One-pot Synthesis of 3-Aminoimidazo[1,2-a]pyridines Catalyzed by Heteropolyacids

Condensation of aldehydes, isonitriles and 2‐aminopyridines in the presence of H₃PMo₁₂O₄₀ affords different derivatives of 3‐aminoimidazo[1,2‐a]pyridine in good to excellent yields.     

A mild and efficient palladium–triethylsilane system for reduction of olefins and carbon–carbon double bond isomerization

The versatility of palladium(II) acetate and palladium on activated charcoal catalysts with triethylsilane has been investigated in the hydrogenation and the isomerization of carbon–carbon double bond of 1‐alkenes. The reduction of 1‐alkenes was carried out in the presence of triethylsilane, ethanol and a catalytic amount of palladium(II) acetate or palladium on activated charcoal, at room temperature. This facile and efficient method affords high yields for hydrogenation of unsaturated alkenes to the corresponding alkanes. Then the carbon–carbon double bond isomerization of 1‐alkenes was tested using the same catalysts in the absence of solvent. The system palladium(II) acetate‐triethylsilane was found to be more effective compared with palladium on an activated charcoal–triethylsilane system at room temperature, while comparable results were obtained at 50 °C for both catalysts. Copyright © 2006 John Wiley & Sons, Ltd.     

An Eco‐friendly Three Component Manifold for the Synthesis of α‐Aminophosphonates under Catalyst and Solvent‐free Conditions,X‐ray Characterization and Their Evaluation as Anticancer Agents

A series of α‐aminophosphonates were synthesized through one‐pot condensation of aryl aldehydes, aryl amines and diethyl phosphite in the absence of any catalyst and organic solvents. All the synthesized α‐aminophosphonates were characterized by spectral and elemental analysis and in the case of compound 4j by X‐ray crystallography. Some of these new α‐aminophosphonate derivatives were found to have cytotoxic activity on the cancer cell line DU145 in vitro by the MTT method.     

A comparison of the inclusion behavior of human serum albumin and holo transferrin with fluoxymesterone in the presence of three different cyclodextrins

This article describes the interaction of fluoxymesterone (Flu) with HSA and HTF in the absence and presence of cyclodextrins (CDs) (α, β and γ). According to fluorescence data, the binding of Flu to the proteins caused strong static quenching in the binary and ternary systems. The fluorescence quenching results demonstrated that HSA and HTF had two and one class of apparent binding sites with a distinct binding constant in the presence of the CDs, respectively. The effects of Flu on the structure of HSA and HTF were analyzed using synchronous fluorescence spectroscopy, which showed that the interaction of Flu with both proteins in the binary and ternary systems altered the microenvironment around the Trp and Tyr residues. The distance, r, between Flu and the proteins was obtained according to FRET which pointed at a successful formation of a drug-protein complex. Far-UV CD spectra indicated that the binding of the drug to both proteins induced changes in the secondary structure of HSA and HTF in the binary and ternary systems. Finally, molecular modeling provided possible binding sites of Flu within the proteins for the binary and ternary systems and also confirmed the experimental results. The obtained data can be useful for determining usage drug doses in drug delivery.     

Decomposable norm minimization with proximal-gradient homotopy algorithm

We study the convergence rate of the proximal-gradient homotopy algorithm applied to norm-regularized linear least squares problems, for a general class of norms. The homotopy algorithm reduces the regularization parameter in a series of steps, and uses a proximal-gradient algorithm to solve the problem at each step. Proximal-gradient algorithm has a linear rate of convergence given that the objective function is strongly convex, and the gradient of the smooth component of the objective function is Lipschitz continuous. In many applications, the objective function in this type of problem is not strongly convex, especially when the problem is high-dimensional and regularizers are chosen that induce sparsity or low-dimensionality. We show that if the linear sampling matrix satisfies certain assumptions and the regularizing norm is decomposable, proximal-gradient homotopy algorithm converges with a linear rate even though the objective function is not strongly convex. Our result generalizes results on the linear convergence of homotopy algorithm for \(\ell _1\)-regularized least squares problems. Numerical experiments are presented that support the theoretical convergence rate analysis.     

CuFe2O4 Nanoparticles: A Magnetically Recoverable and Reusable Catalyst for the Synthesis of Coumarins via Pechmann Reaction in Water

The synthesis of coumarins by hydroxyalkylation of phenols with ethyl acetoacetate (via Pechmann reaction) is attempted using magnetically separable and reusable CuFe₂O₄ nanoparticles in water.

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