El rechazo entre iguales: una visión general

III Jornadas Internacionales del Grupo GREIHablar de aceptación y rechazo entre iguales es un tema de gran relevancia en nuestro contexto social actual. Este hecho es consecuencia de la importancia que tiene la atracción interpersonal como índice de adaptación socioemocional, ya que la realidad evidencia que una buena aceptación en el grupo de compañeros y compañeras favorece una buena adaptación y bienestar socioemocional, mientras que niveles bajos de aceptación social son factores de riesgo y de problemática en el tema de interacción socialAcceptance and rejection between peers have become a relevant issue in our current social context. This is a consequence of the importance that interpersonal attraction is bestowed as a socio-emotional adaptation system. Indeed, as reality evidences, strong acceptance levels among peers foster not only better adaptation within the group but also better levels of socio-emotional well-being. However, low social acceptance levels stand as problematic risk factors regarding social interaction

Recovery and Recycling of Chiral Iridium(N,P Ligand) Catalysts from Hydrogenation Reactions

Despite the high efficiency and broad scope of chiral iridium(N,P ligand) complexes as catalysts for asymmetric hydrogenation, the problem of catalyst recovery and recycling has so far attracted little attention. We have found that at the end of a hydrogenation reaction, iridium(N,P ligand) catalysts form dimeric Ir(III) dihydride complexes, which can be converted back to the original precatalysts by addition of COD. Based on these findings, a practically simple protocol for catalyst recovery was devised. The recovered complexes showed essentially the same reactivity and enantioselectivity as the original catalysts. Especially large-scale applications and hydrogenations of less reactive substrates that require high catalyst loadings will benefit from this protocol that allows recovery and reuse of expensive iridium complexes

Synthèse de ligands fluorés énantiopurs et applications en catalyse asymétrique

La catalyse a connu durant ces dernières années un renouveau considérable dans le développement de nouveaux systèmes biphasiques liquide liquide. Initié par Horvath et Rabai, le concept FBS constitue une approche originale permettant de séparer efficacement les produits de la réaction du catalyseur afin de le recycler. Aussi, nous avons développé la synthèse de phosphines fluorées énantiopures qui ont été appliquées dans les réactions d'alkylation allylique, de Heck, d'hydrogénation et d'hydroboration. Nous avons préparé des bisoxazolines fluorées dont les complexes du palladium et du cuivre se sont révélés actifs dans les réactions d'alkylation allylique (ee = 96 %) et d'oxydation allylique (ee = 77 %). Le recyclage des ligands ou du catalyseur est efficace dans ces deux réactions. Enfin, nous avons synthétisé plusieurs ligands azotés énantiopurs fluorés dont nous avons testé le potentiel dans la réaction de réduction des cétones par transfert d'hydrogène dans les conditions FBSLYON1-BU.Sciences (692662101) / SudocSudocFranceF

Applications and stereoselective syntheses of P-chirogenic phosphorus compounds

International audiencePhosphorus compounds bearing chirality on the P-center are usually qualified as P-chirogenic or P-stereogenic. This chemical class concerns natural products, agrochemistry, molecular materials, biology and pharmacy, although it is certainly in coordination chemistry and in asymmetric catalysis using chiral transition metal complexes that P-chirogenic phosphorus compounds are the most used. The chiral phosphine ligands and their uses in asymmetric metal-catalyzed reactions have been widely reviewed in literature. However, an overview covering the applications as well as the stereoselective syntheses of all classes of phosphorus compounds has not yet been provided. This review reports the best stereoselective or asymmetric syntheses, the most efficient P*-building blocks and functionalisation of P-chirogenic compounds, in the light of chiral phosphorus compound applications. It is an extensive and useful documentation from pioneering work to recent advances in phosphorus stereochemistry

Synthesis of P-Chirogenic Diphosphinotriazoles and Their Use in Asymmetric Catalysis

International audienceThe stereoselective synthesis of P-chirogenic diphosphinotriazoles using ephedrine methodology was described. The coordination behavior of these compounds as P,P-ligands has been demonstrated by the preparation as well as the spectroscopic and X-ray crystallographic analyses of a palladium complex. The efficiency of these new P-chirogenic diphosphines in the palladiumcatalyzed asymmetric allylic substitution reaction was also evaluated

Designing P-Chirogenic 1,2-Diphosphinobenzenes at Both P-Centers Using P(III)-Phosphinites

International audienceA new enantiodivergent synthesis of P-chirogenic 1,2-diphosphinobenzenes (DP*B) bearing the chirality on one or both phosphorus centers is reported using aryne chemistry. The principle is based on successive reactions of 1,2-dibromobenzene with sec-phosphide boranes, then DABCO to remove the borane, and finally with chlorophosphines or P(III)-chirogenic phosphinites. The efficiency of this synthesis was demonstrated by the stereoselective preparation of (S,S)-1,2-bis(o-anisylphenylphosphino)benzene. A comparison of DIPAMP and homochiral DP*B ligands in asymmetric Rh- or Pd-catalyzed reactions was reported