A microwave-assisted diastereoselective multicomponent reaction to access dibenzo[c,e]azepinones: synthesis and biological evaluation

An unprecedented microwave-assisted multicomponent strategy has been elaborated for the fast, efficient, and diastereoselective generation of the dibenzo[c,e]azepinone scaffold. The generated compounds were evaluated for their bioactivity.     

Application d'un tétraasamacrocycle greffé sur polymère à l'extraction et au dosage du cuivre en eau de mer

(Application of a polymer-supported tetraazamacrocyle to the extraction of copper from sea water)Copper is extracted with 1,4,8,11-tetraazacyclotetradecane bound to poly(chloromethyl)vinylbenzene. The material has a very low affinity for alkaline and alkaline earth metals. The influence of salinity, pH and temperature on the complexation of copper is described. Results for waters agree well with those obtained with Chelex-100.     

Stability of the Ion Pair Between Ca<Superscript>2+</Superscript> and 2-(Hydroxymethyl)-3-Deoxy-D-<Emphasis Type="Italic">erythro</Emphasis>-Pentonate (α-Isosaccharinate)

Ion-pair formation between Ca²⁺ and -isosaccharinate, Ca²⁺ + ISA^-CaISA⁺, was studied by two independent methods: an ion-exchange and a potentiometric method (Ca-selective electrode). The two methods gave similar values for the complexation constant, log K_CaISA+^o at I = 0, (22 ± 1)°C. The ion-exchange method gave a value of log K_o^CaISA+ = (1.8 ± 0.1) and the potentiometric method resulted in logK_CaISA+^o = (1.78 ± 0.04). These values are in good agreement with the estimated value, log K_CaISA+^o = 1.7, based on the formation of a Ca-gluconate ion pair.     

thermodynamic/kinetic control in the isomerization of the [[tBuNP(mu-NtBu)]2]2- ion

The unique structure of [(tBuN)(2)PK]( infinity ) (2) (containing [(tBuN)(2)P](-) monoanions) is in stark contrast to the previously reported Li(+) analogue [[[tBuNP(mu-NtBu)](2)](2)]Li(4) (1) (containing the dimeric [[tBuNP(mu-NtBu)](2)](2-) ion). DFT and (31)P NMR spectroscopic studies reveal that the formation of the monoanion arrangements are most thermodyamically favored for Li, Na, and K, 1 being the product of kinetic control and 2 being the product of thermodynamic control.     

Growth and kinetics of in vitro poly([R]‐(–)‐3‐hydroxybutyrate) granules interpreted as particulate polymerization with coalescence

Transmission electron microscopy (TEM) and Cryo‐TEM were used to study the growth kinetics of poly(3‐hydroxybutyrate) granules produced by in vitro polymerization. The in vitro formation of poly(3‐hydroxybutyrate) uses a recombinant form of the PHA synthase to polymerize [R]‐(–)‐3‐hydroxybutyryl‐CoA. Since the in vitro reaction contains only synthase and monomer, it is a simpler system than the in vivo biosynthesis of poly(3‐hydroxybutyrate). TEM and Cryo‐TEM were used in conjunction with image analysis to examine the granules that were formed in the in vitro reaction. The in vitro reaction yielded spherical granules of rapidly increasing size; the initially observed granules were already larger than 0.1 μm. While the average granule diameter and volume increased with reaction time, the number of granules decreased throughout the reaction due to coalescence. Basic kinetic parameters, including K_M and V_max were determined and compared to those reported for the in vivo biosynthesis of poly(3‐hydroxybutyrate). In addition it was found that the granules formed by this process were essentially noncrystalline. A computer simulation of the reaction, based on initial formation of relatively large microporous granules that consolidate by expulsion of water during polymerization, accounted for the shape of the kinetic curves.     

Micro-Raman spectroscopy of natural and synthetic indigo samples

In this work indigo samples from three different sources are studied by using Raman spectroscopy: the synthetic pigment and pigments from the woad (Isatis tinctoria) and the indigo plant (Indigofera tinctoria). 21 samples were obtained from 8 suppliers; for each sample 5 Raman spectra were recorded and used for further chemometrical analysis. Principal components analysis (PCA) was performed as data reduction method before applying hierarchical cluster analysis. Linear discriminant analysis (LDA) was implemented as a non-hierarchical supervised pattern recognition method to build a classification model. In order to avoid broad-shaped interferences from the fluorescence background, the influence of 1st and 2nd derivatives on the classification was studied by using cross-validation. Although chemically identical, it is shown that Raman spectroscopy in combination with suitable chemometric methods has the potential to discriminate between synthetic and natural indigo samples.     

Enantioseparations of basic and bifunctional pharmaceuticals by capillary electrochromatography using polysaccharide stationary phases

A fast screening strategy was developed in capillary electrochromatography (CEC) for the chiral separation of basic and bifunctional compounds. The screening conditions were determined on polysaccharide chiral stationary phases using 15 pharmaceutical compounds. The content and type of organic modifier, as well as the pH of the mobile phase appeared to have the largest influence on the chiral resolution. It was seen that for acidic compounds, our approach was not suitable. A generic mobile phase for basic and bifunctional compounds was determined. The testing on 20 additional compounds showed that the proposed mobile phase performed well since enantioselectivity was observed for 86% of the investigated compounds. A comparison of CEC and reversed-phase liquid chromatography (RPLC) results was attempted to demonstrate the potential of the used technique for chiral method development.     

Secondary ion formation of low molecular weight organic dyes in time-of-flight static secondary ion mass spectrometry

Time-of-flight static secondary ion mass spectrometry (TOF-S-SIMS) was used to characterize thin layers of oxy- and thiocarbocyanine dyes on Ag and Si. Apart from adduct ions a variety of structural fragment ions were detected for which a fragmentation pattern is proposed. Peak assignments were confirmed by comparing spectra of dyes with very similar structures. All secondary ions were assigned with a mass accuracy better than 50 ppm. The intensity of molecular ions as well as fragment ions has been studied as a function of the type of organic dye, the substrate, the layer thickness and the type of primary ion. A large yield difference of two orders of magnitude was observed between the precursor ions of cationic carbocyanine dyes and the protonated molecules of the anionic dyes. Fragment ions, on the other hand, yielded similar intensities for both types of dye. As the dye layers deposited on an Ag substrate yielded higher secondary ion intensities than those deposited on a Si substrate, the Ag metal clearly acts as a promoting agent for secondary ion formation. The effect was more pronounced for precursor signals than for fragment ions. The promoting effect decreased as the deposited layer thickness of the organic dye layer was increased.