Search results for "Isopropyl"

Diastereoselective Synthesis of Dialkylated Bis(phosphino)ferrocenes: Their Use in Promoting Silver-Mediated Nucleophilic Fluorination of Chloroquino…

2017

International audience; The diastereoselective synthesis of dialkylated ferrocenyl bis(phosphane)s bearing aryl, alkyl, and hetero- or polycyclic substituents on the phosphino groups is reported, together with their characterization in the solid state by X-ray structure analysis and in solution by multinuclear NMR spectroscopy. Introduction of various alkyl groups on the ferrocene backbone, namely, tert-butyl, isopropyl, and trimethylsilyl, has a significant influence on the stereoselectivity of the ensuing lithiation/phosphination reactions. Only the introduction of the tert-butyl groups ensures both a high yield and perfect diastereoselectivity, which leads to the exclusive formation of t…

Endothelial Cell Swelling and Brain Perfusion

1997

Background: Whereas the contribution of glial swelling to no-reflow conditions in the ischemic penumbra or during reperfusion after global ischemia is widely discussed, little is known about cell volume control of endothelial cells under reperfusion conditions. Methods: The effect of extracellular acidosis-a key mediator of secondary brain damage-on cell volume was studied in the GM7373 endothelial cell line. Experiments were performed at pH = 6.0 in the presence or absence of bicarbonate, and during exposure to inhibitors of specific transport systems such as ethyl isopropyl amiloride or 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid. Results: Endothelial swelling to 111.1 ± 3.4% was f…

Stereoselective synthesis of perillaldehyde-based chiral β-amino acid derivatives through conjugate addition of lithium amides.

2014

The Michael addition of dibenzylamine to (+)-tert-butyl perillate (3) and to (+)-tert-butyl phellandrate (6), derived from (S)-(−)-perillaldehyde (1), resulted in diastereomeric β-amino esters 7A–D in a moderately stereospecific reaction in a ratio of 76:17:6:1. After separation of the diastereoisomers, the major product, cis isomer 7A, was quantitatively isomerized to the minor component, trans-amino ester 7D. All four isomers were transformed to the corresponding β-amino acids 10A–D, which are promising building blocks for the synthesis of β-peptides and 1,3-heterocycles in three steps. The steric effects of the isopropyl group at position 4 and of the α-methyl substituent of (R)-N-benzyl…

Multipolar interactions in the D pocket of thrombin: large differences between tricyclic imide and lactam inhibitors.

2006

Two series of tricyclic inhibitors of the serine protease thrombin, imides (+/-)-1-(+/-)-8 and lactams (+/-)-9-(+/-)-13, were analysed to evaluate contributions of orthogonal multipolar interactions with the backbone C=O moiety of Asn98 to the free enthalpy of protein-ligand complexation. The lactam derivatives are much more potent and more selective inhibitors (K(i) values between 0.065 and 0.005 microM, selectivity for thrombin over trypsin between 361- and 1609-fold) than the imide compounds (Ki values between 0.057 and 23.7 microM, selectivity for thrombin over trypsin between 3- and 67-fold). The increase in potency and selectivity is explained by the favorable occupancy of the P-pocke…

A model for the formation and degradation of bound residues of the herbicide C-14-isoproturon in soil

1999

Ionic Liquid Based Headspace Solid-Phase Microextraction-Gas Chromatography for the Determination of Volatile Polar Organic Compounds

2010

Solid-phase microextraction (SPME) with an ionic liquid (IL) coating was developed for headspace extraction of a group of low molecular weight alcohols (ethanol, n-propanol, butanol, and isopropyl alcohol), acetone, ethyl acetate, and acetonitrile. A first SPME fiber was simply coated with a dedicated IL whose synthesis is described. A second SPME fiber was prepared by gluing silica (Si) particles on which the synthesized IL was chemically bonded. The analytes SPME extraction was optimized for time, temperature, and NaCl salting out content. The headspace extracted analytes were determined by simple temperature desorption into the hot injection port of a gas chromatograph. The coated-IL fib…

Structural and Spectroscopic Studies of the PCP-Bridged Heavy Chalcogen-Centered Monoanions [HC(PPh2E)(PPh2)]− (E = Se, Te) and [HC(PR2E)2]− (E = Se,…

2009

Selenium- and tellurium-containing bis(diphenylphosphinoyl)methane monoanions were prepared by oxidation of the anion [HC(PPh2)2]− with elemental chalcogens. The selenium-containing isopropyl derivative was synthesized by generating [H2C(PiPr2)2] via a reaction between [H2C(PCl2)2] and 4 equiv of iPrMgCl prior to in situ oxidation with selenium followed by deprotonation with LiNiPr2. The solid-state structures of the lithium salts of the monochalcogeno anions TMEDA·Li[HC(PPh2E)(PPh2)] (E = Se (Li7a), E = Te (Li7b)) and the dichalcogeno anions TMEDA·Li[HC(PR2Se)2] (R = Ph (Li8a), iPr (Li8c)) revealed five- and six-membered LiEPCP and LiSePCPSe rings, respectively. The homoleptic group 12 com…

4-[5-(4-Fluorophenyl)-3-isopropylisoxazol-4-yl]pyridin-2(1H)-one

2007

The crystal structure of the title compound, C17H15FN2O2, was determined as part of a study of the biological activity of pyridine-substituted isoxazole derivatives as mitogen-activated protein kinase (MAPK) inhibitors. In the crystal structure of the title compound, the compound exists in the lactam and not in the tautomeric pyridin-2-ol form. As the aromatic pyridine nitrogen is considered to be important for accepting a hydrogen bond from p38MAPK, the structure of the lactam unit is correlated with the loss of biological activity of the title compound in the p38MAPK assay. In the crystal structure, the lactam is involved in hydrogen bonds, forming chains along the b axis.

Physicochemical Interactions Between Aroma Compounds and Milk Proteins: Effect of Water and Protein Modification

1998

The physicochemical interactions between aroma compounds and sodium caseinate were studied by complementary techniques involving the protein in aqueous solution at 25 or 75 g/L (exponential dilution and equilibrium dialysis) or in a solid state (sorption and infrared spectroscopy). No retention of acetone, ethyl acetate, and 2-propanol in aqueous solutions was found by exponential dilution and equilibrium dialysis. Diacetyl and benzaldehyde interacted with sodium caseinate through strong and weak bonds, as found by equilibrium dialysis. The results obtained by sorption differ from those obtained in aqueous solutions. The compounds that sorbed best to sodium caseinate were acetone and ethyl …

N-{4-[3-(4-Fluorophenyl)pyrido[2,3-b]pyrazin-2-yl]-2-pyridyl}isopropylamine

2009

In the crystal structure of the title compound, C21H18FN5, the pyridopyrazine ring system forms dihedral angles of 33.27 (7) and 48.69 (9)° with the 4-fluorophenyl and pyridine ring, respectively. The dihedral angle of the 4-fluorophenyl and pyridine rings is 57.45 (8)°. The crystal packing is characterized by an intermolecular N—H...N hydrogen bond.