4-aminopyridine Research Articles

Synthesis of Functionalized Iron Oxide Nanoparticle with Amino Pyridine Moiety and Studies on Their Catalytic Behavior

Aim: The main objective of this paper is to study the synthesis of functionalized iron oxide nanoparticle and its reactivity towards chromene synthesis Study design: Functionalized iron oxide nanoparticle study. Place and duration of study: Department of Studies and Research in Industrial Chemistry, School of Chemical Sciences, Kuvempu University, Shankaraghatta, between December 2009 and July 2010. Methodology: This paper describes synthesis of stable functionalized iron oxide nanoparticles through surface modification of magnetic iron oxide nanoparticles by amino pyridine. Iron oxide nanoparticles were synthesized by co-precipitation method and the surface modification process was achieved by treating the nanoparticles with (chloro propyl trimethoxy silane) CPTS and aminopyridine. The developed functionalized iron oxide nanoparticle was evaluated as the catalyst for synthesis of chromones under MW irradiation conditions. Results: The catalysts were magnetically recovered and reusable without significant loss of their catalytic efficiency. To receive morphological and structural information on the obtained functionalized nanoparticle, the samples were analyzed by X-ray diffraction (XRD) measurements, FTIR and scanning electron microscopy (SEM) imaging. All synthesized chromene derivatives were characterized using analytical techniques such as IR, H NMR, and mass spectroscopy. Also the identity of these compounds was easily established by comparison of their melting point with those of reported samples. Conclusion: In summary, we have developed a new magnetically recyclable and Research Article American Chemical Science Journal, 1(3): 97-108, 2011 98 efficient functionalized magnetic nano catalyst for the chromene synthesis. Magnetic nanoparticle catalyst achieves a simple separation of catalyst without filtration including high yield in product.

Recognition ability of temperature responsive molecularly imprinted polymer hydrogels

Temperature responsive imprinted polymer hydrogels were synthesized and characterized, which recognize target molecule, 4-amino pyridine (Apy), via electrostatic interaction and hydrogen bonding. The interaction between Apy and functional monomer methacrylic acid (MAA) was investigated by FTIR and 1H-NMR. Adsorption and release of Apy were determined at 60 °C and 20 °C, respectively. The amount of adsorption of Apy in the imprinted hydrogels was 2–3 times higher than that in the non-imprinted hydrogels. At 20 °C, 82% of Apy is released by the imprinted hydrogels, but only 60% by the non-imprinted hydrogels. The unique aspect of these imprinted polymer hydrogels is that they combine molecular recognition with thermo-responsiveness; reversible recognition and release of target molecule are realized by changing temperature. Selective recognition tests of the imprinted polymer hydrogels were carried out using three compounds structurally related to Apy, pyridine, 4-methylpyridine and 2-aminopyridine. The imprinted hydrogels exhibited the highest selectivity for Apy, while the non-imprinted hydrogels showed similarly low adsorption for all the substrates. As the imprinted polymer hydrogels have good temperature response, selectivity and reusability, they have great potential for application in separation field and in drug controlled release systems.

2D QSAR studies of several potent aminopyridine, anilinopyrimidine and pyridine carboxamide-based JNK inhibitors

The c-Jan N-terminal kinases are members of the mitogen activated protein kinase family of signaling proteins. Amino pyridine based compounds, 4-anilino pyrimidine derivatives, and 2-pyridine carboxamide derivatives have been identified as potent JNK inhibitors with good cellular activity. In this study we calculated molecular topological and quantum chemical descriptors of 15 training compounds and three quantitative structure activity relationships models have been constructed. The significance of three models is judged on the basis of correlation, Fischer F test and quality factor (Q). This study is helpful for screening potent inhibitors of protein kinases.

Synthesis, characterization, and urease inhibition of 5-substituted-8-methyl-2H-pyrido[1,2-a]pyrimidine-2,4(3H)-diones

5-Substituted-8-methyl-2H-pyrido[1,2-a]pyrimidine-2,4(3H)-dione and its anilines, amino pyridines and hydrazides derivatives were prepared in a good to excellent yields. In the first step 8-methyl-2H-pyrido[1,2-a]pyrimidine-2,4(3H)-dione (1) was prepared by reacting 4-methyl-2-aminopyridine, with diethylmalonate. Compounds substituted pyrido[1,2-a]pyrimidine-2,4(3H)-diones (PPMDO) (2)–(17) were prepared by condensing 8-methyl-2H-pyrido[1,2-a]pyrimidine-2,4(3H)-dione in the presence of triethylorthoformte (TEF) and dimethylformamide (DMF), with respective amino components viz. 2-aminoacetophenone, 3-aminoacetophenone, 4-aminoacetophenone, 2,4,6-trimethylaniline, 2-fluoroaniline, 3-fluoroaniline, 4-fluoroaniline, 2-aminothiophenol, 2-amino-4-methylpyridine, 2-amino-5-methylpyridine, 2-amino-5-nitropyridine, Benzoic hydrazide, 4-nitrobenzoic hydrazide, 4-bromobenzoic hydrazide, 4-chlorobenzoic hydrazide and 4-hydroxybenzoic hydrazide, respectively. The chemical structures of all the compounds were elucidated by IR, 1H-NMR, 13C-NMR and elemental analysis data. The synthesized compounds were screened for their in vitro urease inhibition activity, by the phenol hypochlorite method. These compounds were found to exhibit either no or low to moderate or significant activity. The compounds (9) and (14) showed comparatively much higher activity. However, the compound (9) was found to be the most active one. Of the synthesized compounds (2)–(17), two compounds (9) and (14) were found to be significantly more potent inhibitors of urease activity than the starting compound (1). The same two compounds also exhibited anti-urease activity comparable to thiourea, a standard urease inhibitor used in this study as a reference.

A New Strategy for the Synthesis of Poly-Substituted 3-H, 3-Fluoro, or 3-Trifluoromethyl Pyridines via the Tandem C−F Bond Cleavage Protocol

A new strategy for the synthesis of poly-substituted 3-H, 3-F, and 3-trifluoromethyl pyridines based on C-F bond breaking of the anionically activated fluoroalkyl group is described. A series of 2,6-disubstituted 4-amino pyridines were prepared through this domino process in high yields under noble metal-free conditions, making this method a supplement to pyridine synthesis.

A new salen base 5-(phenylazo)-N-(2-amino pyridine) salicyliden Schiff base ligand: Synthesis, experimental and density functional studies on its crystal structure, FTIR, 1H NMR and 13C NMR spectra

A novel Schiff base ligand 5-(phenylazo)-N-(2-amino pyridine) salicyliden is prepared through the condensation of 5-(phenylazo) salicylaldehyde and 2-amino pyridine in methanol at room temperature. The orange crystalline precipitate is used for X-ray crystallography and measuring Fourier transform (FTIR), 1H NMR and 13C NMR spectra. Density functional theory (DFT) calculations at the B3LYP, MPWB1K and B3PW91 levels of theory is used to optimize the geometry and calculate the FTIR, 1H NMR and 13C NMR spectra of the compound. The vibrational frequencies determined experimentally are compared with those obtained theoretically and a vibrational assignment and analysis of the fundamental modes of the compound is performed. We found that the MPWB1K method predicts low vibrational frequencies better than the commonly used B3LYP method. Although the B3PW91 method overestimates the 1H NMR chemical shifts, the values computed at the B3LYP level of theory are in accordance with experimental 1H NMR spectrum. However, both B3LYP and B3PW91 methods tend to overestimate 13C NMR chemical shifts. In addition, a few quantum descriptors of the molecule are calculated and conformational analysis is performed and the result was compared with crystallographic data.

Theoretical studies of 2-nitrobenzaldehyde and furan-2-carbaldehyde Schiff base of 2-amino pyridine

The vibration modes of the title compounds are examined by experimentally and theoretically using the semi-empirical AM1 and PM3 computational methods. Vibration modes for 2N-(2-nitro benzalidine) amino pyridine (2-NBAPy), the correlation coefficients obtained for AM1 and PM3 methods are 0.996483 and 0.992236, respectively. However, vibration modes for 2N-(Furfural) amino pyridine (FAPy), the correlation coefficients for AM1 and PM3 methods are 0.993238 and 0.990477, respectively. AM1 method provides most satisfactory correlations between experimental and calculated fundamental vibration modes of title compounds (CC=0.996483 and 0.993238, respectively).

Enantioselective Henry Addition of Methyl 4-Nitrobutyrate to Aldehydes. Chiral Building Blocks for 2-Pyrrolidinones and Other Derivatives

A catalytic highly enantioselective Henry addition of methyl 4-nitrobutyrate to aldehydes using a Cu(II)-amino pyridine complex as catalyst is described. The products resulting from this reaction constitute a new, highly versatile family of chiral building blocks as a result of the presence of three different functional groups on the molecule. These products have been transformed into nonracemic chiral gamma-lactams, 5-hydroxy-5-substituted levulinic acid derivatives, and delta-lactones.

Vibrational spectroscopy (FTIR and FTRaman) investigation using ab initio (HF) and DFT (B3LYP and B3PW91) analysis on the structure of 2-amino pyridine

The FTIR and FTRaman spectra of 2-amino pyridine (2-AP) molecule have been recorded using Bruker IFS 66 V spectrometer in the range of 4000–100 cm −1. The molecular geometry and vibrational frequencies in the ground state are calculated by using the ab initio Hartree–Fock (HF) and DFT (B3LYP and B3PW91) methods with 6-31++G (d, p) and 6-311++G (d, p) basis sets. The computed values of frequencies are scaled using a suitable scale factor to yield good coherence with the observed values. Making use of the recorded data, the complete vibrational assignments are made and analysis of the observed fundamental bands of molecule is carried out. The geometries and normal modes of vibrations obtained from ab initio HF and B3LYP/B3PW91 calculations are in good agreement with the experimentally observed data. The differences between the observed and scaled wave number values of most of the fundamentals are very small in B3LYP than HF. The influence of N atom and amine group in the skeletal ring vibrations of the title molecule has also been discussed.

A novel one-pot palladium-mediated synthesis of N-[(2-hydroxyphenyl)methyl]-N-(4-phenoxy-3-pyridinyl) acetamide, the precursor to [11C]PBR28, a PET biomarker for the peripheral benzodiazepine receptor

Abstract Due to an urgent need to image the peripheral benzodiazepine receptor (PBR) in living human subjects using positron emission tomography imaging, we had cause to prepare N-[(2-hydroxyphenyl)methyl]-N-(4-phenoxy-3-pyridinyl) acetamide (desmethyl-PBR28 (1)), the precursor to [11C]PBR28. Herein, we report a new synthesis of the precursor in which palladium-mediated reduction of the nitro pyridine to the corresponding amino pyridine, and subsequent reductive amination, can be achieved with decaborane in a convenient one-pot procedure. This procedure is operationally simpler than the current alternatives and provides high quality precursor suitable for use in clinical applications.

Synthesis of ( S)-(+)-sotalol and ( R)-(−)-isoproterenol via a catalytic enantioselective Henry reaction

A unified approach for the synthesis of ( S)-(+)-sotalol and ( R)-(−)-isoproterenol has been developed. The enantioselective Henry reaction of the appropriate aldehyde in the presence of a camphor-derived amino pyridine–Cu(II) complex was the key step of the synthesis. The reduction of the nitro group to give the corresponding amino alcohols followed by reductive alkylation of the amine provided the target products with high enantiomeric excesses.

Acorda aim to assist patients with costs for Ampyra

Acorda aim to assist patients with costs for Ampyra

Selective transport of copper across a bulk liquid membrane using 8-hydroxy quinoline as carrier

The carrier activity of 8-hydroxy quinoline (oxine) towards the facilitated transport of copper ions through chloroform bulk liquid membrane has been studied. The effects of pH of the source phase, the nature of stripping agents in the receiving phase, presence of other cations, nature of synergistic reagents on the transport were investigated. A solution of 0.1 M nitric acid (HNO 3) served as receiving phase for maximum transport of the metal ion. Addition of 2-amino pyridine to the membrane phase had a synergistic effect and caused a pronounced enhancement in the transport, while citric acid or glycine did not change the transport significantly. Maximum transport efficiency was observed for Cu 2+ ion when it was present in the concentration of 10 −4 M. Tolerance to the presence of Pb 2+, Zn 2+, Cd 2+, Ni 2+, Fe 2+ and Fe 3+ ions was investigated and it was found that Cu 2+ transport was not affected even in the presence of 10-fold concentration of these ions. This system was applied for the recovery of copper in electroplating industrial waste water samples.

Spectral characteristics of 2-amino-3-benzyloxy pyridine: Effects of solvents, pH, and β-cyclodextrin

Spectral characteristics of 2-amino-3-benzyloxypyridine (2ABP) has been studied in solvents of different polarity, pH, and β-cyclodextrin (β-CD) and compared with 2-amino pyridine (2AP). The inclusion complex of both amino pyridine (AP) molecules with β-CD are analysed by UV-visible, fluorimetry, FTIR, 1H NMR, SEM and AM1 methods. The solvent studies shows no significant shift observed in absorption maxima between both AP molecules, but in the excited state a slight red shift is noticed in 2ABP than in 2AP which indicates that the addition of benzyloxy group in 2AP does not effectively increase the resonance interaction in 2ABP. The regular red shift observed in acidic pH solutions suggests intramolecular proton transfer (IPT) interaction in both molecules. β-CD studies shows that in pH ∼7, 2ABP forms 1: 2 inclusion complex from 1: 1 inclusion complex and 1: 1 inclusion complex is formed in pH ∼ 1. In pH ∼ 7, a red shift observed in 2ABP with lower β-CD concentration suggests aromatic ring encapsulated in the β-CD cavity and blue shift noticed at higher β-CD concentrations indicates pyridine ring encapsulated in the β-CD cavity.

Synthesis and Anticonvulsant Activity of Certain Substituted Furochromone, Benzofuran and Flavone Derivatives

Synthesis of furochromone, 2-phenylchromone (flavone) and benzofuran derivatives substituted with thiosemicarbazide or thiazolidin-4-one moieties were accomplished. All the newly synthesized compounds were tested for their anticonvulsant activity in both subcutaneous pentylenetetrazole induced seizures (scPTZ) and maximal electric shock induced seizures (MES) tests using valproic acid and phenytoin respectively as reference standards. The most active compounds in scPTZ model were 1c, 2b, 5a and 7e showing 100% protection at 300 mg/kg upon intraperitoneal administration. Also, the effect of pre-treatment of three of the most active compounds (1c, 2b, 5a) on 4-amino pyridine-induced lethality in mice was investigated. Pre-treatment with these compounds significantly increased the latency for clonic and tonic seizures and prevented 4-amino pyridine induced death. Hence, this provides evidence for anticonvulsant activity of these compounds, and a neuroprotective activity for them. The structure-activity relationship was studied based on the obtained data.

Physicochemical Investigations of Th(IV) and UO2(VI) Complexes with New Schiff Bases Along with their Toxic Effects

Schiff bases were obtained using p‐trimethoxy benzaldehyde, p‐hydroxyl benzaldehyde and 2‐amino pyridine to prepare new complexes of thorium(IV) and dioxouranium(VI) metals by various anions. The synthesized ligands and complexes were analytically studied through spectral studies, elemental analysis conductance measurements along with semi empirical and thermogravimetric methods. The complexes were assigned various coordination numbers ranging from 6‐10 on the basis of these studies.

Intramolecular Proton Transfer Effects on 2,6-diaminopyridine

The photophysical behaviour of 2,6-diaminopyridine (DAP) has been studied in solvents of different polarity, pH, beta-cyclodextrin (beta-CD) and compared with 2-amino pyridine (2AP). The inclusion complex of both molecules with beta-CD are analysed by UV-visible, fluorimetry, FT-IR, (1)H NMR, SEM and AM1 methods. The solvent studies shows i) DAP gives more red shifted absorption and emission maxima than 2AP molecule and ii) addition of amino group in 2AP effectively increase the resonance interaction in the pyridine ring. A regular red shift observed in acidic pH solutions suggests intramolecular proton transfer (IPT) present in both molecules. beta-CD studies indicates i) in pH approximately 7, a regular red shifted absorption and emission maxima observed in AP molecules suggests pyridine ring encapsulated in to the beta-CD cavity (1:1 inclusion complex formed) and ii) in pH approximately 1, a blue shifted absorption maxima noticed in 2AP, is due to protonated amino group deeply encapsulated in to the hydrophobic part of the beta-CD cavity.

2-Aminopyridine condensation with formaldehyde

2-Aminopyridine condensation with formaldehyde

The synthesis of N-Zn, N-Cu complexes involving 2-amino pyridine and ethylenediamine ligands and application to the Henry reaction

The synthesis and characterization of a series of N-Zn, N-Cu complexes with 2-amino pyridine and ethylenediamine ligands (1a–b and 2a–b) have been described. They were synthesized with a simple, one-pot method, and the crystal structures of 1a, 1b, 2a and 2b were determined by X-ray crystallography. The complexes were also characterized by NMR, IR, and elemental analysis. They were used as the catalysts in an application to the Henry reaction, and high yields were obtained under the optimum conditions.

Therapy of downbeat nystagmus: differential effects of aminopyridine on the gravity dependence and gaze – holding function

Aminopyridines (AP) have been shown to be an efficient therapy for downbeat nystagmus (DBN). Since AP improve both (i) resting discharge and (ii) excitability of floccular Purkinje cells (PC) we investigated the effect of AP on the vertical eye position sensitivity (EPS) and the gravity dependence (GD) in patients with idiopathic DBN. Eye movements towards targets presented in gaze straight ahead and±10° vertically were recorded prior to and 45 minutes after 20mg DAP or 4-AP ingestion in five pitch positions of the head relative to the upright position, i.e. from prone to supine head positions. Head position dependency of ocular drift was calculated from the difference between the lowest and highest SPV of the different head positions (GD=„gravity-dependence“).