Acetic anhydride-promoted one-pot condensation of 2,4-thiazolidinedione with bisulfite adducts of aldehydes

We describe a simple and efficient one-pot method for condensing bisulfite adducts of aromatic aldehydes directly with 2,4-thiazolidinedione catalyzed by acetic anhydride. The two main highlights of this study are the one-pot condensation of bisulfite adducts with 2,4-thiazolidinedione in non-aqueous media and the use of Design of Experiment to understand and optimize the reaction conditions. This methodology was then generalized using other active methylene compounds, such as malononitrile.     

Single channel tunable wavelength demultiplexer using nonlinear one dimensional defect mode photonic crystal

Transmission characteristics of nonlinear one dimensional photonic crystal with a defect have been studied. GaAs/Si multilayer structure with a single defect has been simulated using transfer matrix method. In this study refractive indices of both layers have been taken to be dependent on intensity and wavelength simultaneously. It is found that central wavelength of defect mode change with intensity of wave. Average change in central wavelength of defect mode is 0.02 nm/(1 GW/cm²). This property can be exploited in the design of a single channel tunable wavelength division demultiplexer for optical communication.     

How should process capabilities be combined to leverage supplier relationships competitively?

Two process capabilities have been identified in the operations management literature to leverage supplier relationships for competitive performance: the ability to continuously improve processes with suppliers (process alignment) and the ability to make changes to these relationships (partnering flexibility). While firms may need both capabilities to be successful, it is unclear what strategy should be used to combine these two seemingly contradictory process capabilities. Using data collected from 318 manufacturing firms on a focal firm’s process capabilities to manage supplier relationships, we examine the performance impacts of two dimensions of a particular strategy: balancing (focusing on achieving a close match between the two process capabilities) and complementing (focusing on creating synergy between the two process capabilities). Our results indicate that the balancing dimension has a much stronger effect on a firm’s competitive performance than the complementing dimension. Also, when a firm pursues a high balance and strong complements strategy (combining high levels of both process capabilities), it is able to reduce its competitive performance risks more than when it pursues a high balance and weak complements strategy (combining low levels of both capabilities) or when it implements unbalanced strategies that emphasize either process alignment or partnering flexibility (combining low levels of one capability with high levels of the other). We conclude by discussing the theoretical contributions and practical guidelines.     

Mild and Efficient Nitration of Aromatic Compounds Mediated by Transition-Metal Complexes

Aromatic compounds were efficiently nitrated under facile reaction conditions by employing 69% nitric acid catalyzed by transition-metal complexes such as [Co(NH₃)₅Cl]Cl₂, [Cu(NH₃)₄]SO₄, Mn(acac)₃, [Ni(NH₃)₆]Cl₂, [Ni(en)₃]S₂O₃, and Hg[Co(SCN)₄]. The reaction was completed smoothly at room temperature and afforded corresponding mono-nitro derivatives in quantitative yield. This new method offers efficient and facile regioselective mononitration of aromatic compounds.

Highly Anti-Selective One-Pot Multicomponent Synthesis of Mannich-Type N-Acylated β-Amino Acid Derivatives by Copper or Sodium Salt Catalysis

A stereo-defined process has been developed for the synthesis of Mannich-type products using readily available copper sulfate or sodium chloride as catalyst. Good to excellent diastereoselectivity has been achieved for a broad array of substrates. The observed diastereoselectivity is explained on the basis of the steric interaction between the acyloxy group of the aldehyde carbon and the more hindered α-substituted enolate anion. This steric interaction helps the addition to take place through the less-hindered face to produce the anti-isomers predominantly.

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

Application of Lipopeptide Biosurfactant Isolated from a Halophile: Bacillus tequilensis CH for Inhibition of Biofilm

Biosurfactants are amphiphilic molecules having hydrophobic and hydrophilic moieties produced by various microorganisms. These molecules trigger the reduction of surface tension or interfacial tension in liquids. A biosurfactant-producing halophile was isolated from Lake Chilika, a brackish water lake of Odisha, India (19°41′39″N, 85°18′24″E). The halophile was identified as Bacillus tequilensis CH by biochemical tests and 16S rRNA gene sequencing and assigned accession no. KC851857 by GenBank. The biosurfactant produced by B. tequilensis CH was partially characterized as a lipopeptide using thin-layer chromatography, Fourier transform infrared spectroscopy, and nuclear magnetic resonance techniques. The minimum effective concentration of a biosurfactant for inhibition of pathogenic biofilm (Escherichia coli and Streptococcus mutans) on hydrophilic and hydrophobic surfaces was found to be 50 μg ml^?1. This finding has potential for a variety of applications.