A natural phenomenon characterized by dense aggregations of unicellular photosynthetic marine organisms has been termed colloquially as red tides because of the vivid discoloration of the water. The dinoflagellate Karenia brevis is the cause of the Florida red tide bloom. K. brevis produces the brevetoxins, a potent suite of neurotoxins responsible for substantial amounts of marine mammal and fish mortalities. When consumed by humans, the toxin causes Neurotoxic Shellfish Poisoning (NSP). The native function of brevetoxin within the organism has remained mysterious since its discovery. There is a need to identify factors which contribute to and regulate toxin production within K. brevis. These toxins are produced and retained within the cell implicating a significant cellular role for their presence. Localization of brevetoxin and identification of a native receptor may provide insight into its native role as well as other polyether ladder type toxins such as the ciguatoxins, maitotoxins, and yessotoxins. In higher organisms these polyether ladder molecules bind to transmembrane proteins with high affinity. We anticipated the native brevetoxin receptor would also be a transmembrane protein. Photoaffinity labeling has become increasingly popular for identifying ligand receptors. By attaching ligands to these photophors, one is able to activate the molecule after the ligand binds to its receptor to obtain a permanent linkage between the two. Subsequent purification provides the protein with the ligand directly attached. A molecule that is capable of fluorescence is a fluorophore, which upon excitation is capable of re-emitting light. Fluorescent labeling uses fluorophores by attaching them covalently to biologically active compounds. The synthesis of a brevetoxin photoaffinity probe and its application in identifying a native brevetoxin receptor will be described. The preparation of a fluorescent derivative of brevetoxin will be described and its use in localizing the toxin to an organelle within K. brevis. In addition, the general utility of a synthesized photoaffinity label with other toxins having similar functionality will be described. An alternative synthetic approach to a general photoaffinity label will also be discussed whose goal was to accelerate the preparation and improve the overall synthetic yields of a multifunctional label.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-01-04T13:24:36Z No. of bitstreams: 1 daniellelobojustopinheiro.pdf: 4869021 bytes, checksum: b4acfc12a41a6f83bf195e5947ae47cc (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-01-25T15:55:49Z (GMT) No. of bitstreams: 1 daniellelobojustopinheiro.pdf: 4869021 bytes, checksum: b4acfc12a41a6f83bf195e5947ae47cc (MD5) / Made available in DSpace on 2016-01-25T15:55:49Z (GMT). No. of bitstreams: 1 daniellelobojustopinheiro.pdf: 4869021 bytes, checksum: b4acfc12a41a6f83bf195e5947ae47cc (MD5) Previous issue date: 2015-03-31 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Carboidratos têm sido utilizados como organocatalisadores em síntese orgânica devido a sua quiralidade intrínseca. Neste trabalho foi sintetizado um novo organocatalisador aproveitando a estrutura da D-galactose como indutor de quiralidade. A síntese ocorreu em cinco etapas, a saber: proteção seletiva das hidroxilas das posições 1, 2, 3 e 4, seguida pela iodação da posição 6, substituição nucleofílica pelo grupo azido, redução à amina e por fim uma reação com anidrido ftálico. O rendimento global foi de 60 %. O organocatalisador foi testado na reação de adição de Michael entre o dibenzilideno acetona e a azalactona derivada da alanina. 20 mol% do catalisador conduziu ao produto com 57 % de rendimento e com total controle da régio- e diasteroseletividade. No escopo, vários produtos com funcionalização no esqueleto de dbas foram preparados e devidamente caracterizados pelas técnicas convencionais de análise. A determinação da estereoquímica relativa foi realizada através do uso de HPLC com fase estacionária quiral e foi atribuída como 1,2-anti após a comparação do tempo de retenção com um padrão já descrito na literatura. De maneira geral, é reportada, pela primeira vez, uma metodologia mais geral para a dessimetrização diasterosseletiva entre dbas e azalactonas catalisadas por ácido de Brønsted. / Carbohydrates have been used as organocatalysts in organic synthesis due to its inherent chirality. In this work, D-galactose was choose as a chiral pool in the catalyst design and it was prepared in five steps: selective ketalyzation of hydroxyl groups, following by an iodination and nucleophilic substitution in the presence of azide. To complete, reduction of the azide to amine and a coupling reaction with phthalic anhydride leading to the catalyst. Overall yield was 60 % for five steps. Then, the catalyst was adopted in the Michael addition reaction between dibenzylidene acetone and azalactone derivative of alanine. The product was obtained in 57% yield and with fully control of both regio- and diastereoselectivity. Next, various funcionalizated dbas were evaluated under the optimized reaction condition and the corresponding final products were fully characterized through conventional elemental analysis. The relative stereochemistry was assigned as being 1,2-anti by using chiral HPLC method. To this end, an authentic sample already described in the literature was prepared in order the retention time. In general, for the first time, a method more general to perform a diastereoselective dessymetrization of dbas in presence of azlactones by using a Brønsted acid as catalyst was described.

O trabalho de tese é dividido em dois capítulos e visou explorar a química das diazocetonas α,β-insaturadas bem como dos ilídeos β-cetosulfoxônios. No primeiro capítulo é apresentado o emprego das diazocetonas α,β-insaturadas como novos aceptores em reações de aza-Michael. A adição conjugada de aminas primárias e secundárias foi explorada, assim como o uso de aminas quirais para avaliar a versão assimétrica da reação. Além da formação desses adutos, também foram investigadas estratégias para a construção de heterocíclicos nitrogenados a partir destes ou via protocolos \"one-pot\" (partindo das diazocetonas α,β-insaturadas) levando à formação de 2- e 3-pirrolidinonas. Por fim, foi avaliada a aplicação da metodologia desenvolvida na síntese do produto natural Barmumicina. O segundo capítulo se dispôs a investigar o emprego dos ilídeos β-cetosulfoxônios como substitutos de compostos diazocarbonílicos em reações de inserção. Num primeiro momento, avaliaram-se reações de inserção S-H intermolecular, visando a construção do fragmento β-cetotioéter. Alguns estudos competitivos e mecanísticos, bem como estratégias assimétricas também compõem o escopo. Num segundo momento, os ilídeos foram empregados em reações de inserção N-H intramolecular, no qual, a partir de sulfoxônios derivados de aminoácidos, vislumbrou-se a formação de 3-azetidinonas. / This thesis is divided into two chapters which are related to the chemistry of α,β-unsaturated diazoketones and β-ketosulfoxonium ylides. The first chapter presents the utility of α,β-unsaturated diazoketones as new aza-Michael acceptors. Conjugate addition of primary and secondary amines was explored, as well as the use of chiral amines to evaluate the asymmetric version of the reaction. In addition to the formation of these adducts, it was also investigated some strategies for the synthesis of 2- and 3-pyrrolidinones via the \"one-pot\" protocols (starting directly from the α,β-unsaturated diazoketones). Finally, the synthesis of the natural product Barmumicyn was evaluated from this methodology. The second chapter aimed to investigate the use of β-ketosulfoxonium ylides as diazocarbonyl compounds substitutes in insertion reactions. At first, the intermolecular S-H insertion reaction was studied aiming the construction of the β-ketothioether fragment. Some competitive and mechanistic studies, as well as asymmetric versions are also part of the scope. Secondly, some ylides were also employed in intramolecular N-H insertion reactions (from sulfoxonium amino acid derivatives) aiming the formation of 3-azetidinones.

No description available.

Non-covalent interactions including nucleobase hydrogen bonding and phosphonium/ammonium ionic aggregation were studied in block and random polymers synthesized using controlled radical polymerization techniques such as nitroxide mediated polymerization (NMP) and reversible addition-fragmentation chain transfer polymerization (RAFT). Non-covalent interactions were expected to increase the effective molecular weight of the polymeric precursors through intermolecular associations and to induce microphase separation. The influence of non-covalent association on the structure/property relationships of these materials were studied in terms of physical properties (tensile, DMA, rheology) as well as morphological studies (AFM, SAXS). Ionic interactions, which possess stronger interaction energies than hydrogen bonds (~150 kJ/mol) were studied in the context of phosphonium-containing acrylate triblock (ABA) copolymers and random copolymers. Phosphonium-containing ionic liquid monomers with different alkyl substituent lengths and counterions enabled an investigation of the effects of ionic aggregation of phosphonium cations on the polymer physical properties. The polymerization of styrenic phosphonium-containing ionic liquid monomers using a difunctional alkoxyamine initiator, DEPN2, afforded an ABA triblock copolymer with an n-butyl acrylate soft center block and symmetric phosphonium-containing external reinforcing blocks. Small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) of triblock copolymers revealed pronounced microphase separation at the nanoscale. Phosphonium aggregation governed block copolymer flow activation energies. In random copolymers, the phosphonium cations only weakly aggregated, which strongly depended on the length of alkyl substituents and the type of counterions. Acrylate random copolymers consisting of quaternary ammonium functionalities were synthesized using reversible addition-fragmentation chain transfer polymerization (RAFT). The obtained copolymers possessed controlled compositions and narrow molecular weight distributions with molecular weights ranging from Mn =50,000 to 170,000 g/mol. DMA evidenced the weak aggregation of ammonium cations in the solid state. Additionally, this ionomer was salt-responsive in NaCl aqueous solutions. Hydrogen bonding, a dynamic interaction with intermediate enthalpies (10-40 kJ/mol) was introduced through complementary heterocyclic DNA nucleobases such as adenine, thymine and uracil. Our investigations in this field have focused on the use of DNA nucleobase pair interactions to control polymer self-assembly and rheological behavior. Novel acrylic adenine- and thymine-containing monomers were synthesized from aza-Michael addition reaction. The long alkyl spacers between nucleobase and polymer backbone afforded structural flexibility in self-assembly process. Adenine-containing polyacrylates exhibited unique morphologies due to adenine-adenine π-π interactions. The complementary hydrogen bonding of adenine and thymine resulted in disruption of adenine-adenine π-π interactions, leading to lower plateau modulus and lower softening temperatures. Moreover, hydrogen bonding interactions enabled the compatibilization of complementary hydrogen bonding guest molecules such as uracil phosphonium chloride. / Ph. D.

Cyanoform (tricyanomethane) is one of the strongest carbon-based organic acids reported in text books of organic chemistry, which has evaded synthesis and isolation in its free state, since 120 years. In this dissertation, the acid-free synthesis of cyanoform by an absolutely new approach has been discussed. Generation of the elusive molecule, cyanoform from the photolysis and thermolysis of 2-(azidomethylidene)malononitrile, has been confirmed at very low temperatures by 1H NMR, 13C NMR, 15N NMR, and the relevant 2D NMR spectroscopic techniques. Moreover, it has been proved that cyanoform is relatively stable, but can be detected only below –85 oC, and not at high temperatures (at –45 oC, as has been reported in literature), because of a rapid equilibration with an another species. Furthermore, the chemistry of cyanoform in the ring enlargement reactions with various highly strained epoxides, azirines, and aziridines, via the highly reactive dicyanoketenimine intermediate, as well as its Michael addition reactions with different α,β-unsaturated carbonyl compounds has been well explored. In addition, the synthesis of N1-substituted 1,2,3-triazoles and study of their rearrangement to the corresponding N2-substituted 1,2,3-triazoles, under thermal and nucleophile-catalyzed reaction conditions, has been well investigated. / Cyanoform (Tricyanomethan) ist eine der stärksten in der Literatur beschriebenen organischen Kohlenstoffsäuren, welche sich seit 120 Jahren einer erfolgreichen Synthese und Isolierung entzogen hat. In dieser Arbeit wird die säurefreie Synthese des Cyanoforms mittels eines neuartigen Ansatzes diskutiert. Die Bildung des schwer fassbaren Moleküls durch Photolyse und Thermolyse von 2 (Azidomethyliden)malonitril ist bei tiefen Temperaturen durch 1H-NMR, 13C-NMR, 15N-NMR und relevante 2D-NMR-Methoden bestätigt worden. Es konnte bewiesen werden, dass Cyanoform relative stabil ist, aber erst unterhalb von –85 °C detektierbar ist und nicht bereits bei hӧherer Temperature (bei –45 °C, wie es in der Literatur beschrieben wurde) bedingt durch die rasche Äquilibrierung mit einer weiteren Species. Des Weiteren wurde die Reaktivität von Cyanoform in Ringerweiterungsreaktionen mit verschiedenen, stark gespannten Epoxiden, Azirinen und Aziridinen untersucht, wobei das hoch reaktive Dicyanoketenimin-Intermediat durchlaufen wird. Auch die Michael-Addition an α,β ungesättigte Carbonylverbindungen wurde ausführlich untersucht. Zusätzlich wurde die Synthese N1 substituierter 1,2,3-Triazole und deren Umlagerung in N2 substituierte 1,2,3-Triazole unter thermischen und nucleophil-katalysierten Bedingungen erforscht.

Im Gegensatz zu „festen Säuren“ sind „feste Basen“ wesentlich seltener Untersuchungsgegenstand in ihrer Anwendung als Katalysatoren in der heterogenen Katalyse. In der vorliegenden Promotionsarbeit wurden entgegen diesem Trend die Herstellung, Charakterisierung und Anwendung basischer Oxide sowie modifizierter Oxide in ihrer Eignung als feste Basen in der Katalyse untersucht. Zu diesen Katalysatoren gehören MgO, hergestellt nach unterschiedlichen Methoden, Kalium modifiziertes ZrO2, calcinierte Mg-Al Hydrotalcite und ein neuartiges Katalysatorsystem auf der Basis von Mg(O,F)-Kompositionen, die zum ersten Mal nach einem Sol-Gel-Fluorierungsverfahren hergestellt wurden. Die Katalysatoren wurden mittels N2 Adsorptions/Desorptionsuntersuchungen (BET), XRD, FTIR, XPS, TG-DTA-DTG und MAS NMR untersucht. Die Säure-Basen-Eigenschaften der Katalysatoren wurden durch TPD, FTIR Spektroskopie und Mikrokalorimetrie charakterisiert und mit den katalytischen Eigenschaften korreliert. Calcinierte Mg-Al Hydrotalcite und Mg(O,F) waren in diesem Zusammenhang am stärksten aktiv und auch selektiv wie für die Flüssigphasenreaktion der Michael-Addition von CH aciden Verbindungen mit Methylvinylketon gezeigt wurde. / In contrast to solid acid catalysts, much fewer efforts have been made to study solid base catalysts. In this thesis, preparation, characterization and application of oxides and modified oxide as solid base catalysts were studied. The catalysts include MgO prepared by different methods, potassium-modified ZrO2, calcined Mg-Al hydrotalcites, and a novel catalyst system Mg(O,F), which was prepared by sol-gel method for the first time. The catalysts were studied by N2 adsorption/desorption measurement, XRD, FTIR, XPS, TG-DTA-DTG and NMR. Acid-base properties of the catalysts were investigated by TPD, FTIR spectroscopy and microcalorimetry to correlate with the catalytic behavior. Calcined Mg-Al hydrotalcite and Mg(O,F) are found to be highly active and selective catalysts for liquid-phase Michael additions of CH-acid compounds with methyl vinyl ketone.

Cyanoform (tricyanomethane) is one of the strongest carbon-based organic acids reported in text books of organic chemistry, which has evaded synthesis and isolation in its free state, since 120 years. In this dissertation, the acid-free synthesis of cyanoform by an absolutely new approach has been discussed. Generation of the elusive molecule, cyanoform from the photolysis and thermolysis of 2-(azidomethylidene)malononitrile, has been confirmed at very low temperatures by 1H NMR, 13C NMR, 15N NMR, and the relevant 2D NMR spectroscopic techniques. Moreover, it has been proved that cyanoform is relatively stable, but can be detected only below –85 oC, and not at high temperatures (at –45 oC, as has been reported in literature), because of a rapid equilibration with an another species. Furthermore, the chemistry of cyanoform in the ring enlargement reactions with various highly strained epoxides, azirines, and aziridines, via the highly reactive dicyanoketenimine intermediate, as well as its Michael addition reactions with different α,β-unsaturated carbonyl compounds has been well explored. In addition, the synthesis of N1-substituted 1,2,3-triazoles and study of their rearrangement to the corresponding N2-substituted 1,2,3-triazoles, under thermal and nucleophile-catalyzed reaction conditions, has been well investigated. / Cyanoform (Tricyanomethan) ist eine der stärksten in der Literatur beschriebenen organischen Kohlenstoffsäuren, welche sich seit 120 Jahren einer erfolgreichen Synthese und Isolierung entzogen hat. In dieser Arbeit wird die säurefreie Synthese des Cyanoforms mittels eines neuartigen Ansatzes diskutiert. Die Bildung des schwer fassbaren Moleküls durch Photolyse und Thermolyse von 2 (Azidomethyliden)malonitril ist bei tiefen Temperaturen durch 1H-NMR, 13C-NMR, 15N-NMR und relevante 2D-NMR-Methoden bestätigt worden. Es konnte bewiesen werden, dass Cyanoform relative stabil ist, aber erst unterhalb von –85 °C detektierbar ist und nicht bereits bei hӧherer Temperature (bei –45 °C, wie es in der Literatur beschrieben wurde) bedingt durch die rasche Äquilibrierung mit einer weiteren Species. Des Weiteren wurde die Reaktivität von Cyanoform in Ringerweiterungsreaktionen mit verschiedenen, stark gespannten Epoxiden, Azirinen und Aziridinen untersucht, wobei das hoch reaktive Dicyanoketenimin-Intermediat durchlaufen wird. Auch die Michael-Addition an α,β ungesättigte Carbonylverbindungen wurde ausführlich untersucht. Zusätzlich wurde die Synthese N1 substituierter 1,2,3-Triazole und deren Umlagerung in N2 substituierte 1,2,3-Triazole unter thermischen und nucleophil-katalysierten Bedingungen erforscht.

Résumé: Dans le but de préparer des complexes de Zr pour la catalyse homogène de la polymérisation des lactides et de l’hydroamination des olefines, l’elaboration et l’optimisation d’une méthode systématique et efficace de synthèse des ligands dikétimines ayant différents substituants alkyles (R) à la position N,N’ a été realisée. Des dikétimines (nacnacRH) symétriques ont été obtenus avec une pureté de plus de 95 % et un rendement de 65 % lorsque R = Me et des rendements allant de 80 à 95 % lorsque le groupe R = n-Pr, i-Pr, i-Bu, Bu, Cy et (+)-CH(Me)Ph. La synthèse des dikétimines ayant des substituants N-alkyls différents, dite asymétriques, donne toujours un mélange statistique de trois ligands: nacnacR,R’H, nacnacR,RH et nacnacR’,R’H qui n’ont pu être separés. Seuls les dikétimines asymétriques avec un substituant N-alkyl et un autre N-aryl (nacnacR,ArH) ont été obtenus avec des rendements plus élevés que celui du mélange statistique. Par la suite, la complexation de ces ligands bidentés au Zr, la caractérisation de ces complexes et l’investigation de la réactivité ont été étudiés. Les complexes de Zr de type (nacnacR)2ZrCl2 ont été obtenus par deux voies de synthèse principales: la première consiste à traiter le sel de lithium du ligand avec le ZrCl4. La seconde est la réaction du ligand avec les complexes neutres d’alkyl-zirconium(IV) par protonation de l'alkyle coordonné. En solution, les complexes obtenus de (nacnacR)2ZrX2 possèdent un comportement dynamique via un « Bailar-twist » et les paramètres d'activation de cette isomérisation ont été calculés. Le complexe octaèdrique (nacnacBn)2ZrCl2 n'est pas réactif dans la carbozirconation et son alkylation n'était pas possible par l’échange des chlorures avec les alkyles. L’analogue diméthylé (nacnacBn)2ZrMe2 peut être préparé par alkylation du ZrCl4 avant la complexation du ligand. On a également observé que ce dernier n’est pas réactif dans la carbozirconation. L‘analogue diéthoxyde (nacnacBn)2Zr(OEt)2 est obtenu par échange des diméthyles avec les éthoxydes. La polymérisation du lactide avec celui-ci en tant que précurseur est relativement lente et ne peut être effectuée que dans le monomère fondu. Par conséquent, pour résoudre les problèmes rencontrés avec les complexes de zirconium (dikétiminates non-pontés), un ligand dikétimines pontés par le diaminocyclohexane, (±)-C6H10(nacnacXylH)2, LH2, (Xyl = 2,6-diméthylphényle) a été préparé. La complexation de ce ligand tetradenté au metal a été réalisée par deux voies de synthèse; la première est la réaction du sel de lithium de ce ligand avec le ZrCl4(THF)2. La deuxième est la déprotonation du ligand neutre avec le Zr(NMe2)4 et l’élimination du diméthylamine. Des complexes du type: (±)-C6H10(nacnacXylH)2ZrX2 avec X = Cl, NMe2 ont été obtenus. Les ligands de chlorure sont dans ce cas facilement remplaçables par des éthoxydes ou des méthyles. On a observé l’activité la plus élevée jamais observée pour un complexe d’un métal du groupe 4 avec le complexe de (±)-C6H10(nacnacXylH)2Zr(OEt)2 dans la polymérisation de lactide. L'étude cinétique a montré que la loi de vitesse est du premier ordre en catalyseur et en monomère et la constante de vitesse est k = 14 (1) L mol-1 s-1. L'analyse des polymères a montré l’obtention de masses moléculaires faibles et l’abscence de stéréocontrôle. La réaction de (±)-C6H10(nacnacXylH)2ZrCl2 avec le triflate d’argent donne le (±)-C6H10(nacnacXylH)2Zr(OTf)2. Le complexe bis-triflate obtenu possède une activité catalytique elevée pour les additions du type aza-Michael. L’utilisation du R,R-C6H10(nacnacXylH)2Zr(OTf)2 énantiopur comme catalyseur, dans les additions du type aza-Michael asymétriques donne le produit desiré avec un excès énantiomérique de 19%. / Abstract: In order to prepare the complexes of Zr targeted for homogeneous catalysis in polymerization of lactides and hydroamination of activated olefins, we focused on the elaboration and the optimization of a systematic and efficient method for the synthesis of diketimines ligands with a variety of substituted alkyl (R) on their position N,N'. Symmetrical diketimines (nacnacRH) were obtained with a greater than 95% purity and a yield of 65% when R = Me and yields ranging from 80 to 95% when R = nPr, iPr, iBu, Bn, and Cy (+)-CH (Me) Ph. The Synthesis of diketimines with different N-alkyl substituents, called asymmetric, always gives a statistical mixture of three ligands: nacnacR,R'H nacnacR,RH and nacnacR',R'H that made their isolation problematic. Yields greater than statistical mixtures were obtained only with asymmetric diketimines bearing N-alky and N-aryl substituents (nacnacR,ArH). Subsequently, we studied the complexation of these bidentate ligands with Zr, the characterization of these complexes and investigation of their reactivity. Zr complexes of type (nacnacRH)2ZrCl2 were obtained via two main synthetic routes: the first consists in treatment of the lithium salt of the ligand with ZrCl4. The second is the reaction of the ligand with neutral complexes of alkyl-zirconium (IV) by protonation of the alkyl coordinated. In solution, the obtained complexes (nacnacR)2ZrX2 showed dynamic behavior via a "Bailar-twist" isomerization and the activation parameters of the isomerization were calculated. Octahedral complex (nacnacBn)2ZrCl2, showed no reactivity in alkylation and carbozirconation was not possible by the exchange of alkyl with chlorides. The dimethyl analogue (nacnacBn)2ZrMe2, can be prepared by alkylation of ZrCl4 before ligand complexing. The diethoxide analogue (nacnacBn)2Zr(OEt)2 is obtained by exchange of dimethyls with ethoxides. The latter had slow reactivity in lactide polymerization under melt conditions. Consequently, to address the problems encountered with unbridged (diketiminate) zirconium complexes, a cyclohexanediyl-bridged diketiminate ligand, (±)-C6H10(nacnacXylH)2, LH2, (Xyl = 2,6-dimethylphenyl) is prepared. Complexation of the tetradentate ligand is realized via two synthetic routes; The first is reaction of the lithium salt of the ligand with ZrCl4(THF)2. The second is deprotonation of the neutral ligand with Zr(NMe2)4 and elimination of dimethylamine. Complexes of the type: (±)-C6H10(nacnacXylH)2ZrX2 with X = Cl, NMe2 are obtained. The chloride ligands are in this case readily replaceable with ethoxides or methyls. The (±)-C6H10(nacnacXylH)2Zr(OEt)2 complex showed the highest activity ever observed for any group 4 metal complex in lactide polymerization. The kinetic study showed that the rate law is first order in catalyst and monomer and the rate constant is k = 14(1) L mol−1 s−1. Analysis of the obtained polymer showed low molecular weight with no-stereocontrol. Reaction of the (±)-C6H10(nacnacXylH)2ZrCl2 with silver triflates yielded the (±)-C6H10(nacnacXylH)2Zr(OTf)2. The obtained bis-triflate complex showed to be a highly active catalyst for aza-Michael additions. The use of the enatiopure R,R-C6H10(nacnacXyl)2Zr(OTf)2 as catalyst for asymmetric aza-Michael additions of activated olefines gave the desired product with an enantiomeric excess of 19%.

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