Synthesis of 2-Chloromethyl-1,4-Dihydropyridines

The title compounds were prepared by condensation of aldehydes with alkyl 3-aminocrotonate and 4-chloroacetoacetate.     

Synthesis of Functionalized Polynorbornanes Employing 2,5‐Bis(trifluoromethyl)‐1,3,4‐oxadiazole

Cycloaddition reaction of 2,5‐bis(trifluoromethyl)‐1,3,4‐oxadiazole with strained olefinic bonds of norbornenes was used to synthetize functionalized polynorbornanes. This simple, one step procedure was more effective when reaction was carried out by classical heating, in comparison to microwave‐assisted reactions. Various functional groups were stable in the reaction conditions (ester, imide, phthalimide, piperidyl, and carboxylic acid), whereas anhydride, N‐Boc, or TMS functionalities do not withstand reaction conditions.     

A phenomenological model of antiferroelectric liquid crystals

Abstract

We present the analysis of static properties of a simple phenomenological model of antiferroelectric liquid crystals, capable of explaining some different sequences of phase transitions found experimentally. Stability analysis shows the existence of three simply modulated phases. Results are summed up in phase diagrams with dependence on the parameters of the model. The existence of doubly modulated incommensurate phases is predicted in parts of the phase diagrams.     

Trifluoromethylated (tetrahydropyrrolo) quinazolinones by a new three‐component reaction and facile assignment of the regio‐ and stereoisomers formed by NMR spectroscopy

A new three‐component cyclisation reactions of methyl 3,3,3‐trifluoropyruvate, 2‐aminobenzylamine and oxo compounds afforded tetrahydropyrroloquinazolinones of the types 4 and 5 as mixtures of regio‐ and stereoisomers. Whereas standard 1D NMR spectroscopy was used for a facile assignment of the cyclization regioisomers, a combination of homo (proton–proton) and heteronuclear (proton–fluorine) NOE experiments allowed the determination of the relative configuration on stereogenic centres. The structure of some compounds was also confirmed by the X‐ray diffraction. Adaptation of the 1D double‐pulsed field‐gradient spin‐echo NOE for a heteronuclear case is presented. Copyright © 2010 John Wiley & Sons, Ltd.     

Lipase-catalyzed kinetic resolution of racemic 1-(10-alkyl-10H-phenothiazin-3-yl)ethanols and their butanoates

The synthesis of both enantiomers of 1-(10-alkyl-10H-phenothiazin-3-yl)ethanols and their butanoates by enantiomer-selective acylation of racemic alcohols with the lipase from Pseudomonas fluorescens (L-AK) or/and by methanolysis of the corresponding racemic esters with lipase B from Candida antarctica (CaL-B) is described. The absolute configuration of the enantiomerically pure enantiomers was determined by X-ray crystallography.     

Diamagnetic susceptibility of solid and liquid paraffins

Experimental values for the diamagnetic susceptibility of a series of mono-disperse n-paraffins ranging between 6 and 50 carbon atoms in the solid (melt and solution crystallized) and in the liquid state are reported. From the dependence of the molecular susceptibility, ScHM, on the molecular weight, information about the intermolecular interactions between adjacent chain molecules and on the arrangement of the methyl end-groups is obtained. The ScHM values of melt- and solution-crystallized paraffins are, within experimental error, indistinguishable from each other. For C₁₂H₂₆ and C₄₄H₉₀ the specific susceptibility ScHM /M rises at the melting point within a few °C and reaches a plateau which characterizes the liquid state II. For the paraffin C₂₄H₅₀ an intermediate plateau between the melting point and the final true liquid state is observed and is called liquid state I. After cooling below the melting point TM, the ScHM value of the equilibrium state can be obtained after a short time only from liquid state I, while from liquid state II days and weeks are needed for this. By combining this information with the observed ScHM values, it is concluded that in liquid state I a higher or smectic-like order exists similar to mesophases, well-known in liquid crystals, while in the real liquid state II this order is lost.     

Methyl 5-Deoxy-α and β-D-Xylofuranosides

Abstract

Synthesized from D-xylose, methyl 5-deoxy-α-D-xylofuranoside (1) and methyl 5-deoxy-β-D-xylofuranoside (2) were obtained in overall yields of 24 and 26 %, respectively. The key step in the synthesis was the separation of an anomeric mixture on a strong anion exchanger in OH^? form. NMR data and mass spectra of title compounds 1, 2, methyl 2,3-di-O-acetyl-5-deoxy-α-D-xylofuranoside (3), and methyl 2,3-di-O-acetyl-5-deoxy-β-D-xylofuranoside (4) are discussed. The conformations of 1 and 2 were established from the best fit between calculated and experimental coupling constants using Karplus equation.     

Numerical solution of a system of nonlinear differential equations with a nonlocal condition

Lithuanian Mathematical Journal -