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A set of four different (Cp x -NHC)Mo(CO) 2 I (Cp x =Cp, Cp*, and Cp Bz , NHC=N-heterocyclic carbenes) complexes has been prepared from the one-pot reaction of [MoCl(η 3 -C 3 H 5 )(CO) 2 -(NCMe) 2 ] and the corresponding lithium NHC-cyclopentadienides. The modification of the Cp x -NHC affords a smooth way to tune the stereoelectronic properties of these new molybdenum complexes. These compounds are air stable both in solution and in the solid state. Preliminary studies on the catalytic epoxidation with cis-cyclooctene and TBHP as oxidant show that the activity of the catalysts clearly depends on the nature of the Cp x -NHC ligand. The reaction proceeds smoothly toward epoxide; no diols or any other byproduct was detected along the reaction course.

No abstract

The molybdenum and tungsten g 3 -allyl dicarbonyl complexes bearing N-heterocyclic carbene (NHC) ligands [M(g 3 -C 3 H 5 )Cl(CO) 2 (bis-NHC Bz )] (M = Mo, W; bis-NHC Bz = 1,1 0 -dibenzyl-3,3 0 -methylenediimidazoline-2,2 0 -diylidene) have been prepared from the corresponding acetonitrile precursors [M(g 3 -C 3 H 5 )Cl(CO) 2 (NCMe) 2 ] by treatment with free carbene. Their catalytic performance in epoxidation of cis-cyclooctene using H 2 O 2 as oxidant has been studied. All complexes can be applied as catalysts precursors in olefin epoxidation displaying 100% selectivity for the formation of cyclooctene oxide. The tungsten acetonitrile precursor [W(g 3 -C 3 H 5 )Cl(CO) 2 (NCMe) 2 ] displayed the highest catalytic activity achieving quantitative conversion of epoxide in 30 min. The molybdenum NHCbased compound [Mo(g 3 -C 3 H 5 )Cl(CO) 2 (bis-NHC Bz )] displayed higher activity when the epoxidation reaction was performed using H 2 O 2 as oxidant compared to tert-butyl hydroperoxide.

Vapor phase synthesis of annelated pyridines from cyclic ketones, aldehydes and ammonia was carried out over various zeolite molecular sieves like Hb, HZSM-5 (240), HZSM-5 (40), HY, HX, HMCM-41 and Mordenite. The preliminary screening of catalyst clearly shows that Hb catalyst was found to be more active for the vapor phase synthesis of annelated pyridines. Hb was further modified with transition metals like Fe, Cu, Pb, Mo, Zn, Ni, Co, Ce, W and Sn to get higher yields. Graphical AbstractO n R H O NH 3 Zeolite, 350 o C 0.5 h -1 W.H.S.V N n n R + + n = 1/2/3 R = H/Alkyl

Objective: The main objective of the research work is to develop and validate a rapid UHPLC method for the estimation of assay and its related substances of Trichostatin A (TSA) in pharmaceutical samples. Methods: The UHPLC method developed for chromatographic separation between TSA and its related compounds on Poroshell 120 SB C18(50×4.6) mm; 2.7 µm RRLC column using Agilent RRLC (UHPLC) system with linear gradient elution. Results: The developed UHPLC method has shown excellent chromatographic separation between TSA and its related compounds within 12 min run time, during validation experiments, specificity study revealed that the peak threshold was more than the peak purity and no purity flag was observed. Repeatability, intra, and inter-day precision results were well within the tolerable limits. Limits of detection concentrations were found between 0.075 to 0.077 ppm and the limit of quantitation is between 0.252 to 0.258 ppm for related compounds and TSA. The related substances method recoveries were found between 80 and 120 % and assay method recovery was found between 98.0 to 102.0%. Conclusion: The developed method capability was proven for the assay of TSA and its related compounds in pharmaceutical samples and the method shows eco-friendlier than routine, conventional HPLC methods in terms of analysis time, cost and HPLC effluent waste.

A simple, linear gradient liquid chromatographic method (RP-HPLC) is proposed for the simultaneous estimation of related compounds in hydroxy naproxen samples. Chromatographic separation was achieved on Zorbax SB C8 (150 × 4.6) mm, 3.5 μm particle size RRLC short column and eluent A used as 0.1% v/v trifluoroacetic acid in water and eluent B used as acetonitrile using Agilent RRLC (UHPLC) system. The mobile phase flow rate was 1.0 mL/min and the eluted compounds were monitored at 235 nm for related substance method and assay method. The excellent resolution was obtained between hydroxy naproxen and its related compounds, which were eluted within 25 min. The performance of the method was validated with respect to ICH guidelines for specificity, limit of detection, limit of quantification, linearity, accuracy, precision and robustness. The correlation coefficient(r) was > 0.995 for both the methods from linearity data and percentage of recovery is 98.0 to 102.0 for assay method and 80.0 to 120.0% for related substance method. Sensitivity of the method was found be less than 0.5 μg/mL. Peak homogeneity data for naproxen in the chromatograms from the selectivity solution obtained by use of the photodiode array detector demonstrated the specificity of the method for analysis of hydroxy naproxen in presence of the related compounds

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