Gas-liquid flow hydrogenation of nitroarenes: Efficient access to a pharmaceutically relevant pyrrolobenzo[1,4]diazepine scaffold

Using a Tube-in-Tube device based on the amorphous Teflon AF-2400 fluoropolymer, a series of nitroarenes was hydrogenated to afford the corresponding aniline compounds. The system was then applied to the construction of a pyrrolobenzo[1,4]diazapene scaffold through a tandem hydrogenation-condensation-hydrogenation sequence.     

Structural architectures of charge-assisted,hydrogen-bonded, 2D layered amine⋯tetraphosphonate and zinc⋯tetraphosphonate ionic materials

The synthesis, characterization and structural analyses of ionic amine-phosphonate and hydrated metal ion-phosphonate compounds are reported. These are (en)(HDTMP), (NH₄)(EDTMP), Zn(H₂O)₆(TDTMP) (en = ethylenediamine, HDTMP = hexamethylenediamine-tetrakis(methylenephosphonate), EDTMP = diethylenediamine-tetrakis(methylenephosphonate), TDTMP = tetramethylenediamine-tetrakis(methylenephosphonate)). All three compounds are composed of discrete anions and cations, stabilized by intricate networks of hydrogen bonds, and form 2D layered architectures.     

Purification and Characterization of an Ethanol-Tolerant β-Glucosidase from Sporidiobolus pararoseus and Its Potential for Hydrolysis of Wine Aroma Precursors

An extracellular ethanol-tolerant β-glucosidase from Sporidiobolus pararoseus was purified to homogeneity and characterized, and its potential use for the enhancement of wine aroma was investigated. The crude enzymatic extract was purified in four steps (concentration, dialysis, ultrafiltration, and chromatography) with a yield of around 40 % for total activity. The purified enzyme (designated Sp-βgl-P) showed a specific activity of approximately 20.0 U/mg, an estimated molecular mass of 63 kDa after sodium dodecyl sulfate polyacrylamide gel electrophoresis, and isoelectric point of 5.0 by isoelectric focusing. Sp-βgl-P has optimal activity at pH 4.0 and at 55 °C. It was stable in a broad pH range at low temperatures and it was tolerant to ethanol and glucose, indicating suitable properties for winemaking. The hydrolysis of glycosidic terpenes was analyzed by adding Sp-βgl-P directly to the wines. The released terpene compounds were evaluated by gas chromatography/mass spectrometry. The enzymatic treatment significantly increased the amount of free terpenes, suggesting that this enzyme could potentially be applicable in wine aroma improvement.     

Coupled system of Korteweg–de Vries equations type in domains with moving boundaries

We consider the initial-boundary value problem in a bounded domain with moving boundaries and nonhomogeneous boundary conditions for the coupled system of equations of Korteweg–de Vries (KdV)-type modelling strong interactions between internal solitary waves. Finite domains of wave propagation changing in time arise naturally in certain practical situations when the equations are used as a model for waves and a numerical scheme is needed. We prove a global existence and uniqueness for strong solutions for the coupled system of equations of KdV-type as well as the exponential decay of small solutions in asymptotically cylindrical domains. Finally, we present a numerical scheme based on semi-implicit finite differences and we give some examples to show the numerical effect of the moving boundaries for this kind of systems.     

Clauson–Kaas-Type Synthesis of Pyrrolyl-phenols,from the Hydrochlorides of Aminophenols,in the Presence of Nicotinamide

A facile Clauson–Kaas-type pyrrolyl-phenol synthesis has been achieved in the presence of nicotinamide, which is inexpensive and nontoxic. The starting material is aminophenol hydrochloride. This is advantageous in certain cases because it is the only isolatable form of the corresponding aminophenol.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource: Full experimental and spectral details.]     

Phase Transfer Catalyzed Aromatic Nucleophilic Substituticn of Triflate Esters of 2-and 4-Nitro-estrone

In this study, a phase transfer catalyzed method was successfully adapted for replacing the 3-triflate ester in 2-and 4-nitro-estrone with an acetylthio-functionality.     

Insertion of functional groups into a Nd3+ metal-organic framework via single-crystal-to-single-crystal coordinating solvent exchange

Single-crystal-to-single-crystal (SCSC) transformations represent some of the most fascinating phenomena in chemistry. They are not only intriguing from a basic science point of view but also provide a means to modify or tune the properties of the materials via the postsynthetic introduction of suitable guest molecules or organic functional groups into their structures. Here, we describe UCY-2, a new flexible Nd(3+) metal-organic framework (MOF), which exhibits a unique capability to undergo a plethora of SCSC transformations with some of them being very uncommon. These structural alterations involve the replacement of coordinating solvent molecules of UCY-2 by terminally ligating solvents and organic ligands with multiple functional groups including -OH, -SH, -NH-, and -NH(2) or their combinations, chelating ligands, anions, and two different organic compounds. The SCSC coordinating solvent exchange is thus demonstrated as a powerful method for the functionalization of MOFs.     

A porous graphitized carbon column HPLC method for the quantification of paracetamol, pseudoephedrine, and chlorpheniramine in a pharmaceutical formulation

A simple, rapid, and stability-indicating HPLC method has been developed, fully validated, and applied to the quantification of paracetamol, pseudoephedrine hydrochloride, and chlorpheniramine maleate in a pharmaceutical formulation, using hydrochlorothiazide as an internal standard. Chromatographic separation was achieved isocratically on an RP porous graphitized carbon analytical column (125 x 2.1 mm id, particle size 5 microm) using 5.0 mM ammonium acetate-acetonitrile (35 + 65, v/v) mobile phase at a flow rate of 0.50 mL/min. UV spectrophotometric detection at 220 nm was used. The method had linear calibration curves over the range of 30-70 microg/mL for paracetamol, 1.8-4.2 microg/mL for pseudoephedrine hydrochloride, and 120-280 ng/mL for chlorpheniramine maleate. The intraday and interday RSD values were less than 3.2% for all compounds, while the relative error was less than 2.9%. Accelerated stability studies performed under various stress conditions proved the selectivity of the method. The developed method was applied successfully to QC and content uniformity tests of commercial tablets.