Reaction Of 2-aminopyridine Research Articles

One-Pot Green Synthesis of Novel Polysubstituted 1,2-Dihydronaphtho[2,1-b]furans

A simple and highly efficient one-pot protocol for the synthesis of novel polysubstituted 1,2-dihydronaphtho[2,1-b] furans has been developed by three-component coupling reaction of 2-aminopyridines, naphthols, and glyoxal in the presence of guanidinium chloride as a polyfunctional organocatalyst under solvent-free conditions. The protocol avoids the use of expensive catalysts, toxic solvents, and chromatographic separation and provides a wide range of novel dihydronaphthofurans in good to excellent yields.

ChemInform Abstract: Nano Fe3O4 Supported Biimidazole Cu(I) Complex as a Retrievable Catalyst for the Synthesis of Imidazo[1,2‐a]pyridines in Aqueous Medium.

AbstractThe title nanocatalyst is successfully employed for the synthesis of imidazopyridines in aqueous medium via three‐component reaction of 2‐aminopyridine, aldehydes, and phenylacetylene.

Synthesis of 3-Nitro-2-arylimidazo[1,2-a]pyridines Using Sodium Dichloro­iodide

Moderate to good yields of various 3-nitro-2-arylimidazo[1,2-a]pyridines have been easily achieved in the reaction of 2-aminopyridines and nitrostyrenes in the presence of sodium dichloriodide. The procedure is simple and various functional groups are tolerated in this reaction system.

Pyridine Group Assisted Addition of Diazo-Compounds to Imines in the 3-CC Reaction of 2-Aminopyridines, Aldehydes, and Diazo-Compounds

A novel three-component coupling (3-CC) reaction of 2-aminoazines, aromatic aldehydes, and diazo-compounds producing polyfunctional β-amino-α-diazo-compounds has been developed. The reaction features an unprecedented heterocycle-assisted addition of a diazo-compound to an imine. The obtained diazoesters were efficiently converted into valuable heterocycles as well as β-amino acid derivatives.

P2O5 Promoted One-Pot Synthesis of 3-aminoimidazo[1,2-a]pyridines under Solvent-Free Conditions

Phosphorus pentoxide is found to be a highly efficient biodegradable catalyst for the three-component reaction of 2-aminopyridines (I) with aromatic aldehydes (III) and isocyanides (II) under solvent-free conditions.

Photoactive azoimine dyes: 4-(2-Pyridylazo)- N, N-diethylaniline and 4-(2-pyridylazo)- N, N-dimethylaniline: Computational and experimental investigation

4-(2-Pyridylazo)- N, N-dimethylaniline and 4-(2-pyridylazo)- N, N-diethylaniline, two photoactive azoimine dyes, were prepared from the reaction of 2-aminopyridine with N, N-dialkyl-1,4-nitrosoaniline at room temperature. Structural characterizations of these dyes using single crystal X-ray diffraction, 1H NMR, elemental analysis, mass spectroscopy and IR spectroscopy have been carried out. The X-ray structure indicates a trans configuration around the azo group. The photochemical behavior of these compounds differs from that of 2-phenylazopyridine, the non-dialkylamino substituent compound. The synthesized compounds show emission spectra at room temperature while 2-phenylazopyridine does not. The excitation spectra of these compounds differ from their absorption spectra which can be explained on the basis of the trans to cis photoisomerization which is supported by the TD-PBE0/6-31G(d,p) calculations. Both oxidation of the dialkylamino substituents (–NR 2; R = –CH 3 and –C 2H 5) and reduction of –N N–/–N N– − and –N N– −/–N N– 2− were observed in the cyclic voltammogram indicating a π-acidity of both dyes.

Mechanistic Studies on a New Catalyst System (CuI-NaHSO4×SiO2) Leading to the One-Pot Synthesis of Imidazo[1,2-a]pyridines from Reactions of 2-Aminopyridines, Aldehydes, and Terminal Alkynes

Correction to: Mechanistic Studies on a New Catalyst System (CuI-NaHSO4×SiO2) Leading to the One-Pot Synthesis of Imidazo[1,2-a]pyridines from Reactions of 2-Aminopyridines, Aldehydes, and Terminal AlkynesSynthesis 2011; 2011(21): 3463-3470DOI: 10.1055/s-0030-1260255

ChemInform Abstract: Synthesis of 3‐Arylimidazo[1,2‐a]pyridines by a Catalyst‐Free Cascade Process.

AbstractA simple protocol allows the synthesis of the title compounds through cascade reaction of 2‐aminopyridines with dibromoalkenes or bromoacetylenes, respectively.

Efficient and Simple Route for the Synthesis of N-(2-Pyridyl)-4-ethoxy-5-oxo-2,5-dihydro-1H-pyrrole-2,3-dicarboxylates

Three-component reaction of 2-aminopyridines, dialkyl acetylenedicarboxylates, triphenylphosphine, and ethyl chlorooxoacetate in the presence of triethylamine provides a sufficient route for the synthesis of dialkyl N-(2-pyridyl)-4-ethoxy-5-oxo-2,5-dihydro-1H-pyrrole-2,3-dicarboxylates in good yields.

General and efficient copper-catalyzed three-component coupling reaction towards imidazoheterocycles: one-pot synthesis of alpidem and zolpidem.

Imidazopyridine is an important pharmacophore widely found in many biologically active compounds.[i] Particularly, imidazo[1,2-a]pyridine is an essential fragment present in pharmacologically important molecules, including several anxyolytic drugs,[ii] such as alpidem (A),[iia,b] necopidem (C), and saripidem (D), and insomnia treatment drug zolpidem (B).[iic,d] Although a variety of synthetic methods for the synthesis of these important cores have been developed,[iii] most of them are limited in scope and require multistep preparation of starting materials.[iv] Accordingly, development of straightforward and general method for the synthesis of imidazo[1,2-a]pyridines from easily available precursors is highly warranted. Herein we wish to report general and efficient synthesis of imidazopyridines 5 via the Cu-catalyzed three component coupling (TCC) reaction of 2-aminopyridines 1 with arylaldehydes 2 and alkynes 3 (Scheme 1).

<b>Conversion of <i>Vernonia galamensis</i> oil to pyridinyl-vernolamides and their antimicrobial activities</b>

Vernonia oil obtained by Soxhlet extraction from the seeds of Vernonia galamensis ssp. nairobensis was reacted with 2-aminopyridine, 2-(aminomethyl)pyridine and 2-(aminoethyl)pyridine using a 1:3 mole ratio of vernonia oil to amine at varied temperatures to give the corresponding vernolamides. The expected vernolamide from the reaction of 2-aminopyridine and the oil was not formed. N-(2-pyridinylmethyl)vernolamide and N-(2-pyridinylethyl)vernolamide exhibited antibacterial activity that was shown to be higher against gram-positive (Bacillus subtilis) than gram-negative (Escherichia coli) bacteria. The vernolamides did not show any antifungal activity. KEY WORDS: Vernonia galamensis, 2-Aminopyridine, N-(2-pyridinylmethyl)vernolamide, N-(2-pyridinylethyl)vernolamide, Antimicrobial activity Bull. Chem. Soc. Ethiop. 2007, 21(1), 103-110.

Synthesis and spectral studies of 2-aminopyridinium para-nitrobenzoate: A novel optoelectronic crystal

A new crystal 2-aminopyridinium para-nitro benzoate (C 5H 7N 2 +·C 7H 4NO 4 −) has been synthesized by the reaction of 2-aminopyridine with para-nitro benzoic acid by slow evaporation method. As synthesized crystals have been characterized by X-ray diffraction (XRD), Fourier transformed infrared (FTIR), and Ultra violet (UV) spectral studies. The XRD and FTIR results indicated that the synthesized compound has the crystal structure of monoclinic with space group P2 1 with lattice parameters a, b, c and β of 7.9403(12) Å, 6.7719(6) Å, 11.1120(15) Å and 99.272(6)° respectively. The synthesized crystal exhibits the UV absorption edge at around 334 nm with the estimated direct band gap ( E g) of 3.53 eV. It is observed from the above studies that the crystal has the maximum transparency in the entire visible region and hence the crystal should exhibit a nonlinear optical property. Further the band gap of the as synthesized crystals was determined to be around 3.53 eV, which makes the crystal suitable for the fabrication of optoelectronic devices. The crystal does not have any inversion symmetry and hence it also exhibits piezoelectricity.

Co(II)-Mediated and microwave assisted coupling between 2,6-diaminopyridine and nitriles. A new synthetic route to N-(6-aminopyridin-2-yl)carboximidamides

The Chinese-lantern-type Co2(O2CBut)4{2,6-(NH2)2C5H3 N}2 complex reacts with RCN (R = Me or Prn) under microwave irradiation (MWI) to give the mononuclear amidine complexes Co(O2CBut)2{H2N(C5H3 N)NHC(R)=NH} (R = Me (4a) or Prn (4c)). Under microwave irradiation, the addition of 2,6-diaminopyridine to acetonitrile in the presence of the pivalate complexes Co2(μ2-OH2)(O2CBut)4(HO2CBut)4 (1) or [Co(OH)n(O2CBut)2−n ]x (2) afforded complex 4a in higher yield compared to the corresponding reaction performed earlier without MWI. The use of MWI makes it possible to perform analogous reactions with nitriles RCN (R = Et, Prn, or Ph) giving rise to complexes 4b—d, respectively. Compounds 4a—d were characterized by elemental analysis and IR spectroscopy. The structure of complex 4c was established by X-ray diffraction. Amidines H2N(C5H3N)NHC(R)=NH, which formed in the coordination sphere of cobalt(II), were isolated in the free state from methanolic solutions of complexes 4a—d under the action of Na2S and were characterized by electrospray mass spectrometry and 1H and 13C{1H} NMR spectroscopy. The reactions of 2-aminopyridine with both complexes 1 and 2 in acetonitrile under microwave irradiation produced the Co(O2CBut)2(H2NC5H4N)2 complex.

Titanium(IV) Chloride Promoted Syntheses of New Imidazo[1,2-a]pyridine Derivatives under Microwave Conditions

A new method is described for the synthesis of imidazo[1,2-a]pyridine derivatives from the reaction of 2-aminopyridines with α-haloketones. The critical reagent is titanium(IV) chloride, which appears to serve as a strong dehydrating agent to promote formation of putative Schiff base intermediates, which cyclize subsequently to form the products. The reactions were performed rapidly under microwave conditions. Multiple reaction conditions were evaluated, including reaction temperature, solvent and other Lewis acids. Various combinations of substitution patterns in both the α-haloketone and 2-aminopyridine substrates were examined to evaluate the scope of the reaction. The reaction is quite sensitive to substituents in both substrates, especially those with basicity or coordination ability.

Polymorphism in an Ionic Pair 2-Aminopyridyl-CoII Complex: Role of N−H···Cl Hydrogen Bonds and π···π Interactions in Tuning the Columnar Packing

The reaction of 2-aminopyridine with cobalt dichloride hexahydrate in solution leads to the isolation of a novel ion pair complex (1). Blue blocklike or plate crystals were obtained upon crystallizing the compound from an acetone solution with or without the presence of nickel(II) acetate dihydrate, which were confirmed to be its two polymorphs. X-ray structure analysis shows that phase A crystallizes in the monoclinic space group Cc, while phase B crystallizes in the triclinic space group P1. The two polymorphs display interesting and remarkably different molecular packing features via strong hydrogen bonds and π···π stacking interactions. The one-dimensional (1D) columnar π···π stacking mode distributed with charge is very significant, and the arrangements are remarkably different for the molecular orientation and interatomic distances in the two phases. Both N−H···Cl and C−H···Cl hydrogen bonds exist in the two polymorphs, which play an essential role in constructing the resulting three- or two-dimens...

Preparation of a Fast-Flow Agarose-Based Chelating Adsorbent with a Novel Dioxime Derivative for Selective Column Preconcentration of Copper

Fast-flow spherical homogeneous agarose beads were prepared by an emulsification method, and were cross-linked and activated by repeated treatment with allylbromide and bromine/water, followed by alkali. Bis(2-aminopyridyl)dioxime (APD) was synthesized by the reaction of 2-aminopyridine, and dichloroglyoxime and characterized by melting-point as well as IR, 1HNMR, 13CNMR and MS spectroscopies. APD was chemically linked to activated agarose beads to be employed for the column preconcentration of metal ions. Capacity measurements for eight metal ions indicated a high selectivity of the adsorbent towards Cu2+ with a capacity of 25.7 micromol per ml packed adsorbent. A factorial design was used for optimization of the effects of 5 different variables on the recovery of Cu2+. Under the optimized conditions, Cu2+ was quantitatively accumulated on a 0.25 ml packed column of the adsorbent in the pH range of 4 to 6, and simply eluted with 2 ml of a 1 mol 1(-1) hydrochloric acid solution. The column could tolerate salt concentrations up to 0.5 mol 1(-1), sample flow rates up to 15 ml min(-1), and sample volumes beyond 1000 ml. Matrix ions of Na+, Mg2+ and Ca2+ and potentially interfering ions of Ni2+, Cd2+, Zn2+, Fe3+ and Co2+ with relatively high concentrations did not show any significant effect on the analyte's signal. Preconcentration factors up to 500 and a detection limit of 0.16 microg 1(-1) were obtained for the determination of the analyte by flame AAS. Application of the method to the determination of natural and spiked copper in river water and seawater samples resulted in quantitative recoveries.

Fluorine‐Containing Pyrido[1,2‐a]quinazolin‐6‐ones.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Fluorine-containing pyrido[1,2-a]quinazolin-6-ones

Reactions of 2-aminopyridine and 2-amino-5-methylpyridine with 2,3,4,5-tetrafluorobenzoyl chloride afforded N,N’-diaroylpyridinium salts, which were converted into 6H-pyrido[1,2-a]quinazolin-6-ones by refluxing in toluene in the presence of triethylamine. The angular structure of the tricyclic derivatives obtained was confirmed by 19F and 13C NMR spectroscopy and 2D heteronuclear HetCOR and HMBC experiments.

Regiospecific Synthesis of 3‐Substituted Imidazo[1,2‐a]pyridines, Imidazo[1,2‐a]pyrimidines, and Imidazo[1,2‐c]pyrimidine.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Regiospecific synthesis of 3-substituted imidazo[1,2-a]pyridines, imidazo[1,2-a]pyrimidines, and imidazo[1,2-c]pyrimidine.

3-Substituted imidazo[1,2-a]pyridines, imidazo[1,2-a]pyrimidines, and imidazo[1,2-c]pyrimidine were obtained regiospecifically in yields of 35-92% in one pot by reaction of 2-aminopyridines or 2-(or 4-)aminopyrimidines, respectively, with 1,2-bis(benzotriazolyl)-1,2-(dialkylamino)ethanes.