Analytical methods for determination of benzodiazepines. A short review

Benzodiazepines (BDZs) are generally commonly used as anxiolytic and/or hypnotic drugs as a ligand of the GABA_A-benzodiazepine receptor. Moreover, some of benzodiazepines are widely used as an anti-depressive and sedative drugs, and also as anti-epileptic drugs and in some cases can be useful as an adjunct treatment in refractory epilepsies or anti-alcoholic therapy. High-performance liquid chromatography (HPLC) methods, thin-layer chromatography (TLC) methods, gas chromatography (GC) methods, capillary electrophoresis (CE) methods and some of spectrophotometric and spectrofluorometric methods were developed and have been extensively applied to the analysis of number of benzodiazepine derivative drugs (BDZs) providing reliable and accurate results. The available chemical methods for the determination of BDZs in biological materials and pharmaceutical formulations are reviewed in this work.      

A Direct Approach to the cis-1-Octalone System. 2-Carbomethoxy-2-Cyclohexenone as a Dienophile

Under stannic chloride catalysis, 2-carbo-methoxy-2-cyclohexenone (1) was found to undergo Diels-Alder reaction with a variety of dienes to give directly the cis-1-octalone system possessing a functionalized substituent at the angular position.     

Palladium-Catalyzed Diastereoselective Cyclization of the Allylic Precursors. A Concise Synthetic Route to 3-Azabicyclo[3.3.0]Octane and Hydroisoindole Skeletons

A useful variant of palladium-catalyzed 1,2-diastereoselective cyclization of the allylic precursors based on the steric nature of the anion stabilizing groups has been developed. The 1,1,2-trisubstituted cycloalkane products have also been efficiently transformed into the azabicyclic systems.     

On fusible rings

We answer in negative two of questions posed in Ghashghaei and McGovern. We also establish a new characterization of semiprime left Goldie rings by showing that a semiprime ring R is left Goldie iff it is regular left fusible and has finite left Goldie dimension.     

Toxicological evaluation of exposed SPMD membranes

This article is focused on bioassay evaluation of exposed SPMDs. Toxicity testing of SPMD extract is a suitable complementary parameter to chemical analysis. Vtox as an integrative parameter describing toxic properties of extract from membrane and thus a level of contamination of assessed ambient is presented here. Two examples of practical use of Vtox is demonstrated: a course of toxicity throw wastewater treatment plant with industrial inlets and increase of toxicity in surface water body caused by leakages of POPs from industrial plant.     

Measurement of work function changes as a research method for structural phase transitions in adsorbate islands: Cu/Mo(011)

The investigation of work function changes due to temperature changes for copper sub-monolayers adsorbed on the Mo(011) face enables one to observe the structural transition in condensed layers. The interaction energy between adsorbed atoms is determined.     

Long periodic shadowing

A general theorem for establishing the existence of a true periodic orbit near a numerically computed pseudoperiodic orbit of an autonomous system of ordinary differential equations is presented. For practical applications, a Newton method is devised to compute appropriate pseudoperiodic orbits. Then numerical considerations for checking the hypotheses of the theorem in terms of quantities which can be computed directly from the pseudoperiodic orbit and the vector field are addressed. Finally, a numerical method for estimating the Lyapunov exponents of the true periodic orbit is given. The theory and computations are designed to be applicable for unstable periodic orbits with long periods. The existence of several such periodic orbits of the Lorenz equations is exhibited. This revised version was published online in June 2006 with corrections to the Cover Date.     

Applications of k-covers

We investigate a role of k-covers in selection principles theory. Some results about relationships between Ramsey theory and game theory and selection principles that involve k-covers are also given.     

Asymmetric reactions based on 1,3-oxathianes3̄: Secondary α-hydroxyacids,RCHOHCO2H and glycols RCHOHCH2OH

Reduction of the previously prepared¹ chiral 2-acyl-l,3-oxathianes derived from (+)-pulegone with various metal hydride combinations proceeds stereoselectively, with diastereomer excess (d.e.) of as much as 97% in the case of reduction of phenyl ketones with lithium tri-sec.butylborohydride. Lesser selectivity (maximum 82% d.e.) is achieved with primary or tertiary alkyl ketones: the predominant diastereomer is readily purified by chromatography. The major product in these cases is that predicted by Cram's chelate rule. The product ratio is reversed with diiasobutylaluminum hydride and also in the reduction of secondary alkyl ketones with lithium sec. butylborohydride, where stereoselectivity is low. The 2-hydroxyalkyl-l,3-oxathianes are cleaved to α-hydroxyaldehydes with N-chlorosuccinimide-silver nitrate and the aldehydes reduced to glycols, RCHOHCH₂OH with sodium borohydride with little or no racemization. Esters, RCHOHCO₂CH₃, are obtained in high enantiomeric purity by O-benzylating the 2-hydroxyalkyl-l,3-oxathianes prior to cleavage, oxidizing with sodium chlorite following cleavage, esterifying and debenzylating. A method for measuring the enantiomeric purity of glycols RCHOHCH₂OH by conversion to 2-phenyl-l,3-dioxolanes with benzaldehyde, followed by proton NMR analysis of the resulting 2-phenyl-4-alkyl-l,3-dioxolane diastereomer pair in the presence of a chiral europium shift reagent is described.