Baseline studies of radon/thoron concentration levels in and around the Lambapur and Peddagattu areas in Nalgonda district, Andhra Pradesh, India

Studies conducted by Atomic Minerals Directorate of Exploration and Research (AMD) of Hyderabad, India had established the presence of higher concentrations of uranium in Lambapur and Peddagattu areas of Nalgonda district, AP, India and it was estimated that it could be a viable source for commercial extraction. The envisaged extraction process involves dispersion of radioactive particulate matter into atmosphere. Environmental radioactive studies in and around proposed mining areas at this point of time will be extremely useful for establishing base line data before a large scale uranium extraction process comes into existence. To this end, Solid State Nuclear Track Detectors were installed to evaluate indoor radon and thoron concentration levels in the dwellings of the area. The geometric means of radon and thoron concentration levels were found to be (7.1±0.2)×10¹ and (6.7±0.3)×10¹ Bq/m³, respectively. Simultaneously, natural background radiation measurements were also made and these levels are found to vary from 770 to 3995 μGy/y in the spatial distribution.     

Application of Polyphosphoric Acid‐Mediated Acyl Migration for Regiospecific Synthesis of Diverse 2‐Acylpyrroles from Chalcones

A metal‐free approach for the synthesis of 2‐acylpyrroles is reported in this paper. Synthesis of the target molecule started from chalcones and was carried out in two steps. Initial step involved the conversion of chalcones to corresponding 4‐substituted‐3‐acylpyrroles by reaction with TosMIC. In the subsequent step, target molecules were obtained in modest to good yields by polyphosphoric acid‐mediated acyl rearrangement of 3‐acylpyrroles to their 2‐acyl congeners. The crucial final step was amenable to diverse substitutions on pyrrole ring. Preliminary experiment for the determination of mechanism indicated the involvement of acylium ion.     

Synthetic Studies Towards Taxol Analogs: Chemoselective Cleavage of C-5 Cinnamoyl Group in Taxane Group of Diterpenoids with Hydroxylamine

Taxane group of diterpenoids 2 and 3 which possess cinnamoyl moiety at C-5 position underwent selective cleavage to C-5 hydroxy compounds 4 and 5 on treatment with hydroxylamine. The resulting compounds were characterised based on their spectral data.     

Synthesis of (R)‐Japonilure and (4R,9Z)‐9‐Octadecen‐4‐olide,Pheromones of the Japanese Beetle and Currant Stem Girdler

Asymmetric total synthesis of the sex pheromones of Japanese beetle and currant stem girdler, (R)‐japonilure (1) and (4R,9Z)‐9‐octadecen‐4‐olide (2), has been achieved.     

A Convenient Synthesis of (Z)-7-Nonadecen-Ll-One and (Z)-7-Eicosen-Ll-Cne -the Pheromones of Peach Fruit Moth

In 1977 Tamaki¹ et al have isolated and synthesized² (Z)-7-nonadecen-ll-one (la) and (Z)-7-eicosen-l1-one (1b) which are active components of the female sex pheromones of the peach fruit moth Carposina niponensis Walsingham, a major economic pest of apple, peach and other fruits of Japan. We report in this communication a practical, convenient and stereospecific route to 1a and 1b.     

Towards the total synthesis of etnangien: synthesis of C32–C42 fragment by using a desymmetrization strategy

The construction of the C32–C42 fragment of etnangien is described using a desymmetrization strategy generating five stereogenic centers from a bicyclic lactone. Another notable feature includes the use of the Sharpless asymmetric epoxidation to generate a stereogenic center at C40.     

Synthesis of diarylheptanoids, (5S)-5-acetoxy-1,7-bis(4-hydroxy-3-methoxyphenyl)-3-heptanone and (3S,5S)-3,5-diacetoxy-1,7-bis(4-hydroxy-3-methoxyphenyl)heptane

The total syntheses of the first examples of diarylheptanoid natural products (5S)-5-acetoxy-1,7-bis(4-hydroxy-3-methoxyphenyl)-3-heptanone 1, and (3S,5S)-3,5-diacetoxy-1,7-bis(4-hydroxy-3-methoxyphenyl)heptane 2 isolated from the rhizomes of Zingiber officinale were accomplished using Sharpless epoxidation and cross-metathesis reactions as the key steps.     

Synthesis of the Janus integer pheromone (4R,9Z)-9-octadecen-4-olide

The synthesis of (4R,9Z)-9-octadecen-4-olide 1, the female sex pheromone of Janus integer is reported using a Zipper isomerization reaction as the key step.     

On the coexistence of spin and lattice polarons in the La0.67−xEuxCa0.33MnO3 CMR system

The electrical and magnetic transport properties of the La_0.67−xEu_xCa_0.33MnO₃ system exhibit lowering of insulator to metal and paramagnetic to ferromagnetic transition temperature (T_C) with the increase of Eu concentration in addition to possessing CMR property. The temperature variation of electrical resistivity and magnetic susceptibility for x=0.21 is found to have two distinct regions in the paramagnetic state for T>T_P; one with the localization of lattice polaron in the high-temperature region (T>1.5T_P) satisfying the dynamics of variable range hopping (VRH) model and the other being the combination of the spin and lattice polarons in the region T_P<T<1.5T_P. The resistivity variation with temperature and magnetic field, the cusp in the resistivity peak and CMR phenomenon are interpreted in terms of coexistence of spin and lattice small polarons in the intermediate region (T_P<T<1.5T_P). The spin polaron energy in the La_0.46Eu_0.21Ca_0.33MnO₃ system is estimated to be 106.73±0.90 meV and this energy decreases with the increase of external magnetic field. The MR ratio is maximal with a value of 99.99% around the transition temperature and this maximum persists till T→0 K, at the field of 8 T.     

Enantiomeric Separation of Moxifloxacin and Its (R,R)-Isomer by Ligand-Exchange Chiral Chromatography

A new stereospecific LC method for the separation and quantification of moxifloxacin and its (R,R)-enantiomer in bulk drug was developed and validated by ligand-exchange liquid chromatography on a reversed phase column using aqueous mobile phase containing the chiral reagent l-isoleucine-Cu(II). The UV detector was operated at 293 nm. The flow rate of mobile phase was set at 0.9 mL min^?1. The achiral ODS column offers good separation of the two enantiomers in less than 20 min. The test concentration was 1,000 μg mL^?1 in the mobile phase. This method was capable of detecting the (R,R)-enantiomer of moxifloxacin up to 0.1 μg mL^?1 for a 20 μL injection volume. The drug was subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal degradation. There was no interference of degradants with the (R,R)-enantiomer in the developed method. The developed chiral RP-LC method was validated with respect to linearity, accuracy, precision and robustness. The percentage recovery for the (R,R)-enantiomer in bulk drug samples ranged from 98.1 to 104.4%. The test solution was found to be stable in the mobile phase for 48 h after preparation.