[pt] O presente trabalho trata da síntese, caracterização e estudo espectroscópico de novo ligante derivado da reação do ácido barbitúrico e isoniazida e seus respectivos complexos de zinco e cobre que foram todos igualmente estudados. Foi proposto um roteiro de síntese em meio aquoso utilizando metodologia gráfica para delinear as melhores condições de obtenção dos produtos. Um estudo espectroscópico completo dos reagentes foi realizado para ajudar na caracterização do ligante e dos complexos. A interpretação dos espectros de infravermelho e Raman foi acompanhada com os cálculos mecânico-quânticos utilizando o método DFT/B3LYP e o conjunto de base 3-21G acompanhado com os dados experimentais obtidos pela análise da segunda derivada do espectro. Os espectros de infravermelho com transformada de Fourier, e Raman tendo como base a estrutura proposta de acordo com os dados de CHN, RMN e absorção atômica, apresentaram uma excelente concordância com os espetros experimentais. A baixa solubilidade do ácido barbitúrico e seus derivados em regiões de pH acima de 5 produz uma mistura de hidroxo-complexos que dificulta o estudo das regiões de baixa energia, onde os modos vibracionais metal-ligante ocorrem. A metodologia gráfica empregada permitiu a obtenção de produtos mais puros e cristalizados possibilitando a correta caracterização espectroscópica de todos os modos vibracionais. / [en] The present study examined the synthesis, characterization, and spectroscopic study of new ligand derived from the reaction of barbituric acid and isoniazid. The ligand was used to synthetize complexes of zinc and copper and these complexes were analyzed. A synthesis plan was proposed in an aqueous medium using a graphical methodology, ensuring the best conditions to obtain the products. A complete spectroscopic study of reagents was implemented to aid in the characterization of both the ligand and the complexes. The interpretation of infrared spectra and Raman was complemented with a quantum-mechanical calculation method using DFT / B3LYP and a 3-21G basis. These calculations were compared with experimental data obtained by analyzing the second derivative of the spectrum. Based on the structure proposed according to the data of CHN, NMR, and the atomic absorption; the infrared spectra with a transformed Fourier and Raman were in line with the experimental spectra. Lastly, these conclusions lead us to better understand the complexities in spectroscopic characterization of compounds derived from barbituric acid and its coordination compounds. The low solubility of barbituric acid and its derivatives in pH regions above 5 creates a mixture of hydroxide complexes which complicate the study of low energy regions, where the metal-ligand vibrational modes occur. The graphical methodology used allowed us to obtain purer crystallized products, enabling the correct spectroscopic characterization of all vibrational modes.

Chapter I deals with novel approaches for α-amino acids. This chapter has been divided into three sections. Section A describes the synthesis of α-amino acids via the Beckmann rearrangement of carboxyl-protected β-keto acid oximes. The synthesis of α-amino acids using the Beckmann rearrangement involves the preparation of the Z-oxime and efficient protection of the carboxyl group. Various 2-substituted benzoylacetic acids were synthesized, in which the carboxyl function was masked as a 2,4,10-trioxaadamantane unit (an orthoacetate), and were converted to their oximes (Scheme 1).1 The oximes were converted to the their mesylates, which underwent the Beckmann rearrangement with basic Al2O3 in refluxing CHCl3. The corresponding 2-substituted-N-benzoyl-α-amino orthoacetates were obtained in excellent overall yields. In Section B, the synthesis of α-amino acids via the Hofmann rearrangement of carboxyl-protected malonamic acids is described. The Hofmann rearrangement involves the migration of the alkyl moiety of the amide onto the N-centre. Various 2-substituted malonamic acids (malonic acid mono amides) were synthesized with the carboxyl group masked as a 2,4,10¬trioxaadamantane unit (an orthoacetate). These underwent the Hofmann rearrangement with phenyliodoso acetate and KOH/MeOH (Scheme 2). The resulting (N-methoxycarbonyl)¬trioxaadmantylmethylamines (carbamates) were formed in yields > 90%, and are α-amino acids with both carboxyl and amino protection.2 In Section C, an approach to chiral amino acids via the reductive amination of ketones, involving the hydride reduction of 1-(S)-phenethyl amine derived Schiff bases of C-protected α¬keto acids is described. An efficient synthesis of α-amino acids has thus been developed in high diastereoselectivity. Various 1-acyl-2,4,10-trioxaadamantanes were prepared from the corresponding 1-methoxycarbonyl derivatives, via conversion to the N-acylpiperidine derivative followed by reaction with a Grignard reagent in refluxing THF (Scheme 3). These α-keto orthoformates were converted to corresponding imines with 1-(S)-phenethyl amine (TiCl4/Et3N/toluene/reflux), the Schiff bases being reduced with NaBH4 (MeOH/0 °C) to the corresponding 1-(S)-phenethyl N-alkylamines (diastereomeric excess by NMR ~ 90:10).3 Hydrogenolysis of the phenethyl group (Pd-C/H2/MeOH) finally led to the (aminoalkyl)trioxaadamantanes, which are chiral C-protected α-amino acids, in excellent overall yields. Here a mild, inexpensive and efficient hydride reducing agent for the reductive amination of α-keto acids has been developed. Chapter II deals with the enantioselective synthesis of piperidines and its applications in the synthesis of piperidine alkaloids.4 This chapter has been divided into two sections. In Section A, the enantioselective synthesis of 2-substituted piperidines and its applications in the synthesis of (R)-(-)-coniine and (R)-(+)-anatabine are described. Various N-tert-butylsulfinyl imines were synthesized, which upon allyl Grignard addition followed by N-allylation gave the diallyl compound with good diastereoselectivity (Scheme 4). The diallyl compound underwent ring closing metathesis with Grubbs’ first generation catalyst and subsequent reduction of the double bond with H2-Pd/C, furnished N-sulfinyl-2-susbstituted piperidines. Using this methodology (R)¬(-)-coniine hydrochloride and (R)-(+)-anatabine were synthesized. In Section B, the enantioselective synthesis of (S)-tert-butyl 2-(2¬hydroxyethyl)piperidine-1-carboxylate and its elaboration to the synthesis of (S)-(+)-δ-coniceine and (S)-(+)-pelletierine are described. The (S)-tert-butyl 2-(2-hydroxyethyl)piperidine-1¬carboxylate is a synthon used for the synthesis of various 2-substituted piperidine natural products. Using the above methodology (S)-tert-butyl 2-(2-hydroxyethyl)piperidine-1¬carboxylate was synthesized starting from (S)-(+)-2-methyl-2-propanesulfinamide and 3¬(benzyloxy)propanal (Scheme 5). This alcohol was further elaborated to furnish two piperidine alkaloids (S)-(+)-pelletierine and (S)-(+)-δ-coniceine. Scheme 5. Enantioselective synthesis of (S)-tert-butyl 2-(2-hydroxyethyl)piperidine-1¬carboxylate, (S)-(+)-pelletierine and (S)-(+)-δ-coniceine. Chapter III deals with the formation of barbituric acid in an aprotic medium and related mechanistic studies. The generally accepted mechanism for the formation of barbituric acid involves the nucleophilic attack of urea anion on diethyl malonate.5 This is debatable for at least two reasons: (1) the normally employed base, sodium ethoxide, is too weak to deprotonate urea and (2) diethyl malonate is more acidic than urea, so the initial deprotonation by base has to be from diethyl malonate. When diethyl malonate (DEM) enolate was treated with urea in DMF, barbituric acid was formed in 61% yield. The reaction was also extended to several 2-substituted DEM derivatives, the corresponding substituted barbituric acids being formed in reasonable yields. The reaction between diethyl 2-(ethoxycarbonyl)malonate and urea, with potassium carbonate in refluxing ethanol, led to the formation of barbituric acid. This is apparently facilitated by hydrogen bonding involving the enolate oxygen atom, which renders one of the carbonyl groups relatively electrophilic (Scheme 6). Meldrum’s acid failed to react with urea, despite its greater acidity, indicating that the reaction requires the formation of the E from of the s-trans enolate ion, in which the hydrogen bonding interaction and nucleophilic attack can occur in concert. Scheme 6. Proposed transition state for formation of Barbituric acid. Chapter IV deals with an improved Erlenmeyer synthesis with 5-thiazolone and catalytic manganese (II) acetate for aliphatic and aromatic aldehydes. A serious limitation to the classical Erlenmeyer reaction is that it generally fails in the case of aliphatic aldehydes. This chapter describes a convenient approach to this problem that extends the scope of the Erlenmeyer synthesis. The present study was aimed at developing milder conditions for the synthesis of 4¬arylidene and alkylidenethioazlactones. Thus, N-(thiobenzoyl)glycine was treated with DCC in DCM at room temperature for 10 min., according to a reported procedure, to form the thioazlactone.6 The same reaction mixture was treated with catalytic Mn(II) acetate and an equivalent of an aromatic aldehyde, to furnish the corresponding 4-arylidenethioazlactones in good yields. The scope of the reaction was extended to alphatic aldehydes also under similar reaction conditions, to obtain the 4-alkylidene thioazlactones in good to moderate yields (Scheme 7). Scheme 7. The Erlenmeyer synthesis with 5-thiazolone and manganese acetate. (for figures & structural formula pl refer pdf file)

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-07-20T17:37:01Z No. of bitstreams: 1 humbertocostagarcia.pdf: 7846659 bytes, checksum: 34217a22d6ed991eb248916aa4a1c452 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-08-09T12:51:50Z (GMT) No. of bitstreams: 1 humbertocostagarcia.pdf: 7846659 bytes, checksum: 34217a22d6ed991eb248916aa4a1c452 (MD5) / Made available in DSpace on 2017-08-09T12:51:50Z (GMT). No. of bitstreams: 1 humbertocostagarcia.pdf: 7846659 bytes, checksum: 34217a22d6ed991eb248916aa4a1c452 (MD5) Previous issue date: 2009-03-30 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Este trabalho descreve a síntese e caracterização de cinco novos complexos de metais de transição de fórmula geral MB2Bipi . 10H2O (onde M = Fe2+, Co2+, Ni2+, Cu2+ e Zn2+, B refere-se ao ânion barbiturato e Bipi a 4,4’-Bipiridina). Para caracterização dos compostos foram utilizadas as técnicas de análise elementar (CHN), análise térmica (TG/DTA), espectroscopia vibracional (Raman e infravermelho) e eletrônica (visível/Reflectância) e difração de raios X de monocristal. Os complexos FeB2Bipi . 10H2O (1), CoB2Bipi . 10H2O (2), NiB2Bipi . 10H2O (3), CuB2Bipi . 10H2O (4) e ZnB2Bipi . 10H2O (5) formam uma unidade básica polimérica, onde Fe(II), Co(II) e Zn(II) são isomorfos com grupo espacial P6422, diferentes de Ni(II) e Cu(II) também isomorfos, mas pertencentes ao grupo espacial P6522; no entanto todos os compostos apresentam a mesma estrutura molecular. O sítio metálico encontra-se em uma geometria octaédrica levemente distorcida, coordenado por dois átomos de nitrogênio do anel piridil e outros quatro átomos de oxigênio provenientes das moléculas de água. Cada estrutura exibe uma cadeia covalente linear [M(Bipi)(H2O)4]2+ unidimensional, a qual interage por interações de hidrogênio com o ânion barbiturato e moléculas de água de cristalização resultando em um arranjo tridimensional. A análise das estruturas dos complexos de Ni2+ e Cu2+ mostram uma interação de hidrogênio bidimensional formada por quatro ânions barbituratos e duas moléculas de água de cristalização, que pode ser considerada um hóspede enquanto a cadeia [M(bipi)(H2O)4]2+ unidimensional pode ser considerada o hospedeiro em uma intrigante e interessante estrutura. Os espectros vibracionais dos compostos são muito similares, e estão de acordo como os dados do cristal. Em todos os espectros na região do infravermelho, uma banda em torno de 1690 cm-1 é observada, atribuída ao estiramento CO [νCO] do ânion barbiturato. No espectro Raman as mais importantes bandas referentes ao ligante 4,4’bipiridina estão localizados em 1616, 1290 e 1020 cm-1, atribuídas aos modos νCC/CN, νring + δCH e νring respectivamente. Para caracterização do ânion barbiturato uma banda Raman de média intensidade é observada em torno de 680 cm-1, atribuído ao modo de respiração do anel. O sucesso na síntese dos compostos (1), (2), (3), (4) e (5) demonstra que a mistura de ligantes pode fornecer múltiplas forças de ligação, como covalente, eletrostática e as interações de hidrogênio, favorecendo a ordenação de uma arquitetura supramolecular multidimensional. Além disto, o uso do ânion barbiturato, o qual atua como doador de hidrogênio pelos grupos NH e CH, e aceptor pelo grupo CO, contribui com uma nova característica para expandir rapidamente a área da química supramolecular no nosso grupo de pesquisa. / This work describes the synthesis and characterization of five new transition metal complexes of general formula MB2Bipy.10H2O (where M = Fe2+, Co2+, Ni2+, Cu2+ and Zn2+, B is barbiturate anion and Bipy is 4,4’-bipyridine) . Several physical and spectroscopical techniques were used to characterize the compounds, such as elemental analysis (CHN), thermal analysis (TG/DTA), vibrational (Raman and infrared) and electronic (absorption and reflectance in the visible region) spectroscopy as well as single crystal X ray diffraction analysis. The FeB2Bipi . 10H2O (1), CoB2Bipi . 10H2O (2), NiB2Bipi . 10H2O (3), CuB2Bipi . 10H2O (4) and ZnB2Bipi . 10H2O (5) complexes give rise to polymeic basic units, where Fe(II), Co(II) and Zn(II) compounds are isomorphous belonging to P6422 space group, different from the Ni(II) and Cu(II) compounds which are also isomorphous, belonging to P6522 space group; however, all compounds present the same molecular structure. In each compound the metal site appears in a distorted octahedral geometry, coordinated by two pyridine nitrogen atoms and also to four oxygen atoms from the coordinated water molecules. Each structure shows a covalent linear [M(Bipy)(H2O)4]2+ one-dimensional chain , which interacts by hydrogen bond with the barbiturate anion and the crystallization waters, resulting in a tridimensional arrangement. The analysis of the Ni2+ and Cu2+ complexes structures shows flexible bidimensional hydrogen bonds networks being constructed by the four barbiturate anions and the two crystallization water molecules; this structure may be deemed to be the host, while the robust 1D [M(bipy)(H2O)4]2+ chains may be deemed to be the guest, in a very intriguing and interesting structure. The vibrational spectra of the compounds are very similar, in agreement to the crystallographic data. In all infrared spectra a medium intensity band at 1690 cm-1 has been observed, assigned to the CO stretch of the barbiturate anion. In the Raman spectra the most important bands referring to 4,4’-bipyridine ligand are the ones at 1616, 1290 and 1020 cm-1, assigned to νCC/CN, νring + δCH and νring modes, respectively. For characterization of barbiturate anion one medium Raman signal is observed around 680 cm-1 assigned to the ring breathing mode. The successful synthesis of the new (1), (2), (3), (4) and (5) compounds demonstrates that the introduction of mixed ligands may provide multiple binding forces such as coordinated covalent, electrostatic and hydrogen bonding interactions, which may endow an enormous potential for assembling multidimensional supramolecular architectures. Furthermore, the use of the barbiturate species, which act as H-donors by the NH and CH moieties, and H-acceptors by the CO groups, can contribute through new features and arrays to the rapidly expanding area of supramolecular chemistry by our research group.

In dieser Arbeit wird die Synthese neuartiger 5-monosubstituierter Barbituratfarbstoffe mit elektronenziehenden Substituenten in 5-Position beschrieben. Durch diese Funktionalisierung entstehen schaltbare Farbstoffe mit einer farblosen Ketoform und einer farbigen Enolform. Die Einflüsse verschieden stark elektronenziehender Substituenten sowie unterschiedlich großer konjugierter π-Systeme auf die Keto-Enol-Tautomerie wurden untersucht. Dies erfolgt einerseits mittels Röntgeneinkristallstrukturanalysen der Festkörper und andererseits mit solvatochromen Untersuchungen in Lösung. Durch die Keto-Enol-Tautomerie der Barbituratfarbstoffe wird die Wasserstoffbrücken¬bindungssequenz beim Übergang zwischen Keto- und Enol-Form verändert. Es wurde gezeigt, dass durch Zugabe von Rezeptoren mit komplementärer Wasserstoffbrückenbindungssequenz zur Enol-Form das tautomere Gleichgewicht der Barbitursäuren hin zur Enol-Form verschoben werden kann. Um hierzu verlässliche Aussagen zu erhalten wurden vergleichende Experimente mit N,N´-dialkylierten Barbituratfarbstoffen durchgeführt. Aufgrund der Synthesestrategie der Barbituratfarbstoffe, welche ausgehend von Barbituratanionen über nukleophile aromatische Substitutionsreaktionen hergestellt wurden, war es zweckmäßig die Nukleophilieparameter der Barbituratanionen zu ermitteln. Dazu wurde der Ansatz von Mayr gewählt und die Nukleophilie von vier Barbituratanionen bestimmt. Weiterhin konnte in dieser Arbeit die Charakterisierung von ionischen Flüssigkeiten nach der 4-Parameter-Gleichung von Catalán umgesetzt werden. Dabei gelang es erstmal für eine vielzahl verschiedener ionischer Flüssigkeiten die Polarisierbarkeit und Dipolarität getrennt voneinander mit Hilfe zweier solvatochromer Farbstoffe zu ermitteln.

In dieser Arbeit wird die Synthese neuartiger 5-monosubstituierter Barbituratfarbstoffe mit elektronenziehenden Substituenten in 5-Position beschrieben. Durch diese Funktionalisierung entstehen schaltbare Farbstoffe mit einer farblosen Ketoform und einer farbigen Enolform. Die Einflüsse verschieden stark elektronenziehender Substituenten sowie unterschiedlich großer konjugierter π-Systeme auf die Keto-Enol-Tautomerie wurden untersucht. Dies erfolgt einerseits mittels Röntgeneinkristallstrukturanalysen der Festkörper und andererseits mit solvatochromen Untersuchungen in Lösung. Durch die Keto-Enol-Tautomerie der Barbituratfarbstoffe wird die Wasserstoffbrücken¬bindungssequenz beim Übergang zwischen Keto- und Enol-Form verändert. Es wurde gezeigt, dass durch Zugabe von Rezeptoren mit komplementärer Wasserstoffbrückenbindungssequenz zur Enol-Form das tautomere Gleichgewicht der Barbitursäuren hin zur Enol-Form verschoben werden kann. Um hierzu verlässliche Aussagen zu erhalten wurden vergleichende Experimente mit N,N´-dialkylierten Barbituratfarbstoffen durchgeführt. Aufgrund der Synthesestrategie der Barbituratfarbstoffe, welche ausgehend von Barbituratanionen über nukleophile aromatische Substitutionsreaktionen hergestellt wurden, war es zweckmäßig die Nukleophilieparameter der Barbituratanionen zu ermitteln. Dazu wurde der Ansatz von Mayr gewählt und die Nukleophilie von vier Barbituratanionen bestimmt. Weiterhin konnte in dieser Arbeit die Charakterisierung von ionischen Flüssigkeiten nach der 4-Parameter-Gleichung von Catalán umgesetzt werden. Dabei gelang es erstmal für eine vielzahl verschiedener ionischer Flüssigkeiten die Polarisierbarkeit und Dipolarität getrennt voneinander mit Hilfe zweier solvatochromer Farbstoffe zu ermitteln.