Montmorillonite KSF,a Mild and Efficient Catalyst for Benzodithiepination of Carbonyl Compounds

A mild and efficient procedure for the protection of carbonyl compounds as 1,5-dihydro-3H-2,4-benzodithiepines in high yields is described by using a readily available and inexpensive KSF clay catalyst.     

Sulfonated Charcoal,a Mild and Efficient Reagent for the Tetrahydropyranylation of Alcohols and Phenols

Sulfonated charcoal has been demonstradted to be very effective and mild catalyst for the tetrahydropyranylation of alcohols and phenols.     

Synthesis of melicodenines C,D and E

A synthesis of the unusual cyclobutane-quinolinone alkaloids melicodenines C, D and E by intermolecular [2+2] cycloaddition is described.     

S-Substituted-2-mercaptobenzthiazolium-based chiral ionic liquids: efficient organocatalysts for enantioselective sodium borohydride reductions of prochiral ketones

Novel chiral ionic liquids having chirality in their cationic part have been synthesized for evaluation of their catalytic potential as organocatalysts in sodium borohydride reduction of prochiral ketones to yield optically active secondary alcohols. The chiral ionic liquids have been synthesized from the reaction of (?)-menthol or (?)-borneol, chloroacetic acid and S-methyl/benzyl-2-mercaptobenzthiazole. The synthesized chiral ionic liquids have been characterized by ¹H, ¹³C NMR and Mass spectrometry. Moderate to excellent enantiomeric excess (ee > 99%) has been obtained in asymmetric sodium borohydride reduction of prochiral ketones using these salts as chiral catalysts.     

Volumetric and Acoustic Studies of Binary Liquid Mixtures of Dipropylene Glycol Dimethyl Ether with Methyl Acetate, Ethyl Acetate and n-Butyl Acetate in the Temperature Range T = (288.15, 293.15, 298.15, 303.15, and 308.15) K

Densities and ultrasonic speeds have been measured over the whole composition range for binary liquid mixtures of dipropylene glycol dimethyl ether, CH₃(OC₃H₆)₂OCH₃, with methyl acetate, ethyl acetate, and n-butyl acetate using an Anton Paar DSA 5000 M density and speed sound analyzer at T = (288.15, 293.15, 298.15, 303.15, and 308.15) K and atmospheric pressure in order to evaluate the behavior of these binaries. From these data excess the molar volume, $ V_{m}^{\text{E}} $ , and deviation in isentropic compressibility, ?κ _S , have been calculated. These excess properties have been fitted with the Redlich–Kister type polynomial equation to get their coefficients and standard deviations which provide a base for discussing the forces operating in solutions.     

Computer modelling of the director configuration in a supertwist nematic liquid crystal cell

Abstract

The director distribution in a supertwist nematic cell, containing La-Roche liquid crystal mixture 3010, has been studied extensively using Berreman's computer simulation approach. It is seen that the director distribution in the cell depends critically on the total twist angle θ_t, the surface tilt angle θ_o and the ratio of the cell thickness to the pitch d/p. The values of θ_o and φ_t have been optimized to yield a small bistability (ΔV = 0.06 V) and a relatively large change in the midplane tilt angle (Δθ_m = 51°) in an unstrained cell with ?_t = (d/p) × 360°. The optimum values of θ_o and Ø_t were found to be 15° and 240°, respectively. The effect of varying d/p on the director distribution has also been studied in great detail in supertwist cells with θ_o = 30° and Ø_t = 270°. Some interesting features in understrained and overstrained cells have been observed.     

Molecular structural investigations of quinoxaline derivatives through 3D-QSAR,molecular docking,ADME prediction and pharmacophore modeling studies for the search of novel antimalarial agent

In the present article, a dataset of 63 quinoxaline derivatives were taken for antimalarial activity and pharmacophore were developed. Atom based method was used to develop a three dimensional quantitative structure activity relationship (3D-QSAR) model. On comparison of all statistical parameters, model AHRRR23 was found to be the most effective and predictive QSAR model as it satisfied all statistical parameters of a good model. The model AHRRR23 showed an adequate R² value for the training set 0.9446, good predictive power with Q² of 0.6409, good F- value, low SD 0.1218 value and outstanding Pearson-R values and low RMSE 0.2779 values of the model. The docking studies also gives very good results with good RMSD values. 3D QSAR, docking and ADME studies exhibits that the developed model could be employed as a potential lead for further study as antimalarial drug.     

In Vitro Propagation,Encapsulation, and Genetic Fidelity Analysis of Terminalia arjuna: a Cardioprotective Medicinal Tree

The present study described an improved and reproducible in vitro regeneration system for Terminalia arjuna using nodal segment explants obtained from a mature plant. Shoot tips excised from in vitro proliferated shoots were encapsulated in 3 % sodium alginate and 100 mM CaCl₂?2H₂O for the development of synthetic seeds which may be applicable in short-term storage and germplasm exchange of elite genotype. Shoot multiplication was significantly influenced by a number of factors, namely types and concentrations of plant growth regulators, medium composition, repeated transfer of mother explants, subculturing of in vitro regenerated shoot clumps, agar concentrations, and temperature. Maximum numbers of shoots (16.50?±?3.67) were observed on modified Murashige and Skoog (MMS) medium containing 0.5 mg l^?1 of benzylaminopurine (BAP) and 0.1 mg l^?1 of naphthalene acetic acid (NAA). To shortening the regeneration pathway, rooting of micropropagated shoots under in vitro condition was excluded and an experiment on ex vitro rooting was conducted and it was observed that the highest percentage of shoots rooted ex vitro when treated with indole-3-butyric acid (IBA, 250 mg l^?1)?+?2-naphthoxy acetic acid (NOA, 250 mg l^?1) for 5 min. The well-developed ex vitro rooted shoots were acclimatized successfully in soilrite under greenhouse conditions with 80 % survival of plants. Randomly amplified polymorphic DNA (RAPD) analysis confirmed that all the regenerated plants were genetically identical to the mother plant, suggesting the absence of detectable genetic variation in the regenerated plantlets. To the best of our knowledge, this is the first report on synthetic seed production as well as ex vitro rooting and genetic fidelity assessment of micropropagated shoots of T. arjuna.     

A Predictive Model Towards Site‐Selective Metalations of Functionalized Heterocycles,Arenes, Olefins,and Alkanes using TMPZnCl⋅LiCl

The development of a predictive model towards site‐selective deprotometalation reactions using TMPZnCl?LiCl is reported (TMP=2,2,6,6‐tetramethylpiperidinyl). The pK_a values of functionalized N‐, S‐, and O‐heterocycles, arenes, alkenes, or alkanes were calculated and compared to the experimental deprotonation sites. Large overlap (>80 %) between the calculated and empirical deprotonation sites was observed, showing that thermodynamic factors strongly govern the metalation regioselectivity. In the case of olefins, calculated frozen state energies of the deprotonated substrates allowed a more accurate prediction. Additionally, various new N‐heterocycles were analyzed and the metalation regioselectivities rationalized using the predictive model.