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Allous I.,CNRS Organic and Macromolecular Chemistry Research Unit | Allous I.,Damascus University | Comesse S.,CNRS Organic and Macromolecular Chemistry Research Unit | Sanselme M.,CNRS Separative Sciences and Methods | Daich A.,CNRS Organic and Macromolecular Chemistry Research Unit
European Journal of Organic Chemistry

Herein, we present a new development of the previously described aza-Michael-initiated ring closure (MIRC) process to access spirooxindole cores. The key spiro-cyclization step between various α-bromoacetamides and methyleneindolinones was efficient and tolerant of a wide range of functional groups. Yields and diastereoselectivities for the spirocyclization were usually high and furnished original spiro[oxindole-3,3′-γ-lactam] derivatives. The utility of these novel building blocks for the preparation of more sophisticated derivatives was demonstrated by the preparation of four pentacyclic spirooxindoles. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Mendoza-Palomares C.,French Institute of Health and Medical Research | Mendoza-Palomares C.,University of Strasbourg | Ferrand A.,French Institute of Health and Medical Research | Ferrand A.,French National Center for Scientific Research | And 10 more authors.
ACS Nano

Figure Persented: Nanobiotechnology enables the emergence of entirely new classes of bioactive devices intended for targeted intracellular delivery for more efficacies and less toxicities. Among organic and inorganic approaches currently developed, controlled release from polymer matrices promises utmost clinical impact. Here, a unique nanotechnology strategy is used to entrap, protect, and stabilize therapeutic agents into polymer coatings acting as nanoreservoirs enrobing nanofibers of implantable membranes. Upon contact with cells, therapeutic agents become available through enzymatic degradation of the nanoreservoirs. As cells grow, divide, and infiltrate deeper into the porous membrane, they trigger slow and progressive release of therapeutic agents that, in turn, stimulate further cell proliferation. This constitutes the first instance of a smart living nanostructured hybrid membrane for regenerative medicine. The cell contact-dependent bioerodable nanoreservoirs described here will permit sustained release of drugs, genes, growth factors, etc., opening a general route to the design of sophisticated cell-therapy implants capable of robust and durable regeneration of a broad variety of tissues. © 2011 American Chemical Society. Source

Martins D.,CNRS Separative Sciences and Methods | Stelzer T.,Martin Luther University of Halle Wittenberg | Ulrich J.,Martin Luther University of Halle Wittenberg | Coquerel G.,CNRS Separative Sciences and Methods
Crystal Growth and Design

This work presents an original general route to obtain faceted tubular organic crystals (of several tens of micrometers in section) by putting the compound inside a thermal gradient. These hollow whiskers grow spontaneously when the thermal gradient exceeds a certain threshold, the highest temperature being close to the melting point, the lowest temperature being RT. This phenomenon could be explained by heat dissipation and transport of matter thanks to sublimation mechanisms and/or capillarity, i.e. by convective heat transfer. The open system is characterized by energy transport, entropy creation and spontaneous apparition of anisotropy. That is the reason why these hollow whiskers can be considered as relics of dissipative structures (Prigogine, I.Wiley: New York, 1967). © 2011 American Chemical Society. Source

Levilain G.,CNRS Separative Sciences and Methods | Coquerel G.,CNRS Separative Sciences and Methods

The mirror symmetry relationship between enantiomers makes their separations by 'classical' separation methods difficult. When applicable, preferential crystallization is a productive and cost effective process which consists of alternate crystallizations of both enantiomers crystallizing as a conglomerate. Addition of in situ racemization to 'classical' preferential crystallization allows the yield to increase up to 100% in a single batch operation. Furthermore, the implementation of continuous 'gentle' grinding can solve the main problem of this method, i.e. the nucleation of the counter enantiomer. Preferential crystallization methodology can be also applied to any system composed of non symmetrical species. However, a set of thermodynamic and kinetic parameters must be determined for every compound that is supposed to crystallize selectively. This 'highlight' details the basic principles and the limitations of 'classical' preferential crystallization and its applications on 'exotic' systems by an extensive usage of phase diagrams. © 2010 The Royal Society of Chemistry. Source

Galeta J.,Masaryk University | Man S.,Masaryk University | Bouillon J.-P.,CNRS Separative Sciences and Methods | Potaacek M.,Masaryk University
European Journal of Organic Chemistry

Thermally initiated cycloaddition reactions of nonsymmetrical allenyl azines 1 with alkynes or other dipolarophiles usually lead to compounds with three fused, five-membered heterocyclic rings. With alkynes with pronounced "push-pull" systems, however, the reaction ends with the formation of substituted pyrrolidino[1,2-b]pyrazoles 4 and, in the case of azines with trifluoromethyl substitution, ring opening leads to the isolation of compounds 9. Reaction mechanisms for these transformations are proposed. The molecular structures of the new heterocycles 4 and 9 were confirmed by X-ray crystal structure analysis. Six alkynes A-F were reacted with four nonsymmetrical allenyl aldoketazines 1a-d in combined intra-intermolecular criss-cross cycloaddition reactions to afford compounds 2 (with alkynes A-D), and newfused bicyclic heterocycles 4 and 9 (withalkynes E and F). The new pyrrolidino[1,2-b]pyrazoles 4 are structurally related to the biologically active alkaloid withasomnine. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

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