Thermal treatments of dairy products favor oxidations, Maillard reactions, and the formation of sugar or lipid oxidation products. Additives including flavorings might enhance these reactions or even induce further reactions. Here we aimed to characterize protein modifications in four flavored milk drinks using samples along the production chain—raw milk, pasteurization, mixing with flavorings, heat treatment, and the commercial product. Therefore, milk samples were analyzed using a bottom up proteomics approach and a combination of data-independent (MSE) and data-dependent acquisition methods (DDA). Twenty-one small carbonylated lipids were identified by shotgun lipidomics triggering 13 protein modifications. Additionally, two Amadori products, 12 advanced glycation end products (AGEs), and 12 oxidation-related modifications were targeted at the protein level. The most common modifications were lactosylation, formylation, and carboxymethylation. The numbers and distribution of modification sites present in raw milk remained stable after pasteurization and mixing with flavorings, while the final heat treatment significantly increased lactosylation and hexosylation in qualitative and quantitative terms. The processing steps did not significantly affect the numbers of AGE-modified, oxidized/carbonylated, and lipid-carbonylated sites in proteins.

[ES] La presente tesis doctoral se basa en la síntesis, caracterización y uso de catalizadores basados en especies de Pd soportadas sobre matrices sólidas en reacciones de interés en química fina. En general, se ha pretendido obtener catalizadores multifuncionales, estables y reutilizables que se puedan separar fácilmente de la mezcla de reacción y que contribuyan a desarrollar protocolos más sostenibles que den lugar a compuestos orgánicos de interés. En primer lugar, el material [Pd/Al2O3], constituido por nanoagregados de Pd(0) de un tamaño medio de 2.8 nm y soportados sobre una matriz de tipo ¿-Al2O3 con elevada densidad de sitios ácidos, ha demostrado ser altamente activo y eficiente en la ciclación deshidrogenativa entre ureas y 1,2-dioles para la síntesis de imidazol-2-onas. Al utilizar ureas y 1,2-dioles desactivados, la cooperatividad Pd-Zn ha demostrado ser imprescindible para el éxito del proceso, obteniendo los mejores resultados al emplear el sistema de [Pd/Al2O3]-ZnO. Ambos materiales, [Pd/Al2O3] y [Pd/Al2O3]-ZnO, han demostrado ser reusables y estables bajo las condiciones de reacción al no presentar problemas de lixiviación. Además, este protocolo catalítico ha permitido obtener hasta 28 imidazol-2-onas con buenos resultados, demostrando su amplio potencial sintético. Por otra parte, el nanomaterial [Pd(0.75%)/Mg3Al-LDH]-300(D), constituido por nanopartículas de Pd(0) de un tamaño medio de 2.8 nm y soportado sobre una matriz básica de tipo dh-LDH, ha demostrado ser altamente activo para mediar la síntesis de propiolamidas mediante la aminocarbonilación oxidativa entre alquinos terminales y aminas secundarias, en presencia de CO/O2. Se ha determinado que un soporte con estructura dh-LDH con una relación de Mg/Al de 3 es el idóneo para estabilizar especies de [PdI2] generadas in situ en el medio de reacción así como para promover la activación de los reactivos de partida. El sistema catalítico ha demostrado ser reusable y estable bajo las condiciones de reacción, además de poseer una elevada aplicabilidad sintética al haber obtenido más de 60 propiolamidas diferentes, destacando el uso por primera vez en este tipo de procesos de aminas N-aromáticas y N-heterocíclicas. Finalmente, se ha llevado a cabo la síntesis de materiales híbridos derivados de soportar mediante interacciones no covalentes complejos de Pd con geometría plano-cuadrada sobre matrices grafénicas. Los resultados de caracterización apuntan a que estos materiales están constituidos, principalmente, por especies aisladas de Pd(II), demostrando el papel estabilizante de los ligandos utilizados al evitar la agregación del metal. Esos materiales han sido, en general, altamente activos y selectivos como catalizadores en la semi-hidrogenación de alquinos, y lo que es más relevante, se ha demostrado una sinergia complejo - grafeno en la actividad catalítica estudiada. El material de [Pd-Phen/OGr-C] ha sido reutilizado en varios ciclos y es estable bajo las condiciones de reacción. Además, este protocolo catalítico posee una elevada aplicabilidad, al haberse podido utilizar hasta con 37 alquinos diferentes obteniendo muy buenos resultados de rendimiento y quimioselectividad. / [CA] La present tesi doctoral es basa en la síntesi, caracterització i ús de catalitzadors basats en espècies de Pd suportades sobre matrius sòlides en reaccions d'interés en química fina. En general, s'ha pretès obtenir catalitzadors multifuncionals, estables i reutilitzables que es puguen separar fàcilment de la mescla de reacció i que contribuïsquen a desenvolupar protocols més sostenibles que donen lloc a compostos orgànics d'interès. En primer lloc, el material [Pd/Al2O3], constituït per nanoagregats de Pd(0) d'una grandària mitjana de 2.8 nm i suportats sobre una matriu de tipus ¿-Al2O3 amb elevada densitat de llocs àcids, ha demostrat ser altament actiu i eficient en la ciclació deshidrogenativa entre urees i 1,2-diols per a la síntesi d'imidazol-2-ones. En utilitzar urees i 1,2-diols desactivats, la cooperativitat Pd-Zn ha demostrat ser imprescindible per a l'èxit del procés, aconseguint els millors resultats emprant el sistema de [Pd/Al2O3]-ZnO. Tots dos materials, [Pd/Al2O3] i [Pd/Al2O3]-ZnO, han demostrat ser reutilitzables i estables sota les condicions de reacció ja que no presenten problemes de lixiviació. A més, aquest protocol catalític ha permès obtenir fins a 28 imidazol-2-ones amb bons resultats, demostrant el seu ampli potencial sintètic. D'altra banda, el nanomaterial [Pd(0.75%)/Mg3Al-LDH]-300(D), constituït per nanopartícules de Pd(0) d'una grandària mitjana de 2.8 nm suportades sobre una matriu bàsica de tipus dh-LDH, ha demostrat ser altament actiu per a catalitzar la síntesi de propiolamides mitjançant l'aminocarbonilació oxidativa entre alquins terminals i amines secundàries, en presència de CO/O2. S'ha determinat que un suport amb estructura dh-LDH amb una relació de Mg/Al de 3 és l'idoni per a estabilitzar les espècies de [PdI2] generades in situ en el medi de reacció així com per a promoure l'activació dels reactius de partida. El sistema catalític ha demostrat ser reutilitzable i estable sota les condicions de reacció, a més de posseir una elevada aplicabilitat sintètica en haver obtingut més de 60 propiolamides diferents, destacant l'ús per primera vegada en aquesta mena de processos d'amines N-aromàtiques i N-heterocícliques. Finalment, s'ha dut a terme la síntesi de materials híbrids derivats de suportar mitjançant interaccions no covalents complexos de Pd amb geometria pla-quadrada sobre matrius grafèniques. Els resultats de caracterització apunten a que aquests materials estan constituïts, principalment, per espècies aïllades de Pd(II), demostrant el paper estabilitzant dels lligands utilitzats per a evitar l'agregació del metall. Aquests materials han sigut, en general, altament actius i selectius com a catalitzadors en la semi-hidrogenació d'alquins, i el que és més rellevant, s'ha demostrat una sinèrgia complex - grafè en l'activitat catalítica estudiada. El material [Pd-Phen/OGr-C] ha sigut reutilitzat en diversos cicles i es estable sota les condicions de reacció. A més, aquest protocol catalític posseeix una elevada aplicabilitat i s'ha pogut aplicar a 37 alquins diferents obtenint molt bons resultats de rendiment i quimioselectivitat. / [EN] The present PhD thesis is focused on the synthesis, characterisation and use of catalysts based on Pd species supported on solid matrixes in reactions of interest in fine chemistry. In general, the aim is to obtain multifunctional, stable and reusable catalysts that can be easily separated from the reaction mixture and that contribute to the development of more sustainable protocols leading to relevant organic compounds. Firstly, the [Pd/Al2O3] material, consisting of Pd(0) nanoaggregates with an average size of 2.8 nm and supported on a ¿-Al2O3-type matrix with a high density of acid sites, has been designed as a highly active and efficient catalyst in the dehydrogenative cyclisation between ureas and 1,2-diols for the synthesis of imidazole-2-ones. When using ureas and deactivated 1,2-diols, Pd-Zn cooperativity has been shown to be essential for the success of the process, with the best results obtained using a [Pd/Al2O3]-ZnO system. Both materials, [Pd/Al2O3] and [Pd/Al2O3]-ZnO, have proved to be reusable and stable under the reaction conditions as they do not present leaching problems. Moreover, this catalytic protocol has allowed to obtain up to 28 imidazole-2-ones with good results, demonstrating it is wide synthetic potential. On the other hand, the nanomaterial [Pd(0.75%)/Mg3Al-LDH]-300(D), consisting of Pd(0) nanoparticles with an average size of 2.8 nm and supported on a basic dh-LDH-type matrix, has been shown to be highly active for catalysing the synthesis of propiolamides via oxidative aminocarbonylation between terminal alkynes and secondary amines in the presence of CO/O2. A dh-LDH-structured support with an Mg/Al ratio of 3 has been found to be suitable for stabilising [PdI2] species generated in situ in the reaction medium, as well as for promoting the activation of the starting reagents. The catalytic system has proved to be reusable and stable under the reaction conditions, besides having a high synthetic applicability as more than 60 different propiolamides have been obtained. It is especially relevant the use of N-aromatic and N-heterocyclic amines for the first time in this type of processes. Finally, the synthesis of hybrid materials derived from supporting Pd complexes with planar square geometry on graphene matrices through non-covalent interactions has been carried out. The characterisation results show that these materials are mainly constituted by isolated Pd(II) species, demonstrating the stabilising role of the ligands to avoid the aggregation of the metal. These materials have been, in general, highly active and selective as catalysts in the semi-hydrogenation of alkynes, and what is more relevant, a complex - graphene synergy has been demonstrated in the studied catalytic activity. In addition, [Pd-Phen/OGr-C] has shown to be reusable in several catalytic cycles and stable under the reaction conditions. Moreover, this catalytic protocol has demonstrated a high applicability, in fact it has been applied to 37 different alkynes with very good results, in terms of yield and chemoselectivity. / Arango Daza, JC. (2023). Materiales basados en especies de Pd soportadas sobre matrices sólidas como catalizadores eficientes para reacciones de interés en química fina [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/201576

The carbonylation of methanol to acetic acid is one of the most important applications in homogeneous catalysis. The first chapter comprises a review on the mechanistic studies into the catalytic cycle of the ‘Monsanto process’ and includes some of the most prominent studies into the use of phosphines in the rhodium-catalysed carbonylation of methanol. The second chapter of this thesis reports on an investigation into the application of rhodium complexes containing several C4 bridged diphosphines, namely BINAP, dppb, dppx and dcpb as catalysts for hydrogen tolerant methanol carbonylation. An investigation into the structure, reactivity and stability of pre-catalysts and catalyst resting states of these complexes has also been carried out. The origin of this hydrogen tolerance is explained based on the differing reactivities of the Rh acetyls with hydrogen gas, and by considering the structure of the complexes. In the third chapter I report on an investigation into how electronic properties and coordination mode affect the elimination of phosphonium salts from rhodium complexes. The stability of a range of monodentate, bidentate and tridentate rhodium-phosphine complexes was tested. I also report on the formation of a novel bidentate complex containing a partially quaternised TRIPHOS ligand and investigate the mechanism of formation using 13CH3I. Strong evidence is also presented supporting a dissociative mechanism as the means of phosphine loss from the rhodium centre. In the final chapters I report an investigation into the stability of rhodium-aminophosphine ligand complexes and into increasing the solubility of potential rhodium pre-catalysts through the use of amine-containing phosphine ligands.

<p>One-step photoinitiated free radical carbonylation was employed for the rapid (5–7 min) labelling of aliphatic carboxylic acids, esters, and amides with a short-lived positron emitter ¹¹C (t_½ = 20.3 min) at the carbonyl position. The labelled compounds were synthesized from alkyl iodides (0.05–0.1 mmol), [¹¹C]carbon monoxide, and appropriate nucleophiles. Decay-corrected radiochemical yields were up to 74%; conversion of [¹¹C]carbon monoxide reached 85–90%; specific radioactivity was 158–192 GBq/mmol. The labelled compounds were identified and characterized using HPLC, LC-MS, and ¹H and ¹³C NMR. The effects of solvents, additives, photoirradiation, temperature, and reaction time were studied and discussed.</p><p>[<i>carbonyl-</i>¹¹C]Amides were synthesized using amines in 1–2 equiv. to iodides, exploiting solvent effects to control reactivity. [<i>carboxyl-</i>¹¹C]Acids were synthesized using water as a nucleophile, in binary and ternary aqueous solvent mixtures; the addition of TBAOH or KOH was necessary to obtain high radiochemical yields. [<i>carbonyl-</i>¹¹C]Esters were synthesized using primary and secondary alcohols, <i>tert-</i>butanol, and phenol. Bases were KOH, BuLi, LiHDMS.</p><p>The effects of photosensitizers were studied and exploited to accelerate the labelling of carboxylic acids and esters resulting in 75–85% decay-corrected radiochemical yields under mild conditions without the use of bases.</p><p>A mild procedure for the ¹¹C-carboxylation of alkyl iodides using DMSO as an oxygen nucleophile was developed. This method is expected to be suitable in the macroscale synthesis of carboxylic acids using isotopically unmodified carbon monoxide.</p><p>Radical carbonylation was applied to improve the synthesis of an extensively used PET tracer, [<i>carbonyl</i>-¹¹C]WAY-100635. The tracer was synthesized in one step, whereas a common approach via Grignard reagents requires three steps.</p><p>In addition, several (¹³C)compounds were synthesised using the described methods.</p><p>Free radical carbonylation may be used for the ¹¹C-carbonylation of alkyl iodides, whereas transition-metal carbonylation – of aryl halides and triflates. Thus, the two carbonylation methods are complementary with respect to the scope of synthetic targets.</p>

<p>Transition metals have played an important role in synthetic organic chemistry for more than a century, and offer catalytic transformations that would have been impossible with classical chemistry. One of the most useful and versatile of the transition metals is palladium, which over the years has catalyzed many important carbon-carbon forming reactions. Popular cross-coupling reactions such as the Suzuki, Stille and the Heck reaction are all catalyzed by palladium, or more correctly, by palladium in its ground state, Pd(0). </p><p>Recently, interest in palladium(II)-catalyzed transformations has started to grow, partly due to the development of the vinylic substitution reaction, commonly called the oxidative Heck reaction, presented in this thesis. This Pd(II)-catalyzed, ligand-modulated reaction occurs under air at room temperature, and for the first time a general protocol employing a wide range of olefins and arylboronic acids was obtained. Ligand screening showed that the bidentate nitrogen ligand, 2,9-dimethyl-1,10-phenanthroline (dmphen), was the most suitable ligand. Dmphen is believed to facilitate regeneration of active Pd(II), increase catalytic stability and improve the regioselectivity in the reaction. A mechanistic investigation was conducted using electrospray ionization mass spectrometry (ESI-MS), making it possible to observe cationic intermediates in a productive oxidative Heck arylation. The results obtained are in agreement with the previously proposed catalytic cycle.</p><p>The emerging discipline of high-speed synthesis is making contributions to society’s growing demand for new chemical entities. This inspired the development of two ultrafast, microwave-accelerated carbonylation reactions with dicobalt octacarbonyl acting both as an in situ carbon monoxide supplier and reaction mediator. A wide range of symmetrical benzophenones was produced in only 6 to 10 s, using aryl iodides as the substrate. The second carbonylation reaction provided symmetrical and unsymmetrical ureas in process times ranging from 10 s to 40 minutes using primary and secondary amines.</p>

One-step photoinitiated free radical carbonylation was employed for the rapid (5–7 min) labelling of aliphatic carboxylic acids, esters, and amides with a short-lived positron emitter 11C (t½ = 20.3 min) at the carbonyl position. The labelled compounds were synthesized from alkyl iodides (0.05–0.1 mmol), [11C]carbon monoxide, and appropriate nucleophiles. Decay-corrected radiochemical yields were up to 74%; conversion of [11C]carbon monoxide reached 85–90%; specific radioactivity was 158–192 GBq/mmol. The labelled compounds were identified and characterized using HPLC, LC-MS, and 1H and 13C NMR. The effects of solvents, additives, photoirradiation, temperature, and reaction time were studied and discussed. [carbonyl-11C]Amides were synthesized using amines in 1–2 equiv. to iodides, exploiting solvent effects to control reactivity. [carboxyl-11C]Acids were synthesized using water as a nucleophile, in binary and ternary aqueous solvent mixtures; the addition of TBAOH or KOH was necessary to obtain high radiochemical yields. [carbonyl-11C]Esters were synthesized using primary and secondary alcohols, tert-butanol, and phenol. Bases were KOH, BuLi, LiHDMS. The effects of photosensitizers were studied and exploited to accelerate the labelling of carboxylic acids and esters resulting in 75–85% decay-corrected radiochemical yields under mild conditions without the use of bases. A mild procedure for the 11C-carboxylation of alkyl iodides using DMSO as an oxygen nucleophile was developed. This method is expected to be suitable in the macroscale synthesis of carboxylic acids using isotopically unmodified carbon monoxide. Radical carbonylation was applied to improve the synthesis of an extensively used PET tracer, [carbonyl-11C]WAY-100635. The tracer was synthesized in one step, whereas a common approach via Grignard reagents requires three steps. In addition, several (13C)compounds were synthesised using the described methods. Free radical carbonylation may be used for the 11C-carbonylation of alkyl iodides, whereas transition-metal carbonylation – of aryl halides and triflates. Thus, the two carbonylation methods are complementary with respect to the scope of synthetic targets.

Transition metals have played an important role in synthetic organic chemistry for more than a century, and offer catalytic transformations that would have been impossible with classical chemistry. One of the most useful and versatile of the transition metals is palladium, which over the years has catalyzed many important carbon-carbon forming reactions. Popular cross-coupling reactions such as the Suzuki, Stille and the Heck reaction are all catalyzed by palladium, or more correctly, by palladium in its ground state, Pd(0). Recently, interest in palladium(II)-catalyzed transformations has started to grow, partly due to the development of the vinylic substitution reaction, commonly called the oxidative Heck reaction, presented in this thesis. This Pd(II)-catalyzed, ligand-modulated reaction occurs under air at room temperature, and for the first time a general protocol employing a wide range of olefins and arylboronic acids was obtained. Ligand screening showed that the bidentate nitrogen ligand, 2,9-dimethyl-1,10-phenanthroline (dmphen), was the most suitable ligand. Dmphen is believed to facilitate regeneration of active Pd(II), increase catalytic stability and improve the regioselectivity in the reaction. A mechanistic investigation was conducted using electrospray ionization mass spectrometry (ESI-MS), making it possible to observe cationic intermediates in a productive oxidative Heck arylation. The results obtained are in agreement with the previously proposed catalytic cycle. The emerging discipline of high-speed synthesis is making contributions to society’s growing demand for new chemical entities. This inspired the development of two ultrafast, microwave-accelerated carbonylation reactions with dicobalt octacarbonyl acting both as an in situ carbon monoxide supplier and reaction mediator. A wide range of symmetrical benzophenones was produced in only 6 to 10 s, using aryl iodides as the substrate. The second carbonylation reaction provided symmetrical and unsymmetrical ureas in process times ranging from 10 s to 40 minutes using primary and secondary amines.

Many peptide receptors are of pharmaceutical interest and there is thus a need for new ligands for such receptors. Unfortunately, peptides are not suitable as orally administrated drugs since they are associated with poor absorption, rapid metabolism and low sub-receptor selectivity. One approach that should allow identification of more drug-like ligands is to use the structural information of the endogenous ligand to develop peptidomimetic compounds. The main objective of the work described in this thesis was to convert angiotensin II (Ang II, Asp-Arg-Val-Tyr-Ile-His-Pro-Phe) to small drug-like compounds with retained bioactivity at the AT2 receptor. The study was performed step-wise via incorporation of well-defined secondary structure mimetics and repeated truncation of the peptide. Five scaffolds, comprising a benzene ring as a central element, suitable as a γ-turn or dipeptide mimetics were designed and synthesized. In order to decorate the scaffolds, a method of microwave-assisted alkoxycarbonylation was developed. After incorporation of the scaffolds into Ang II-related peptides or peptide fragments, the affinities for both the AT1 and the AT2 receptor were determined. In the first series of ligands, two tyrosine-related scaffolds were introduced as γ-turn mimetics in Ang II. All five pseudopeptides exhibited good affinities for the AT2 receptor. One compound was chosen for functional studies and was shown to act as an AT2 receptor agonist. After truncation of Ang II it was shown that C-terminal pentapeptide analogs were AT2 receptor selective agonists. A series of pseudopeptides comprising tyrosine-related scaffolds, derived from the pentapeptides, displayed high AT2 receptor affinities. Two compounds had agonistic effect at the AT2 receptor. This study revealed that the N-terminal part was of less importance while a C-terminal Ile residue was a key element for enhanced AT2 receptor affinity. In the final set of compounds, the peptide was truncated to tripeptide C-terminal fragments. After replacing His-Pro by a histidine-related scaffold small drug-like peptidomimetic compounds with nanomolar affinity for the AT2 receptor were identified.

There is a continuing interest in the subject of arene carbonylation, especially in strong acids and environmentally-benign alternatives are sought to HF/BF3 and to AlCl3 as conversion agents. Ionic liquids offer a powerful solvent for useful conversion agents such as aluminum chloride. The ILs permit AlCl3 to be used at lower HCl partial pressures than with other solvents. The superior reactivity demonstrated by acidic, chloroaluminate ILs is probably due to their enhanced solvation power for HCl and CO. Addition of HCl gas increased reactivity of the system by forming Brnsted acids, and toluene carbonylation is a Brnsted demanding reaction. It was found that reaction is stoichiometric in Al species and only intrinsically acidic ILs are active for toluene carbonylation, therefore it was possible to correlate observed conversion with predicted amounts of Lewis + Brnsted acids. Molecular modeling provided information about the different species present in these ILs and predicted 1H NMR, and 27Al NMR spectrum. Predictions suggested that three types of HCl species are present; and these predictions were confirmed using data of 13C-labeled acetone and its 13C-NMR spectra. These data showed that only one of the three types of HCl in the IL were super acidic. Reactivity towards arene formylation can be tuned by adjusting the ligands R and R in the organic cation and by changing the anion. This reactivity tuning can be exploited in a process where high acidity is required for the conversion of substrate but where separation of product from IL is facilitated by low acidity.

In the first part of this thesis, palladium(0)-catalyzed and -mediated carbonylations are discussed. Paper I describes a new method for the safe, efficient use of a solid carbon monoxide source in the synthesis of primary and secondary benzamides. In total, 35 benzamides were synthesized from aryl iodides (20 examples, 69-97% yield) and aryl bromides (15 examples, 32-93% yield). Reduction-prone groups were used successfully in the reactions. In paper II, the same protocol was adopted for the palladium(0)-catalyzed synthesis of N-cyanobenzamides from aryl iodides/bromides, carbon monoxide and cyanamide. In total, 22 N-cyanobenzamides were synthesized (42-88% yield). The radiosynthesis of [11C]N-cyanobenzamides is discussed in paper III. In total, 22 compounds were synthesized from various aryl halides in 28-79% decay corrected radiochemical yield. The protocol was then applied to the radiosynthesis of [11C]N-cyanobenzamide analogs of flufenamic acid and dazoxibene. In the second part of this thesis, compounds of interest in relation to amyloid diseases are discussed. Paper IV describes the solid-phase synthesis of BACE-1 enzyme inhibitors containing secondary and tertiary hydroxyl as the transition state isostere. In total, 22 inhibitors were synthesized. The most potent compound (IC50= 0.19 µM) was co-crystallized at the active site of the enzyme to reveal a new binding mode. In paper V, the evaluation of a potent BACE-1 inhibitor as a potential radiotracer for use in PET is described. The radiolabeled [11C]BSI-IV was obtained in 29±12% decay corrected radiochemical yield by a three-component palladium(0)-mediated aminocarbonylation. Its properties as a potential PET tracer were investigated in vitro by autoradiography and in vivo in rats using small animal PET-CT. A new class of amyloid-binding PET ligands is described in paper VI. Three polythiophenes were labeled with carbon-11 or fluorine-18 (26-43% decay-corrected radiochemical yield). The in vitro studies showed that these ligands bind specifically to amyloid deposits. In vivo PET showed low uptake in the organs of interest in healthy rats and a monkey. These results suggest the labeled thiophenes derivatives could be useful as PET tracers for the study of amyloid diseases.