Littérature scientifique sur le sujet « Acide-phosphorique-chiraux »
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Thèses sur le sujet "Acide-phosphorique-chiraux"
Stadler, Adrien. « Concept du ligand chiral relais en catalyse tandem assistée asymétrique ». Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASF011.
Texte intégralIn the context of environmentally friendly chemistry, successful approaches to the recovery and reuse of costly components have proven effective in non-asymmetric reactions. However, their application in asymmetric reactions is less common due to challenges associated with maintaining control over the formed asymmetric centers. This doctoral thesis focuses on the development of a versatile strategy for the reuse of the chiral auxiliary in a sequence of asymmetric assisted tandem metallo-organo-catalysis. The use of a crucial chiral species for controlling the formation of multiple stereocenters is explored. Independent analysis of reactions, coupled with the exploration of the tandem sequence, demonstrates that the use of the chiral relay ligand in asymmetric assisted tandem catalysis is a promising strategy for streamlining complex product synthesis procedures, successfully ensuring control and successive formation of two asymmetric centers within the same reactor
Laurent, Grégory. « Réactions de cycloadditions énantiosélectives catalysées par des dérivés d’acides de Brønsted chiraux ». Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112419.
Texte intégralThis thesis works were aimed the asymmetric synthesis of optically pure heterocycles by high added value methodology. On one hand, the asymmetric organocatalysis allows using an inexpensive chiral materials in small quantities to generate chiral products, on the other hand, the cycloaddition reactions allow atom economy and the creation of several bonds in one reaction.The first part of this thesis concerns inverse electron demand aza-Diels-Alder cycloaddition reaction. These works involve 1-Azadienes and enecarbamates to generate tetrahydropyridines with three contiguous stereocenters.The products were obtained as a single diastereomer in good yields and good enantiomeric excess. The modification of substrates at various positions was possible without influencing the efficiency of the reaction.In the second part, a cycloaddition reaction between quinones and enecarbamates was studied. The use of a backbone SPINOL phosphoric acid proved to be very effective, leading to optically active 2,3-Dihydrobenzofurans. The products are isolated in excellent yields and enantiomeric excesses, but low diastereomeric ratios. These can be improved by engaging enethiocarbamates.A cascade reaction may also be carried out by forming the quinone in situ with a hypervalent iodine reagent. The scope of our cycloaddition and its variant initiated by PIDA is substantial but still needs to be improved. Different hydroquinones will thus be evaluated. The cycloadducts will later be transformed to develop this methodology.The last part concerns a 1,3-Dipolar cycloaddition reaction between nitrones and enecarbamates. If the use of a phosphoric acid has not proved effective, using a copper phosphate is convincing. Initially, the reaction shown excellent results, unfortunately not reproducible. A rigorous optimization was necessary to obtain satisfactory results. This reaction requires an assessment of its extent. Transformations are also envisaged to enhance the methodology
Albini, Mathieu. « Synthèse et application d'acides de Brønsted Chiraux pour l'organocatalyse asymétrique ». Caen, 2015. http://www.theses.fr/2015CAEN2012.
Texte intégralChiral Brønsted acids are particularly important in asymmetric organocatalysis due to their remarkable catalytic properties in several reactions. Herein, we studied their use in cooperative catalysis with Lewis acid for the direct aldol reaction previously reported by our laboratory. This work has been followed by the addition of ketones and aldehydes onto acetals under superacid catalysis. Then, an original mode of action for N-triflyl phosphoramides was discussed in a study of the aza-Petasis-Ferrier rearrangement of trichloroacetimidate. Finally, catalyst synthesis has been simplified using an optimized Suzuki coupling under microwave irradiation and a newly developed synthesis of arylboronic acids from anilines in aqueous conditions
Pousse, Guillaume. « Acides de Brønsted chiraux : Synthèses et applications en organocatalyse asymétrique ». Caen, 2010. http://www.theses.fr/2010CAEN2067.
Texte intégralOrganocatalysts has recently emerged as an alternative to transition metals for enantioselective catalysis. Since 2004, chiral Brønsted acids appeared as an important contribution to this area of research. In this work, a range of novel phosphoric and phosphorodithioic acids derived from BINOL have been synthesized to modulate the acidity and the steric hindrance of the catalysts. These acids have been used to investigate asymmetric Nazarov, Mannich and aldol reactions. The phosphoric acids appeared as more selective catalysts whilst the phosphorodithioic acids were shown to be more acidic. A syn-enantioselective aldol reaction has been developed using a strongly hindered phosphoric acid. This reaction is the first example of an enantioselective direct aldol reaction using Brønsted acid catalysis. This method affords the asymmetric synthesis of various β-hydroxyketones, some of which could not be synthesized using enamine organocatalysis. This confirms the potential of phosphoric acids as chiral catalysts in enantioselective reactions
Gelis, Coralie. « Développement de réactions énantiosélectives organocatalysées pour la synthèse de molécules cycliques énantioenrichies ». Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS430.
Texte intégralThe development of new enantioselective methodologies is essential for the synthesis of bioactive compounds. In this context, we were interested in using organocatalysts for the synthesis of enantioenriched cyclic molecules. In a first part will be describe chiral phosphoric acid catalyzed (3+2), (4+2) and (4+3) formal cycloadditions using enecarbamate or dienecarbamate. These catalysts are bifunctional and can interact with both cycloaddition partners leading to the synthesis of 2,3-dihydrobenzofuranes, carboannulated benzoquinones, cyclohepta[b]indoles and tetrahydroquinolines with high stereocontrol. In a second phase, we were interested in using chiral hypervalent iodine as organocatalyst. Theses compounds present interesting reactivity while being stable and not very toxic. Their use permits us to develop a lactonisation starting from flexible substrate and led to the synthesis of various heterocycles with good results
Saidah, Milane. « Synthèse énantiosélective de gamma-lactames possédant un centre tétrasubstitué ». Electronic Thesis or Diss., Aix-Marseille, 2023. http://www.theses.fr/2023AIXM0034.
Texte intégralIn view of the emergence of organocatalysts compounds as powerful tools for asymmetric catalysis, the development of processes involving chiral ion pairs has proven successful. Notably, Asymmetric Counterion-Directed Catalysis (ACDC) is well-known to be an efficient strategy for enantioselective reactions involving cationic species and enantiomerically pure counteranions. More specifically, cyclic N-acyliminium ions are key intermediates in the preparation of enantioenriched gamma-lactams. Based on the concept of ACDC, this work has focused on the construction of tetrasubstituted carbon centers via an organocatalyzed alpha-amidoalkylation reaction by chiral phosphoric acids from gamma-hydroxylactams
Dumoulin, Audrey. « Synthèse asymétrique de 1,2-diamines et développement de nouveaux organoiodanes chiraux pour des réactions d'oxygénation ». Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS364.
Texte intégralThe 1,2- diamines can be found in many biologically active compounds, which pushed organic chemists to develop new methodologies to synthesize those molecules. In this context, the stereochemistry is essential because the biological activity ensues. Thus, we were interested in developing an enantioselective amination of enamide derivatives catalyzed by chiral phosphoric acids. These catalysts interact with substrates via hydrogen bonds to activate a nucleophile and an electrophile simultaneously. Our strategy proved to be very effective and allowed us to synthesize a wide range of 1,2- diamine. Many compounds of biological interest, including heterocycles used in pharmaceutical and cosmetic industry, were tolerated with this process. In another project, we looked at the design of chiral hypervalent iodine compounds. These compounds have recently gained considerable attention because of their stability to air and moisture, their low toxicity and their interesting reactivity. However, despite considerable development, the use of hypervalent iodine derivatives in catalytic asymmetric reactions deserves to be further studied. In this context, new pre-catalysts were developed in our laboratory and used in enantioselective oxygenation reactions. The special structure of these compounds yielded the best enantiomeric excesses of the literature to date