Highly regio- and stereoselective Michael addition of pseudouridine with propiolates: An efficient method for the synthesis of (E)-pseudouridine-N1-acrylate

The Michael addition of pseudouridine with various propiolates in the presence of DBU as a base and DMF as a solvent is described. It is noteworthy that the reaction is highly regio- and stereoselective and affords (E)-pseudouridine-N1-acrylate in good yields with high purities.     

Electromagnetic shielding studies on plasma‐sprayed superconducting high-TC coatings

Electromagnetic shielding behaviour of plasma-sprayed Y₁Ba₂Cu₃O_7-x coatings has been studied in the frequency range of 1 to 100 kHz. Experiments with 180 μm thick coatings on stainless-steel substrates have shown that the normal-to-superconducting phase transition introduces an additional 15 to 20 db shielding.     

Homophtalonitrile for Multicomponent Reactions: Syntheses and Optical Properties of o-Cyanophenyl- or Indol-3-yl-Substituted Chromeno[2,3-c]isoquinolin-5-Amines

Malononitrile is a useful reagent for multicomponent reactions with hundreds of methods developed. In this paper, we suggest α-(cyano)-o-tolunitrile (homophtalonitrile) to work as a vinylogous malononitrile. Thus, a organocatalytic pseudo-three-component reaction of homopthalonitrile (2 equiv) and o-hydroxybenzaldehyde, leading to the diastereoselective formation of 5-amino-12H-chromeno[2,3-c]isoquinolin-12-yl)(cyano)methyl)benzonitriles, was discovered. The possibility to employ other nucleophiles was demonstrated for indoles, and a sequential three-component reaction of homophtalonitrile, o-hydroxybenzaldehyde, and (aza)indole, giving 12-(1H-Indol-3-yl)-12H-chromeno[2,3-c]isoquinolin-5-amines, was developed. The photophysical properties of the synthesized compounds have been studied, revealing high fluorescence quantum yields (42–70 %) for indol-3-yl substituted 12H-chromeno[2,3-c]isoquinolin-5-amines and reversible fluorescence quenching under acidic conditions.     

Complexometric determination of palladium(II) using thioacetamide as a selective masking agent

A simple, rapid and accurate complexometric method for the determination of palladium(II) is proposed, based on the selective masking property of thioacetamide towards palladium(II). In the presence of diverse metal ions, palladium(II) is complexed with excess of EDTA and the surplus EDTA is back titrated at pH 5-5.5 (acetic acid-sodium acetate buffer) with standard lead nitrate solution using xylenol orange as indicator. An excess of a 0.5% aqueous solution of thioacetamide is then added to displace EDTA from Pd(II)-EDTA complex. The released EDTA is titrated with the same standard lead nitrate solution as before. Reproducible and accurate results are obtained in the concentration range 0.5 mg - 17.80 mg of palladium with relative error of +/- 0.16% and coefficient of variation not exceeding 0.26%. The effect of diverse ions is studied. The method is used for the determination of palladium in its complexes, catalysts and synthetic alloy mixtures.     

Siderophore-Mediated Iron Uptake Promotes Yeast–Bacterial Symbiosis

In the present study, siderophore produced by the marine yeast Aureobasidium pullulans was characterized as hydroxamate by chemical and bioassays. The hydroxamate assignment was supported by the appearance of peaks at 1,647.21?C1,625.99?cm^?1 and at 1,435.04?cm^?1 in the infrared spectrum. The purified siderophore exhibited specific growth-promoting activity under iron-limited conditions for siderophore auxotrophic probiotic bacteria. Cross-utilization of siderophore indicates a symbiotic relationship between the yeast A. pullulans and the selected probiotic bacterial strains. Statistical optimization of medium components for improved siderophore production in A. pullulans was depicted by response surface methodology. The shift in UV?CVis spectroscopy indicates the photoreactive property and subsequent oxidative cleavage of purified siderophore on exposure to sunlight.     

A novel,green 1-glycyl-3-methyl imidazolium chloride-copper(Ⅱ) complex catalyzed C-H oxidation of alkyl benzene and cyclohexane

A variety of alkyl-arenes and cyclohexane were converted to the corresponding ketones with NaCIO as the oxidant in the presence of l-glycyl-3-methyl imidazolium chloride-copper(Ⅱ) complex.This method contains simplified product isolation and catalyst recycling,affording benzylic C-H oxidation of alkyl-arenes imparting high yield of ketones.Furthermore,complex could be reused seven times without a significant loss of its catalytic activity.     

Templating photodimerization of coumarins within a water-soluble nano reaction vessel

An octahedral Pd nanocage serves as a reaction vessel to control photodimerization of coumarins in water. The coumarin derivatives explored in this study react within the Pd nanocage to selectively yield a syn head-head dimer, whereas in water, they yield either a mixture of dimers or a different isomer. The selective dimerization is interpreted to mean that the monomers are preorganized by the cage through weak intermolecular forces. The selectivity obtained within the nanocage is more general and predictable compared to other hosts used previously to control the geometry of photodimerization reactions.     

Inhibition of O-GlcNAcase by a gluco-configured nagstatin and a PUGNAc-imidazole hybrid inhibitor

Synthesis of a PUGNAc-imidazole hybrid and its characterization as an inhibitor of human O-GlcNAcase through enzyme kinetics and X-ray structural analysis.