Efficient, selective deprotection of aromatic acetates catalyzed by Amberlyst-15 or iodine

Aromatic acetates were selectively deprotected in the presence of aliphatic acetates to the corresponding phenols in excellent yields using Amberlyst-15 or iodine as catalysts in methanol at room temperature. The first catalyst can be recovered.     

Microwave‐assisted synthesis of new isoxazolyl triazinethiones and isoxazolyl oxadiazinethiones in dry media

Trimolecular condensation of N‐(3‐meihyl‐5‐styryl‐isoxazol‐4‐yl)‐N'‐aryl thioureas ( 2 ), paraformaldehyde and primary amines using montmorillonite K‐10 in dry media under microwave irradiation leads to isoxazolyl triazinethiones ( 3 ) in high yield. Condensation of 2 with paraformaldehyde alone under similar conditions provide isoxazolyl oxadiazinethiones ( 4 ) in excellent yield.     

New lathyrane and podocarpane diterpenoids from Jatropha curcas

Chemical investigation on Jatropha curcas resulted in the isolation of twenty constituents among which four diterpenoids were unknown and six compounds, tetradecyl-(E)-ferulate, 3-O-(Z)-coumaroyl oleanolic acid, heudelotinone, epi-isojatrogrossidione, 2alpha-hydroxy-epi-isojatrogrossidione, and 2-methyanthraquinone had not been reported earlier from this species. The structures of the new compounds were established by extensive studies of their 1D- and 2D-NMR spectra.     

Copper(II) tetrafluoroborate-catalyzed ring-opening of epoxides by amines

Copper(II) tetrafluoroborate catalyzes efficiently the selective opening of epoxides by amines leading to the synthesis of β-amino alcohols. The reaction works well with aromatic and aliphatic amines in high yields under solvent-free conditions.     

Characterization and Diagnosis of Cancer by Native Fluorescence Spectroscopy of Human Urine

Urine is one of the diagnostically important bio fluids, as it has different metabolites in it, where many of them are native fluorophores. Native fluorescence characteristics of human urine samples were studied using excitation–emission matrices (EEMs) over a range of excitation and emission wavelengths, and emission spectra at 405 nm excitation, to discriminate patients with cancer from the normal subjects. The fluorescence spectra of urine samples of cancer patients exhibit considerable spectral differences in both EEMs and emission spectra with respect to normal subjects. Different ratios were calculated using the fluorescence intensity values of the emission spectra and they were used as input variables for a multiple linear discriminant analysis across different groups. The discriminant analysis classifies 94.7% of the original grouped cases and 94.1% of the cross‐validated grouped cases correctly. Based on the fluorescence emission characteristics of urine and statistical analysis, it may be concluded that the fluorophores nicotinamide adenine dinucleotide (NADH) and flavins may be considered as metabolomic markers of cancer.     

Synthesis,electrochemical and e.p.r. spectral studies of binuclear copper(II) complexes with new pentadentate L-proline-based binucleating ligands

The synthesis, reduction, optical and e.p.r. spectral properties of a series of new binuclear copper(II) complexes, containing bridging moieties (OH^–, MeCO₂ ^–, NO₂ ^–, and N₃ ^–), with new proline-based binuclear pentadentate Mannich base ligands is described. The ligands are: 2,6-bis[(prolin-1-yl)methyl]4-bromophenol [H₃L¹], 2,6-bis[(prolin-1-yl)methyl]4-t-butylphenol [H₃L²] and 2,6-bis[(prolin-1-yl)methyl]4-methoxyphenol [H₃L³]. The exogenous bridging complexes thus prepared were hydroxo: [Cu₂L¹(OH)(H₂O)₂] · H₂O (1a), [Cu₂L²(OH)(H₂O)₂] · H₂O (1b), [Cu₂L³(OH)(H₂O)₂] · H₂O (1c), acetato [Cu₂L¹(OAc)] · H₂O (2a), [Cu₂L²(OAc)] · H₂O (2b), [Cu₂L³(OAc)] · H₂O (2c), nitrito [Cu₂L¹(NO₂)(H₂O)₂] · H₂O (3a), [Cu₂L²(NO₂)(H₂O)₂] · H₂O (3b), [Cu₂L³(NO₂)(H₂O)₂] · H₂O (3c) and azido [Cu₂L¹(N₃)(H₂O)₂] · H₂O (4a), [Cu₂L²(N₃)(H₂O)₂] · H₂O (4b) and [Cu₂L³(N₃)(H₂O)₂] · H₂O (4c). The complexes were characterized by elemental analysis and by spectroscopy. They exhibit resolved copper hyperfine e.p.r. spectra at room temperature, indicating the presence of weak antiferromagnetic coupling between the copper atoms. The strength of the antiferromagnetic coupling lies in the order: NO₂ N₃ OH OAc. Cyclic voltammetry revealed the presence of two redox couples Cu^IICu^II Cu^IICu^I Cu^ICu^I. The conproportionality constant K _con for the mixed valent Cu^IICu^I species for all the complexes have been determined electrochemically.     

A short approach to the synthesis of the ritonavir and lopinavir core and its C-3 epimer via cross metathesis

A short synthesis of hydroxyethylene dipeptide isostere, a core unit of the HIV-protease inhibitors ritonavir and lopinavir, its C-3 epimer and C₂ symmetric diamino diol is described. The crucial aspects of the synthesis are self-cross metathesis and exploitation of C₂-symmetric of the metathesis product 8 to obtain the required skeleton.     

Electrochemical impedance spectroscopic studies on aging-dependent electrochemical degradation of p-toluene sulfonic acid-doped polypyrrole thin film

The conducting polymer polypyrrole thin film was galvanostatically polymerized on stainless steel substrate for the supercapacitor electrode. The electrochemical stability of the electrode was monitored each 30 days of aging up to 90 days. The FTIR analysis showed an increase in intensity of the absorption peaks, especially high growth of the carbonyl peaks after 90 days of aging. The electrochemical capacitance degradation of the electrode was studied using cyclic voltammetric and galvanostatic charge/discharge analysis in 1 M Na₂SO₄ electrolyte, which showed ~?53% of fading in the initial specific capacitance value after 90 days. Further, the electrochemical degradation of polypyrrole electrodes was analyzed in detail using electrochemical impedance spectroscopy. The analysis showed a large increase in the internal resistance and low-power deliverability of the electrode with respect to aging as the main reasons for the degradation of specific capacitance of the polypyrrole electrode.     

Interlaboratory calibration of track-etch detectors for the measurement of radon and radon daughter levels

This paper reports the results of the second interlaboratory calibration experiments, which were carried out in two parts. In the first, five types of commercially available and economically cheap membranes were tested as the barrier against thoron for “radon-only” measurements. It was found that all the membranes tested are good barriers against thoron and can be used in the “radon-only” device. In the second, actual calibration experiments were performed with LR-115 type-II and CR-39 track-etch detectors for different radon measuring configurations in a radon exposure chamber.