meta-Nitration of Arenes Bearing ortho/para Directing Group(s) Using C−H Borylation

Herein, we report the meta-nitration of arenes bearing ortho/para directing group(s) using the iridium-catalyzed C−H borylation reaction followed by a newly developed copper(II)-catalyzed transformation of the crude aryl pinacol boronate esters into the corresponding nitroarenes in a one-pot fashion. This protocol allows the synthesis of meta-nitrated arenes that are tedious to prepare or require multistep synthesis using the existing methods. The reaction tolerates a wide array of ortho/para-directing groups, such as −F, −Cl, −Br, −CH₃, −Et, −iPr −OCH₃, and −OCF₃. It also provides regioselective access to the nitro derivatives of π-electron-deficient heterocycles, such as pyridine and quinoline derivatives. The application of this method is demonstrated in the late-stage modification of complex molecules and also in the gram-scale preparation of an intermediate en route to the FDA-approved drug Nilotinib. Finally, we have shown that the nitro product obtained by this strategy can also be directly converted to the aniline or hindered amine through Baran's amination protocol.     

Can a ‘magnesium sulfate admixtured l-threonine’ crystal be grown by slow evaporation solution growth method?

Slow evaporation of an aqueous solution containing l-threonine and magnesium sulphate heptahydrate, results in the fractional crystallization of the less soluble l-threonine crystal and not any novel optoelectronic ‘magnesium sulfate admixtured l-threonine’ crystal as reported by Puhal Raj et al. in Optik, 124 (2013) 6887–6891.     

Asymmetric Synthesis Using Sulfinimines (N-Sulfinyl Imines)

Abstract

Sulfinimine-derived polyfunctionalized chiral building blocks, often prepared in one pot, provide efficient access, with a minimum of chemical manipulation, to enantiopure, multifunctional amine derivatives including piperidines and pyrrolidines.     

GPU‐accelerated direct numerical simulations of decaying compressible turbulence employing a GKM‐based solver

Gas Kinetic Method‐based flow solvers have become popular in recent years owing to their robustness in simulating high Mach number compressible flows. We evaluate the performance of the newly developed analytical gas kinetic method (AGKM) by Xuan et al. in performing direct numerical simulation of canonical compressible turbulent flow on graphical processing unit (GPU)s. We find that for a range of turbulent Mach numbers, AGKM results shows excellent agreement with high order accurate results obtained with traditional Navier–Stokes solvers in terms of key turbulence statistics. Further, AGKM is found to be more efficient as compared with the traditional gas kinetic method for GPU implementation. We present a brief overview of the optimizations performed on NVIDIA K20 GPU and show that GPU optimizations boost the speedup up‐to 40x as compared with single core CPU computations. Hence, AGKM can be used as an efficient method for performing fast and accurate direct numerical simulations of compressible turbulent flows on simple GPU‐based workstations. Copyright © 2016 John Wiley & Sons, Ltd.     

Binary collision simulations of ion transmission through silicon single crystal films

Abstract

Computer simulation studies of the energy distribution of transmitted ions such as alpha-particles, He-, and B-ions through crystalline silicon, using the enhanced binary-collision cascade simulator MARLOWE, will be reviewed. The enhancement includes an additional electronic-energy loss (EEL) model which takes into account explicitly both the target electron density variation via the structure factors and the electron density of the projectile. Investigations of the stopping power for He ions and protons in silicon, at intermediate- and high-energies, based on the adapted EEL model and a velocity-dependent effective charge will be presented. The overall agreement between the calculated and experimentally determined stopping power data and the simulated and measured transmission spectra will be demonstrated. Effects of energy-loss straggling, core-electron contribution to the energy loss at high-energies and charge-state effects at low energies on the transmission spectra will also be discussed.     

Fabrication of anti-poisoning core-shell TiO2 photocatalytic system through a 4-methoxycalix[7]arene film

TiO₂ nanoparticles with unique crystalline-core/disordered-shell structures were synthesized in a one step process by employing 4-methoxycalix[7]arene nanoreactors. The nanoparticles were anchored on the surface of quartz beads as a monolayer and showed high visible-light driven photocatalytic activity, excellent long term durability and anti-poisoning property. Photocatalytic performance of the TiO₂ nanoparticles was tested in a packed bed and complete decolorization of methyl orange was achieved under ultraviolet light or visible light. The decolorization process followed first-order kinetics and showed different behaviors for ultraviolet and visible radiation, while the overall rates of degradation were the same.     

Spectral and electrochemical investigation of p-sulfonatocalix[4]arene-stabilized vitamin E aggregation

The host–guest interaction of α-tocopherol (vitamin E) with p-sulfonatocalix[4]arene (p-SC4) in solution state is studied using emission and cyclic voltammetric techniques. The lipid soluble α-tocopherol (α-T) forms a solid complex with p-SC4. FTIR and NMR spectral analysis of the solid complex reveals the tight packing of α-T inside the cavity of p-SC4. The structural deformation is confirmed by XRD analysis. SEM images differentiate the highly porous gel like structure of vitamin E aggregate and the solid structure of the host–guest complex prepared. NOESY spectra confirm the tight penetration of α-T within the hydrophobic cavity of p-SC4.