Novel Synthesis and Structures of Amines and Triazole-Derived Glycoside and Nucleoside Derivatives of Phosphanyl Sugar Analogs

ABSTRACT

3-Methyl-1-phenyl-2-phospholene and 1-phenyl-2-phospholene 1-oxides were converted into 2-bromo-3-hydroxy-3-methyl-1-phenylphospholane and 2-bromo-3-hydroxy-1-phenylphospholane 1-oxide (1-bromo-1,3,4-trideoxy-1,4-C-[(R, S)-phenylphosphinylidene]-glycero-tetrofuranose) by the action of bromine in aqueous medium. The bromo substituent of the phospholane was substituted by treatment with amines or an azide anion to afford novel glycoside derivatives of phosphanyl sugar analogs such as 2-amino-3-hydroxy-1-phenylphospholane (3,4-dideoxy-1,4-C-[(R, S)-phenylphosphinylidene]-glycero-tetrofuranosylamine) and 2-azido-3-hydroxy-3-methyl-1-phenylphospholane 1-oxides with retention of the configuration. The 1,3-dipolar cycloaddition of the 2-azido derivative of the phospholane with alkynes gave 3-hydroxy-3-methyl-1-phenyl-2-(triazol-1′-y1)phospholane 1-oxides as a novel triazole-derived nucleoside of phosphanyl sugar analogs. The structure of the glycoside and nucleoside derivatives of the phosphanyl sugar analogs prepared was deterimined from IR, NMR, and X-ray crystallography analysis.     

A Simple and Convenient Strategy for the Synthesis of Novel Ten,Twelve, and Fourteen‐membered Phosphorus Macrocyclic Compounds

Synthesis of the title compounds 4(a – i) was accomplished through a two‐step process. The synthetic route involves the cyclization of equimolar quantities of 2,2′‐methylene(methyl)bis(4,6‐di‐tert‐butyl‐phenol) ( 1 ) with tris‐(2‐chloro‐ethyl) phosphite ( 2a ), tris‐(2‐bromo‐ethyl) phosphine ( 2b ), and tris‐bromo methyl phosphine ( 2c ) in the presence of sodium hydride in dry tetrahydrofuran at 45–50°C. They were further converted to the corresponding oxides, sulfides, and selenides under N₂ atmosphere by reacting them with hydrogen peroxide, sulfur, and selenium, respectively ( 4a – c , 4d – f, and 4g – i ). But the compounds 6a , b were prepared by the direct cyclocondensation of equimolar quantities of 1 with (2‐chloro‐ethyl)‐phosphonic acid dibromomethyl ester ( 5a ) and (2‐chloro‐ethyl)‐phosphonic acid bis(2‐bromo‐ethyl) ester ( 5b ) in the presence of sodium hydride in dry tetrahydrofuran at 45–50°C in moderate yields. All the newly synthesized compounds 4 ( a – i ) and 6 ( a – b ) exhibited moderate in vitro antibacterial and antifungal activities.     

A study of small impact parameter ion channeling effects in thin crystals

We have recorded channeling patterns produced by 1–2 MeV protons aligned with ?1 1 1? axes in 55 nm thick silicon crystals which exhibit characteristic angular structure for deflection angles up to and beyond the axial critical angle, ψ _a . Such large angular deflections are produced by ions incident on atomic strings with small impact parameters, resulting in trajectories which pass through several radial rings of atomic strings before exiting the thin crystal. Each ring may focus, steer or scatter the channeled ions in the transverse direction and the resulting characteristic angular structure beyond 0.6ψ _a at different depths can be related to peaks and troughs in the nuclear encounter probability. Such “radial focusing” underlies other axial channeling phenomena in thin crystals including planar channeling of small impact parameter trajectories, peaks around the azimuthal distribution at small tilts and large shoulders in the nuclear encounter probability at tilts beyond ψ _a .     

A probabilistic approach to second order variational inequalities with bilateral constraints

We study a class of second order variational inequalities with bilateral constraints. Under certain conditions we show the existence of aunique viscosity solution of these variational inequalities and give a stochastic representation to this solution. As an application, we study a stochastic game with stopping times and show the existence of a saddle point equilibrium.     

Cobalt Ferrite from Citrate Precursor by Self-Propagating Combustion Reaction

A Mangelsdorf's approach to modeling the epoxy-amine cure kinetics has been developed. Analysis of the data by means of Mangelsdorf's approach makes it possible not only to determine the reaction rate constant and the heat of epoxy ring opening, but also to elucidate the reaction mechanism. However, to model the kinetic curves obtained by the calorimetric method for the complicated reaction should be derived an equation expressing the rate of change of the heat with time, as a function of the reaction rate and the extent of conversion. In a detailed examination the thermokinetic data, we found that glassy state transition is kinetically feasible. Using data available in literature, the kinetic model for epoxy-amine cure reaction was developed. Our treatment of glass formation is based on the picture of the reaction system as a miscible mixture of two structurally different liquids. This approach is similar to that presented by Bendler and Shlesinger as a Two-Fluid model. In the application of this model to reaction kinetics, we believe the explanation of glass structure formation lies in the splitting of the homogeneous mixture into two liquid phases. This revised version was published online in August 2006 with corrections to the Cover Date.     

Stress Degradation Behavior of Desipramine Hydrochloride and Development of Suitable Stability-Indicating LC Method

A simple reverse phase liquid chromatographic method was developed for the quantitative determination of desipramine hydrochloride and its related impurities in bulk drugs which is also stability-indicating. During the forced degradation at hydrolysis, oxidative, photolytic and thermal stressed conditions, the degradation results were only observed in the oxidative stress condition. The blend of the degradation product and potential impurities were used to optimize the method by an YMC Pack Pro C₁₈ stationary phase. The LC method employs a linear gradient elution with the water–acetonitrile–trifluoroacetic acid as mobile phase. The flow rate was 1.0 mL min⁻¹ and the detection wavelength 215 nm. The stressed samples were quantified against a qualified reference standard and the mass balance was found close to 99.0% (w/w) when the response of the degradant was considered to be equal to the analyte (i.e. desipramine). The developed RP-LC method was validated in agreement with ICH requirements.

     

Room Temperature Bulk Synthesis of Silver Nanocables Wrapped with Polypyrrole

Wet chemical synthesis of silver cables wrapped with polypyrrole is reported in aqueous media without use of any surfactant/capping agent and/or template. The method employs direct polymerization of pyrrole in an aqueous solution with AgNO₃ as an oxidizing agent. The four probe conductivity results for the as‐synthesized silver nanocables of polypyrrole films were found to be 3, 5, 5, and 9 S · cm⁻¹ for a 1: 2, 1: 1, 1: 0.5, and 1: 0.1 silver‐to‐pyrrole ratio, respectively. This approach can be extended to other monomers such as aniline and N‐methylaniline (NMA) to prepare different morphologies of silver nanostructures. Aniline monomer polymerization occurred at room temperature to produce a coating of a silver mirror on the side walls of the glass vial, as in the case of Tollen's process of making silver mirrors. The silver mirror coating strategy was extended to a poly(ethylene terephthalate) (PET) surface and the resistivity of the polyaniline‐coated Ag nanocomposites were measured and found to be semiconducting.