Oxidation Kinetics of Simvastatin Using Cetyltrimethylammonium Dichromate

This article reports an attempt on the studies on resistance of oxidative stress by the prodrug, simvastatin (SV). Cetyltrimethylammonium dichromate has been used as a lipid compatible oxidant to study the oxidation kinetics of SV in organic media. The reaction undergoes via an ionic mechanism without any side product. The reaction is found to be acid catalyzed and sensitive to solvent polarity. The increase in the rate constant due to an increase in hydrophobicity (apolarity) of the solvent indicates the existence of a less polar transition state. Furthermore, the decrease in the rate constant due to an increase in [CTAB] suggests partitioning of the substrates and the oxidants into two different domains with different polar characteristics akin to a reversed micellar aggregates. Considering the above results and the thermodynamic parameters, a reaction mechanism has been proposed, wherein a complex formed at the interface of the two domains due to the reactant and the oxidant in a fast process decomposes to the products in a slow process in the nonpolar bulk.     

Approximation by complex summation-integral type operator in compact disks

In the present paper we estimate a Voronovskaja type quantitative estimate for a certain type of complex Durrmeyer polynomials, which is different from those studied previously in the literature. Such estimation is in terms of analytic functions in the compact disks. In this way, we present the evidence of overconvergence phenomenon for this type of Durrmeyer polynomials, namely the extensions of approximation properties (with quantitative estimates) from real intervals to compact disks in the complex plane. In the end, we mention certain applications.     

Oxidation of Arylthiourea by Cetyltrimethylammonium Dichromate

With a view to investigate the oxidation behaviors of cetyltrimethylammonium dichromate on multifunctional groups, some arylthioureas were subjected to oxidation, both in neutral and in acidic conditions. In neutral conditions, the products were found to be a mixture of corresponding urea and isonitrile. In acidic conditions, the products were corresponding ureas only. A probable mechanism was proposed for the formation of the product, wherein the first step involves coupling of –NH₂ and –SH of one molecule to the –NH₂ and –SH of another molecule, respectively, which is followed by removal of nitrogen and sulfur. The microwave irradiation resulted in great yield of isonitrile than urea in neutral conditions.

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

CeCl3·7H2O: a highly efficient catalyst for the synthesis of 1-substituted-octahydro-[1,3,2]diazaphospholo[1,5-a]pyridine-1-oxide

An efficient and simple protocol is reported for the synthesis of a new class of 1-substituted-octahydro-[1,3,2]diazaphospholo[1,5-a]pyridine-1-oxides in good to excellent yield (88–95%) via Michaelis–Arbuzov rearrangement. Condensation of diamido phosphite with various halides at 60 °C using CeCl₃·7H₂O as a highly efficient catalyst afforded the products within a short period of reaction time. This procedure is mild, efficient, and non-toxic and stability of the catalyst is the merit of this process. Therefore, this protocol being environmentally benign and efficient, serves as an alternative procedure for the preparation of the title compounds.     

Selective Nucleophilic Openings Of 2,3-Epoxy Alcohols Catalysed By Pd(Pph3)4

Selective nucleophilic openings of 2, 3-epoxy alcohols with high regie selectivity by various nucleophiles in the presence of Pd(PPh₃)₄ catalyst for the first time is described.     

Hypervalent Iodine Oxidation of Hydrazones of Some Nitrogen Heterocyclic Ketones and Aldehydes: An Efficient Synthesis of Fused 1,2,3-Triazoloheterocycles

Fused 1,2,3-triazoloheterocycles have been prepared by iodobenzene diacetate mediated oxidation of hydrazones of nitrogen heterocyclic ketones and aldehydes.     

An optical tweezers-based immunosensor for detection of femtomoles-per-liter concentrations of antigens

We used optical tweezers—optical trapping with focused laser beams—to pull microspheres coated with antigens off of an antibody-coated surface. Using this technique, we could quantify the force required to separate antigen to antibody bonds. At very low surface density of antigen, we were able to detect the single antigen to antibody binding. The force required to break the antigen-antibody bonds and pull the microsphere off the surface was shown to increase monotonically with increasing surface density of antigens. Using the force determination as a transducer, we were able to detect concentrations of free antigens in solution as small as 10⁻¹⁵ mol/L in a competitive binding assay.     

Synthesis of benzosuberone-tethered spirooxindoles: 1-3-dipolar cycloaddition of azomethine ylides and arylidene benzosuberones

Molecular Diversity - Expedient synthesis of benzosuberone-tethered spirooxindoles was accomplished by a three-component 1,3-dipolar cycloaddition reaction between azomethine ylide (generated in...