Synthesis and Characterization of Metabolites and Potential Impurities of the Antiulcerative Drug Tenatoprazole

Tenatoprazole (Ulsacare^®) is a recently developed antiulcerative drug used for the treatment of both erosive and nonerosive gastroesophageal reflux disease. During the bulk synthesis of tenatoprazole, we have observed four impurities (tenatoprazole N‐oxide, tenatoprazole sulfone N‐oxide, N‐methyl tenatoprazole, and desmethoxy tenatoprazole) and two metabolites (tenatoprazole sulfide and tenatoprazole sulfone). The present work describes the synthesis and characterization of these impurities.     

Sequential 1,3-Dipolar Cycloadditions in the Synthesis of Novel Tri-spiro Cyclohexanones and Piperidin-4-ones

The sequential 1,3-dipolar cycloadditions of azomethine ylide and nitrile oxide to a series of 2,6-bis[(E)-arylmethylidene]cyclohexanones and 1-methyl-3,5-bis[(E)-arylmethylidene]tetrahydro-4(1H)-pyridinones afforded novel tri-spiro heterocycles comprising isoxazoline, pyrrolidine and acenaphthylen-1(2H)-one rings in good yields and stereoselectivity.     

Design,Synthesis, and Anticancer Activity of 1,2,3-Triazole Linked 1,2-Isoxazole-imidazo[4,5-b]pyridine Derivatives

Russian Journal of General Chemistry - A series of novel 1,2-isoxazole-pyridobenzimidazole is synthesized. Structures of the products are supported by 1H and 13C NMR, and mass spectra. All...     

A Facile One‐Pot Synthesis of Pyrrolo[1, 2‐a] Indoles by Intramolecular 1,3‐Dipolar Cycloaddition under Neat‐Microwave Irradiation

A straightforward and general approach for the stereoselective synthesis of fused pyrrolo[1,2‐a] indoles frameworks from>intramolecular 1,3‐dipolar cycloaddition using N‐alkylated Baylis–Hillman derivatives is presented. It was found that the cycloaddition proceeded efficiently under microwave irradiation in solvent‐free condition to afford highly stereoselective cycloadducts in good yield.     

Synthesis, structures and membrane properties of siloxane-imide co-polymers produced by aqueous polymerization

We report for the first time, the synthesis of siloxane-imide co-polymers by the reaction of mixtures of 1,4-bis(aminobutyl)tetramethyldisiloxane (ABTMDS) and 1,3-bis(4-aminophenoxy)benzene (TPE-R) with bisphenol A diphthalic anhydride (BPADA) using water as the polymerization solvent. A series of co-polymers were prepared incorporating 10, 20, 40 and 100 mol% of ABTMDS with the aromatic diamine TPE-R as the co-monomer. The synthesized co-polymers showed number average molecular weights in the range of 25,000–60,000. As expected the glass transition temperatures (T_gs) and moduli of the polymers were found to decrease with increasing amounts of the siloxane monomer and the homo-polymer containing only the siloxane diamine showing the lowest T_g (60 °C). The resulting polymers could be solution cast into strong and flexible membranes which showed significant decreases in water absorption and moisture permeability compared to the control polymer without siloxane groups. The polymers were characterized by FTIR, ¹³C and ¹H NMR, GPC, DSC and mechanical properties and structural comparisons were made with similar polymers made by standard solvent synthesis methods. Also cross-linked polymers were prepared by the reaction of ABTMDS with the aromatic homo-polymer control and their membrane properties were compared to those of the water synthesized siloxane co-polymers with a similar siloxane content.     

A Convenient Synthesis of Novel Pentacyclo [5.4. 0.02,6 .03,10 .05,9] Undecane-8,11-dione-4-spiro-1-cyclopropane

An efficient synthesis of the title compound by Diels-Alder cycloaddition of spiro(4.2) heptadiene with p-benzoquinone followed by photochemical ring closure is described.     

Spectral studies on VO ions in potassium thiourea bromide single crystals using EPR and optical absorption spectroscopy

Electron paramagnetic resonance (EPR) studies have been carried out on VO²⁺ ions doped in single crystals of ferroelectric material, potassium thiourea bromide (PTB) at room temperature and in the temperature range 103–343 K on X-band MW frequency. An isotropic octet spectrum characteristic of VO²⁺ ion was obtained due to the fast re-orientation of the VO²⁺ in PTB lattice, which exhibits glassy nature at certain range around room temperature. The temperature dependant EPR spectra of VO²⁺ ions in this host lattice has been attributed to the occurrence of multiple phase transitions due to the combined environment effects of KBr and thiourea materials in the single crystal. From the optical absorption spectrum, the crystal field splitting parameter Dq, tetragonal parameters Ds and Dt have been evaluated and discussed.     

EPR and optical absorption studies on Cr3+ ions doped in KZnClSO4 x 3H2O single crystals

EPR and optical absorption spectra of Cr3+ ions doped in KZnClSO4 x 3H2O single crystals have been studied at room temperature. The EPR spectrum exhibits a group of three fine structure transitions characteristic of Cr3+ ions. From the observed EPR spectra, the spin-Hamiltonian parameters have been determined. The optical absorption spectrum exhibits two broad bands characteristic of Cr3+ ions in an octahedral symmetry. From the observed band positions, the crystal field parameters have been evaluated.     

Synthesis and α‐glucosidase inhibitory,DPPH scavenging activity of substituted 2‐oxo‐2H‐chromen‐7‐yl‐dihydrogen phosphate derivatives

Series of phosphorylated coumarin derivatives ( 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i , 4j ) were synthesized by Pechmann condensation, phosphorylation, and debenzylation reactions in very good yields. Thus, synthesized compounds ( 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i , 4j ) were evaluated for their α‐glucosidase and 1,1‐diphenyl‐2‐picrylhydrazyl scavenging activities; few compounds showed moderate to good activity. J. Heterocyclic Chem., 00 , 00 (2011).     

Differentiation of Boc‐protected α,δ‐/δ,α‐ and β,δ‐/δ,β‐hybrid peptide positional isomers by electrospray ionization tandem mass spectrometry

Two new series of Boc‐N‐α,δ‐/δ,α‐ and β,δ‐/δ,β‐hybrid peptides containing repeats of L ‐Ala‐δ⁵‐Caa/δ⁵‐Caa‐L ‐Ala and β³‐Caa‐δ⁵‐Caa/δ⁵‐Caa‐β³‐Caa (L ‐Ala = L ‐alanine, Caa = C‐linked carbo amino acid derived from D ‐xylose) have been differentiated by both positive and negative ion electrospray ionization (ESI) ion trap tandem mass spectrometry (MS/MS). MSⁿ spectra of protonated isomeric peptides produce characteristic fragmentation involving the peptide backbone, the Boc‐group, and the side chain. The dipeptide positional isomers are differentiated by the collision‐induced dissociation (CID) of the protonated peptides. The loss of 2‐methylprop‐1‐ene is more pronounced for Boc‐NH‐L ‐Ala‐δ‐Caa‐OCH₃ (1), whereas it is totally absent for its positional isomer Boc‐NH‐δ‐Caa‐L ‐Ala‐OCH₃ (7), instead it shows significant loss of t‐butanol. On the other hand, second isomeric pair shows significant loss of t‐butanol and loss of acetone for Boc‐NH‐δ‐Caa‐β‐Caa‐OCH₃ (18), whereas these are insignificant for its positional isomer Boc‐NH‐β‐Caa‐δ‐Caa‐OCH₃ (13). The tetra‐ and hexapeptide positional isomers also show significant differences in MS² and MS³ CID spectra. It is observed that ‘b’ ions are abundant when oxazolone structures are formed through five‐membered cyclic transition state and cyclization process for larger ‘b’ ions led to its insignificant abundance. However, b₁⁺ ion is formed in case of δ,α‐dipeptide that may have a six‐membered substituted piperidone ion structure. Furthermore, ESI negative ion MS/MS has also been found to be useful for differentiating these isomeric peptide acids. Thus, the results of MS/MS of pairs of di‐, tetra‐, and hexapeptide positional isomers provide peptide sequencing information and distinguish the positional isomers. Copyright © 2010 John Wiley & Sons, Ltd.