The reaction of 1-(diphenylphosphino)-2-(diphenylphosphito)benzene (PP*) and Os3(CO)10(ACN) has been investigated. A combined experimental and computational study on the isomerization of 1,2-Os3(CO)10[μ-1,2-Ph2P(C6H4)P(OPh)2] (A) and 1,1-Os3(CO)10[μ-1,2-Ph2P(C6H4)P(OPh)2] (B) and reversible ortho-metalation exhibited by the triosmium cluster B are reported. The subsequent conversion of cluster B to the hydrido cluster HOs3(CO)9[μ-1,2-PhP(C6H4-η1)C6H4P(OPh)2] (E) and the benzyne-substituted cluster HOs3(CO)8(µ3-C6H4)[μ-1,2-PhP(C6H4)P(OPh)2] (N) has been established. All of these new clusters have been isolated and fully characterized in solution by IR and NMR spectroscopy; in addition, X-ray diffraction analyses have been performed on the clusters A, B, J, and N. The ortho-metalation reaction that gives cluster E is shown to be reversible, and the mechanism has been probed using selectively deuterated PP* isotopomers. Kinetic and thermodynamic isotope data, in conjunction with DFT calculations, are presented that support the existence of an intermediate unsaturated cluster in the ortho-metalation reaction. Due to interest in the coordination chemistry of formamidines, the non-symmetric amidine ligands PhNC(Me)NHPri, PhNC(Et)NHPri, and (2,4,6-Me3C6H2)NC(Me)NHPri, have been synthesized, and their reaction with Os3(CO)10(MeCN)2 has been investigated. Of the twelve new clusters prepared in section, seven have been structurally characterized by X-ray crystallography.

Palladium-catalyzed reactions have become one of the most important tools in modern organic chemistry due to its ability to catalyze the formation of new carbon-carbon bonds. The aim of the work presented in this thesis was to develop new palladium(II)-catalyzed addition reactions. In this work, cyanamides were investigated as a new substrate to give aryl amidines as products. The first protocol developed employed aryltrifluoroborates as the aryl partner, and the insertion of the aryl group into un-, mono-, and di-substituted cyanamides was successful for a wide variety of aryltrifluoroborates. An alternative method of generating the necessary intermediate for insertion into the cyanamide is the decarboxylative formation of aryl-palladium from aryl carboxylic acids. A protocol was developed for this reaction, but was unfortunately limited to a small number of ortho-substituted electron-rich aryl carboxylic acids. The mechanism was investigated by the means of DFT calculations and ESI-MS studies, and the rate-determining step was suggested to be the 1,2-carbopalladation based upon those results. A translation of the batch protocol to continuous-flow conditions was also demonstrated. The ideal method of generating the aryl-palladium species is by C-H bond activation, and this approach was demonstrated with indoles, giving a variety of 3-amidinoindoles as products. The mechanism was investigated by DFT calculations and a plausible catalytic cycle was proposed. A continuous-flow application of a desulfitative palladium(II)-catalyzed addition to nitriles to give ketones was developed. In addition, different reactor materials were evaluated in the microwave heated reactor cavity. Thus the reaction was shown to proceed with microwave heating in a borosilicate glass and an aluminum oxide reactor, and also in conditions mimicking conventional heating in a silicon carbide reactor. Finally, a protocol was developed for the convenient synthesis of sodium aryl sulfinates from Grignard and lithium reagents using a solid sulfur dioxide source as a safe alternative to the gas. The products of this protocol can be used as aryl-palladium precursors by a desulfitative process.

Les trachycladindoles sont des composés naturels extraits de l’éponge marine Trachycladus laevispirulifer, récoltée au large de la grande baie sur de l’Australie.Cette famille composée de 7 membres, du trachycladindole A au trachycladindole G, présente des activités cytotoxiques intéressantes contre diverses souches de cellules cancéreuses comme le colon, le sein ou les poumons. C’est le trachycladindole E qui présentes les activités les plus intéressantes et donc sur lequel nous nous concentrerons.D’un point de vue chimique, tous les membres de cette famille présentent un squelette indolique substitué en position C2 par une fonction acide carboxylique et en position C3 par une guanidine cycle à 5 chaînons. La position C5 peut présenter un atome de brome alors que la position C6 peut porter un hydroxyle. Une méthode récemment développée au laboratoire permet l’introduction d’un groupemenet alkoxy et d’un atome d’azote sur un motif de type énamide. Cette méthode a été appliquée à la formation de la guanidine portée par la position C3.La synthèse d’un modèle simplifié des trachycladindoles, assurant la faisabilité de la formation de la guanidine au moyen de l’alkoxyamination, est décrite tout comme les efforts pour son application à la synthèse totale du trachycladindole E. Alors que nous essayions d’obtenir le motif énamide nécessaire à l’application de l’alkixyamination, nous avons observé un résultat surprenant qui nous a donné l’opportunité de développer une nouvelle réaction entre les indoles et les ynamides.Les ynamides sont des outils synthétiques puissants connus pour présenter à la fois un centre nucléophile et un centre électrophile. En effet, grâce à la délocalisation du doublet non liant de l’azote, la position α est électrophile alors que la position β est nucléophile.Nous avons observé que le traitement d’un indole par une base en présence d’un N-sulfonylynamide menait à une réactivité inhabituelle, formant exclusivement un Z-indoloéthènamide N-substitué. Etonnemment, la formation de ce composé serait le fruit d’une addition de l’atome d’azote de l’indole sur la position β, ce qui constitue formellement une réaction entre deux centres nucléophiles.Cette réactivité peut être inversée en modifiant les substituants sur l’atome d’azote de l’ynamide d’un sulfonamide pour un carbamate ou un acétamide. Dans ces cas, la réaction a lieu sur la position α de l’ynamide, accompagnée par la perde du groupement électro-attracteur, aboutissant à l’amidine correspondante. La post-fonctionnalisation des composés issus de ces transformations a été effectuée, permettant l’accès à des squelettes macrocycliques inédits. / The trachycladindoles are natural compounds extracted from the marine sponge Trachycladus laevispirulifer, harvested in the great south bay of Australia. This family presents 7 members, from trachycladindole A to trachycladindole G, which show interesting cytotoxic activities against diverse cancer cells e. g. colon, breast or lung. It is trachycladindole E which presents the most interesting activity and on which we will focus.From a chemical point of view, all the members of this family present an indolic scaffold substituted in C2 position by a carboxylic acid function and in C3 position by a five membered cyclic guanidine moiety. The C5 position may present a bromine atom while the C6 position may bear a hydroxyl.A method recently developed in our laboratory allows the introduction of an alkoxy and an amine moiety on an enamide scaffold. This method was applied to the formation of the guanidine borne by the C3 position. The synthesis of a simplified model of trachycladindole, insuring the formation of the guanidine using alkoxyamination, is described as well as the efforts toward its application to the natural product trachycladindole E.While trying to obtain the enamide moiety necessary for the application of the alkoxyamination, we observed a surprising result which gave us the opportunity to develop a new reaction between indoles and ynamides.Ynamides are powerful synthetic tools known to present both an electrophilic and a nucleophilic center. Thus, due to the delocalization of the nitrogen atom lone-pair, the α-position is electrophilic while the β-position is nucleophilic.We observed that the treatment of an indole by a base in presence of an N-sulfonyl-ynamide led to an unusual reactivity, giving birth exclusively to an N-substituted Z-indoloethenamide. Quite surprisingly, the formation of this compound arises from the addition of the indole nitrogen on the ynamide β-position, which formally constitutes a reaction between two nucleophilic centers. This reactivity can be reversed by varying the substituent on the ynamide nitrogen from sulfonamide to carbamate or acetamide. In these cases, the reaction takes place at the α-position of the ynamide, along with the loss of the EWG, leading to the corresponding amidine. The post-functionalization of the compounds arising from these transformations has been performed, allowing the access to unprecedented macrocyclic scaffolds.Mechanistic investigations using DFT calculations were carried out to understand how the reaction proceeds.

Palladium-catalyzed reactions have found widespread use in contemporary organic chemistry due to their impressive range of functional group tolerance and high chemo- and regioselectivity. The pioneering contributions to the development of the Pd-catalyzed C-C bond forming cross-coupling reaction were rewarded with the Nobel Prize in Chemistry in 2010. Today, this is a rapidly growing field, and the development of novel methods, as well as the theoretical understanding of the various processes involved are of immense importance for continued progress in this field. The aim of the work presented in this thesis was to develop novel palladium(0)- and palladium(II)-catalyzed reactions. The work involved in achieving this aim led to the development of a Mo(CO)6-mediated carbonylative Stille cross coupling reaction for the preparation of various deoxybenzoins. The protocol utilized convenient gas-free conditions to facilitate the carbonylative coupling of benzyl bromides and chlorides with aryl and heteroaryl stannanes. Mo(CO)6-assisted conditions were then used in the development of a general protocol suitable for the aminocarbonylation of aryl triflates. Both electron-poor and electron-rich triflates were coupled with primary, secondary and aryl amines. In addition, DMAP was found to be a beneficial additive when using sterically hindered or poorly nucleophilic amines. An efficient and convenient method for the synthesis of styrenes from arylboranes was developed, employing the relatively inexpensive vinyl acetate as the ethene source under Pd(II)-catalyzed conditions. The reaction mechanism was studied using ESI-MS, and a plausible catalytic cycle was proposed. A method for the oxidative Heck reaction employing aryltrifluoroborates and aryl MIDA boronates was also developed. Electron-rich and electron-poor olefins were regioselectively arylated under microwave-assisted conditions. Various arylboron species were identified in an ongoing reaction using ESI-MS.    Further investigations led to the development of a direct method for the synthesis of arylamidines from aryltrifluoroborates and cyanamides. Under Pd(II)-catalyzed conditions it was possible to insert the aryl into primary, secondary and tertiary cyanamides. Finally, a desulfitative method for the synthesis of aryl ketones was developed. A variety of aryl sulfinates were effectively inserted into alkyl- and aryl nitriles. The mechanism was further investigated using ESI-MS and a plausible catalytic cycle was proposed.

Diss. med. dent. Zürich. / Literaturverz.

Universiẗat, Diss., 2004--Jena.

Indiana University-Purdue University Indianapolis (IUPUI) / The DNA minor groove continues to be an important biological target in the development of anticancer, antiviral, and antimicrobial compounds. Among agents that target the minor groove, studies of well-established benzimidazole-based DNA binders such as Hoechst 33258 have made it clear that the benzimidazole-amidine portion of these molecules promotes an efficient, site-selective DNA association. Building on the beneficial attributes of existing benzimidazole-based DNA binding agents, a series of benzimidazole-amino acid conjugates was synthesized to investigate their DNA recognition and binding properties. In this series of compounds, the benzimidazole-amidine moiety was utilized as a core DNA “anchoring” element accompanied by different amino acids to provide structural diversity that may influence DNA binding affinity and site-selectivity. Single amino acid conjugates of benzimidazole-amidines were synthesized, as well as a series of conjugates containing 20 dipeptides with the general structure Xaa-Gly. These conjugates were synthesized through a solid-phase synthetic route building from a resin-bound amino acid (or dipeptide). The synthetic steps involved: (1) the coupling of 4-formylbenzoic acid to the resin-bound amino acid (via diisopropylcarbodiimide and hydroxybenzotriazole); followed by (2) introduction of a 3,4-diaminobenzamidoxime in the presence of 1,4-benzoquinone to construct the benzimidazole ring; and, finally, (3) reduction of the resin-bound amidoxime functionality to an amidine via treatment with 1M SnCl2•2H2O in DMF before cleavage of final product from the resin. The synthetic route developed and employed was simple and straightforward except for the final reduction that proved to be very arduous. All target compounds were obtained in good yield (based upon weight), averaging 73% mono-amino acid and 78% di-amino acid final compound upon cleavage from resin. Ultimately, the DNA binding activities of the amino acid-benzimidazole-amidine conjugates were analyzed using a fluorescent intercalator displacement (FID) assay and calf thymus DNA as a substrate. The relative DNA binding affinities of both the mono- and di-amino acid-benzimidazole-amidine conjugates were generally weaker than that of netropsin and distamycin with the dipeptide conjugates showing stronger binding affinities than the mono-amino acid conjugates. The dipeptide conjugates containing amino acids with positively charged side chains, Lys-Gly-BI-(+) and Arg-Gly-BI-(+), showed the strongest DNA binding affinities amongst all our synthesized conjugates.

<p>In this thesis work, two new CO₂-responsive monomers have been synthesized. These amidine-containing monomers were prepared in a simple and effective one-step reaction, giving a very high yield (98.5 %) of product. Furthermore, there was no complicated further purification required to obtain the highly pure product. The CO₂ switchability, conductivity and partitioning of the monomers were measured. It was confirmed that the monomers could be protonated CO₂ in the present of trace amount of water and reversibly switched back and forth to their natural forms by N₂ at room temperature.</p> <p>The polymers having different molecular weights were prepared from one monomer via conventional free radical polymerization method. The polymers also showed the reversible switchability property with CO₂ and N₂ stimuli. This was confirmed by the results of conductivity and partitioning tests. Temperature showed a major influence on the conductivity of the monomer and polymers. The effect of molecular weight on the polymer switchability of was further investigated through conductivity tests and potentiometric titration. The conductivity decreased with the increased molecular weight. The apparent equilibrium constant (pK_a)decreased with the degree of protonation (δ) suggesting that the basicity of the polymers is strongly depended on the value of δ.</p> / Master of Applied Science (MASc)

Plusieurs nouveaux complexes pinceurs de cobalt et de nickel ont été préparés avec le ligand pinceur de type POCOP : 2,6-(i-Pr2PO)2C6H4. Dans le cas du cobalt, une nouvelle voie de synthèse a été développée. Contrairement au cas du nickel, il s’agit ici de cobalt au degré d’oxydation +III. Les composés obtenus sont paramagnétiques. En outre, le dérivé bromé est instable à la lumière et se décompose en perdant un brome pour former le complexe pinceur de Co(II). La réactivité de ces complexes a été étudiée. Pour ce qui est du nickel, la catalyse de l’hydroamination a été élargie aux dérivés de l’acrylonitrile et aux amines aromatiques. En outre, la réaction d’hydroaryloxylation a été étudiée dans les mêmes conditions. Enfin, avec le 4-cyanostyrène et le cinnamonitrile, la formation d’amidines a été observée. Un complexe pinceur portant cette amidine a été isolé. Enfin, le cation réagit avec des anions fortement coordonnants tels le cyanure ou l’isocyanate. En outre, l’anion triflate peut être déplacé par l’eau, l’acrylonitrile et ses dérivés. Enfin, une réactivité particulière a été observée avec la morpholine, l’acétone et un mélange 1:1 aniline/triéthylamine. / A large variety of new POCOP pincer type complexes of cobalt and nickel have been prepared. All those complexes are based on the following POCOP pincer type ligand: 2,6-(i-Pr2PO)2C6H4 In the case of cobalt, a new synthetic pathway has been developped. Unlike nickel, complexes containing cobalt in the +III oxidation state are obtained, the mechanism of their formation remains unknown. These complexes are paramagnetic. The dibromo derivative is light-sensitive, decomposing by losing a bromine to form the Co(II) pincer complex. The reactivity of those complexes has been studied. Concerning nickel, the catalyzed hydroamination has been extended to the derivates of acrylonitrile, crotonitrile and methacrylonitrile and to aromatic amines. Moreover, hydroaryloxylation reaction has been studied under the same conditions. Finally, amidines formation was obtained with 4-cyanostyrene and with cinnamonitrile. A pincer complex bearing this amidine moiety has been isolated. The cationic complex reacts with strong coordinating anions like cyanide and isocyanate. Moreover, the triflate anion is displaced by water, acrylonitrile and acrylonitrile derivates. Finally, a particular reactivity has been observed with morpholine, acetone and a 1:1 mixture of aniline and triethylamine.

Les travaux de thèse retranscrits dans ce mémoire ont pour sujet l’élaboration de nouveaux ligands pour la coordination de métaux et l’application des complexes correspondants pour la catalyse et la thérapie.La première partie du manuscrit traite de l’élaboration de ligands phosphine-diène, de leurs analogues saturés et des complexes arène-ruthénium correspondants. Le départ d’arène permet au ligand phosphine-cycloheptadiène de former avec le ruthénium un complexe bimétallique cationique où le ligand est chélate κ-P/diène-η4. Ces complexes ont été appliqués en catalyse pour l’addition radicalaire par transfert d’atome (ATRA) de CCl4 au styrène. Lors de l’utilisation de conditions dures, la supériorité des complexes « diène » a pu être mise en évidence par rapport aux analogues saturés.La seconde partie rapporte le développement de nouveaux analogues de base de Schiff : les « salicylamidines ». L’utilisation de différentes voies de synthèse a permis d’obtenir plusieurs générations de ligands. Ils ont été utilisés pour la coordination de métaux et sont particulièrement adaptés à la formation de complexes avec le zinc et l’aluminium. Certains de ces composés ont été utilisés pour la polymérisation par ouverture de cycle (ROP) de lactides et ont démontré une bonne activité.La dernière partie concerne la synthèse et l’évaluation de complexes métalliques comme agents anticancéreux. Des complexes phosphine-or et phosphine-ruthénium ont été synthétisés et évalués pour leur activité antiproliférative. Les complexes phosphine-or présentent une activité remarquable, meilleure que le cisplatine. La nature de l’arène des complexes phosphine-ruthénium influe fortement sur leur activité, les dérivés « benzoate d’éthyle » donnent des cytotoxicités significativement meilleures que les analogues « p-cymène ». Des complexes de titane et de zirconium avec un ligand de type aza-dipyrrométhène ont été synthétisés. Une étude préliminaire de leurs propriétés photophysiques a été réalisée et a indiqué que les composés étaient fluorescents. L’étude de leur propriété anticancéreuse a démontré une faible cytotoxicité. / The subject of this thesis concerns the development of new ligands, their coordination chemistry, and the synthesis of the corresponding metal complexes for catalysis and therapy.The first part of this work relates to the synthesis of diene-phosphine ligands, their saturated analogs, and the corresponding arene-ruthenium complexes. Arene decoordination allows the formation of a cationic bimetallic complex where the ligand is diène-η4/κ-P coordinated to the ruthenium. These complexes have been applied to atom transfer radical addition (ATRA) of CCl4 to styrene. When harsh reaction conditions are used, the superiority of the “diene” complexes is highlighted comparing to saturated analogs.The second part concerns the development of new Schiff base analogs: the “salicylamidines”. Several ligand generations have been obtained following different synthetic paths. They have been used for metal coordination, and are especially well-suited for the formation of zinc and aluminium complexes. Some of the compounds have been applied to ring opening polymerization (ROP) of lactides, and demonstrated good activity.The last part reports on the synthesis and assessment of metal-based anticancer agents. Some phosphine-gold and phosphine-ruthenium complexes have been synthesized and tested for their antiproliferative activity on several cancer cell lines. The phosphine-gold complexes showed impressive activities, better than cisplatine. Activity of phosphine-ruthenium is strongly influenced by the nature of the arene, ethyl benzoate derivatives are significantly more cytotoxic than p-cymene ones. Titanium and zirconium complexes with aza-dipyrromethene ligand were synthesized. Preliminary photophysical study was performed and indicated fluorescence. Their anticancer properties were assessed, and they are only poorly cytotoxic.