Dealkenylative Alkenylation: Formal σ‐Bond Metathesis of Olefins

The dealkenylative alkenylation of alkene C(sp³)?C(sp²) bonds has been an unexplored area for C?C bond formation. Herein 64 examples of β‐alkylated styrene derivatives, synthesized through the reactions of readily accessible feedstock olefins with β‐nitrostyrenes by ozone/Fe^II‐mediated radical substitutions, are reported. These reactions proceed with good efficiencies and high stereoselectivities under mild reaction conditions and tolerate an array of functional groups. Also demonstrated is the applicability of the strategy through several synthetic transformations of the products, as well as the syntheses of the natural product iso‐moracin and the drug (E)‐metanicotine.     

Complexation of sodium picosulphate with beta cyclodextrin: NMR spectroscopic study in solution

Sodium Picosulphate (SPL) is a synthetic drug, widely used for thorough evacuation of the bowel, usually for patients who are preparing to undergo a colonoscopy. Cyclodextrins (CDs) are chiral, truncated cone shaped, cyclic oligosaccharides that can encapsulate a variety of drug molecules into inclusion complexes, thereby increasing their stability and solubility. ¹H NMR spectroscopic studies showed the inclusion complexation between β-CD and SPL, based on the upfield shift changes in the β-CD cavity protons (H-3′ and H-5′) and downfield shift changes in the guest (SPL) protons. The structure of inclusion complexes was determined by 2D ROESY spectral data. The 1:1 stoichiometry and overall association constant (Ka) were determined by using Scott’s plot method to be 450 M^?1.     

Liquid chromatographic methods for separation,determination, and bioassay of enantiomers of etodolac: A review

The control of enantiomeric purity and determination of individual enantiomeric drug molecules remains the subject of importance for clinical, analytical, and regulatory purposes and to facilitate an accurate evaluation of the risks posed by them to human health. A large number of pharmaceuticals are marketed and administered as racemates. Etodolac is among such nonsteroidal anti‐inflammatory drugs. Overall literature reports on its enantioseparation are scanty. Liquid chromatography (LC) methods of enantioseparation of (±)‐etodolac, including certain unconventional ones, are well covered and discussed in this paper. Methods of direct approach without using chiral columns or chiral thin‐layer chromatography plate and of indirect approach using certain chiral derivatizing agents such as (S)‐naproxen and (S)‐levofloxacin are described. Most interesting aspects include establishment of structure and molecular asymmetry of chemically different types of diastereomeric derivatives using liquid chromatography with mass spectrometry (LC–MS), ¹H NMR spectroscopy and by drawing conformations in three dimensional views by using certain software. The methods provide chirality recognition even in the absence of pure enantiomers. Besides, recovery of pure enantiomers by detagging or via solubility difference of chiral inducing reagent and the analyte, without racemization at any stage, has been achieved. The limits of detection and quantification are much lower than the industry benchmarks.     

Influence of fluorine substitution on the molecular conformation of 3′‐deoxy‐3′‐fluoro‐5‐methyluridine

Fluorine substitutions on the furanose ring of nucleosides are known to strongly influence the conformational properties of oligonucleotides. In order to assess the effect of fluorine on the conformation of 3′‐deoxy‐3′‐fluoro‐5‐methyluridine (^RT^F), C₁₀H₁₃FN₂O₅, we studied its stereochemistry in the crystalline state using X‐ray crystallography. The compound crystallizes in the chiral orthorhombic space group P2₁2₁2₁ and contains two symmetry‐independent molecules (A and B) in the asymmetric unit. The furanose ring in molecules A and B adopts conformations between envelope (²E, 2′‐endo, P = 162°) and twisted (²T₃, 2′‐endo and 3′exo, P = 180°), with pseudorotation phase angles (P) of 164.3 and 170.2°, respectively. The maximum puckering amplitudes, ν_max, for molecules A and B are 38.8 and 36.1°, respectively. In contrast, for 5‐methyluridine (^RT^OH), the value of P is 21.2°, which is between the ³E (3′‐endo, P = 18.0°) and ³T₄ (3′‐endo and 4′‐exo, P = 36°) conformations. The value of ν_max for ^RT^OH is 41.29°. Molecules A and B of ^RT^F generate respective helical assemblies across the crystallographic 2₁‐screw axis through classical N—H…O aand O—H…O hydrogen bonds supplemented by C—H…O contacts. Adjacent parallel helices of both molecules are linked to each other via O—H…O and O…π interactions.     

Facile synthesis and coupling of 3,9-dibromo-6-aryl-5H-dibenzo[d,f][1,3]diazepine derivatives

A route has been developed to prepare 3,9-dibromo-6-aryl-5H-dibenzo[d,f][1,3]diazepine derivatives which undergo facile Suzuki coupling to generate extended conjugated moieties bearing this unit. Single crystal X-ray studies on three of the coupled products provide valuable information on the conformation and bulk packing of these materials.     

Explicit expressions for moments of gamma order statistics

Explicit closed form expressions are derived for the moments of order statistics from the gamma and generalized gamma distributions. The expressions involve the Lauricella functions of type A and type B. The usefulness of the result is illustrated through two quality control data sets.     

Efficient Synthesis of N‐Cyano α and β‐Amino Esters

A versatile method for the synthesis of N‐cyano α and β‐amino esters is described. Reaction of different amino esters with cyanogen bromide in dry ether gave the corresponding N‐cyano α and β‐amino esters in excellent yields.     

A convenient Baker yeast accelerated,one-pot synthesis of pentasubstituted thiopyridines

Here we report a novel Baker yeast catalyzed one pot cyclocondensation, performed at room temperature in ethanol for obtaining high yields of polyfunctionalized pyridines, 2-amino-4-aryl-3,5-dicyano-6-phenylthiopyridines. The developed protocol obeys certain green principles and is scalable and cost effective.     

A Comparative study on synthesis, characterization and photocatalytic activities of MgO and Fe/MgO nanoparticles

MgO and Fe/MgO particles in the nanometer-size regime have been successfully synthesized by a hydrothermal crystallization process using dodecyl benzenesulphonic acid as a surfactant. The prepared catalysts were characterized in details by multiform techniques: XRD, SEM, TEM, UV-DRS, TGA-DSC, BET surface area, and EPR spectroscopy. Comparative photocatalytic activity of the samples was evaluated through the photodegradation of Acid Blue 80 dye under sunlight. The results of the photocatalytic degradation of Acid Blue 80 dye in aqueous solution demonstrated that Fe ions doping greatly improved the photocatalytic efficiency of MgO nanoparticles. Most interestingly, this is the first time that it has been observed that the Fe/MgO system is quite an effective visible light active catalyst.