Domino allylic amination/Sonogashira/heterocyclisation reactions: palladium-catalysed three-component synthesis of pyrroles

International audienceThree-component reactions with 3,4-diiodoalk-2-enoic derivatives, primary amines, and terminal alkynes proceeded to give trisubstituted pyrroles in fair to good yields in the presence of palladium and copper catalysts under mild reaction conditions

Métaux de transition : outils indispensables pour la synthèse organique

National audienc

Hétérocyclisations en présence de sels cuivreux

Nous avons mis au point une réaction tandem couplage/cyclisation entre des dérivés acides carboxyliques ß-iodés et des alcynes vrais en présence sels de cuivre. Cette transformation conduit régio et stéréosélectivement à la formation de ?-alkylidènebuténolides. Les différents essais effectués ont montré que la méthodologie tolère un grand nombre de substrats et de fonctions. L extension de la réactivité sur des acides carboxyliques a,ß-dihalogénés nous a permis d accéder régio et stéréosélectivement à la formation d a-halogéno-?-alkylidènebuténolides. La conservation d un halogène sur le buténolide obtenu dénote la flexibilité de la transformation et permet ensuite d étendre la structure du buténolide par les réactions de couplage croisés. Cette flexibilité nous a permis d accéder à la synthèse de rétinoïdes et de précurseurs de nostoclides I et II. Une étude annexe sur des substrats de type aromatiques et hétéroaromatiques a montré l invertion de la régiosélectivité au profit de la formation d a-pyranone. Ces essais ont conduit à la synthétiser de nombreux indoles, isocoumarines et thiophènes originaux.We have developed a tandem coupling/cyclization reaction between ß-iodided acrylic acid derivatives and true alkynes in the presence of copper salts. This transformation led regio and stereoselectively to the formation of ?-alkylidenebutenolides. Different tests have shown that the method tolerates many substrates and functions. The extension of the reactivity on a,ß-dihalogenated acrylic acids derivatives allowed us to access regio and stereoselectively to the formation of a-halo-?-alkylidenebutenolides. The conservation of a halogen on the butenolides obtained indicates the flexibility of the process and allows then the extention of the butenolide structure by cross-coupling reactions. This flexibility has allowed us to access to the synthesis of retinoids and nostoclides I and II precursors. An annex study on other substrates like aromatic and heteroaromatic systems showed the inversion of the regioselectivity of our methodology in favor of the formation of a-pyranone. These tests led to the synthesis of many original indoles, isocoumarines and thiophenes moietiesTOURS-Bibl.électronique (372610011) / SudocSudocFranceF

A novel Zn(II) complex of N-nicotinyl phosphoramide: Combined experimental and computational studies

International audienceA novel Zn(II) coordination polymer of N-nicotinyl phosphoric triamide ligand, {[Zn(L)(2)(H2O)(2)]center dot(NO3)(2)}(n) C1 (L = 3-NC5H4C(O)NHP(O)(NC6H12)(2)), has been synthesized and characterized by IR and H-1, C-13, P-31 NMR spectroscopy. Crystal structure analysis of C1 demonstrates a distorted octahedral geometry for Zn(II) ions. The oxygen atom of phosphoryl group (O-phosphoryl) and the nitrogen atom of pyridine ring (N-pyridine) of ligand take part in coordination to Zn(II) centers in a bidentate bridging mode. This coordination pattern results in infinite 1D polymeric chains along c axis, which are composed of metal shared 16-membered puckered rings. Structural data show that despite binding through O-phosphoryl, the P=O bond distance unexpectedly shortens in C1 when compared to that of the ligand, conceivably due to the steric factors in the solid state. This is confirmed by comparing the structural and electronic properties of C1 and L in the gas phase by using density functional theory (DFT) calculations. Natural bond orbital (NBO) analysis reveals the metal-ligand interaction for C1 as donor-acceptor type delocalizations (charge transfer). Besides, on the basis of the quantum theory of atoms in molecules (QTAIM) analysis, the nature of Zn-O and Zn-N bondings is found to be mainly electrostatic with a small amount of covalent character. (C) 2015 Elsevier B.V. All rights reserved

Efficient One-Pot Synthesis of Triazole-Linked Morpholinone Scaffolds by CuAAC in the Presence of 18-Crown-6

International audienc

Réalisation et caractérisation d'aérogels organiques à fortes teneurs métalliques obtenus à partir d'un complexe de titane polymérisable

L'étude de la fusion par confinement inertiel du mélange deutérium + tritium (DT) est une problématique depuis longtemps abordée par le CEA. Les expérimentations liées à cette thématique, effectuées prochainement au sein du laser mégajoule (LMJ), nécessitent l'utilisation de matériaux aux propriétés particulières. Cela concerne entre autres les mousses de polymères (aérogels organiques) composant les cibles de pré-ignition. De tels matériaux doivent notamment associer une importante porosité à une forte teneur métallique (1% atomique de Ti), tout en étant compatible avec les procédés de préparation utilisés. Dans ce contexte, un nouveau complexe polymérisable de titane a été préparé et caractérisé par plusieurs techniques d'analyses. Ce monomère dispose d'une forte teneur métallique tout en présentant une bonne stabilité vis-à-vis l'air et l'humidité. Sa copolymérisation radicalaire selon différentes conditions suivie d'un séchage en condition supercritique a permis l'obtention d'une série d'aérogels organiques. Les caractérisations chimiques (RMN, infrarouge et analyses élémentaires) ainsi que les caractérisations structurales (MEB-EDS, MET, mesure des isothermes d'adsorption/désorption de l'azote et SAXS) de ces polymères ont permis de valider les critères mentionnés dans notre cahier des charges. En outre, ces données ont permis de déterminer les mécanismes de formation de la nanostructure des mousses.Inertial Confinement Fusion (ICF) is a technique widely studied by the French atomic commission (CEA). Experiments will be performed within the Laser Megajoule (LMJ). They require innovative materials like organic aerogels that constitute laser targets. Such polymeric material must provide both a high porosity and a significant titanium percentage (1 atom %). Moreover, the monomers developed must be compatible with the synthesis procedure already in use. According to these specifications, a new polymerizable titanium complex was synthesized and fully characterized. This air and moisture-stable monomer provides a high metal percentage. Its free-radical cross-linked copolymerization affords several titanium-containing polymers. These gels were dried under supercritical conditions and organic aerogels were obtained. The chemical compositions of these materials were investigated by NMR, IR and elemental analysis while their structure was characterized by MEB-EDS, MET, N2 adsorption/desorption isotherms measurements and SAXS. The data collected fit the specification requirements. Moreover, the mechanisms responsible of the foam nanostructure formation were discussed.TOURS-Bibl.électronique (372610011) / SudocSudocFranceF

Palladium and Copper Catalyzed Sonogashira Decarboxylative Coupling of Aryl Halides and Alkynyl Carboxylic Acids

International audienceThe Sonogashira cross-coupling reaction is the most useful tool for the formation of the C(sp2) – C(sp) bond and it is used as a key step in total synthesis. This reaction proceeds via palladium catalyzed coupling between aryl halides and terminal alkynes in the presence of copper salts as co-catalysts. One limitation of this coupling is the alkyne source, in particular the use of volatile terminal alkynes. The decarboxylative Sonogashira reaction between aryl halides and alkynyl carboxylic acids has emerged as an alternative to the Sonogashira reaction, and terminal alkynes are replaced by the corresponding alkynyl carboxylic acids that are easily available and stable for handling and storage.A mild procedure of palladium and copper catalyzed decarboxylative cross-coupling reaction of aryl halides and alkynyl carboxylic acids has been developed. Low molecular weight acids, to introduce small building blocks, were specifically used. This methodology is easy to implement and uses common reactants and catalysts

Preparation of 3‐Alkylidenephthalides: Recent Advances

3-Alkylidenephtalides represent a large class of structurally diverse molecules containing natural products or pharmaceutically designed compounds, and they exhibit a wide variety of biological activities. The goal of this review is to focus on the recent advances for the preparation of 3-alkylidenephtalides