Enantioselective palladium-catalyzed addition of malonates to 3,3-difluoropropenes

Monofluoroalkenes bearing a malonate unit at the β position can be synthesized by the enantioselective addition of diesters to 3,3-difluoropropenes. The difference in reactivity regarding the geometry and the substituents of the alkene of the 3,3-difluoropropenes, as well as the alkyl groups of the malonates, was studied and limitations were identified. The reaction was also performed with different 3,3-difluoropropenes. Further synthetic transformations of a newly functionalized monofluoroalkene were also accomplished.     

Absolute configuration assignment of 3-indolylacetate esters

Herein we describe a straightforward method for the determination of the absolute configuration of 3-indolyl(bromo)acetate 7, 3-indolyl(alkoxy)acetates 8a–f and 3-indolyl(amino)acetate 8g, based on ¹H NMR spectral analysis. The conformational preferences for two diastereomeric esters were calculated by DFT, which matched very well with the experimental results. X-ray diffraction analysis allowed us to validate the methodology, and independent absolute configuration evidence was obtained by vibrational circular dichroism.     

Hydrolytic Pathway of Glufosfamide,a New Phosphorylated Anticancer Agent

31 P NMR was used to demonstrate that glufosfamide is hydrolyzed into isophosphoramide mustard (IPM) with a half-life of about 25 h at 37;C and pH 7.4 in buffer as well as in human plasma. Through a cascade of reactions, IPM gives rise to three final products, dihydroxyIPM, phosphate ion, and phosphorylethanolamine, which is by far the major compound.     

Surface modified‐magnetic nanoparticles by molecular imprinting for the dispersive solid‐phase extraction of triazines from environmental waters

Magnetic nanoparticles have been surface modified by molecular imprinting and evaluated as selective sorbents for the extraction of triazines from environmental waters. The use of propazine as template allowed us to synthesize a selective material able to simultaneously recognize and selective extract not only the template but also several other herbicides of the same family. A magnetic molecularly imprinted‐based dispersive solid‐phase extraction procedure was developed and fully optimized. Magnetic molecularly imprinted polymer particles can be easily collected and separated from liquid solvents and samples with the help of an external magnetic field, avoiding in that way any centrifugation or filtration steps, which represents a remarkable advantage over traditional procedures. Under optimum conditions, selective extraction of several triazines (cyanazine, simazine, atrazine, propazine, and terbutylazine) from environmental water samples was performed prior to final determination by high‐performance liquid chromatography with diode‐array detection. Recoveries for the studied triazines were within the range of 75.2–94.1%, with relative standard deviations lower than 11.3% (n = 3). The limits of detection were within 0.16–0.51 µg/L, depending upon the triazine and the type of sample analyzed.     

Stability and bifurcation in epidemic models describing the transmission of toxoplasmosis in human and cat populations

A five‐dimensional ordinary differential equation model describing the transmission of Toxoplamosis gondii disease between human and cat populations is studied in this paper. Self‐diffusion modeling the spatial dynamics of the T. gondii disease is incorporated in the ordinary differential equation model. The normalized version of both models where the unknown functions are the proportions of the susceptible, infected, and controlled individuals in the total population are analyzed. The main results presented herein are that the ODE model undergoes a trans‐critical bifurcation, the system has no periodic orbits inside the positive octant, and the endemic equilibrium is globally asymptotically stable when we restrict the model to inside of the first octant. Furthermore, a local linear stability analysis for the spatially homogeneous equilibrium points of the reaction diffusion model is carried out, and the global stability of both the disease‐free and endemic equilibria are established for the reaction–diffusion system when restricted to inside of the first octant. Finally, numerical simulations are provided to support our theoretical results and to predict some scenarios about the spread of the disease. Copyright © 2017 John Wiley & Sons, Ltd.     

The Combination of Chemotherapy and Radiotherapy towards More Efficient Drug Delivery

Research on anticancer therapies has advanced significantly in recent years. New therapeutic platforms that can further improve the health of patients are still highly demanded. We propose the idea of combining regular chemotherapy with radiation therapy to minimize side effects as well as increase drug‐delivery efficiency. In this Focus Review, we seek to provide an overview of recent advances that can combine chemotherapy and radiotherapy. We begin by reviewing the current state of systems that can combine chemotherapy and gamma radiation. Among them, diselenide‐containing polymers are highlighted as sensitive drug‐delivery vehicles that can disassemble under gamma radiation. Then X‐ray responsive materials as promising alternative systems are summarized, including X‐ray responsive drug‐delivery vehicles, prodrugs that can be activated by X‐rays, and radiation‐site‐targeting systems. Finally, we describe strategies that involve phototherapies.     

Synthesis of 2-Amino-4-(2-hydroxynaphthyl)-4H-chromene-3-carbonitriles by Michael Addition and Their Transformation into New Pentacyclic Compounds

2-Amino-4-(2-hydroxynaphthyl)-4H-chromene-3-carbonitriles were synthesized by Michael addition of various 3-cyanoiminocoumarins and β-naphthol in good yield. The heterocyclization of these materials in an acidic medium leads new heterocyclic compounds, which have not previously been described, in moderate to good yields and good selectivity. The synthesized compounds were characterized by infrared, ¹H NMR, ¹³C NMR, two-dimensional NMR, and elemental analysis.