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.     

Polygon dissections and some generalizations of cluster complexes

Let W be a Weyl group corresponding to the root system An−1 or Bn. We define a simplicial complex in terms of polygon dissections for such a group and any positive integer m. For m=1, is isomorphic to the cluster complex corresponding to W, defined in [S. Fomin, A.V. Zelevinsky, Y-systems and generalized associahedra, Ann. of Math. 158 (2003) 977-1018]. We enumerate the faces of and show that the entries of its h-vector are given by the generalized Narayana numbers , defined in [C.A. Athanasiadis, On a refinement of the generalized Catalan numbers for Weyl groups, Trans. Amer. Math. Soc. 357 (2005) 179-196]. We also prove that for any m?1 the complex is shellable and hence Cohen-Macaulay.     

Synthesis,in vitro lipoxygenase inhibition,docking study and thermal stability analyses of novel indole derivatives

A series of indole derivatives has been synthesized and biologically evaluated to identify potent new lipoxygenase (LOX) inhibitors. All selected indole derivatives were screened for their LOX inhibition studies. Most of compounds showed good in vitro LOX inhibition properties exhibiting IC₅₀ values in the range of 53.61 ± 0.14 to 198.61 ± 0.11 μM (mean ± SEM), as compared to the standard inhibitor baicalein with IC₅₀ value 22.4 ± 1.3 μM. Structure activity relationship has been discussed and docking stimulation of most active compound 4f has also performed. Thermal stability and melting point of indole derivatives have been performed by thermal gravimetric analysis and differential scanning calorimetry analysis under nitrogen atmosphere at heating rate of 20 °C min^?1. Compound 4f bearing bis-phenyl moiety has been found to be the most potent (IC₅₀ 53.61 ± 0.14 μM) and thermally most stable among the tested compounds. Imine (C=N) was found to be the key moiety for increasing the thermal stabilities of indole derivatives. FT-IR, NMR and elemental analysis techniques were performed for structural characterization.     

Low-Cost Synthesis of Fullerene Derivatives

Refined mixed fullerenes were used as a reagent in known organic reactions instead of the pure fullerene C₆₀ with aim to find an alternative, low-cost method for the synthesis of fullerene derivatives potentially exhibiting photoconductive properties. The isolation of C₆₀ or C₇₀ in clean form without admixtures requires the use of large quantities of toluene or other nonpolar solvents, polluting the environment and multiplying the production cost. 1,3-Dipolar cycloaddition of azomethine ylide to fullerite was chosen because this reaction is one of the most widely used for fullerene functionalization, producing material possibly presenting photoinducing behavior. The data showed that the use of the cheaper mixed fullerenes instead of pure C₆₀ leads to the isolation of the same expected products with similar yields. The photoelectric properties of mixed fullerenes and their organic derivatives were also examined. A slightly semiconductive behavior was confirmed as well as a noticeable photoresponse.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

Cure Kinetics Study of Two Epoxy Systems with Fourier Tranform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC)

This work was aimed at the study of cure kinetics of two commercial thermosetting epoxy systems, Epikote resin 816 LV/Epikure F205 and Epikote resin 240/Epikure F205, by Fourier Tranform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC). The studied systems consist of a resin (A), based on a diglycidyl ether of bisphenol A and a hardener (B) based on the Isophorodiamine (IPDA) a cycloaliphatic diamine. These systems are used for the building and civil engineering industries, e.g. flooring compounds, adhesives, mortars and grouts. FTIR spectroscopy was employed to investigate the isothermal curing kinetics at 30, 50 or 70°C and DSC analysis to study the non-isothermal curing kinetics at different heating rates 2.5, 5, 10 and 20°C/min, from 20 to 300°C. A kinetic model was employed to simulate the FTIR isothermal experimental data using two kinetic rate constants and incorporating also diffusion control at high degrees of conversion. Finally, the variation of the effective activation energy with the extent of curing was estimated using isoconversional analysis of non-isothermal DSC data.     

Structural Insight into IAPP‐Derived Amyloid Inhibitors and Their Mechanism of Action

Designed peptides derived from the islet amyloid polypeptide (IAPP) cross‐amyloid interaction surface with Aβ (termed interaction surface mimics or ISMs) have been shown to be highly potent inhibitors of Aβ amyloid self‐assembly. However, the molecular mechanism of their function is not well understood. Using solution‐state and solid‐state NMR spectroscopy in combination with ensemble‐averaged dynamics simulations and other biophysical methods including TEM, fluorescence spectroscopy and microscopy, and DLS, we characterize ISM structural preferences and interactions. We find that the ISM peptide R3‐GI is highly dynamic, can adopt a β‐like structure, and oligomerizes into colloid‐like assemblies in a process that is reminiscent of liquid–liquid phase separation (LLPS). Our results suggest that such assemblies yield multivalent surfaces for interactions with Aβ40. Sequestration of substrates into these colloid‐like structures provides a mechanistic basis for ISM function and the design of novel potent anti‐amyloid molecules.