CATALYSE INTRAMOLECULAIRE DE L'AMINOLYSE DES HETEROCYCLES PHOSPHORES DERIVES DES α AMINOAMIDES. II: ETUDE DE LA CYCLISATION DES PHOSPHORDIAMIDES INCORPORANT UN RESIDU DE β AMINOACIDE,REACTIVITE VIS A VIS DE NUCLEOPHILES DES HETEROCYCLES FORMES

Abstract

Derivatives of β aminoacids in form of esters 1 or nitrile 4 (table I) undergo in an alcohol-ate/alcohol medium a rearrangement (Fig. 2), with formation of a β peptide link, resulting in the formation of esters 6 (table II). According to the experimental conditions the six membered ring heterocycles 5 are detected or isolated. They are also synthetized by cyclisation of acids 2 or hydrazide 3 (Fig. 5). While phosphorus easily reacts with alcohols and water, leading respectively to esters 6 and acids 9 (Fig. 7), it remains unaffected by amines. These results are discussed in term of mechanisms of the phosphorylation. The applications for β peptide synthesis and the participation of the p amide group in phosphorylation are limited.     

Antibacterial effect,efflux pump inhibitory (NorA,TetK and MepA) of Staphylococcus aureus and in silico prediction of α, β and δ-damascone compounds

ObjectiveThe present study aimed to evaluate the antibacterial effect and inhibitory capacity against NorA, TetK and MepA efflux pump of Staphylococcus aureus multiresistant by in vitro and in silico approach of α, β and δ-damascone compounds.ResultsThe compounds α, β and δ-damascone showed a clinically relevant effect against S. aureus ATCC 6538 standard strain. A modulating effect was also observed in association with antibiotics against MDR strains. Regarding the inhibition of the efflux pump, the compounds showed a modulating effect with antibiotics, against SA-1199, SA-1199B, SA IS-58 and K2068. Only δ-damascone demonstrated an efflux pump inhibitory effect. Regarding ADME properties, α, β and δ-damascone showed similar physicochemical properties with good pharmacokinetic characteristics, such as lipophilicity, oral bioavailability and low toxicity. In addition, they exhibited the binding energy and Ligand Efficiency (LE) ?81.17 (5.4), ?77.48(-5.4) and ?64.55 (-5.1), which shows good interactions with the critical residues of the MepA receptor.ConclusionsFrom the results it is concluded that the compounds α, β and δ-damascone do not have antibacterial activity, but show a modulating effect in association with antibiotics, as well as not showing direct activity on the efflux pump, but they do have a modulating effect with antibiotics and with EtBr (α and β-damascone).     

EASY SYNTHESIS OF 1-ALLYL-1-DEOXY-β- AND α- d-LYXOFURANOSES

2,3;5,6-Di-O-isopropylidene-α-d-mannofuranosyl chloride reacted with allylmagnesium bromide with preferential inversion of the anomeric configuration to furnish a mixture of the 1-allyl-1-deoxy-β- and α-d-mannofuranoses. Separation of β and α derivatives was possible only after conversion to the 1-allyl-1-deoxylyxofuranoses 2 and 3. The β configuration of the predominant product 2 was proved using the NOE method.     

Synthese de O-Glycosides d'Alcenyles Catalysée par les Complexes du Palladium(0)

Abstract

Allylic carbonates reacted with carbohydrates having a free anomeric hydroxyl group in the presence of a catalytic amount of palladium(0) giving the unsaturated O-glycosides under neutral conditions with excellent yields. In the mannofuranose and ribofuranose series, the reaction was stereospecific leading only to the α and the β anomers respectively, although a mixture of α and β anomers was obtained in the glucopyranose series.     

Syntheses,Spectroscopy and Calculated Second-Order Nonlinear Optical Properties of a New Series of Square-Pyramidal Substituted Phenylthiourea Zinc(II) Complexes

A new series of square-pyramidal coordination compounds L·Zn(acac)₂ (acac = acetylacetonate; L is a variety of substituted phenylthioureas: p-N,N ′-dimethylaminophenylthiourea 1, p-methoxy-phenylthiourea 2, p-nitrophenylthiourea 3, p-acetylphenylthiourea 4) have been synthesized and characterized by ¹H NMR and IR spectra and elemental analysis. Most of these compounds exhibit wide transparent ranges in the visible region. Their electronic spectra have been studied experimentally, and theoretically by ZINDO/S calculation. The MOPAC software package has been used to evaluate their first-order molecular hyperpolarizabilities (β). All β values of the four coordination compounds are greater than or equal to those of p-nitroaniline, and are larger than β values of their corresponding substituted phenthylthiourea ligands.     

AMINO-ACIDS AS LIGANDS: THE SYSTEM LEAD(II)-AMINOACETATE

Abstract

The equilibria occurring between lead(II) and aminoacetate ion (L) have been investigated in 1 M ionic medium, (Na)ClO₄, at 25°C by potentiometric methods using lead stationary amalgam and glass electrodes.

The experimental data are explained by assuming the formation of the complexes PbL (log β = 4.78), PbHL (log β = 10.75), PbL ₂ (log β = 7.66), PbHL ₂ (log β = 14.7), and PbH₂ L ₂ (log β = 21.15).     

Orientational fluctuations in a nematic liquid crystal as seen by neutron scattering

Abstract

Real time neutron scattering is used in the study of the slow orientational fluctuations of the director in a nematic sample. A statistical analysis of the observed time series gives the Hurst exponent H and β exponent of the frequency power spectrum that satisfy the scaling relationship β = 2H + 1. In the nematic phase, but not in the solid and in the isotropic liquid phases, the exponent values are those expected for a self-organized critical state. When a magnetic field, of the order of the Freedericksz field is applied, the nematic sample is observed to display persistent oscillations of the director. We confront this observation with theoretical predictions.     

Saturated Liquid Densities of Cryogenic Fluids

Abstract

Experimental saturated liquid densities available in the literature for the cryogenic fluids, hydrogen, neon, argon, nitrogen, oxygen, carbon monoxide, and methane show that their temperature dependence can be expressed by the relationship, With the exception of hydrogen, the saturated liquid density of all the other polyatomic cryogenic fluids can be represented with β = 0.408 and k = 2.36 giving rise to an average deviation of 0.99% (127 points). For the monatomic cryogenic fluids, β = 0.410 and k = 2.21 from which an average deviation of 0.49% (29 points) results. For the specific case of hydrogen, β = 0.378 and k = 1.82 which produce an average deviation of 0.54% (85 points).     

Efficient Differentiation of the Hydroxyl Groups of 3,4-O-Isopropylidene-D-Galactopyranosides by Lipase Catalyzed Esterification and De - Esterification

Abstract

The Pseudomonas sp. (LPS) promoted acyl transfer from vinyl acetate to selected 3,4-O-isopropylidene-D-galactopyranosides takes place in a completely selective manner giving in high yield the corresponding 6-O-acetates. The acetylation rate is strongly dependent on the type and the orientation of the aglycon, varying from a maximum of reactivity for the 1-deoxy derivative, 1,5-anhydro-3,4-O-isopropylidene-D-galactitol (1d), to a minimum for β configurated alkyl glycosides and showing a complete loss of reactivity for 3′,4′:2,3:5,6-tri-O-isopropylidenelactose dimethyl acetal (1e). The latter compound is, however, selectively 6′-O-esterified in good yield by lipase from Candida Antarctica and vinyl acetate. Also the course of the enzymatic hydrolysis of 2,6-di-O-acetyl-3,4-O-isopropylidene-D-galactopyranosides 2 is dependent on the type of the aglycon, both for the reaction rate and the selectivity. The 2-O-acetates 4 are selectively obtained in good yields with porcine pancreatic lipase (PPL) promoted hydrolysis in the case of β and α-methyl, and 1-deoxy derivatives (2a, 2b and 2d), while for β-benzyl (2c) and lactose (2e) analogues satisfactory results are obtained with lipase from Mucor miehei (IM20).

     

One-Pot Synthesis of Dialkyl Succinates Containing an α -Amino Group and a β-Ylide Moiety Using Electron-Deficient Acetylenic Esters

The new succinic esters containing an α -amino group and a β -ylide moiety have been prepared in excellent yields by the three-components approach starting with the commercially available activated acetylenic esters and 2-aminothiazole or 4,5-dihydrothiazole-2-thiol in the presence of trivalent phosphine.     

Slater Sum for a Three-Dimensional Inhomogeneous Fermi Fluid with One-Dimensional Harmonic Confinement

Abstract

In early work, Bardeen [1] proposed a model whereby a three-dimensional Fermi fluid is confined to a half-space by a planar infinite barrier in the xy plane. Brown, Brown and March [2] subsequently worked out the Slater sum S(z, β), β = 1/k^B for this same model of partial confinement. The present work considers S(z, β) for additional harmonic confinement in the z direction. When the harmonic force constant is switched off the Slater sum calculated by Brown, Brown and March is recovered. The off-diagonal Slater sum, namely the canonical density matrix, is treated which in turn yields the Feynman propagator for this model when the reciprocal temperature β is replaced by the pure imaginary time.     

Spectres 13C-nmr de Quelques Glutarimides Substitues en α et en β

Abstract

¹³C-nmr spectra of α and β glutarimides have been determined and analyzed. Assignments related to the imidocarbonyls are discussed.     

A Novel Reverse Phase HPLC Method to Separate and Quantify Androstenedione and Its Stereospecific Hydroxyaromatic Derivatives

Abstract

Reverse - phase High Pressure Liquid Chromatography with a gradient elution on a LiChrocart 250-4 LiChrospher 100 RP-18 column has been used to separate and quantify 7 α-hydroxyandrostenedione (7α-OHA), 6β-hydroxyandrostenedione (6β- OHA), 16α-hydroxyandrostenedione (16α - OHA), 2 β - hydroxyandrostenedione (2 β - OHA), testosterone (T) and androstenedione (A). These steroids are the major products of androstenedione hydroxylation by adult rat liver microsomes. Separation was achieved in 30 minutes by using a linear gradient of acetonitrile (CH³CN) and water in increasing amounts from 30% to 60% of the first solvent (CH₃CN).

This new method compares very favourable with other methods already reported for studying microsomal hydroxylations of androstenedione in different positions of the steroidal skeleton.     

BiCl3 Catalyzed Thiolyzation Reaction of 1,2-Epoxides with Diaryl Disulfides in the Presence of Zinc Powder and Ionic Liquid

A new and efficient method has been developed for the regio- and chemoselective synthesis of β -hydroxysulfides with the ring-opening reaction of 1,2-epoxides by diaryl disulfides and zinc powder in the presence of a catalytic amount of BiCl ₃ in molten tetrabutyl phosphonium bromide as an ionic liquid.     

Determination Coulometrique de L'acide β Amino-Naphtylamido Thioglycolique (Thionalide)

Abstract

Mercury and silver were determined by precipitation from aqueous solution with β amino-naphthylamido thioglycolic acid (thionalid). The metallic thionalidate phases were separated, dissolved in ethanol and analyzed by coulometric titration of the thionalid with electrogenerated iodine.     

1H-NMR-Untersuchungen an Sialinsäuren,V1 N-Acetyl-α-D-Neuraminsäure: Chemische Verschiebungen und Kopplungskonstanten; Konfiguration und Konformation in Lösung

Abstract

The enzymatic cleavage of N-acetyl-2-azido-2-deoxy-α-d-neuraminic acid in the probe of the NMR spectrometer allows the accumulation of ¹H NMR spectra of the released a anomer of the N-acetyl-d-neuraminic acid before it mutarotates to the β anomer. The analysis and computer simulation of the spectra yield the ¹H NMR data set of chemical shifts and coupling constants of N-acetyl-α- d-neuraminic acid. Using this data set, configuration and conformation in solution are discussed by comparing it with the ¹H NMR data set of the β anomer, the structure of which is known from an X-ray study.     

A dielectric study of chain motions in poly(vinyl methyl ether)

The dielectric permittivity and loss of poly(vinyl methyl ether) (mol. wt. 30,000) have been measured from 12 Hz to 100 kHz at temperatures from 77 K to 320 K. Two relaxation processes, γ and β, are observed at T < T_g (245 K), and one above T_g. The Arrhenius plots of the γ and β processes have activation energies of 20 and 41 kJ mole^?1 respectively. The relaxation rate of the α process is described by the Vogel-Fulcher-Tamman equation or the William-Landel-Ferry equation. The relaxation rates of γ and β processes evaluated from the isochrones differ from those evaluated from the isothermal spectrum. The features of chain motions observed are similar to those in other polymer and rigid molecular glasses.     

Novel Syntheses and Reactions of Polynuclear Heterocyclic Derivatives Derived From Thioxopyridopyrimidine,With a New Ring System

Pyridopyrimidine derivatives 2 reacted with hydrazonoylchloride derivatives and yielded triazolopyridopyrimidines 6a–f. Compound 4b reacted with aliphatic acids and afforded triazolo-pyridopyrimidines 7a,b, and the reaction with carbon disulfide afforded 10-mercapto-triazolopyridopyrimidine (10). Moreover, the reaction of 4b with β -ketoesters afforded 10-pyrazolyl-pyridopyrimidines derivatives 11, 13, 14, and 15. Compound 4b reacted with nitrous acid to give tetrazolopyridopyrimidine 16, which reduced to 10-amino-derivative 17. On the other hand, the reaction of 4b with aromatic aldehydes afforded arylidines derivatives 18a–c, which were later cyclized to triazolo-pyridopyrimidines deivatives 19a–c. Finally, 4b reacted with α-haloketones to give triazines derivativrs 20, with new ring systems.     

Supramolecular Assembly of Functionalized Metalloporphyrins. Porous Crystalline Networks of Zinc-Tetra(4-Carboxyphenyl)Porphyrin

Abstract

Two crystalline compounds based on the Zn-tetra (4-carboxyphenyl)porphyrin building block have been prepared and structurally analysed by x-ray diffraction in order to ellucidate the characteristic supramolecular aggregation modes of this functionalized metalloporphyrin moiety. Crystals of the 1:1 complex with sec-phenethyl alcohol (1) are monoclinic, space group I2/a (No. 15), a = 14.420(1), b = 24.678(2), c = 33.688(2) Å, β = 90.03(2)°, D_c = 1.082 g/cm³, Z = 8, R = 0.080 for 3053 data. Those of the 1:3 complex with dimethylsulphoxide (2) are monoclinic, space group P2₁/n (No. 14), a = 14.881(1), b = 8.986(2), c = 37.550(3) Å, β = 94.21(1)°, D_c = 1.444 g/cm³, Z = 4, R = 0.093 for 4200 data. The two compounds consist of nearly square-pyramidal five-coordinate metalloporphyrin species, molecules of the sec-phenethyl alcohol (in 1) and dimethylsulphoxide (in 2) linking to the metal center at the axial site. In 2, two additional molecules of dimethylsulphoxide associate through H-bonds to the terminal carboxylic substituents of the porphyrin framework. Incorporation of the carboxylic functionality into the tetraarylporphyrin unit leads to the formation of hollow hydrogen-bonded lattices in both crystals. Uniquely structured two-dimensional networks of the porphyrin building blocks with very large cavities (approximately 16 × 21 Å) are formed in 1. These networks mutually interpenetrate each other in order to fill the empty voids, yielding a spectacular ‘concatenated’ arrangement.

One-dimensional polymeric patterns with smaller cavities (6.5 × 10 Å) are built in 2 by the interacting molecular components. In the condensed crystalline environment each such cavity is occupied by two dimethylsulphoxide molecules of adjacent chains. This study is part of an ongoing evaluation of the utility of functionalized metalloporphyrin building blocks in the designed construction of hollow lattices (with varying degree of rigidity and pore size) in molecular based solids. Correlation of current results to previous findings is also discussed.     

Hydrogen Migration and Reductive Elimination of Alkyne in Fe(CO)4 P(tBu) (C °CPh)H Induced by the Action of Co2 (CO)8

Abstract

One of the possible ways of getting phosphacumulene complexes could be the complexation of phosphinoalkynes, which might induce the migration of hydrogen from phosphorus to the β carbon of the alkynyl group.