by Fung Wing-chuen. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1994. / Includes bibliographical references (leaves 57-59). / Abstract --- p.i / Acknowledgments --- p.ii / Biography --- p.iii / Abbreviation --- p.v-vi / Chapter 1. --- Introduction / Chapter 1.1 --- Natural O-heterocycles --- p.1 / Chapter 1.2 --- Methods for the construction of O-heterocycles --- p.5 / Chapter 1.3 --- Intramolecular nitrone cycloaddition in the construction of O-heterocycles --- p.9 / Chapter 2. --- Results and discussion / Chapter 2.1 --- Introduction --- p.12 / Chapter 2.2 --- Synthesis of 68，77，84 Via INC --- p.13 / Chapter 2.3 --- Acyclic INC of nitrones --- p.16 / Chapter 2.4 --- "Studies on 7-, 8-membered rings formation" --- p.24 / Chapter 3. --- Conclusions --- p.29 / Chapter 4. --- Experimental --- p.34 / Chapter 5. --- References --- p.57 / Chapter 6. --- List of spectra --- p.60 / Chapter 7. --- Appendices --- p.72

Pang Sik Wing. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1979. / Bibliography: leaves 70-73. / Acknowledgement --- p.i / Abstract --- p.ii / Chapter Section I --- Introduction -- Annulenes, azaannulenes, bridged annulenes, and bridged azaannulenes --- p.1 / Chapter Section II --- Synthetic Plans --- p.19 / Chapter Section III --- Results and Discussions --- p.26 / Chapter Section IV --- Experimental --- p.51 / Bibliography --- p.70 / List of Spectra

by Yong-li Zhong. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (p. 234-246). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web.

Chapter one introduces N-heterocyclic carbenes (NHCs) and discusses their use as ligands for rare earth metal complexes, with particular emphasis upon compounds synthesised from 2009 until the present day. Chapter two details the synthesis and characterisation of the homoleptic scandium-NHC complex [Sc(L)3] (L = [OCMe2CH2(1-C{NCHCHNiPr})]). Reactions of [Sc(L)3] with boranes, CO2 and CS2 are described which exploit the relative lability of the Sc–Ccarbene bond and allow formation of [Sc(L)2(OCMe2CH2(1-B'C{NCHCHNiPr}))] (B' = 9-BBN, BPh3, B(C6F5)3, BH3), [Sc(OCMe2CH2(1-O2CC{NCHCHNiPr})3]n, [Sc(L)2(OCMe2CH2 (1-S2CC{NCHCHNiPr})] and [Sc(L)(OCMe2CH2(1-S2CC{NCHCHNiPr})2]2. The chapter also discusses the reactivity of [Sc(L)3] towards substrates containing acidic C–H and N–H bonds and substrates containing polar E–X bonds (where E = C, Si, B, P and X = Cl, I). Chapter three describes the synthesis and characterisation of the NHC substituted scandium benzyl complexes [Sc(Bn)2(L)]2 and [Sc(Bn)(L)2], and the attempted synthesis of NHC substituted scandium aminobenzyl complexes. The reactivity of [Sc(Bn)2(L)]2 with RX substrates (R = alkyl) is discussed in detail; depending on the nature of the alkyl group, these reactions can allow formation of R–Bn , the result of carbon-carbon coupling. The complex [Sc(Bn)(L)Cl]2 has been isolated from these reactions and is structurally characterised. The reactivity of [Sc(Bn)2(L)]2 towards C–H bonds is explored and attempts to prepare NHC substituted scandium hydrides are described. Comparisons of the relative stability and reactivity of [Sc(Bn)2(L)]2 and [Sc(Bn)3(thf)3] are drawn. Chapter four documents the synthesis and characterisation of [Sc(Odtbp)2(L)] (Odtbp = 2,6-di-tert-butylphenoxide), [Sc(Odtbp)(L)2], and the samarium analogue [Sm(Odtbp)(L)2]. The reactivity of these complexes towards various small molecules is described. The chapter also details attempts to prepare the cationic scandium complexes [Sc(L)2][Bort] (Bort = bis[3,3',5,5'-tetra-(tert-butyl)-2,2-diphenolato]borate) and [Sc(L)2][B(Ph)4]. Chapter five provides overall conclusions to the work presented in this thesis. Chapter six contains all experimental and characterising data for the complexes and reactions detailed in this work.

The primary aim of this project was to synthesize new heterocyclic dimers of isoflavones and flavones, and investigate various methodologies for their synthesis. The secondary aim of the project was to synthesize some flavonoid natural products. Dimeric systems were synthesized using various methodologies including acid catalyzed arylation of isoflavanols and flavanols, acid catalyzed dimerization of flavenes, oxidative dimerization, Sonogashira coupling, Ullmann coupling and Suzuki-Miyaura coupling reactions. The acid catalyzed arylation of isoflavanols was found to proceed in a very stereoselective fashion to give trans-4-arylisoflavans in good yield in a single step. However, related flavanols under similar conditions gave mixtures of cis and trans isomers of 4-arylflavans. Interestingly, it was found that appropriately substituted flavenes, upon treatment with acid undergo stereoselective rearrangement and dimerization to give benzopyranobenzopyrans in high yields. A rationale for the rearrangement is proposed and this dimerization was used for the stereoselective synthesis of the natural product dependensin. As part of the project, some polycyclic natural products such as octandrenolone, flemiculosin, 3-deoxy-MS-II and laxichalcone were also synthesized. Oxidative dimerization of activated isoflavones was found to be very regioselective, and novel isoflavone dimeric systems were synthesized. Related flavones however, failed to undergo dimerization under similar conditions. A probable explanation for high regioselectivity in the case of isoflavones and unreactivity of flavones has been presented. Phenol oxidative coupling was used for the one-step synthesis of another natural product kudzuisoflavone-A from daidzein. Sonogashira coupling was utilized for the synthesis of dimeric systems linked via an acetylic linker. A variety of soflavone isoflavone, flavone-flavone and isoflavone-flavone dimers were synthesized in "one-pot" by this methodology and in excellent yields. Although Ullmann coupling was found not to be suitable for the synthesis of isoflavone or flavone dimers, one-pot Suzuki-Miyaura methodology gave flavone dimers and various other heterocyclic dimers in good yields.

Four main series of novel heterocyclic compounds were successfully syniliesised. Two of these series were found to be post-emergence herbicides with the activities of each being based on a different mode of action. The (pyrazole-4-yl)alkanones are inhibitors of protoporphyrinogen oxidase, an enzyme in chlorophyll biosynthesis, whereas alkyl 3-arylsulfonylamino- 3-methyllhio-2-(pyrimidin-2-ylcarbamoyl)acrylates and pyrimidin-2-yl 3-(2- chlorophenyl)sulfonyl-amino-3-methylthio-2-cyanoacrylamides (collectively termed "vinylogous sulfonylureas") are inhibitors of acetohydroxy acid synthase (AHAS). an enzyme in branched-chain amino acid biosynthesis. Both these enzymes are established targets for current commercial herbicides. Studies of the utility of 2-(l-ethoxyalkylidene)-3-oxoaIkanenitriles (acrylonilriles) in heterocycle synthesis were facilitated by the recent development of a convenient route to these starting materials. Acrytonitriles were reacted with different hydrazines to give (pyrazol-4-yl)alkanones and pyrazole-4-carbonitriles in varying proportions depending on the reaction conditions and the substituents on the reactants. Although distinction between alternative 3- and 5-substituted pyrazoles is a perennial problem in pyrazole synthesis, in this case the products of these reactions were successfully characterised and identified using a range of n.m.r. spectroscopy techniques. Once the herbicidal mode of action of the (pyrazol-4-yl)alkanones had been confirmed, synthesis of a series of analogues allowed the structural elements contributing to biological activity to be identified. The reaction of acrylonitriles with bidetate nucleophiles such as thiourea gave novel pyrimidines. but these compounds were not herbicidal. The vinylogous sulfonylureas were synthesised using established procedures to obtain novel compounds structurally related to the commercial herbicide chlorsulfuron. The biological activity of the vinylogous sulfonylureas was found to be sensitive to apparently minor changes in structure, but x-ray crystallographically-generated structures of an active and an inactive member of the series revealed marked differences in conformation. Some of the vinylogous sulfonylureas were used as synthons for pyrazole and pyrazolopyrimidine derivatives. Although these compounds did not exhibit herbicidal activity, this synthesis provided the basis for some interesting chemistry. Unexpected elimination of the arylsulfonylamino group was observed when a vinylogous sulfonyurea was treated with methyl hydrazine. In order to confirm the identity of the 3-methylthiopyrazole product, model compounds were synthesised using alternative routes. The resulting pairs of 3- and 5-substituted pyrazoles were characterised using n.m.r spectroscopy.

207 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Organic Chemistry, 1981

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

This thesis deals with the synthesis of new organicmaterials for electronic applications. Several new ring-formingmethods are employed to construct sulphur heterocycles: Tandemelectrophilic aromatic substitution and acid-catalyzedtransetherification of methoxythiophene, double electrophilicaromatic substitutions with ethane-1, 2-disulphenyl chloride,and also, the reaction of dienes with sulphur dichloride. Twonew condensed thiophenes have been incorporated in end-cappedoligothiophenes. An improvement of the synthesis of [3,2-b:2’, 3-d]thiophene is reported, with some attempts toincorporate it in oligomers. A synthesis of substitutednaphthalenes is also described. A new method of producingdisubstituted thiophenes from substituted butadienes anssulphur dichloride is employed in a new route to 3, 4-ethylenedioxythiophene, a very important monomer for conductingpolymers. Keywords :Organic Semiconductors, Thiophenes,Heterocyclic Synthesis, Dithienothiophene, Naphthalene,Ethylenedioxythiophene

A range of N-H alkynylaziridines were prepared from amphoteric unprotected aziridine aldehydes without protecting-group manipulation. Unprotected alpha -amino allenes can be obtained from these strained propargyl amines via a 9-BBN mediated hydride transfer. Further transformation of alpha -amino allenes to 2,4,6-trisubstituted pyridines was realized. We also developed another class of amphoteric molecules – alpha-boryl aldehydes, equipped with the tetrahedral MIDA boryl group. A wide range of boryl-substituted building blocks or functionalized boronic acid derivatives have been accessed from these bench-stable alpha-borylcarbonyl compounds. Further chemoselective transformations of these alpha-boryl aldehyde derived building blocks have been conducted, where alph-boryl isocyanates, alpha-aminoboronic acids, acylboronates, and borylated heterocycles were achieved through the decarboxylative functionalization of alpha-borylcarboxylic acids.