21 / Chapter 2.1 --- Structural Criteria of Chiral NHCs for Asymmetric H.A. --- p.21 / Chapter 2.2 --- Successful Asymmetric H.A. Using Selected Chiral C2 Symmetric Ligands Rationalized by Stereo-Chemical Models --- p.24 / Chapter CHAPTER 3 --- STUDIES AND OPTIMIZATION OF CHIRAL C₁-NHC CATALYZED H.A. --- p.28 / Chapter CHAPTER 4 --- SECOND GENERATION OF CATALYST --- p.41 / Chapter 4.1 --- A New Lead: Substrates Electronic and Steric Effects on Ee --- p.41 / Chapter 4.2 --- Ee Enhancement by Using Electronic Modified N[superscriptAr] NHC --- p.48 / Chapter 4.3 --- Scope of Asymmetric Hydroalkenylation --- p.55 / Chapter 4.4 --- Conclusion --- p.62 / Chapter REFERENCE --- p.64 / Chapter APPENDIX (I) - --- ASYMMETRIC HYDROALKENYLATION --- p.71 / EXPERIMENTAL SECTION --- p.71 / GC CHROMATOGRAM --- p.178 / HPLC CHROMATOGRAM --- p.192 / Chapter REFERENCE OF APPENDIX (I) --- p.207 / Chapter APPENDIX (II) - --- APPLICATIONS OF ALLYL SILYL ETHER OBTAINED FROM HA CATALYST GENERATION: SELECTIVE PREPARATION OF ALLYL DIARYLPHOSPHONYLATION --- p.209 / Chapter A.1 --- Importance of Allyl Phosphonates --- p.209 / Chapter A.2 --- Conventional Methods and Challenges of Allyl Phosphonates Preparation with Higher Alkenes Functionality --- p.210 / Chapter A.3 --- Objective and Approach --- p.212 / Chapter A.4 --- Preliminary Results of Allyl Diarylphosphonylation --- p.213 / Chapter A.4.1 --- Strategies for Chemoselectivity Improvement --- p.215 / Chapter A.4.2 --- Proposed Mechanism: Ritter-like Reaction Pathway --- p.219 / Chapter A.5 --- Scope of Allyl Diarylphosphonylation --- p.222 / Chapter A.6 --- Introduction of Allyl Arylation --- p.228 / Chapter A.7 --- Scope of Allyl Arylation --- p.229 / Chapter A.8 --- Conclusion --- p.232 / EXPERIMENTAL SECTION --- p.234 / Chapter REFERENCE OF APPENDIX (II) --- p.274 / Chapter NMR --- SPECTRA COMPOUNDS FOR APPENDIX (I) -ASYMMETRIC HYDROALKENYLATION --- p.280 / Chapter COMPOUNDSFOR APPENDIX (II) - --- APPLICATIONS OF ALLYL SILYL ETHER OBTAINED FROM HA CATALYST GENERATION: SELECTIVE PREPARATION OF ALLYL DIARYLPHOSPHONYLATION --- p.388
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Synthetic studies of carbocyclic nucleosides. / CUHK electronic theses & dissertations collectionJanuary 2012 (has links)
本文描述了以D-核糖為起始原料,通過分子內的Diels-Alder (IMDA) 反應來構建雙碳環,以及其在雙碳環核苷合成方面的研究。 / D-核糖 (20) 經丙酮化,乙烯化作用和乙二醇裂解反應 (在硅膠的輔助作用下)可以得到乳醇68。本文考察了通過不同的方法來合成關鍵中間體三烯65。三烯中間體 65 經氧化和環化,最終可以合成出雙環[4. 3. 0]壬烷結構的碳環物64。由D-核糖為起始原料,只需6 步驟就可以得到碳環物64[附圖]。 / 為了引入C -5'的羥基,進行了環氧化和環氧化物還原反應的研究。由碳環物64 開始通過10 至15 步,可以合成出一系列含新型的[4. 3. 0]結構碳環核苷59-62[附圖]。 / 以疊氮化炔的Huisgen 環加成反應(點擊化學)作為關鍵步,合成出一系列含新型的[4. 3. 0]結構碳環核苷利巴韋林類似物[附圖]。 / In this thesis, the construction of bicyclic carbocycle from D-Ribose via an intramolecular Diels Alder (IMDA) reaction and its application to the syntheses of carbobicyclic nucleosides are presented. / D-Ribose (20) underwent acetonation, vinylation, mild silica gel supported glycol cleavage to give the lactol 68. Different methods were studied in the synthesis of the key triene intermediate 65. Oxidation of the triene intermediate and employing IMDA reaction finally afforded the bicyclo[4.3.0]nonane framework carbocycle 64 in 6 steps from D-Ribose [With images]. / To install the C-5’ hydroxyl group, epoxidation and epoxide reduction reactions were studied and reported. A series of carbobicyclic nucleosides 59-62 with a novel bicyclo[4.3.0]nonane framework were synthesized from cycloadduct 64 in 10 to 15 steps [With images]. / The syntheses of a series of carbobicyclic ribavirin analogues with bicyclo[4.3.0]nonane framework using azide alkyne Huisgen cycloaddition (Click Chemistry) as the key step were also studied and reported [With images]. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Wong, Wing Ho Anthony. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 175-185). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Acknowledgment --- p.i / Table of Contents --- p.ii / Abstract --- p.iv / Abstract (Chinese Version) --- p.vi / Abbreviation --- p.vii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- General Background --- p.1 / Chapter 1.2 --- Conformation of nucleosides --- p.3 / Chapter 1.2.1 --- Conformation of conventional nucleosides --- p.3 / Chapter 1.2.2 --- Conformation of carbocyclic nucleosides --- p.7 / Chapter 1.3 --- Previous syntheses and development of conformationally locked carbocyclic nucleosides --- p.9 / Chapter 1.3.1 --- Synthesis of dideoxyribonucleosides in N conformation --- p.9 / Chapter 1.3.2 --- First enantioselective synthesis of 2’-Deoxyribonucleosides Analogues with N conformation --- p.10 / Chapter 1.3.3 --- Most recent synthesis of bicyclo[3.1.0]hexane system ribonucleoside analogue --- p.12 / Chapter 1.3.4 --- Synthesis of bicyclo[3.3.0]octane system carbocyclic nucleosides --- p.13 / Chapter 1.3.5 --- Synthesis of nucleosides with bicyclo[2.2.1]heptene/heptanes skeleton --- p.16 / Chapter 1.3.6 --- Synthesis of spirocarbocyclic nucleosides --- p.18 / Chapter 2 --- Results and Discussion --- p.20 / Chapter 2.1 --- Construction of Bicyclic Carbocycle via Intramolecular Diels-Alder Reaction (IMDA) --- p.20 / Chapter 2.1.1 --- Synthesis of triene precusor and the bicyclo[4.3.0]nonane framework --- p.21 / Chapter 2.1.2 --- Synthesis of triene precusor and the bicyclo[4.3.0]nonane framework using open chain approach --- p.27 / Chapter 2.1.3 --- Synthesis of triene precusor by the use of Wittig Reaction --- p.29 / Chapter 2.2 --- Attempted epimerization of C-6 position of the cycloadduct --- p.40 / Chapter 2.2.1 --- Attempted epimerization of cycloadduct 64 --- p.40 / Chapter 2.2.2 --- Attempted epimerization of saturated ketone 84 --- p.41 / Chapter 2.2.3 --- Attempted epimerization of diols 86 and 88 --- p.42 / Chapter 2.2.4 --- Attempted epimerize of dibenzyl ether 90 --- p.45 / Chapter 2.3 --- Synthesis of the target nucleosides --- p.47 / Chapter 2.3.1 --- Synthesis of alcohol 106 and 107 --- p.47 / Chapter 2.3.2 --- Attempted synthesis of target nucleosides by convergent method --- p.57 / Chapter 2.3.3 --- Synthesis of adenosine analogue 59 via linear methods --- p.62 / Chapter 2.3.4 --- Synthesis of thymidine analogue 60 and uridine analogue 61 --- p.68 / Chapter 2.3.5 --- Synthesis of citidine analogue 62 --- p.70 / Chapter 2.3.4 --- Attempted synthesis of guanosine analogue 63 --- p.75 / Chapter 2.4 --- Syntheses of ribavirin analogues by Click Chemistry --- p.78 / Chapter 2.4.1 --- Synthesis of 5’-deoxyribavirin analogues --- p.78 / Chapter 2.4.2 --- Synthesis of ribavirin analogues --- p.84 / Chapter 3 --- Conclusion --- p.89 / Chapter 4 --- Experimental Section --- p.95 / Chapter 5 --- References --- p.175 / Chapter 6 --- Appendix --- p.186 / X-ray crystallographic data and structures --- p.189 / NMR spectra --- p.207
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Biomimetic total synthesis of (±)-pallavicinolide A. / CUHK electronic theses & dissertations collectionJanuary 2009 (has links)
Dong, Jiaqiang. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 169-186). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.
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Synthesis feasibility and efficiency of post-modification of multifunctional dendrimers. / CUHK electronic theses & dissertations collectionJanuary 2010 (has links)
The synthetic efficacy of the dendrimer backbone rearrangement was examined by conducting heterogeneous Ramburg-Backlund rearrangements (alumina supported KOH, CBr2F2/THF/t-BuOH = 1/1/1) on dibenzylsulfone G3-CCSO2-dendrimer 141 and G3-CSO2C-dendrimer 142. Again, steric inhibition was found to play a prominent role in dictating the chemical reactivity of the sulfone moieties under heterogeneous conditions. The innermost sulfones in compound 141 were found to be relatively inert and at most only 1 out of the 3 sulfones could undergo the rearrangement, and the major product was the starting material. On the other hand, up to 3 or 4 of the intermediate layer sulfone moieties underwent the rearrangement reaction to give the triene-tris(sulfone) 145 or tetraene-bis(sulfone) 144 products. For the first time in the literature, conclusive mass spectral evidence was obtained to unveil the detailed outcome of such complex dendrimer backbone rearrangement reactions. / The synthetic efficiency of the dendrimer interior functional group conversion method was exemplified by converting the dibenzyl sulfide moieties in G3-CCS-dendrimer 68 and G3-CSC-dendrimer 69 to the corresponding dibenzyl sulfone under either heterogeneous (oxone in CH2Cl2) or homogeneous (35% H2O2 in CH2Cl2/HOAc) conditions. The effect of steric inhibition was prominent under the heterogeneous conditions as the solid oxone particles failed to penetrate into the dendrimer interior to initiate the oxidation reaction. On the other hand, dendrimers 68, 69 and 136 could be oxidized to the corresponding dibenzyl sulfones via the dibenzyl sulfoxides under homogeneous conditions. For the first oxidation to the dibenzyl sulfoxides, both compounds 68 and 69 proceeded with similar speed, indicating the similar steric environment between the innermost and intermediate layers of dibenzylsulfide moieties. On the other hand, the innermost dibenzyl sulfoxides in compound 68, in comparison to the dibenzyl sulfoxides in the middle layer in compound 69, underwent further oxidation to the dibenzyl sulfones with greater ease. This finding suggested that there were other factors, in addition to steric inhibition, in controlling the chemical reactivity of functional groups inside the dendrimer matrix. Our speculation was that the microenvironment polarity of the dendrimer interior could also play an important role in facilitating/retarding the diffusion of external chemical reagents into the interior of the dendrimer. / Two layer-block G3-CCS-dendrimer 68 and G3-CSC-dendrimer 69 with dibenzylsulfide functionalities embedded in the innermost and intermediate dendritic layers, respectively, were synthesized by a convergent method. The key steps involved in their constructions were Horner-Wadsworth-Emmons olefination and thiol-mediated alkylation reaction. A third target G3-SCC-dendrimer 70, with dibenzylsulfide moieties located in the outermost dendritic layer, could not be synthesized despite many attempts. A fourth model G3-SSS-dendrimer 136 containing 21 dibenzyl sulfone moieties in the innermost, middle and outermost layers was also prepared. All synthesized compounds were characterized by 1H and 13C nuclear magnetic resonance spectroscopy, mass spectrometry, elemental analysis and/or size exclusion chromatography. They were prepared in order to probe the feasibility of and the effect of dendritic shielding on two novel dendrimer synthesis methodologies, namely, dendrimer interior functional group conversion and dendrimer backbone rearrangement. / Cheng, Wing Sum. / Adviser: H. F. Chow. / Source: Dissertation Abstracts International, Volume: 73-01, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 117-124). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.
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