Transformations of schiff bases derived from quinoline‐8‐carbaldehyde. Synthesis of C‐8 substituted quinolines

The Schiff bases derived from quinoline‐8‐carbaldehyde and substituted aromatic amines were used in the synthesis of C‐8 substituted quinolines. 3‐Aryl‐2‐(8‐quinolinyl)‐4‐thiazolidinones were prepared from obtained aldimines by means of the cyclocondensation of mercapto acids. A series of 4‐N‐arylamino‐4‐(8‐quinolinyl)‐1‐butenes was synthesized through the addition of the Grignard reagent (allylmagnesium bromide) to the double bond C=N of these aldimines. The structure of the prepared compounds was established on the basis of their elemental analyses and spectral data.     

Epibatidine alkaloid chemistry: 5. Domino-Heck reactions of azabicyclic and tricyclic systems

Palladium-catalyzed hydroarylations and additional domino reactions of aza-bicyclic and tricyclic norbornene derivatives were investigated and a series of new epibatidine analogues were synthesized.     

The Synthesis of Epiboxidine and Related Analogues as Potential Pharmacological Agents

Methyl epiboxidine‐N‐carboxylate ( 8 ) was synthesized from 7 under reductive Heck conditions (Scheme 2). The C? C coupling of the new epiboxidine analog 9 with aryl and heteroaryl halides gave by hydroarylation C‐aryl, N‐(3‐methylisoxazol‐5‐yl)‐substituted tricyclic imides 10a – 10f (Table). The [3+2] cycloaddition of 9 with nitrile oxides yielded the bridged dihydroisoxazole derivatives 11a – 11d with potential biological activity (Scheme 4).     

Gerstenhaber brackets on Hochschild cohomology of general twisted tensor products

We present techniques for computing Gerstenhaber brackets on Hochschild cohomology of general twisted tensor product algebras. These techniques involve twisted tensor product resolutions and are based on recent results on Gerstenhaber brackets expressed on arbitrary bimodule resolutions.     

A three-component,one-pot synthesis of 1,8-naphthyridine and isoxazole derivatives and computational elucidation of the mechanism

Research on Chemical Intermediates - An efficient and general method for the synthesis of substituted 3,4-dimethylisoxazolo[5,4-b]pyridine-5-carboxamide and benzo[b][1,8]naphthyridine-3-carboxamide...     

Two and three positive solutions of m-point boundary value problems for functional dynamic equations on time scales

In this paper, by using fixed point theorems in a cone, we study the existence of at least two and three positive solutions of a nonlinear second-order m-point boundary value problem for functional dynamic equations on time scales. As an application, we also give an example to demonstrate our results.     

Structure of Quinoline-4-Carboxaldehyde-2,4-Dinitrophenyl-N Methylhydrazone

Abstract

The crystal structure of the title compound, C₁₇H₁₃N₅O₄, has been determined by single crystal x-ray diffraction at room temperature. The molecule is not planar, with dihedral angles of 7.2(1)° between the quinoline ring and N-methylhydrazone group, and 17.45(2)° between the N-methylhydrazone group and the phenyl ring. The crystal parameters of this compound are as follows: monoclinic P 21/n, a=9.525(2)Å, b = 15.192(2) Å, c = 11.302(2) A, β = 94.722(3)°, V = 1629.8(6) ų, Z = 4, Dx = 1.432 g/cm³, F(000) = 728, λ (MoKα) = 0.71070 Å, μ = 0.106 mm^?1, R_int = 0.017. The structure was solved by SHELXS-86 and refined by SHELXL-93. R = 0.07 for 2438 observed reflections with I > 2σ (I).     

Surface microstructure of the oxide protective layers grown on vanadium-free Ti alloys for use in biomedical applications

In this work, we present a surface study by SFM (scanning force microscopy) of three new Ti alloys of composition (in wt%) Ti-7Nb-6Al, Ti-13Nb-13Zr and Ti-15Zr-4Nb, developed for biomedical applications. V was not included in these alloys since this element has been reported to be cytotoxic. The surface of these materials has been modified by a thermal treatment in air at 750 °C for different times. As a consequence of this treatment an oxide layer develops on the surface, resulting in both an improvement of the corrosion resistance and an increase of the roughness, which enhances the adhesion of the tissue cells to the implant. SFM has been used to characterize the surface structure and topography of the oxide layers grown on the three alloys. The surface roughness analysis obtained by SFM points to a correlation between the mean square roughness, the thickness of the oxide layer, and the α-phase/β-phase ratio in the base material.     

Domino‐Heck Reactions of Carba‐ and Oxabicyclic,Unsaturated Dicarboximides: Synthesis of Aryl‐Substituted,Bridged Perhydroisoindole Derivatives

The C? C coupling of the two bicyclic, unsaturated dicarboximides 5 and 6 with aryl and heteroaryl halides gave, under reductive Heck conditions, the C‐aryl‐N‐phenyl‐substituted oxabicyclic imides 7a – c and 8a – c (Scheme 3). Domino‐Heck C? C coupling reactions of 5, 6 , and 1b with aryl or heteroaryl iodides and phenyl‐ or (trimethylsilyl)acetylene also proved feasible giving 8, 9 , and 10a – c , respectively (Scheme 4). Reduction of 1b with LiAlH₄ (→ 11 ) followed by Heck arylation and reduction of 5 with NaBH₄ (→ 13 ) followed by Heck arylation open a new access to the bridged perhydroisoindole derivatives 12a , b and 14a , b with prospective pharmaceutical activity (Schemes 5 and 6).