The reactions of 4,6-dinitrobenzofuroxan, (DNBF) with aniline and six of its N- and ring- substituted derivatives have been studied. It is known that aniline usually reacts as a nitrogen nucleophile, forming nitrogen-bonded σ-adducts with trinitrobenzene, (TNB) in the presence of a strong base. However, in acidic solutions, a-adducts are formed with bonding between a ring carbon atom of the anilines and the 7-position of DNBF. A value of 2.0 for k(_H)/k(_D), the kinetic isotope effect, indicates that bond formation is largely rate determining in the substitution pathway. Estimates were made for the pK(_a) values relating to carbon protonation of the anilines. In solutions of aniline buffered with aniline hydrogen chloride it was possible to distinguish an initial, rapid reaction via the nitrogen centre to give anionic a-adducts. The thermodynamically more stable carbon-bonded σ-adducts were observed to form over time. In the presence of excess amine, these zwitterionic σ-adducts were in rapid equilibrium with the deprotonated forms. Equilibrium constants for this acid-base process were measured, and indicate that the negatively charged DNBF moiety is electron withdrawing relative to hydrogen. Kinetic and equilibrium studies are reported for the reactions of several aliphatic amines with a selection of nitrobenzofurazan derivatives in DMSO. Rapid reaction at the 5- position to yield σ-adducts was followed by slower formation of the thermodynamically more stable adducts at the 7-position. Proton transfer from the zwitterionic intermediates to a second molecule of amine was generally rapid, and the attack of the amine rate determining. This is in direct contrast with reactions involving TNB, where the proton transfer step is usually rate limiting. The reactions of four nitrobenzofurazan derivatives with sulfite have been studied in aqueous solutions. The stability of the initially formed 5-adducts was remarkably high in comparison with the corresponding σ-adducts formed from attack of sulfite on TNB. A slow isomerisation was observed to yield the thermodynamically more stable 7-adducts, except in the reaction with 4-nitro-7-chlorobenzofurazan, where attack at the 7-position would lead to nucleophilic substitution of the chloro-group to yield the substitution product. The mechanism of the isomerisation was found to occur via an intermolecular rearrangement, and not according to an intramolecular Boulton-Katritzky rearrangement. Sulfite attack on DNBF was also studied. A value for the equilibrium constant for the formation of a 1:1 adduct, K(_7) 1.1 x 10(^13) dm(^3) mol(^-1) was determined. This high value is a reflection of the high carbon basicity of the sulfite ion, and the highly electrophilic character of DNBF. Evidence was also obtained for the formation of 1:2 di-adducts in the presence of excess sulfite, which are present in the isomeric cis and trans forms.

This thesis comprises three projects on the theme of catalytic C(sp3)–H carbonylation of secondary aliphatic amines. Chapter 2 describes the development of a general methyl C–H carbonylation of secondary aliphatic amines to form synthetically useful β-lactam building blocks. Amines exhibiting a range of substitution patterns around the nitrogen functionality, and bearing a wide variety of functional groups, could be tolerated in the reaction. The desired β-lactam products were delivered in high yields, with excellent selectivity observed for the β-C–H position. Computational studies suggested that the reaction proceeds through a novel carbamoyl cyclopalladation pathway, which is distinct from classical cyclopalladation. The subsequent discovery of a selective methylene C–H carbonylation of α-tertiary amines (ATAs) is discussed in chapter 3. By employing the ATA motif, remarkable levels of selectivity for β-methlyene C–H bonds were achieved, even in the presence of traditionally more reactive methyl C–H and C(sp2)–H bonds. Once more, the reaction was found to exhibit excellent functional group tolerance, delivering highly functionalised β-lactam building blocks in high yields and selectivity. Chapter 4 presents work towards the total synthesis of the marine natural product (±)cylindricine C. The key step of this synthesis was demonstrated to proceed in good yield and excellent selectivity.

Carbonyl compounds are of central importance to organic chemistry and their reactions have been described as the ‘backbone of organic synthesis’. Over recent decades, palladium-catalysed C–H carbonylation reactions have emerged as a powerful means of introducing carbonyl motifs to organic molecules. This thesis describes the development of a general C–H carbonylation reaction of secondary aliphatic amines, which provides facile access to synthetically useful β-lactam products. The first part of the thesis explores the scope and limitations of this reaction. Whilst previous C(sp3)–H carbonylation methodologies were restricted to ‘Type F’ secondary aliphatic amines, the reaction described in this thesis was found to be broadly applicable all structural sub-classes of secondary aliphatic amine. Furthermore, the reaction was found to be remarkably tolerant of functional groups, even those that commonly cause issues in palladium-catalysed C–H activation reactions such as heteroaromatics and thioethers. The second part of this thesis investigates the mechanism of this C–H carbonylation reaction. Interestingly, the reaction was found not to proceed via a traditional C–H carbonylation mechanism comprising of C–H activation, 1,1-migratory carbon monoxide insertion and reductive elimination. Instead, a new mechanistic paradigm for palladium-catalysed C–H carbonylation is proposed, which invokes a putative ‘palladium anhydride’ intermediate. A series of DFT calculations and experiments were conducted in order to support this mechanistic proposal. The work described within this PhD thesis was published in Science.

In order to explore the N-H stretching region of aliphatic amines, we performed a study of the Raman spectrum of n-propylamine at various concentrations in cyclohexane. Statistical analysis provided evidence of a second symmetric stretching vibration, which we were able to assign to nonhydrogen bonded NH2 groups. To obtain additional evidence on the existence of monomers in n-propylamine and to further study hydrogen bonding and Fermi resonance in aliphatic amines, we extended the investigation to the analysis of the Raman spectrum of this compound over an extended range of temperature in the neat liquid phase. This study corroborated our finding that the peak previously assigned to the symmetric stretching mode of hydrogen bonded amines is actually composed of two bands. Furthermore, trends in both the resolved band parameters and the Fermi resonance analysis were tabulated, allowing one to monitor the change in the N-H valence region with concentration and temperature.

N5-deoxyribosyl derivatives of 2,5-diaminoimidazolone formed by oxidative damage to the guanine bases in 2-deoxyguanosine and highly polymerized DNA readily undergo nucleophilic substitution at C5 in reaction with primary amines in neutral aqueous solutions at 37–70 °C, as it was found in a kinetic study using reverse-phase HPLC. The reaction of 2-amino-5-[(2′-deoxy-β-D-erythro-pentofuranosyl)amino]-4H-imidazol-4-one (dIz) with excess of ethanolamine, alanine and γ-aminobutyric acid (0.2–1 M) is a pseudo-first-order process that proceeds with 45–80 % yields depending on the nature of the amine, its concentration, and the reaction temperature. In the case of ethanolamine, the corresponding bimolecular rate constant has a pre-exponential factor and activation energy of 1.1 × 105 s−1 and 47 kJ mol−1, respectively. The reaction is highly competitive with the previously described hydrolysis of dIz into 2,2-diamino-4-[(2-deoxy-β-D-erythro-pentofuranosyl)amino]-5(2H)-oxazolone under biologically relevant conditions. A similar reaction with the same lesion in polymeric DNA results in the release of a low-molecular-weight analog of dIz, presumably producing an abasic site as the second reaction product. Kinetic characteristics of this process make it a potentially important source of abasic sites in oxidatively damaged DNA, formed through the reaction of 2,5-diaminoimidazolone lesions with naturally abundant DNA-affinic amines and proteins. The release of low-molecular-weight analogs of dIz can potentially be employed for quantification of imidazolone lesions in oxidized DNA. The half-life of imidazolone lesions in double-stranded DNA evaluated using this approach was found to be 154 min at 37 °C.

As aminas heterocíclicas alifáticas, piperidina, piperazina e pirrolidina, interagem com o dióxido de enxofre, gasoso ou líquido, dando origem a uma série de compostos em diferentes estequiometrias, os quais foram investigados fundamentalmente por técnicas espectroscópicas vibracionais, infravermelho e Raman, utilizando-se como técnicas auxiliares a espectroscopia eletrônica, espectros de massas e de ressonância magnética nuclear. Os resultados obtidos caracterizam as espécies estudadas como complexos moleculares formados entre as aminas e o SO2, especialmente devido aos deslocamentos de frequências observados nos espectros Raman, para os modos vibracionais de estiramento simétrico e deformação angular do dióxido de enxofre. Os dados indicam no sentido do estabelecimento de intensas ligações de hidrogênio, as quais devem desempenhar importante papel na estabilização dos complexos. Os deslocamentos observados nos espectros Raman encontram-se de acordo com o comportamento previsto para a interação de transferência de carga, em que o LUMO do SO2 apresenta caráter antiligante em relação à ligação S-O e ligante em relação à interação O-O. / The interaction of alifatic heterocyclic amines piperidine, piperazine and pyrrolidine, with sulfur dioxide yields a variety of products of different stoichiometry. The investigation of the formed species were carried out mainly by vibrational spectroscopic techniques, infrared and Raman, and electronic spectroscopy, mass spectrometry and nuclear magnetic resonance spectra were used as auxiliary techniques. The obtained results indicate that the studied species are charge transfer molecular complexes due to the frequency shifts of the symmetric stretching and angular deformation modes of sulfur dioxide in the Raman spectra. The data are in agreement with an S-O antibonding and a O-O bonding character of the LUMO of SO2. Hydrogen bonds play an important role in the complex stabilization.

As aminas heterocíclicas alifáticas, piperidina, piperazina e pirrolidina, interagem com o dióxido de enxofre, gasoso ou líquido, dando origem a uma série de compostos em diferentes estequiometrias, os quais foram investigados fundamentalmente por técnicas espectroscópicas vibracionais, infravermelho e Raman, utilizando-se como técnicas auxiliares a espectroscopia eletrônica, espectros de massas e de ressonância magnética nuclear. Os resultados obtidos caracterizam as espécies estudadas como complexos moleculares formados entre as aminas e o SO2, especialmente devido aos deslocamentos de frequências observados nos espectros Raman, para os modos vibracionais de estiramento simétrico e deformação angular do dióxido de enxofre. Os dados indicam no sentido do estabelecimento de intensas ligações de hidrogênio, as quais devem desempenhar importante papel na estabilização dos complexos. Os deslocamentos observados nos espectros Raman encontram-se de acordo com o comportamento previsto para a interação de transferência de carga, em que o LUMO do SO2 apresenta caráter antiligante em relação à ligação S-O e ligante em relação à interação O-O. / The interaction of alifatic heterocyclic amines piperidine, piperazine and pyrrolidine, with sulfur dioxide yields a variety of products of different stoichiometry. The investigation of the formed species were carried out mainly by vibrational spectroscopic techniques, infrared and Raman, and electronic spectroscopy, mass spectrometry and nuclear magnetic resonance spectra were used as auxiliary techniques. The obtained results indicate that the studied species are charge transfer molecular complexes due to the frequency shifts of the symmetric stretching and angular deformation modes of sulfur dioxide in the Raman spectra. The data are in agreement with an S-O antibonding and a O-O bonding character of the LUMO of SO2. Hydrogen bonds play an important role in the complex stabilization.

The toxicity of 36 aliphatic amines on the embryos of the zebrafish Danio rerio were investigated. The DarT (Danio rerio Toxicity assay) was used to determine the lethal concentrations within a 48 h static acute toxicity test. A QSAR (Quantitative Structure-Activity Relationship) was performed using the LC50 values and molecular descriptors such as lipophilicity, maximum positive charge on hydrogen atom and the effective diameter of the molecule. In general, the toxicity of primary and secondary amines could be described by the lipophilicity as descriptor. The toxicity of the tertiary amines tested could be only described by a bilinear regression model. Further, regression models for other aquatic species such as the fathead minnow Pimephales promelas, Daphnia magna and Tetrahymena pyriformis showed that the toxicity of each species is a good predictor for each other.

Isocyanates, aromatic-, aliphatic- and alkanolamines are commonly used in the industry today. Millions of workers in Europe are exposed. The most frequent health symptoms are respiratory and dermal disorder. Due to the health risk most of the compounds in this thesis are regulated by authorities and have occupational exposure limits (OELs). Consequently, reliable and robust air sampling methods are urgently needed. In this thesis dry samplers for isocyanates, aliphatic- and alkanolamines have been developed and evaluated. The isocyanate sampler is now a commercial product (ASSET EZ4-NCP Dry Sampler, Supelco). The samplers were based on a denuder with a filter in series. The denuder and filter were impregnated with di-n-butylamine for the isocyanate sampler and with sulphuric acid for the aliphatic- and alkanolamine sampler. The robustness of the dry samplers was extensively evaluated. This was performed in a climate chamber containing a controlled atmosphere of the studied compounds. New methods based on hydrophilic interaction liquid chromatography (HILIC) coupled with tandem mass spectrometry (MSMS) were developed for determination of aromatic-, aliphatic- and alkanolamines in aqueous solutions. Isocyanates were determined by reversed-phase liquid chromatography MSMS. HILIC in combination with MS is a most powerful system, and highly sensitive determinations, several orders of magnitude below the OELs, of polar compounds present in the work environment can be accomplished. The selected samplers enable sampling during short sampling times and for whole work shifts. The samplers can be stored for months before and after sampling. The performance of the samplers was unaffected by variation in temperature, humidity, flow-rate and pre- and post-sampling of ambient air. Sampling for the compounds studied is now greatly simplified, and assessment of the work environment is facilitated. / <p>At the time of the doctoral defence the following papers were unpublished and had a status as follows: Paper 1: Epub ahead of print; Papers 3-5: Manuscripts</p>

The toxicity of 36 aliphatic amines on the embryos of the zebrafish Danio rerio were investigated. The DarT (Danio rerio Toxicity assay) was used to determine the lethal concentrations within a 48 h static acute toxicity test. A QSAR (Quantitative Structure-Activity Relationship) was performed using the LC50 values and molecular descriptors such as lipophilicity, maximum positive charge on hydrogen atom and the effective diameter of the molecule. In general, the toxicity of primary and secondary amines could be described by the lipophilicity as descriptor. The toxicity of the tertiary amines tested could be only described by a bilinear regression model. Further, regression models for other aquatic species such as the fathead minnow Pimephales promelas, Daphnia magna and Tetrahymena pyriformis showed that the toxicity of each species is a good predictor for each other.