Synthesis and first applications of a new family of chiral monophosphine ligand: 2,5-diphenylphosphospholanes

International audienceThe cyclic phosphinic acid 1-hydroxy-1-r-oxo-2c,5-t-diphenylphospholane was synthesized and resolved into enantiomers through fractional crystallization of the quinine salts. The P-phenyl, P-methyl and P-benzyl tertiary phosphine oxides were obtained from the secondary phosphine oxide, reduction of the oxides afforded the corresponding tertiary P-phenyl and P-benzyl phosphines. Hydrogenation of prochiral enamides were performed with Rh/(S,S)-1-1,2c,5-t-triphenylphospholane catalytic system. Methyl (Z)-N-acetyl dehydrocinnamate was hydrogenated to give the N-acetyl phenylalaninate in 93% ee

De Pasteur aux liquides ioniques chiraux. Petite histoire de l’induction asymétrique promue par le solvant

National audienceParmi les nombreuses approches testées pour la production de substances chirales énantiomériquement enrichies ou pures, les réactions asymétriques promues par un solvant chiral ont longtemps été négligées. Cependant, l’apparition récente des liquides ioniques, solvants peu nocifs pour l’environnement et dotés d’une modularité structurale sans précédent, relance depuis quelques années cette approche particulière de la synthèse organique asymétrique

Luminescent properties of Eu3+-activated lithium rare earth borates and oxyborates

The luminescence characteristics of Eu3+ in the borates Li6Y(BO3)3 and Li3La2(BO3)3 and the recently discovered oxyborates LiLa2O2BO3, LiLn6O5(BO3)3 (Ln=Y,Gd) and Li2Lu5O4(BO3)3 have been investigated and compared to those in the borates LnBO3 (Ln=La,Y) and the oxyborates “Ln3BO6” (Ln=La,Gd). The probability of electric dipole f–f transitions is generally markedly higher in oxyborates than in borates. This is ascribed to the highly anisotropic environment of rare earth ions and the low position of the charge transfer states. Consequently, the Eu3+-activated oxyborates are characterized by a deeper red emission and faster decay. The luminescence characteristics of Eu3+ in the borates Li6Y(BO3)3 and Li3La2(BO3)3 and the recently discovered oxyborates LiLa2O2BO3, LiLn6O5(BO3)3 (Ln=Y,Gd) and Li2Lu5O4(BO3)3 have been investigated and compared to those in the borates LnBO3 (Ln=La,Y) and the oxyborates “Ln3BO6” (Ln=La,Gd). The probability of electric dipole f–f transitions is generally markedly higher in oxyborates than in borates. This is ascribed to the highly anisotropic environment of rare earth ions and the low position of the charge transfer states. Consequently, the Eu3+-activated oxyborates are characterized by a deeper red emission and faster decay

Yb3+ and Yb3+-Eu3+ luminescent properties of the Li2Lu5O4(BO3)3 phase

The luminescence of Yb3+ in the oxyborate Li2Lu5O4(BO3)3 is reported. At low temperature, in addition to the usual ytterbium infrared emission, this phosphor presents an emission in the ultraviolet (lmax = 345 nm) which corresponds to the transition from the charge transfer state (O–Yb) to the 4f levels of Yb3+. The temperature quenching Tq50% is equal to 120 K. The infrared emission studied at room temperature is located between 950 and 1100 nm. Europium emission quenching in the Li2Yb5O4(BO3)3 phase is related to Eu→Yb transfer by cross-relaxation. The reverse Yb→Eu transfer by cooperative sensitization is highlighted in the codoped Li2Lu5O4(BO3)3 compound

Efficient enantiodiscrimination of chiral monophosphine oxides and boranes by phosphorus coupled 13C NMR spectroscopy in the presence of chiral ordering agents

International audienceThe synthesis of new chiral phospholanes via the corresponding oxides or boranes is reported and the analytical potential of C-13-{H-1} NMR spectroscopy in weakly ordering polypeptide liquid crystalline phases in view to differentiate between enantiomers of these chiral phosphines precursors is explored. In particular results involving organic solutions of poly-gamma-benzyl-L-glutamate (PBLG) and poly-epsilon-carbobenzyloxy-L-lysine (PCBLL) are described. This NMR approach allows determination of the enantiomeric composition, and provides therefore a new efficient alternative to classical methods usually used to analyze this class of compounds. A description of various spectral enantiodifferentiation patterns expected to be observed using C-13-{H-1} NMR of enantiomers having a spin-1/2 heteroatomic nucleus, embedded in a chiral liquid crystal is presented

Ionic Liquids: New Targets and Media for α-Amino Acid and Peptide Chemistry

International audienc

Chiral ionic liquids, a renewal for the chemistry of chiral solvents? Design, synthesis and applications for chiral recognition and asymmetric synthesis

International audienceChiral ionic solvents were almost unexplored before the last five years. This field which is of increasing importance could constitute a renewal for the chemistry of chiral solvents. So far reported examples are designed either from the chiral pool (amino-acids, hydroxyacids, amines, aminoalcohols, terpenes and alkaloids) or by asymmetric synthesis; they can bear central, axial or planar chirality. Modern applications in asymmetric synthesis, enzymatic chemistry, chiral chromatography and NMR are surveyed. Their use in the field of liquid crystals and for stereoselective polymerisation are also discussed. At the end of the article, a series of tables is compiled including all the CILs described to date and their physical properties

Thiazolinium salt: an efficient catalyst for the Mukaiyama reaction

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Role of endogenous adenosine as a predictive marker of vasoplegia during cardiopulmonary bypass and postoperative severe systemic inflammatory response.

OBJECTIVE: Systemic inflammatory response (SIRS) and severe SIRS (SIRS with organ dysfunction) occurring after cardiopulmonary bypass (CPB) are common causes of morbidity and mortality among cardiac surgical patients. These syndromes are often preceded by a profound vasodilation, characterized by vasoplegia occurring during surgery. Many substances have been implicated in their pathophysiology. Adenosine is a strong endogenous vasodilating agent released by endothelial cells and myocytes under metabolic stress and may be involved in blood pressure failure during CPB induced by severe SIRS. DESIGN: A prospective comparative observational study. SETTING: The operating room and intensive care unit of a tertiary care university hospital. PATIENTS: Adenosine plasma levels (mean+/-sd; APLs) were measured before (baseline), during, and immediately after surgery in 35 patients who underwent aortic valve replacement involving CPB. APLs were correlated to operative and postoperative clinical courses. MEASUREMENTS AND MAIN RESULTS: APLs were significantly higher in seven patients with vasoplegia and postoperative severe SIRS (1.6 micromol.L [0.2-2.6] vs. 0.4 micromol.L [0.1-1.0]) at baseline and during surgery. The duration of mechanical ventilation and stay in the intensive care unit were significantly longer for patients with higher APLs. Mean arterial pressure was inversely correlated with mean arterial APLs (Pearson's correlation coefficient: R=-0.66; p<.001). CONCLUSIONS: High APLs were found in patients with operative vasoplegia and postoperative severe SIRS occurring after cardiopulmonary bypass. This suggests that adenosine release is involved in vasoplegia that occurs during the systemic inflammatory response to cardiac surgery. Further studies are needed to clarify the association between cytokine production and adenosine release in severe SIRS following cardiac surgery