Literatura científica selecionada sobre o tema "Réaction photochimique en tandem"
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Artigos de revistas sobre o assunto "Réaction photochimique en tandem"
Ivanoff, Melle N. "Sur la Réaction Photochimique des Composés Polyaromatiques Avec le Tétrachlorure de Carbone". Bulletin des Sociétés Chimiques Belges 71, n.º 11-12 (2 de setembro de 2010): 759–63. http://dx.doi.org/10.1002/bscb.19620711124.
Texto completo da fonteTeses / dissertações sobre o assunto "Réaction photochimique en tandem"
Yu, Xiaodan. "New functionalized alkylidenecyclobutanes : multicomponent synthesis and applications". Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASF034.
Texto completo da fonteCyclobutane derivatives have become increasingly important as molecular building blocks because of their inherent ring strain that facilitates the selective modification of their structures for strategic used in organic synthesis. Cyclobutane rings also appear in the molecular structures of a wide panel of natural and synthetic molecules that display interesting biological activities. Within this large family, alkylidenecyclobutane subunits are encountered in natural products, such as providencin, and they exhibit enhanced reactivity providing access to complex molecular structures, including enlarged ring and highly functionalized cyclobutane derivatives. In our laboratory, we recently developed an efficient synthesis of functionalized cyclobutenes through a domino photochemical reaction starting from cyclopent-2-enones and ethylene. Based on this study, we first explored a straight-forward transformation of functionalized cyclobutenes into alkylidenecyclobutanes. We then combined both sequences in a domino-multicomponent process. This was accomplished in a single protocol, comprising a tandem photochemical [2+2]-cycloaddition / Norrish-I / γ-H transfer reaction followed by an acetal-protection and an allylic substitution reaction. Additionally, the intramolecular version of these reactions allowed the synthesis of complex fused-bicyclic alkylidenecyclobutanes. Finally, the post-funtionalization of selected alkylidenecyclobutanes was studied, aiming to prepare novel fused tricyclic compounds through a intramolecular [2+2] photochemical process
Peyrane, Frédéric. "Origine des mutations tandem CC vers TT dans les cancers de la peau : approche synthétique des adduits cyclobutaniques de cytosine". Paris 11, 2004. http://www.theses.fr/2004PA112092.
Texto completo da fonteThe cyclobutane photoproducts (CPD) of cytosine are natural damages of DNA and are potentially involved in skin carcinogenesis. Their precise mutagenic effect has however not been fully assessed because of instability problems. We have developped three approaches for the synthesis of this photoproduct that could be incorporated into a shuttle vector for mutagenicity studies. The photosensitized irradiation of a protected dCpdC dinucleotide (path 1) failed, because of a lack of reactivity. The photolysis of a tetrazolo[1,5-c]pyrimidin-2-one dinucleotide analogue (path 2) led to the isolation of Iwo CPOs (cis-syn 41%, trans-syn Il 16%). Moreover it obviates the deamination process. Unfortunately, the subsequent reduction of the tetrazole ring, regenerating the cytosine CPD adduct, could not be accomplished. A thiation/amination sequence of dUpdU CPD compounds (path 3) was then investigated. Despite the conversion of the silylated 2'-deoxy-5,6-dihydrouridine, used as a model, into its cytosine analogue, the application of this strategy to a dinucleotide was unsuccessful, because of the sensitivity of the phosphotriester group under the reaction conditions used
Laurent, Michel. "Comportement de molécules chromophores dans des mésophases nématiques lyotropes et application à l'analyse d'une réaction photochimique". Paris 11, 1987. http://www.theses.fr/1987PA112005.
Texto completo da fonteGodineau, Edouard. "Synthèse de Pipéridinones fonctionnalisées par cascade radicalaire-ionique et réaction multicomposants". Bordeaux 1, 2007. http://www.theses.fr/2007BOR13502.
Texto completo da fonteThe piperidine framework is ubiquitous in Nature and found in a wide number of biologically active natural products. Piperidinone analogues are often encountered as key elements in the retrosynthetic plans of such targets. We first have developed a new stereoselective access to fused bicyclic piperidinones. Our approach relies on a cascade reaction which is on a mechanistic standpoint, built upon the combination of radical and ionic processes. We next turned toward the development of an even more convergent strategy. We indeed devised a one-pot protocol for the synthesis of functionalized piperidinones by assembly of three independent components. A sequential four component variant was also discovered, allowing for the synthesis of piperidinones bearing up to three stereogenic centers with total stereocontrol
Marin, Lucile. "Réaction d’aza-Piancatelli : nouvelles applications, version diastéréosélective et utilisation en synthèse totale". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS206.
Texto completo da fonteDue to their various functionalizable sites, cyclopentenones are very useful intermediates for the synthesis of natural products of therapeutic value. In particular, 4-aminocyclopentenones enable the access to the aminocyclopentitol frameworks, which are present in a variety of bioactive molecules such as peramivir, pactamycin, or trehazolin. One of the most efficient methods to access 4-aminocyclopentenones is the aza-Piancatelli reaction. It is based on the rearrangement of 2-furylcarbinols in the presence of a nitrogen nucleophile following a mechanism involving a 4π-conrotatory electrocyclization. In our laboratory, a simple catalytic system using a calcium complex combined with an ammonium salt was developed to gain access to these compounds. This method has many advantages : it is effective (yields up to 98%), fast (15 to 30 minutes), it requires only 1 mol% of catalyst under pratical conditions (undistilled solvents without an inert atmosphere) on a large scale (multi-gram). In this context, we sought to extend the scope of this reaction by designing more complex 2-furylcarbinols in order to directly access skeletons of bioactive compounds. In particular, we focused on the total synthesis of jogyamycin. In addition, we achieved the total synthesis of bruceollin D with an overall yield of 16% over five steps. We also developed a new reaction sequence involving an aza-Piancatelli reaction followed by a hydroamination reaction promoted by a copper salt. This sequence provides a wide range of highly functionalized cyclopenta[b]pyrroles from readily-available 2-furylcarbinols substituted by an alkyne moiety. Following this method, 42 cyclopenta[b]pyrroles were obtained with yields up to 98%. An original feature of this transformation is related to the use of ortho-substituted anilines. Indeed, in this case, atropisomers with a diastereomeric excess superior to 20:1 could be obtained accompanied by the creation of an chiral N-C axis during the hydroamination step. To date, no other example of atropodiastereoselective synthesis of cyclopenta[b]pyrroles has been reported. During our investigations on the scope of the reaction, we noticed that cyclopenta[b]pyrroles underwent a rearrangement into cyclopenta[b]pyrrolines, following a dearomatization when hexafluoroisopropanol was used as solvent. This transformation led to 13 cyclopenta[b]pyrrolines with yields ranging from 44% to 73%. We also investigated the functionalization of the cyclopenta[b]pyrrole motif to illustrate the synthetic utility of our methodology, notably by combining this reaction sequence with a Friedel-Crafts reaction. One of the objectives of this Ph.D. was the development of an enantioselective version of the reaction. After the recent publication of three papers using chiral phosphoric acids as catalysts, we devised another approach for the asymmetric synthesis of 4-aminocyclopentenones, relying on the use of a chiral auxiliary (chiral sulfoxide) in collaboration with Dr. Wencel-Delord and Pr. Colobert (University of Strasbourg). Thus, we were able to provide the corresponding 4-aminocyclopentenones with excellent yields and diastereoselectivity
Favre, Annaïck. "Applications de la réaction tandem hétéro Diels-Alder / Allylboration à la synthèse de produits naturels". Rennes 1, 2007. http://www.theses.fr/2007REN1S120.
Texto completo da fonteHe utilisation of an hetero Diels-Alder/allylboration asymmetric tandem reaction for the synthesis of several natural products, has been studied. It has been shown that the hydroxyalkylated dihydropyran unit, obtained frome this reaction, opens the access to different molecules from the Styryllactones’ family. It has been shown that the use of the paraformaldehyde during the process, makes possible the synthesis of natural products bearing a double bond adjacent to the heteroatom of the cycle. This tandem reaction has also been employed for the synthesis of the laulimalide’s C₁₅-C₂₇ fragment and three analogs. Finally, some tests have been managed for the second C₁-C₁₄ fragment’s synthesis
Moussa, Saber. "Réactions tandem de type aza-MIRC et ions N-acyliminiums : accès rapide et stéréocontrôlé à des nouvelles structures aza-cycliques". Le Havre, 2010. http://www.theses.fr/2010LEHA0009.
Texto completo da fonteThis report presents a new method of the preparation of a new class of highly functionalized N, O – acétals and the study of their ability to react towards catalytic intra – and intermolecular α-amidoalkylation reactions. In a first chapter, we described some methods of synthesis of the precursors of N–acyliminiums ions and their various activation pathways. In the second chapter we elaborated the synthesis of functionalized 5-alkoxypyrrolidinones as precursors of N–acyliminiums species according to a new aza-MIRC tandem process with involves commercial diester-, cyanoester-, and dicyano alkoxymethylenes and various N-substitued α-bromoacetamides as dipole-[1,3]. A first application of the N,O-acetalic moiety in previously synhesized lactams is described in the third chapter involving intramolecular Friedel-Crafts reactions. This study, conducted from N-arylethyl substituted γ-lactams, and leading and a simple and fast way to tricyclic compounds of biological interest. These results allowed us to point out the positive effects of both arms ester in α-position of the reaction site. Explained essentially by an assistance to the generation of the N-acyliminium ion and also by an increase of its reactivity potential by the formation of a pseudocyclic intermediate resulting from an anchimeric assistance. The fourth chapter was the object of a complementary study that led previously by the investigation of the intermolecular approach of the α-amidoalkylation reaction. The reactivity results showed a perfect analogy with those of the intramolecular study. The synthetic application of thes adducts was demonstrated by some examples of synthesis of bicycles compouds by metathesis
Coudanne, Isabelle. "Réactions "tandem" palladocatalysées : nouvelles voies d'accès à des systèmes polycycliques fonctionnalisés". Lyon 1, 1997. http://www.theses.fr/1997LYO10348.
Texto completo da fonteLescarbeau, André. "Étude de la réaction de Cope et d'oxy-Cope en tandem pour la formation de squelettes carbonés". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0031/MQ67306.pdf.
Texto completo da fonteMac, Dinh Hung. "Nouveaux développements de la réaction tandem isomérisation-aldolisation intramoléculaire à partir d'alcools allyliques et/ou de lactols". Rennes 1, 2009. http://www.theses.fr/2009REN1S111.
Texto completo da fonteThis thesis work is an extension of our group's research programme on the tandem intramolecular isomerization-aldolization reaction from allylic alcohols and/or lactols. The first chapter deals with the application of this reaction towards the enantioselective total synthesis of bioactive natural compounds, the Gabosines. In the second chapter, we describe an original synthesis of new iminosugars with a polyhydroxypiperidine skeleton. This family of compounds is particularly interesting from a biological point of view because they are glycosidases inhibitors and, as such, they are developed against various diseases (cancer, diabetes, etc. . . ). The final chapter concerns the first extension of this reaction to a bicyclic system, leading to new fonctionalized bicyclo [3. 2. 1] octane derivatives. In this particular case, we observed a total stereocontrol for the tandem reaction and this result could be rationalized by the DFT calculation of the transitions states