CNRS Organic and Macromolecular Chemistry Research Unit

Le Havre, France

CNRS Organic and Macromolecular Chemistry Research Unit

Le Havre, France
SEARCH FILTERS
Time filter
Source Type

Othman R.B.,CNRS Organic and Macromolecular Chemistry Research Unit | Othman R.B.,Gafsa University | Affani R.,CNRS Organic and Macromolecular Chemistry Research Unit | Tranchant M.-J.,CNRS Organic and Macromolecular Chemistry Research Unit | And 3 more authors.
Angewandte Chemie - International Edition | Year: 2010

(Chemical Equation Presentation) Atom-economical: Unmodified hemiN,O-acetals are used in a catalytic, highly efficient α- amidoalkylation of a broad range of carbon-centered nucleophiles, including silicon-based components, active methylene derivatives, electron-rich arenes, and even simple ketones (see scheme). The reactions proceed in a highly efficient manner and typically require only 1 mol% of the Lewis super-acidic reagent Sn(NTf2)4 as the catalyst. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.


Comesse S.,CNRS Organic and Macromolecular Chemistry Research Unit | Martel A.,University of Maine, France | Daich A.,CNRS Organic and Macromolecular Chemistry Research Unit
Organic Letters | Year: 2011

A totally new acid-free domino process to access highly functionalized bicyclic γ- and δ-lactams starting from commercially available and inexpensive ethoxymethylene derivatives is reported. Mechanisms elucidated by computational calculations led to new reaction conditions that boosted the yields up to 3.5 times higher. © 2011 American Chemical Society.


Briere J.-F.,French National Center for Scientific Research | Oudeyer S.,French National Center for Scientific Research | Dalla V.,CNRS Organic and Macromolecular Chemistry Research Unit | Levacher V.,French National Center for Scientific Research
Chemical Society Reviews | Year: 2012

Over the last decade, with the surge in the development of organocatalysis, many processes involving chiral ion pairs have emerged as powerful tools in the design of new efficient organocatalysts. This tutorial review focuses on the recent evolutions of these organocatalytic systems in which both anionic and cationic parts are working in a cooperative fashion in order to develop unique catalytic processes which outperform the existing approaches. In this respect, chiral ion pairs opened new avenues in the design of bifunctional organocatalysts by means of combinatorial approaches. © 2012 The Royal Society of Chemistry.


Pesquet A.,CNRS Organic and Macromolecular Chemistry Research Unit | Othman M.,CNRS Organic and Macromolecular Chemistry Research Unit
Tetrahedron Letters | Year: 2013

A novel approach to diversely spirocyclic isoindoles has been developed by using N-acyliminium/ring-closing metathesis strategy. Spirocyclization precursors, diolefinic, and enyne spiro-fused-isoindole derivatives have been obtained by a regioselective reduction of the spiro-imide compounds, followed by the allylation of the N-acyliminium intermediates (generated from the acetoxylactam compounds). Ruthenium catalyzed ring-closing metathesis of the above unsaturated derivatives provided novel spiroisoindoles. © 2013 Elsevier Ltd. All rights reserved.


Antoniotti S.,University of Nice Sophia Antipolis | Dalla V.,CNRS Organic and Macromolecular Chemistry Research Unit | Dunach E.,University of Nice Sophia Antipolis
Angewandte Chemie - International Edition | Year: 2010

The continuously increasing need for novel and selective methods in organic synthesis to aid drug discovery and to address environmental concerns is a constant source of stimulation to develop novel and more efficient reaction systems. This has often resulted in a focus on transition metals, ligands, and additives, with much less attention paid to the counterion(s) of the metal cation. Recently, metal salts with one or more triflimidate counterion(s) have appeared as a unique class of catalysts that display outstanding σ- and π-Lewis acid character. The highly delocalized nature of the triflimidate counterion, combined with its high steric hindrance results in virtually no nucleophilic behavior and an extremely high positive charge density on the metal cation, thus enhancing its Lewis acid character. Consequently, these metal triflimidates often outperform their metal halide or triflate analogues. This Review describes general methods for the preparation of metal triflimidate salts and their use as catalysts. Worth its salt: The triflimidate anion, by virtue of its highly delocalized charge and steric hindrance, enhances the electrophilic character of the metal center and, therefore, its Lewis acidity. In most cases, triflimidate catalysts are superior to triflates or other salts. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Renou F.,CNRS Organic and Macromolecular Chemistry Research Unit | Petibon O.,CNRS Organic and Macromolecular Chemistry Research Unit | Malhiac C.,CNRS Organic and Macromolecular Chemistry Research Unit | Grisel M.,CNRS Organic and Macromolecular Chemistry Research Unit
Food Hydrocolloids | Year: 2013

Xanthan (X) and locust bean gum (LBG) are well known to exhibit strong rheological enhancement when mixed as a result of specific interactions between both gums. On the one hand, the present work deals with the influence of the thermal treatment of xanthan/LBG mixtures on their interactions. The rubber elasticity theory evidences that the viscoelasticity enhancement after heating is related to an increase of the cross-linking density between smooth region of LBG and disordered segment of xanthan (from 1 per 62 to 1 per 10 repeating units of xanthan molecules for unheated and heated systems, respectively). Additionally, based on different xanthan samples with various acetate and pyruvate rates, we clearly illustrate how rheological properties and thus interactions evolve with both acetate and pyruvate contents. © 2013 Elsevier Ltd.


Savary G.,CNRS Organic and Macromolecular Chemistry Research Unit | Grisel M.,CNRS Organic and Macromolecular Chemistry Research Unit | Picard C.,CNRS Organic and Macromolecular Chemistry Research Unit
Colloids and Surfaces B: Biointerfaces | Year: 2013

This study deals with the impact of emollients on the spreading properties of cosmetic products using a combined sensory-instrumental approach. To that purpose, three esters and one silicone were selected and incorporated separately into an oil phase. Different cosmetic o/w emulsions were then prepared with these different oil phases. Both of them were analyzed by instrumental techniques and in vivo sensory analyses. A significant effect of the emollient used was established in emulsions and in oil phases as well. Concerning emulsions, results reveal a clear correlation between in vivo spreading evaluation and friction coefficient parameters measured by texture analyzer, despite a fairly low correlation coefficient (Pearson coefficient = -0.78). Concerning oil phases, characterization of spreading was done by monitoring the contact angle relaxation of a drop of solution after deposition on a flat PMMA surface whereas sensory procedure was based on spontaneous spreading of oil phases onto the skin. Finally, good correlations between in vivo sensory analysis and instrumental measurements of both oils and emulsions were found, thus promising the possible development of predictive tools to evaluate spreadability. © 2012 Elsevier B.V.


Le Goff R.,CNRS Organic and Macromolecular Chemistry Research Unit | Lawson A.M.,CNRS Organic and Macromolecular Chemistry Research Unit | Daich A.,CNRS Organic and Macromolecular Chemistry Research Unit | Comesse S.,CNRS Organic and Macromolecular Chemistry Research Unit
Organic and Biomolecular Chemistry | Year: 2013

An aza-Michael induced ring closure (aza-MIRC) tandem reaction of benzyl (2-bromoethyl)carbamate with various Michael acceptors is described. The N-Cbz-β-gem-disubstituted pyrrolidines thus obtained were proved to be versatile intermediates for the rapid access to both martinelline and spirooxindole backbones. An application of this strategy towards an expedient 4 step total synthesis of (±)-coerulescine is also presented. © 2013 The Royal Society of Chemistry.


Boiaryna L.,CNRS Organic and Macromolecular Chemistry Research Unit | El Mkaddem M.K.,CNRS Organic and Macromolecular Chemistry Research Unit | Taillier C.,CNRS Organic and Macromolecular Chemistry Research Unit | Dalla V.,CNRS Organic and Macromolecular Chemistry Research Unit | Othman M.,CNRS Organic and Macromolecular Chemistry Research Unit
Chemistry - A European Journal | Year: 2012

Gold catalysts have been applied in cascade-type reactions for the synthesis of different nitrogen-based compounds. The reactions likely proceed by a new gold-catalyzed cascade intermolecular α-amidoalkylation/ intramolecular carbocyclization cascade process by unifying both the σ- and π-Lewis acid properties of the gold salts. In the first part of this report we show that the σ-Lewis acidity of gold(I) and gold(III) could be exploited to efficiently catalyze the nucleophilic substitution of various alkoxy- and acetoxylactams. The reaction was found to be applicable to a wide range of cyclic N-acyliminium ion precursors and various nucleophiles, including allyltrimethylsilane, silyl enol ethers, arenes, and active methylene derivatives. As a logical progression of this study, a combined hard/soft binary catalytic gold system was then used to implement an unprecedented tandem intermolecular Friedel-Crafts amidoalkylation/intramolecular hydroarylation sequence allowing an expedient access to new, complex, fused polyheterocyclic structures from trivial materials. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Desplanques S.,CNRS Organic and Macromolecular Chemistry Research Unit | Renou F.,CNRS Organic and Macromolecular Chemistry Research Unit | Grisel M.,CNRS Organic and Macromolecular Chemistry Research Unit | Malhiac C.,CNRS Organic and Macromolecular Chemistry Research Unit
Food Hydrocolloids | Year: 2012

Xanthan gum (GX) and acacia gum (GA) are widely employed in food industry, indeed xanthan gum is used for its thickening properties of aqueous solutions and acacia gum for its emulsifying ability. The present work aims to study the effect of GX-GA mixtures on the stability of oil-in-water (o/w) emulsions; attention is particularly focused on the impact of the chemical structure of each gum. Emulsion stability has been evaluated by monitoring the evolution of droplet size and viscometric properties over time when submitted to accelerated ageing conditions. On the one hand results show that the higher the ArabinoGalactanProtein (AGP) content the more stable the emulsion as observed when GA is used alone. On the other hand, we proved, unexpectedly, that the most viscous aqueous phase does not exhibit the best emulsion stability. Besides, we clearly evidenced the presence of specific interactions between GX and GA in both emulsion and aqueous solution, these interactions being governed by the gums chemical composition. © 2011 Elsevier Ltd.

Loading CNRS Organic and Macromolecular Chemistry Research Unit collaborators
Loading CNRS Organic and Macromolecular Chemistry Research Unit collaborators