Search results for "IOS"
showing 10 items of 8115 documents
γ-Silylboronates in the chiral Brønsted acid-catalysed allylboration of aldehydes.
2014
The use of functionalised allylboronic esters in the catalytic enantioselective allylboration of aldehydes is described for the first time. γ-Silylallyl pinacolate derivatives give rise to α-silyl homoallylic alcohols in high yields, with complete diastereoselectivities and high enantioselectivities, in most of the cases. The usefulness of such intermediates is showcased by their transformation into fluorinated allylic alcohols.
Nutritional Interventions, Complementary and Alternative Medicine for Endometriosis
2022
Since endometriosis symptoms can significantly impact women’s quality of life, while the short-term and particularly long-term therapeutic benefits of the currently available approaches are quite limited, there is increasing frustration among patients who undergo only hormonal and/or surgical intervention. The discovery of changeable risk factors for endometriosis, such as diet and exercise, and the search for complementary and alternative medicine (CAM), has become increasingly attractive. The importance of nutrition in controlling the growth and development of endometriosis has lately emerged as a matter of study, mainly due to the finding that some of the disease-related physiological an…
Efficient Addition of Acid Enediolates to Epoxides
2004
We report new conditions to facilitate the addition of dianions of carboxylic acids to epoxides as an alternative method to the use of aluminum enolates. These conditions require the use of a sub-stoichiometric (10%) amount of amine for dianion generation and the previous activation of the epoxide with LiCl. Other Lewis acids have been shown to be less effective. Yields are good but only low diastereoselectivity is attained, which has not been controlled despite attempts at optimization. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
El capitalismo, contra el planeta / 2
2007
La somministrazione di amfotericina B per via endoarteriosa rappresenta una valida e sicura terapia della mucormicosi
2003
ENANTIOSELECTIVE REDUCTION OF PROCHIRAL KETONES PROMOTED BY AMINO AMIDE RUTHENIUM COMPLEXES: A DFT STUDY
2021
International audience; The origin of enantioselectivity in the reaction of chiral Ru amino amide complexes in the asymmetric transfer hydrogenation of acetophenone was investigated using DFT calculations. For the most stable active catalysts, the full free energy profiles for the reaction were calculated according to the concerted hydrogen transfer mechanism. We succeeded in reproducing the experimentally observed enantioselectivity for the studied Ru amino amide complexes. Our results indicate that the high enantioselectivity can be explained by a stabilizing CH-π interaction existing between the phenyl group of acetophenone and the aromatic substituent of the catalyst, which plays a sign…
Stabilization of hsp70 mRNA on prolonged cell exposure to hypertonicity
2002
AbstractProlonged exposure of 3T3 cells to 0.5 osM hypertonic medium induced the accumulation of hsp70 mRNAs. This increase in mRNA levels required active protein synthesis. A weak and transient activation of heat shock factor 1 (HSF1) was noted, but it was temporally uncoupled to the accumulation of the hsp70 mRNAs. Nuclear run-on assay and transfection experiments showed that hsp70 gene transcription was not affected by hypertonicity. ActD chase experiments showed that during hypertonic treatment, degradation of hsp70 mRNAs was markedly reduced. This effect did not appear to be a general phenomenon since the increase in mRNA level of another gene induced by hypertonicity (ATA2 transporter…
Amino-phosphanes in Rh(I)-catalyzed hydroformylation: new mechanistic insights using D2O as deuterium-labeling agent
2005
International audience; In previous work, we have demonstrated that the dangling amino group in amino-phosphane ligands increases the rate of Rh-catalyzed styrene hydroformylation as a function of the amino group basicity and of the distance between the P and N functions. We now report additional stereochemical and mechanistic insights resulting from new catalytic experiments performed with Rh-α-P,N catalytic systems in the presence of D2O. In addition to the expected D0 product, the formation of the β-D1 aldehyde, PhCH(CH2D)CHO was observed in all cases by 1H and 13C NMR spectroscopy, indicating that H/D exchange occurs for the rhodium-hydride complex. Minor amounts of a β-D2 product, PhCH…
Low-loading asymmetric organocatalysis
2011
Asymmetric organocatalysis is now recognized as the third pillar of asymmetric synthesis. Recent years have witnessed increasing interest towards the use of highly active and stereoselective organocatalysts. This critical review documents the advances in the development of chiral organocatalysts which are systematically used in ≤3 mol% loading in all the sub-areas of the field, namely aminocatalysis, Brønsted acids and bases, Lewis acids and bases, hydrogen bond-mediated catalysis, phase transfer and N-heterocyclic carbene catalyses (194 references).