Unexpected reaction of melatonin derivatives with performic acid

A series of carbamate melatonin derivatives was treated with performic acid, providing tricyclic products with a 3-hydroxytetrahydropyrrolo[2,3-b]indole skeleton. An unusual migration of carbamate groups was observed in some cases, and the reaction appeared to be strongly dependent on the type of substituent in the phenyl ring of the phenylcarbamate group. Theoretical calculations suggest that the reaction is kinetically controlled.     

Inclusions of Waterman–Shiba spaces into generalized Wiener classes

The characterization of the inclusion of Waterman–Shiba spaces ΛBV^(p)$\Lambda {\mathit{BV}}^{(p)}$ into generalized Wiener classes of functions BV(q;δ)$\mathit{BV}(q;\delta )$ is given. It uses a new and shorter proof and extends an earlier result of U. Goginava.     

Determination of l-Ascorbic Acid after Chromatographic Separation

JPC – Journal of Planar Chromatography – Modern TLC - A simple and accurate analytical procedure is proposed for determination of L-ascorbic acid after chromatographic separation....     

Nonextensive model of self‐organizing systems

The article concerns the new nonextensive model of self‐organizing systems and consists of two interrelated parts. The first one presents a new nonextensive model of interaction between elements of systems. The second one concerns the relationship between microscopic and macroscopic processes in complex systems. It is shown that nonextensivity and self‐organization of systems is a result of mismatch between its elements. © 2013 Wiley Periodicals, Inc. Complexity 18: 28–36, 2013     

Stereoselectivity of the Hydrogen‐Atom Transfer in Benzophenone–Tyrosine Dyads: An Intramolecular Kinetic Solvent Effect

To be or not to be solvated is the decisive parameter that controls the photoinduced hydrogen‐atom transfer in diastereomeric ketone/phenol dyads. A kinetic solvent effect that refers to hydrogen bonding between the phenol and the solvent is suggested to be the main source of the stereoselective discrimination in the hydrogen transfer (see figure).

     

How To Recognize The Creation Operator

We discuss three characterizations of the creation operator of diverse sort, which in this or another way refer to the commutation relation of the quantum harmonic oscillator.     

Enantioselective CE method for pharmacokinetic studies on ibuprofen and its chiral metabolites with reference to genetic polymorphism

A stereospecific CE method was elaborated for the quantification of ibuprofen enantiomers and their major phase I metabolites: 2'-hydroxy-ibuprofen and 2'-carboxy-ibuprofen in plasma and urine. Optimal temperature and pH of BGE were established to obtain complete separation of eight ibuprofen chiral compounds and (+)-S indobufen, applied as an internal standard, during one analytical run. After isolation from biological matrices using SPE on an octadecyl stationary phase, the analytes were separated and resolved up to 10 min in a silica capillary filled with BGE, consisting of heptakis 2,3,6-tri-O-methyl-beta-CD in triethanolamine-phosphate buffer, pH 5.0. Complete enantioseparation of the all analytes confirmed specificity of the method. The calibration curves were linear in the range of 0.1-25.0 mg/L for IBP enantiomers and their chiral metabolites in 0.5 mL of plasma and 1.0-200.0 mg/L in 0.05 mL of urine. Following SPE procedure, recovery of the chiral analytes from the two media was in the ranges of 82-87%, 90-95% and 70-76% for ibuprofen, 2'-hydroxy-ibuprofen and 2'-carboxy-ibuprofen enantiomers, respectively. The validated method was successfully applied in pharmacokinetic investigations of IBP enantiomers as well as free chiral metabolites in reference to the genetic polymorphism of CYP450 2C isoenzymes.