Quantitative characterization and pharmaceutical compatibility between teneligliptin and widely used excipients by using thermal and liquid chromatography tandem mass spectrometry techniques

Journal of Thermal Analysis and Calorimetry - The aim of this work was to evaluate the quantitative characterization and pharmaceutical compatibility study of teneligliptin (TNG) with the commonly...     

Studies towards iodine-catalyzed dehydrative-cycloisomerization of pent-4-yne-1,2-diols to di- and tri-substituted furans

An efficient and single-step iodine catalyzed and metal-free synthesis of di and tri-substituted 2-methylfuran derivatives were achieved from 1-popargyl-1,2-diols. Stereospecific synthesis of starting 1,2-diols was achieved by indium mediated Barbier type propargylation on corresponding keto-alcohols or by sodium borohydride mediated reduction of 2-hydroxy-2-propargyl ketones. The furan synthesis proceeded through iodine mediated 5-exo-trig cyclization, dehydration and reductive deiodination. The method was applied to the synthesis of 2-methylfuran fused to phenanthrene, pyrene and acenaphthylene rings.     

Tris-hydroxymethylaminomethane (THAM): An efficient organocatalyst in diversity-oriented and environmentally benign synthesis of spirochromenes

Tris-hydroxymethylaminomethane has been demonstrated to be an efficient organocatalyst in diversity-oriented synthesis of medicinally prevalent spirochromenes by one-pot, three-component reactions between isatins, malononitrile, and enolizable CH acids like dimedone, 4-hydroxycoumarin, 4-hydroxy-N-methylquinolin-2-one, or in situ generated 2-methylpyrazolon-2-one. Biodegradability and extremely low cost of the catalyst are the noteworthy features of this chromatography-free protocol.     

Rhenium(I)‐Catalyzed ortho‐C−H Addition to Bicyclic Alkenes

Hydroarylation of bicyclic alkenes has been developed using a low‐valent Re^I‐catalyzed, directing group‐assisted C?H bond activation strategy. The addition of sodium acetate significantly improves the reaction efficiency; moreover, bicyclic alkenes such as 7‐oxa and aza benzonorbornadienes worked efficiently under this reaction condition. Preliminary mechanistic studies suggest that, after the alkene insertion, the rhenacycle preferentially undergoes protonolysis rather than reductive elimination.     

Complexometric Determination of Mercury(II) Using 2-Mercaptopropionylglycine as a Selective Masking Reagent

 A selective complexometric method for the determination of mercury(II) in the presence of associated metal ions is reported, based on the selective masking ability of 2-mercaptopropionylglycine (MPGH₂) towards mercury. Mercury, along with other associated metal ions, is first complexed with excess of EDTA and the surplus EDTA is back titrated at pH 5–6 (hexamine buffer) with standard zinc sulfate solution using xylenol orange as indicator. An aqueous 1% solution of MPGH₂ is then added to displace EDTA selectively from the Hg-EDTA complex and the released EDTA is titrated with the same standard zinc sulfate solution. Reproducible and accurate results are obtained for 4–85 mg of mercury with a relative error of ≤ 0.26% and coefficient of variation not exceeding 0.42%. The interferences of various cations and anions are studied. The method is used for the analysis of mercury in its complexes and alloy samples. Received August 30, 2000. Revision January 15, 2001.     

alpha-thiocyanation of carbonyl and beta-dicarbonyl compounds using (dichloroiodo)benzene-lead(II) thiocyanate

The combination reagent (dichloroiodo)benzene and lead(II) thiocyanate in dichloromethane effects oxidation of various enol silyl ethers, ketene silyl acetals, and beta-dicarbonyl compounds, thereby providing an efficient and convenient method for alpha-thiocyanation of carbonyl and beta-dicarbonyl compounds.     

Ab initio study of the structures and stabilities of the dimer of ethyl cation, (C(2)H(+)(5))(2) and related C(4)H(10)(2+) isomers.

Ab initio calculations at the MP4(SDTQ)/6-311G//MP2/6-31G level were performed to study the structures and stabilities of the dimer of ethyl cation, (C(2)H(+)(5))(2), and related C(4)H(10)(2+) isomers. Two doubly hydrogen bridged diborane type trans 1 and cis 2 isomers were located as minima. The trans isomer was found to be more favorable than cis isomer by only 0.6 kcal/mol. Several other minima for C(4)H(10)(2+) were also located. However, the global energy minimum corresponds to C-H (C(4) position) protonated 2-butyl cation 10. Structure 10 was computed to be substantially more stable than 1 by 31.7 kcal/mol. The structure 10 was found to be lower in energy than 2-butyl cation 13 by 34.4 kcal/mol.     

Nafion-H catalysed sulfonylation of aromatics with arene/alkenesulfonic acids for the preparation of sulfones1a

Synthesis of both symmetric and unsymmetric diaryl/aryl alkyl sulfones is easily achieved by Friedel-Crafts type sulfonylation of aromatics with suitable arene- or alkane-sulfonic acids in the presence of Nafion-H, a perfluorinated resinsulfonic acid catalyst.     

Use of kinetic plots for relative assessment of reactor throughput and energy consumption

The progress of high temperature processes is generally described in terms of variation of the degree of conversion () with time (t). The present paper outlines a procedure for making use of-t plots for comparative assessment of productivity and energy requirements for a test system with respect to a reference, on the basis of some simplifying assumptions. It is assumed that the throughput is inversely proportional to reaction time as in the case of batch reactors and plug flow reactors. It is also assumed that the energy requirement is a simple function of process temperature. The principles outlined is illustrated with reference to some laboratory data for reduction of iron oxide by coal.The authors wish to thank Prof. P. R. Rao, Director National Metallurgical Laboratory, Jamshedpur, India, for providing facilities for experimental work and for according permission to publish this work.