Efficient and Straightforward Synthesis of Tetrahydrocarbazoles and 2,3-Dimethyl Indoles Catalyzed by CAN

A simple protocol was established to synthesize 2,3-dialkyl indoles and various tetrahydrocarbazoles via Fischer indole synthesis. This method uses ceric ammonium nitrate as a catalyst for the Fischer indole synthesis with substituted phenyl hydrazine hydrochlorides and 2-butanone, phenyl propanal, and cyclohexanone. This process is a practical synthetic method for the preparation of various 2,3-disubstituted alkyl indoles and tetrahydrocarbazoles.     

Use of an oxidation reaction for the quantitative determination of albendazole with Chloramine-T and acid dyes.

One titrimetric and two spectrophotometric procedures have been reported for the determination of albendazole and its tablets. Using titrimetry, the drug was titrated directly with Chloramine-T under acidic conditions using a Methyl Orange indicator. The spectrophotometric procedures involve treating the sample solution with a measured excess of Chloramine-T in an acid medium, followed by an estimation of unreacted Chloramine-T by reacting with a fixed amount of either Methyl Orange or Indigo Carmine dye solution and measuring the absorbance at 510 nm or 610 nm. The stoichiometric ratio, which forms the basis for the calculations in titrimetry as well as the range of the applicability, are reported. The Beer's law range and sensitivity values for spectrophotometric procedures are included. The methods were applied to the determination of albendazole in tablets with satisfactory results.     

On limiting for higher order discontinuous Galerkin method for 2D Euler equations

We present an implementation of discontinuous Galerkin method for 2-D Euler equations on Cartesian meshes using tensor product Lagrange polynomials based on Gauss nodes. The scheme is stabilized by a version of the slope limiter which is adapted for tensor product basis functions together with a positivity preserving limiter. We also incorporate and test shock indicators to determine which cells need limiting. Several numerical results are presented to demonstrate that the proposed approach is capable of computing complex discontinuous flows in a stable and accurate fashion.     

Imino <Emphasis Type="Italic">Diels-Alder</Emphasis> Reactions: Efficient Synthesis of 2-Aryl-4-(2′-oxopyrrolidinyl-1′)-1,2,3,4-tetrahydroquinolines catalyzed by Antimony(III) Sulfate

Summary. Antimony(III) sulfate is found to catalyze the imino Diels-Alder reaction of Schiff’s bases with N-vinylpyrrolidin-2-one to afford 2-aryl-4-(2′-oxopyrrolidinyl-1′)-1,2,3,4-tetrahydroquinolines. One-pot synthesis of 1,2,3,4-tetrahydroquinolines from 3-nitro benzaldehyde and aromatic amines with N-vinylpyrrolidin-2-one catalyzed by antimony(III) sulfate is also reported. This catalyst is inexpensive, easily available, and it was also found that catalyst could be recovered quantitatively and reused without much loss of catalytic activity.     

One-pot synthesis of core-modified meso-aryl calix[5]phyrin and N-fused [24]pentaphyrin

Synthesis and characterization of core-modified meso-aryl calix[5]phyrins and N-fused pentaphyrins are reported.     

Phenylene‐Bridged Core‐Modified Planar Aromatic Octaphyrin: Aromaticity,Photophysical and Anion Receptor Properties

The synthesis of a planar expanded meso porphyrin with an intramolecular para‐phenylene‐bridged core is reported. The planarity of the octaphyrin macrocycle was confirmed by single‐crystal X‐ray structural analysis, in which the bridged para‐phenylene unit deviated by 27° from the mean macrocyclic plane. Spectroscopic analyses and theoretical calculations suggested that the macrocycle was Hückel aromatic and followed a major [34 π] single‐conjugation pathway, which indicated that the bridging para‐phenylene unit was not involved in the macrocyclic conjugation. Analysis of the photophysical properties of this system by steady‐state absorption/fluorescence spectroscopy and transient absorption spectroscopy revealed moderate enhancement in the parameters of the octaphyrin as compared to its non‐bridged octaphyrin congeners, which was attributed to the planarity and rigidity of the macrocycle as imposed by the bridging para‐phenylene unit. Preliminary anion‐binding studies revealed that the protonated macrocycle bound selectively with chloride ions through N?H???Cl hydrogen‐bonding interactions.     

A convergent approach to the synthesis of aprepitant: a potent human NK-1 receptor antagonist

A simple and convergent approach to enantiomerically pure 5-[[2-[1-[3,5-bis(trifluoromethyl)phenyl]ethoxy-3-(4-fluorophenyl)morpholin-4-yl]methyl]-1,2-dihydro-1,2,4-triazol-3-one 1, a potent orally active antagonist of the human neurokinin-1 (NK-1) receptor, is described. The synthetic procedure starts from p-fluorobenzaldehyde to access the racemic morpholinone 2 via a modified Strecker synthesis and utilizes a diastereomeric salt resolution technique to accomplish the synthesis of 1 in enantiomerically pure form and good yield.     

One-pot synthesis of oxidized and reduced heptaphyrins with unusual TFA binding

Synthesis and reversible redox interconversion between core-modified [32]heptaphyrin (1.1.1.1.1.0.0) and [30]heptaphyrin (1.1.1.1.1.0.0) are reported.     

Convolutions of meromorphic multivalent functions with respect to n-ply points and symmetric conjugate points

It is well-known that the classes of starlike, convex and close-to-convex univalent functions are closed under convolution with convex functions. In this paper, closure properties under convolution of general classes of meromorphic p-valent functions that are either starlike, convex or close-to-convex with respect to n-ply symmetric, conjugate and symmetric conjugate points are investigated.