[PDF] Chiral Iron Pyridine Complexes And Ruthenium Complexes With N Heterocyclic Carbene And Macrocyclic N O Donor Atom Ligands eBook

Author : Kar-Yee Lam
Publisher :
Page : pages
File Size : 14,36 MB
Release : 2017-01-26
Category :
ISBN : 9781361034422

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This dissertation, "Chiral Iron Pyridine Complexes and Ruthenium Complexes With N-heterocyclic Carbene and Macrocyclic (N, O) Donor Atom Ligands: Synthesis, Catalytic Activity and Biological Studies" by Kar-yee, Lam, 林嘉儀, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled CHIRAL IRON PYRIDINE COMPLEXES AND RUTHENIUM COMPLEXES WITH N-HETEROCYCLIC CARBENE AND MACROCYCLIC(N, O) DONOR ATOM LIGANDS: SYNTHESIS, CATALYTIC ACTIVITY AND BIOLOGICAL STUDIES Submitted by Lam Kar Yee For the degree of Doctor of Philosophy at The University of Hong Kong in April 2016 Transition metal complexes are widely applied as catalysts for organic transformation reactions such as the oxygen atom and nitrene transfer reactions and there is a growing interest to develop the medicinal applications of transition metal complexes. The studies of reactive metal-oxo and metal-nitrene intermediates are important in probing the underlying reaction mechanisms. This thesis is comprised of three main parts. In the first part, iron complexes with chiral pyridine ligands, such as 4′,6-disubstituted 2,2′ 6′,2″-terpyridine (NNN ) and 4′,6,6″-trisubstituted 2,2′ 6′,2″''-terpyridine (NNN ), were studied for their catalytic activities in asymmetric epoxidation, aziridination, amidation and sulfimidation reactions. The Fe-NNN complex catalyzed intermolecular nitrene transfer/CN bond formation reactions of styrenes with PhINTs in moderate product yields. For the asymmetric intramolecular amidation, the Fe-NNN complex can catalyze intramolecular C-N bond formation using PhI(OAc) as oxidant to form five- or six-membered ring products. The highest product yield obtained was 91 %. The complete conversion of para-substituted phenyl methyl sulfides to corresponding sulfimides was observed by using the Fe-NNN 1 2 complex as catalyst. Both the Fe-NNN and Fe-NNN complexes catalyzed asymmetric epoxidation of styrene using PhIO as oxidant at 0 C. The reaction intermediates of the nitrene/oxygen transfer reactions were studied by ESI-MS and high-valent iron-ligand multiple bonded species are proposed to be the reaction intermediates. In the second part, ruthenium pincer N-heterocyclic carbene (CNC) complexes were prepared and characterized by spectroscopic means and X-ray crystallography. II 2+ Complex [Ru (CNC)(bpy)(MeCN)], in which the CNC ligand adopts a fac-coordination mode and contains reactive CH bond of bridging methylene group, was found to react with PhINTs to result in the formation of a new CN bond and cleavage of one existing NC(methylene) bond of the CNC ligand, as revealed by X-ray crystal structure determination of the ruthenium complex product. The reaction 2+ of [Ru(CNC)(bpy)(MeCN)] with PhINTs was monitored by ESI-MS, UV-vis, and NMR spectroscopy; a paramagnetic Ru(III)-amido complex was isolated, which apparently resulted from intramolecular imido/nitrene CH insertion of a Ru(IV)-imido/nitrene intermediate and was found to undergo the observed CN bond cleavage. Such type of CN bond cleavage induced by metal-mediated imido/nitrene insertion is unprecedented in literature. The final part of this thesis is the study of the anti-angiogenic and anti-metastatic properties of the ruthenium complexes. Ruthenium complexes with different oxidation states (+2 and +3) and ligands (pincer NHC and macrocyclic (N, O) donor atom ligands) were examined for their cytotoxicity and anti-angiogenesis activity. III Among the complexes studied, [Ru (N O )Cl ]Cl (Ru-1) displays promising 2 2 2 inhibi

Author : Ka-Ho Chan
Publisher : Open Dissertation Press
Page : pages
File Size : 32,47 MB
Release : 2017-01-27
Category :
ISBN : 9781361379714

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This dissertation, "Ruthenium-N-heterocyclic Carbene and Ruthenium Acetylide Complexes Supported by Macrocyclic Porphyrin or Tetradentate Schiff Base Ligands: Synthesis, Structure and Catalytic Applications" by Ka-ho, Chan, 陳嘉豪, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled RUTHENIUM-N-HETEROCYCLIC CARBENE AND RUTHENIUM ACETYLIDE COMPLEXES SUPPORTED BY MACROCYCLIC PORPHYRIN OR TETRADENTATE SCHIFF BASE LIGANDS: SYNTHESIS, STRUCTURE AND CATALYTIC APPLICATIONS Submitted by Chan Ka Ho for the degree of Doctor of Philosophy at The University of Hong Kong in March 2015 Transition metal-catalyzed C-C and C-N bond formation reactions are important transformations in synthetic organic chemistry. In the endeavor of this thesis to develop robust/versatile catalysts for these reactions, the trans effect imposed by N-heterocyclic carbene (NHC) and acetylide ligand onto ruthenium complexes supported by macrocyclic porphyrin or tetradentate Schiff-base ligands was studied. The catalytic activity of these novel ruthenium complexes towards carbene and/or nitrene transfer and insertion reactions was also explored. II A series of bis(NHC)ruthenium(II) porphyrin complexes [Ru (Por)(NHC) ] were synthesized by deprotonation of imidazolium salt using a strong base. These complexes displayed unprecedentedly high catalytic activity towards carbene/nitrene transfer and insertion reactions, including alkene cyclopropanation and aziridination, carbene C-H, S-H, N-H and O-H insertions, and nitrene C-H insertion with product -1 turnover frequency up to 1950 min . Carbene modification of N-terminus of peptide o II at 37 C was achieved. Chiral [Ru (D -Por)(NHC) ] catalyst led to highly 4 2 enantioselective carbene/nitrene transfer and insertion reactions with up to 98% ee. DFT calculations revealed that the strong σ-donor strength of trans axial NHC ligand stabilizes the formation of metal-carbene and metal-nitrene intermediate from decomposition of diazo compounds and organic azides, which is crucial for the transition metal-catalyzed oxidative C-C and C-N bond formation reactions to proceed under mild reaction conditions. II A series of ruthenium Schiff-base complexes cis-β-[Ru (Schiff-base)(CO) ] were synthesized and characterized. These complexes showed high catalytic activity towards enantioselective cyclopropanation, carbene C-H and Si-H bond insertions. II t The cis-[Ru (2-CPh -4- Bu-Schiff-base)(CO) ]-catalyzed intermolecular 3 2 cyclopropanation of styrene with EDA in CH Cl afforded desired cyclopropane 2 2 product in 90% isolated yield and 95% ee with a product turnover number of 9000. Excellent trans- and high enantioselectivity were observed with wide substrate scope, including conjugated, electron-rich, electron-deficient and aliphatic terminal alkenes. Carbene C-H and Si-H insertion reactions proceeded smoothly with II t cis-[Ru (2-CPh -4- Bu-Schiff-base)(CO) ] as catalyst, giving the desired products in 3 2 82-97% yields with excellent enantioselectivity (up to 99% ee). The same complex was also catalytically active towards intramolecular cyclopropanation and intramolecular alkyl carbene sp C-H bond insertion to give cis-products with up to 99:1 cis: trans ratio and with excellent enantioselectivities (up to 98% ee). DFT calculations on the intermolecular cyclopropanation catalyzed by II cis-β-[Ru (Schiff-base)(CO) ] revealed that among the ruthenium-carbene intermediates possibly involved in the reactions, the cis-β species are more stable than their trans isomer with

Author : Belakatte Parameshwarappa Nandeshwarappa
Publisher : BoD – Books on Demand
Page : 250 pages
File Size : 46,14 MB
Release : 2020-05-27
Category : Science
ISBN : 1789859433

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The book ‘Organic Synthesis - A Nascent Relook’ is a compendium of the recent progress in all aspects of organic chemistry including bioorganic chemistry, organo-metallic chemistry, asymmetric synthesis, heterocyclic chemistry, natural product chemistry, catalytic, green chemistry and medicinal chemistry, polymer chemistry, as well as analytical methods in organic chemistry. The book presents the latest developments in these fields. The chapters are written by chosen experts who are internationally known for their eminent research contributions. Organic synthesis is the complete chemical synthesis of a target molecule. In this book, special emphasis is given to the synthesis of various bioactive heterocycles. Careful selection of various topics in this book will serve the rightful purpose for the chemistry community and the industrial houses at all levels.

Author : Walter Kaminsky
Publisher : Wiley-VCH
Page : 0 pages
File Size : 38,33 MB
Release : 2006-08-18
Category : Technology & Engineering
ISBN : 9783527317424

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With an enormous velocity, olefin polymerization has expanded to one of the most significant fields in polymers since the first industrial use about 50 years ago. In 2005, 100 million tons of polyolefins were produced - the biggest part was catalyzed by metallorganic compounds. The Hamburg Macromolecular Symposium 2005 with the title "Olefin Polymerization" involved topics such as new catalysts and cocatalysts, kinetics, mechanism and polymer reaction engineering, synthesis of special polymers, and characterization of polyolefins. The conference combined scientists from different disciplines to discuss latest research results of polymers and to offer each other the possibility of cooperation. This is reflected in this volume, which contains invited lectures and selected posters presented at the symposium.

Author : Steven Alan Cramer
Publisher :
Page : 0 pages
File Size : 48,51 MB
Release : 2014
Category : Ligand binding (Biochemistry)
ISBN :

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A small ringed macrocyclic tetracarbene ligand was developed due to the inherent ability of N-heterocyclic carbenes (NHCs) to stabilize high oxidation states of transition metals. This new strong donor ligand was prepared by first synthesizing an 18-atom ringed macrocyclic tetraimidazolium ligand precursor. The tetraimidazolium can be prepared by a two-step procedure. This ligand precursor was deprotonated to prepare a monomeric platinum tetracarbene complex. A new iron macrocyclic tetra-carbene complex was synthesized by an in situ strong base deprotonation strategy of the ligand precursor. The iron tetracarbene complex was found to catalyze the aziridination of a wide array of functionalized aryl azides and a variety of substituted aliphatic alkenes, including tetra-substituted. The aziridination intermediate was probed by mass spectrometry and found to likely be and iron(IV) imido. Further investigation of this intermediate discovered that the an iron(IV) tetrazene forms when excess aryl azide was added, probably by a 1,3-cycloaddition of an additional equivalent of azide to an imido. Utilizing single crystal X-ray diffraction, NMR spectroscopy, and Mossbauer spectroscopy the metal center was formally assigned as a low spin (S = 0) iron(IV). Additional reactivity studies indicates this tetrazene is capable of performing aziridination and therefore is an additional reaction pathway in the catalytic cycle. A large disadvantage of the aforementioned iron tetracarbene catalyst is poor yield. To overcome low yields and to prepare several transition metal tetracarbene complexes, a dimeric macrocyclic tetracarbene silver complex was synthesized. This complex was shown to successfully extend transmetallation of polydentate NHCs beyond bidentate NHCs. The silver complex was utilized in the preparation of a variety of mononuclear tetracarbene complexes ranging from early first row to late third row transition metals in moderate to high. In an attempt to move toward improving solubility of the tetracarbene catalysts, a second generation variant with two borate moieties in the ligand backbone was utilized. With this dianionic 18-atom macrocyclic tetracarbene ligand, the first tetracarbene complexes of Group 13 and 14 metals were synthesized. The tin, indium, and aluminium tetracarbene complexes are structurally analogous to their catalytically active porphyrin or salen analogues.

Author : LAI-MING ELLA. WONG
Publisher :
Page : pages
File Size : 13,58 MB
Release : 2017-01-27
Category :
ISBN : 9781361426647

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This dissertation, "Iron and Ruthenium Complexes With Nitrogen and Oxygen Donor Ligands for Anti-cancer and Anti-viral Studies" by Lai-Ming, Ella, Wong, 黃禮明, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled IRON AND RUTHENIUM COMPLEXES WITH NITROGEN AND OXYGEN DONOR LIGANDS FOR ANTI-CANCER AND ANTI-VIRAL STUDIES Submitted by Ella Lai-Ming Wong For the degree of Doctor of Philosophy at The University of Hong Kong in February 2006 Development of drug resistance in cancer chemotherapy has stimulated the search for new anti-cancer drugs. Due to the versatile oxidation states and diverse coordination chemistry, iron and ruthenium compounds are potential candidates for new anti-cancer agents and metallopharmaceuticals. In this study, iron(II) complexes containing polypyridines as auxiliary ligand and ruthenium-oxo oxalato cluster were synthesized and characterized by X-ray crystallography, and their anti-cancer and anti-viral properties were examined. The iron(II) complexes, [Fe(R-qpy)(CH CN) ](ClO ) [qpy = 3 2 4 2 2,2′ 6′,2″ 6″,2′″ 6′″,2″″-quinquepyridine, R = H (1a) and Ph (1b)] and [Fe(Py -OH)(CH CN)](ClO ) (2) [Py-OH = 5 3 4 2 5 2,6-bis[hydroxybis(2-pyridyl)methyl]pyridine] were stable in physiological buffers and exhibited significant cytotoxicities against some established human cancer cell lines. According to the MTT assay, their IC values were 0.1 - 70 50 M; they exhibited more pronounced cytotoxicities against hepatocellular carcinoma cells than against other type of cancer cells. Flow cytometry studies revealed that 1a could cause cell cycle arrest of HeLa cells at the S-phase, which involved DNA synthesis. Complex 1a was found to catalyze epoxidation, aziridination and amidation of hydrocarbons with good substrate conversions and high product yields. The iron(IV)-oxo and -imido reactive intermediates were generated in situ and their formulations were verified by mass spectroscopy. By Evan''s method, the result supported the iron(IV) formulation with a low-spin d electronic configuration (S = 1). A ruthenium-oxo oxalato cluster formulated as Na [Ru ( -O) (C O ) ] (3) 7 4 3 4 2 4 6 was prepared. Structural studies and magnetic measurements revealed that the ruthenium atoms adopted the oxidation states of +III, +III, +III and +IV. Complex 3 showed anti-HIV properties on infected cells. Using the HIV-1(BaL) virus infected Hut/CCR5 cells, 3 was found to exhibit >90% inhibition on viral replication at 5 M concentration. Similar findings were obtained with other HIV-infected cell lines including GHOST/CXCR4 and PBMCs. Complex 3 was non-cytotoxic to these cells even at 50 M concentration. Relevant to anti-HIV activity, 3 was found to inhibit HIV-1 reverse transcriptase activity in vitro with IC = 2 nM. 50 III A series of ruthenium complexes, cis-[Ru (Me -tet)Cl ]ClO [Me -tet = 6 2 4 6 N, N, N′, N′-tetramethyl-3,6-dimethyl-3,6-diazaoctane-1,8-diamine], III III trans-[Ru (pyz) Cl]Cl (pyz = pyrazole), trans-[Ru (3Mepyz) Cl ]Cl 4 2 4 2 II III [3Mepyz = 3-methylpyrazole], [Ru (3Mepyz) ]Cl, [Ru (salen)(H O) ]Y 6 2 2 2 [H-salen = N, N''-bis(salicylidene)ethylenediamine, Y = Cl and PF ], 2 6 III cis-[Ru (cyclen)Cl]Cl [cyclen = 1,4,7,10-tetraazacyclododecane], 2III trans-[Ru (BiIml) Cl]Y [BiIml = biimidazole, Y = Cl and PF], and 2 2 6 II cis-[Ru (BiIml) (DMSO) ](ClO ) were examined for anti-cancer activities. 2 2 4 2 Their IC values were 4 - 100 M and their cytotoxicities could be affected by 50 the auxiliary ligands. The reduction potentials of the ruthenium compounds were +/0 in

Author : Steven P. Nolan
Publisher : John Wiley & Sons
Page : 330 pages
File Size : 50,72 MB
Release : 2006-10-27
Category : Science
ISBN : 9783527314003

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This first handbook to focus solely on the application of N-heterocyclic carbenes in synthesis covers metathesis, organocatalysis, oxidation and asymmetric reactions, along with experimental procedures. Written by leading international experts this is a valuable and practical source for every organic chemist.