Asymmetric oxidation of sulfides catalyzed by (R)-6,6'-dibromo-BINOL derived titanium complex

Abstract

An efficient asymmetric oxidation of sulfides was achieved using (R)-6,6'-dibromo-BINOL as chiral ligand in combination with Ti(OⁱPr)₄ using 70% aqueous tertiary butyl hydroperoxide as oxidant. The resulting sulfoxides had high enantiopurities and good yields. A range of aryl alkyl and aryl benzyl sulfides were oxidized to the corresponding sulfoxides with 78–95% ee in 72–80% yields.     

High-Performance Thin-Layer Chromatographic Analysis of Bicalutamide in Bulk Drug and Liposomes

JPC – Journal of Planar Chromatography – Modern TLC - A sensitive, accurate, precise, and specific high-performance thinlayer chromatographic (HPTLC) method for analysis of bicalutamide...     

Coherent crosstalk in passive microring based Optical Networks-on-Chip

Optical Networks-on-Chip (ONoC) is emerging technology for future optical interconnects used in all optical networks. The electrical interconnects face lot of problems due to their inability to support higher data rates used in the System-on-Chip (SoC) technologies. Integrated optical interconnects based on SoC avoid this bottleneck with their support to higher data rates. In this paper for the first time we have studied and analyzed ONoC at physical level for the system performance based on crosstalk, BER, throughput, system frequency, and other related parameters. The investigation of ONoC performance is carried out for the multistage microring optical crossconnect on SoC for coherent WDM signals. The analysis can be used in the design of ultra-high speed photonic routers for reliable data communication and processing. The results show the dependency of a coherent crosstalk on the system frequency of SoC and also illustrate the reduction in throughput with increase in number of WDM signals due to higher probability of packet transmission. Minimum 2 dB signal to noise ratio can be obtained when crosstalk is ?25 dB with 60 wavelengths for probability of packet transmission is 0.5.     

Drug repurposing approach for the identification and designing of potential E6 inhibitors against cervical cancer: an in silico investigation

Structural Chemistry - Repurposing of ‘old’ drugs to treat both common and rare diseases has garnered huge attention of the researchers because of the high attrition rates and...     

Assay of tolnaftate and related impurities by isocratic supercritical fluid chromatography

Tolnaftate, an antifungal drug (TF) and related impurities arising from synthesis, viz., N-methyl-m-toluidine (NMmT) and β-naphthol-1-chlorothio carbamate (β-NCTC) can be determined by supercritical fluid chromatography. Even though it was possible to elute TF completely with neat SCF CO₂, the peaks of the impurities were found to merge. The chromatographic figures of merit of the three analytes such as retention time (t_R), capacity factor (k^|), selectivity factor (α), no. of theoretical plates (N), were optimized. The three compounds can be resolved in 5 min on a Hypersil (250 × 4.0 mm) 5 μ, C₁₈ column with supercritical carbon dioxide, modified with 1.96% methanol as the mobile phase at 9.81 MPa and at 40?°C. Detection was carried out at 220 nm. The data as evaluated by the linear regression least squares fit method gave linearity ranges from 0.2 to 10.0 μg/mL for TF and NMmT and 0.3 to 10.0 μg/mL for β-NCTC with correlation coefficients > 0.99. The method was successfully employed to estimate levels of 0.01% for NMmT and 0.02% for β-NCTC with respect to TF.     

Stereoselectivity ratios in a simple Diels-Alder reaction in aqueous salt solutions of alcohols

This is the first exhaustive report on the variation of stereoselectivity ratios for a simple Diels-Alder reaction between cyclopentadiene and methyl acrylate. The reaction was carried out in aqueous mixtures of methanol, ethanol, propan-1-ol and butan-1-ol in presence of LiClO₄, LiCl, NaCl, KCl, CaCl₂ and MgCl₂. The endo stereoisomer decreases with the increase in carbon chain length of the alcohol. However, LiClO₄, a salting-in agent in water becomes salting-out in aqueous mixtures of alcohols. The solvent properties, thus can be attuned by adjusting the amount of solvents and salts.     

Direct determination of uranium in seawater by laser fluorimetry

A method for estimation of uranium in seawater by using steady state laser flourimetry is described. Uranium present in seawater, in concentration of approximately 3 ng ml⁻¹ was estimated without prior separation of matrix. Quenching effect of major ions (Cl⁻, Na⁺, SO₄⁻, Mg⁺, Ca⁺, K⁺, HCO₃⁻, Br⁻) present in seawater on fluorescence intensity of uranium was studied. The concentration of phosphoric acid required for maximum enhancement of fluorescence intensity was optimized and was found to be 5%. Similarly the volume of concentrated nitric acid required to eliminate the quenching effect of chloride and bromide completely from 5 ml of seawater were optimized and was found to be 3 ml. A simple equation was derived using steady state fluorescence correction method and was used for calculation of uranium concentration in seawater samples. The method has a precesion of 1% (1 s, n = 3). The values obtained from laser fluorimetry were validated by analyzing the same samples by linear sweep adsorptive stripping voltametry (LSASV) of the uranium-chloranilic acid (2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone) complex. Both the values are well in agreement.     

Synthesis and evaluation of urea and thiourea derivatives of oxazolidinones as antibacterial agents

Urea and thiourea derivatives of oxazolidinones were synthesized and their inhibitory activity (MIC) was determined on the bacterial strains which includes clinical isolates and quality control organisms. The structure activity relationships were studied and a 3D-QSAR model was built using Genetic Function Approximation. Interestingly found that electron withdrawing groups at the ortho position of the phenyl ring enhances the activity.