Design,Synthesis, and Biological Evaluations of Several Y‐26732 Analogues

A series of pyridine Rho kinase inhibitors were designed and synthesized utilizing the ligand‐binding pocket model with Y‐26732 as the lead compound. These compounds were evaluated on cell lines for their biological activities.     

Palladium-catalyzed direct arylation of pyridine N-oxide with 2-bromoacetanilides. Synthesis of benzisoxazolo[2,3-a]pyridinium tetrafluoroborates

The synthesis of a variety of novel benzisoxazolo[2,3-a]pyridinium tetrafluoroborates is described. These compounds are conveniently prepared from pyridine N-oxide via a microwave-promoted palladium-catalyzed direct arylation of pyridine N-oxide with 2-bromoacetanilides to give 2-(2-acetamidoaryl)pyridine N-oxides, followed by hydrolysis, diazotization and intramolecular displacement of nitrogen which affords the target benzisoxazolo[2,3-a]pyridinium tetrafluoroborates.     

Studies on antiulcer drugs. V. Synthesis and antiulcer activity of aralkylbenzazoles.

A series of 2-alkylamino-5- or 6-aralkyl-substituted benzazoles were synthesized and tested for histamine H2-receptor antagonist and anti-stress ulcer activities. These new compounds showed little or no histamine H2-receptor antagonist activity in contrast to imidazo[1,2-a]pyridine analogues (I). On antiulcer assay, however, some pyridine derivatives (II) exerted higher activity than the reference compounds, sofalcone, sucralfate and cimetidine. The structure-activity relationships of these compounds are discussed.     

Novel strategy for three-dimensional fragment-based lead discovery

Fragment-based drug design (FBDD) is considered a promising approach in lead discovery. However, for a practical application of this approach, problems remain to be solved. Hence, a novel practical strategy for three-dimensional lead discovery is presented in this work. Diverse fragments with spatial positions and orientations retained in separately adjacent regions were generated by deconstructing well-aligned known inhibitors in the same target active site. These three-dimensional fragments retained their original binding modes in the process of new molecule construction by fragment linking and merging. Root-mean-square deviation (rmsd) values were used to evaluate the conformational changes of the component fragments in the final compounds and to identify the potential leads as the main criteria. Furthermore, the successful validation of our strategy is presented on the basis of two relevant tumor targets (CDK2 and c-Met), demonstrating the potential of our strategy to facilitate lead discovery against some drug targets.     

Syntheses and oxidation of methyloxorhenium(V) complexes with tridentate ligands

Four new methyloxorhenium(V) compounds were synthesized with these tridentate chelating ligands: 2-mercaptoethyl sulfide (abbreviated HSSSH), 2-mercaptoethyl ether (HSOSH), thioldiglycolic acid (HOSOH), and 2-(salicylideneamino)benzoic acid (HONOH). Their reactions with MeReO(3) under suitable conditions led to these products: MeReO(SSS), 1, MeReO(SOS), 2, MeReO(OSO)(PAr(3)), 3, and MeReO(ONO)(PPh(3)), 4. These compounds were characterized spectroscopically and crystallographically. Compounds 1 and 2 have a five-coordinate distorted square pyramidal geometry about rhenium, whereas 3 and 4 are six-coordinate compounds with distorted octahedral structures. The kinetics of oxidation of 2 and 3 in chloroform with pyridine N-oxides follow different patterns. The oxidation of 2 shows first-order dependences on the concentrations of 2 and the ring-substituted pyridine N-oxide. The Hammett analysis of the rate constants gives a remarkably large and negative reaction constant, rho = -4.6. The rate of oxidation of 3 does not depend on the concentration or the identity of the pyridine N-oxide, but it is directly proportional to the concentration of water, both an accidental and then a deliberate cosolvent. The mechanistic differences have been interpreted as reflecting the different steric demands of five- and six-coordinate rhenium compounds.     

Synthesis and characterization of 4-(alkylaminoisonitrosoacetyl)biphenyls and their complexes

Three new substituted 4-(alkylaminoisonitrosoacetyl)biphenyls (ligands) derived from 4-biphenylhydroxymoyl chloride and corresponding amines were synthesized. The following aromatic and aliphatic amines were used for ligands: ethanolamine, 2-amino-4-methylphenol, and 2-(aminomethyl)pyridine. Mononuclear or binuclear cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II), and lead(II) complexes with these ligands were synthesized. These compounds were characterized by elemental analyses, AAS, infrared spectra, and magnetic susceptibility measurements. The ligands were additionally characterized by ¹H NMR. The results suggest that the ligands act as tridentate ligands. The text was submitted by the authors in English.     

Arylation of halogenated thiophene carboxylate via Suzuki–Miyaura reaction: Anti-bacterial study against clinically isolated extensively drug resistant Escherichia coli sequence type 405 and computational investigation

In present study, Pd(0) catalysed Suzuki-Miyaura cross coupling reaction was used to synthesize 2,4-biarylphenyl-5-arylthiophene-2-carboxylate (7a–7f) and 2-aryl-4-chlorophenyl-5-arylthiophene-2-carboxylate derivatives (8a–8l) in moderate to good yields. While 2,4-dibromophenyl-5-bromothiophene-2-carboxylate (4) and 2-bromo-4-chlorophenyl-5-bromothiophene-2-carboxylate (5) were synthesized via Steglich esterification of 5-bromothiophene-2-carboxylic acid (1) with 2,4-dibromo phenol (2) and 2-bromo-4-chlorophenol (3) in the presence of N, N?-dicyclohexylcarbodiimide (DCC) and 4-(dimethylamino)pyridine (DMAP). ¹H and ¹³C NMR were used to confirm all of the compounds. To screen out the most active lead compounds, binding interactions of all synthesized compounds with MurD and MurE Escherichia coli proteins were evaluated theoretically via molecular docking studies indicating the good binding affinities. DFT calculations were performed out by using DFT-B3LYP/3-21g and structural and reactivity parameters were calculated. Compounds 5, 8b, 8e, 8h, and 8j have demonstrated potential reactivities and charge distributions that indicate their efficiency towards biological targets. These chemicals were tested in vitro for antibacterial activity against Gram-negative bacteria (Escherichia coli) at different concentrations based on theoretical results. The total results were quite close to the theoretical predictions and compound 8j was found to be having the greatest potential value, strongest binding affinities, and a promising antibacterial agent with MIC value of 50 mg/ml against Escherichia coli.     

新型含吡啶环取代的吡唑肟醚类化合物的合成及生物活性研究

为了寻找新型高效低毒的农药先导化合物,通过N-吡啶基吡唑肟与2-氯-5-氯甲基吡啶的缩合反应,合成了一系列含吡啶环取代的吡唑肟醚类化合物.目标化合物的结构均经1H NMR,13C NMR和元素分析确证.初步生物活性试验结果表明,部分化合物具有一定的杀菌、杀虫和植物生长调节活性.如化合物5e在浓度为50 μtg/mL时对番茄早疫的抑制率为61.4％;化合物5j在浓度为50 μg/mL时对花生褐斑的抑制率为60.2％;化合物5i在浓度为500 μg/mL时对蚜虫表现出50.3％的杀死率;化合物5f在浓度为10 μg/mL时对黄瓜子叶生根表现出71.0％的促进生长作用.     

Synthesis of 3,5-difunctionalized 1-methyl-1H-pyrazolo[3,4-b]pyridines involving palladium-mediated coupling reactions

Indirect iodination of 2-chloro-nicotinonitrile gave 2-chloro-5-iodonicotinonitrile, which was cyclized with methylhydrazine to lead to 3-amino-5-iodopyrazolo[3,4-b]pyridine. Position 3 was then protected by pivaloyl group and the resulting 5-iodo-3-pivaloylaminopyrazolo[3,4-b]pyridine was engaged in palladium-promoted coupling reactions with various reagents to give 3-pivaloylamino-5-substituted compounds. Deprotection and iododediazoniation followed by cross-coupling reactions in position 3 afforded novel unsymmetrical 3,5-disubstituted pyrazolo[3,4-b]pyridine species.     

Preparation and characterization of novel basic polysulfone polymers

Two synthesis routes for the preparation of novel base‐modified polysulfones (PSUs; Udel®) were investigated: (1) the addition of the basic aromatic ketones 2,2′‐dipyridylketone and 4,4′‐bis‐(diethylamino)benzophenone and the basic aromatic aldehydes N,N‐dimethylamino‐benzaldehyde, pyridine‐2‐aldehyde, pyridine‐3‐aldehyde, and pyridine‐4‐aldehyde to lithiated PSU and (2) the reaction of lithiated PSU with basic aromatic carboxylic acid esters such as 4‐N,N‐dimethylaminobenzoic acid ethylester, pyridine‐2‐carboxylic acid ethylester, pyridine‐3‐carboxylic acid ethylester, and pyridine‐4‐carboxylic acid ethylester. Both synthesis routes lead to a high degree of conversion, without the occurrence of crosslinking. This is remarkable, especially for the reaction of lithiated PSU with the ester compounds, because the ? (C?O)? Ar groups formed by the reaction of the ester with PSU–Li are not further converted with the remaining PSU–Li sites to (crosslinked) PSU? C(? OLi)? Ar? PSU alcoholates, as normally observed when esters are reacted with Li‐organic compounds. Starting with dilithiated PSU, we obtained degrees of substitution of 0.8–2 groups per PSU repeating unit. The structures and compositions of the modified PSU polymers were confirmed with NMR spectroscopy and elemental analysis. The modified polymers were also characterized via thermogravimetric analysis (thermal stability). Interestingly, the product of the reaction of lithiated PSU with 4,4′‐bis‐(diethylamino)benzophenone could be oxidized to a deep blue polymeric dye that showed proton self‐conductivity. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2874–2888, 2001     

Synthèse régiosélective par voie organométallique de pyridines, 4-picolines et 3,5-lutidines substituées en 2 par un groupe insaturé et/ou fonctionnel

A regioselective one-pot synthesis of 2-substituted pyridine derivatives from N-alkoxycarboxylpyridinium salts and α-unsaturated organozinc compounds is described. Similarly, functional alkynyl organomagnesium compounds lead to 2-alkynyl-ω-functional pyridines, from which (E)-2-alkenyl or 2-alkyl-ω-functio pyridines can be obtained by partial or complete reduction.     

2-Aryl-4H-3,1-benzoxazin-4-ones alcoholysis

The reaction of 2-(2-tosylaminophenyl)-4H-3,1-benzoxazine-4-one with alcohols in pyridine gives tosylanthraniloylanthranilic acid esters. The synthesized compounds luminesce in the crystalline state and in solutions at room temperature. The anomalously high Stokesian shift characteristic for this series of compounds is due to intramolecular hydrogen bonding with the participation of the tosylamino group. Interaction of polar solvents and irradiation with UV light lead to cleavage of the hydrogen bond, and as a consequence, to a decrease in the Stokesian shift.     

Decarboxylative Fluorination of 2-Pyridylacetates

Syntheses of substituted pyridines and fluorinated compounds, which are often pharmaceutical targets, are important objectives in organic chemistry. Herein, we found that decarboxylative fluorination of lithium 2-pyridylacetates occur under catalyst-free conditions. The phenomenon can be applied to one-pot transformation of substituted methyl 2-pyridylacetate to 2-(fluoroalkyl)pyridine by decarboxylative fluorination of the intermediate lithium 2-pyridylacetate. This method was also applied to the syntheses of 2-(difluoroalkyl)pyridines.     

新型桥连双卟啉化合物的合成及结构表征

通过将4,4′-二羧基-2,2′-联吡啶、2,6-二溴甲基吡啶、2,6-二羟甲基吡啶和1,8-二氨基萘分别与5-(4-羟基苯基)-10,15,20-三苯基卟啉(1a)、5-(4-甲酰苯基)-10,15,20-三苯基卟啉(1b)和5-[4-(4′-溴代丁氧基)苯基]-10,15,20-三苯基卟啉(1c)反应,合成了3类新型的双卟啉化合物2a-2e,经IR,¹HNMR,MS,UV-Vis光谱及元素分析对中间体和目标化合物的结构进行了表征.     

Copper-bispidine coordination chemistry: syntheses,structures, solution properties,and oxygenation reactivity

Copper(I) and copper(II) complexes of two mononucleating and four dinucleating tetradentate ligands with a bispidine backbone (2,4-substituted (2-pyridyl or 4-methyl-2-pyridyl) 3,7-diazabicyclo[3.3.1]nonanone) have been prepared and analyzed structurally, spectroscopically, and electrochemically. The structures of the copper chromophores are square pyramidal, except for two copper(I) compounds which are four-coordinate with one noncoordinated pyridine. The other copper(I) structures have the two pyridine donors, the co-ligand (NCCH(3)), and one of the tertiary amines (N3) in-plane with the copper center and the other amine (N7) coordinated axially (Cu-N3 > Cu-N7, approximately 2.25 A vs 2.20 A). The copper(II) compounds with pyridine donors have a similar structure, but the axial amine has a weaker bond to the copper(II) center (Cu-N3 < Cu-N7, approximately 2.03 A vs 2.30 A). The structures with methylated pyridine donors are also square pyramidal with the co-ligands (Cl(-) or NCCH(3)) in-plane. With NCCH(3) the same structural type as for the other copper(II) complexes is observed, and with the bulkier Cl(-) the co-ligand is trans to N7, leading to a square pyramidal structure with the pyridine donors rotated out of the basal plane and only a small difference between axial and in-plane amines (2.15, 2.12 A). These structural differences, enforced by the rigid bispidine backbone, lead to large variations in spectroscopic and electrochemical properties and reactivities. Oxygenation of the copper(I) complexes with pyridine-substituted bispidine ligands leads to relatively stable mu-peroxo-dicopper(II) complexes; with a preorganization of the dicopper chromophores, by linking the two donor sets, these peroxo compounds are stable at room temperature for up to 1 h. The stabilization of the peroxo complexes is to a large extent attributed to the square pyramidal coordination geometry with the substrate bound in the basal plane, a structural motif enforced by the rigid bispidine backbone. The stabilities and structural properties are also seen to correlate with the spectroscopic (UV-vis and Raman) and electrochemical properties.     

Efficient synthesis of 2-(trifluoromethyl)nicotinic acid derivatives from simple fluorinated precursors

Novel routes to 2-trifluoromethyl-nicotinic acid derivatives have been developed involving synthesis of the pyridine ring. These pyridyl compounds serve as key intermediates in the manufacture of the recently discovered COMT inhibitor, 3-(5-(3,4-dihydroxy-5-nitrophenyl)-1,2,4-oxadiazol-3-yl)-2-(trifluoromethyl)pyridine 1-oxide.     

Stabilization of High‐Valence Ruthenium with Silicotungstate Ligands: Preparation,Structural Characterization,and Redox Studies of Ruthenium(III)‐Substituted α‐Keggin‐Type Silicotungstates with Pyridine Ligands, [SiW11O39RuIII(Py)]5−

Ruthenium(III)‐substituted α‐Keggin‐type silicotungstates with pyridine‐based ligands, [SiW₁₁O₃₉Ru^III(Py)]^5?, (Py: pyridine ( 1 ), 4‐pyridine‐carboxylic acid ( 2 ), 4,4′‐bipyridine ( 3 ), 4‐pyridine‐acetamide ( 4 ), and 4‐pyridine‐methanol ( 5 )) were prepared by reacting [SiW₁₁O₃₉Ru^III(H₂O)]^5? with the pyridine derivatives in water at 80 °C and then isolated as their hydrated cesium salts. These compounds were characterized using cyclic voltammetry (CV), UV/Vis, IR, and ¹H NMR spectroscopy, elemental analysis, titration, and X‐ray absorption near‐edge structure (XANES) analysis (Ru K‐edge and L₃‐edge). Single‐crystal X‐ray analysis of compounds 2 , 3 , and 4 revealed that Ru^III was incorporated in the α‐Keggin framework and was coordinated by pyridine derivatives through a Ru? N bond. In the solid state, compounds 2 and 3 formed a dimer through π? π interaction of the pyridine moieties, whereas they existed as monomers in solution. CV indicated that the incorporated Ru^III–Py was reversibly oxidized into the Ru^IV–Py derivative and reduced into the Ru^II–Py derivative.     

Spectral (u.v.-vis,i.r.MS), electrochemical and metallochromic properties of 2-hydroxy-benzoylhydrazones of acetylpyridines

The synthesis, electronic, infra-red and mass spectra of salicyloylhydrazones of 2-, 3-, and 4-acetylpyridine are reported. Ultraviolet absorption spectra have been applied to determine the dissociation constants which are ranged between 4.0–4.5 (pyridine nitrogen) and 6.2–6.3 (OH group). Infrared spectra show that strong intramolecular H-bonding exists in the solid compounds. Fragmentation of these compounds were found to undergo skeletal rearrangement in addition to either CON or NN simple bond cleavage; pyridine nitrogen position contributes in the paths leading to ions. These aroylhydrazones exhibit polarograms that show several reduction waves, the positions of which change with the pH value. Of the three compounds, 3-pyridyl derivative was the most difficult to reduce. The chelating properties of the compounds towards metal ions were investigated. The 2-acetylpyridine derivative results to be the most adequate ligand, as well as a good preconcentrating agent for metal ions.     

Synthesis,Structure, and Reactivity of Lewis Base Stabilized Plumbacyclopentadienylidenes

Plumbacyclopentadienylidenes, in which the lead atoms have divalent states and are coordinated by THF, pyridine and N‐heterocyclic carbene, were synthesized and characterized. The THF‐ and pyridine‐stabilized compounds can be regarded as rare examples of hypervalent 10‐X‐4 species. The equilibrium between the THF adduct and the free plumbacyclopentadienylidene was evidenced by spectroscopic analysis and theoretical calculations. The THF adduct in benzene converted into a plumbylene dimer, where one of the lead centers is coordinated by THF and the other lead atom is coordinated by a divalent lead atom, the dimer gradually decomposing into spiroplumbole. The THF adduct unexpectedly reacted with trifluoroborane and trichlorogallane to afford fluoroborole and chlorogallole, which are the first examples of non‐annulated fluoroborole and gallole, respectively.     

Synthesis of various fused heterocyclic rings from thiazolopyridine and their pharmacological and antimicrobial evaluations

Various fused-heterocyclic-derivatives containing thiazolopyridine moieties has been synthesized by allowing 5-aminothiazolo[3,2-a]pyridine derivative 1 to undergo annulations reactions with different reagents under different-reaction conditions. The biological assessment of compounds 2 , 11 , 14 , 15 , and 19 showed remarkable antimicrobial activities. In addition, selected derivatives of the products were screened for their anticancer activities against two tumor cell lines using MTT assay and the results showed that some of these compounds have potent cytotoxic effect, as concluded from their IC₅₀ values. Meanwhile, compounds 3a , 7 have exhibited very strong potency as anticancer candidates. Thiazolopyridine structures have been confirmed as a useful lead compounds for the development of new anticancer agents. Molecular docking showed that,-some of the synthesized compounds more suitable inhibitor against-ALR2 with farther alteration in future.