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.     

Hydration and interfacial activity of methyl 8-pyridyloctanoates and extraction of copper(II) from chloride solutions

The interfacial tension of individual methyl 8-pyridyloctanoates containing the hydrophobic group at different positions of the pyridine ring was measured at the tolune/water interface. The extraction of copper(II) fom chloride solutions with these reagents was studied. Considering solvent extraction, methyl 8-(2-pyridyl)octanoate had a worse orientation at the interface than methyl 8-(3-pyridyl)octanoate and methyl 8-(4-pyridyl)octanoate. PM3 semiempirical quantum chemical computing indicates that the oxygen of the carbonyl group forms hydrogen bonds with water molecules more easily than the second oxygen atom and the nitrogen in the pyridine ring. However, at the adsorption layer, this hydration is possible only for methyl 8-(2-pyridyl)octanoate. Methyl 8-(3-pyridyl)octanoate and methyl 8-(4-pyridyl)octanoate are strong copper extractants from chloride solutions, while extraction is not observed for methyl 8-(2-pyridyl)octanoate.     

Fluoroalkyl chloroformates in treating amino acids for gas chromatographic analysis

Novel fluoroalkyl chloroformates with three and four carbon atoms were investigated for the immediate conversion of amino acids into hydrophobic derivatives in water-containing media. Derivatization conditions were extensively studied and optimized sample preparation protocols elaborated. More than 30 amino acids were treated with the particular reagent in isooctane by simply vortexing the reactive organic phase with a slightly basified aqueous medium containing pyridine or 3-picoline as a catalyst. Outstanding separation of nearly all components on 5% phenylmethylsilicone phase in gas chromatographic (GC) analysis with mass spectrometric (MS) or flame ionization detection (FID) required <10 min. Quantitation characteristics involving linearity in the range of 0.1-100 nmol, regression coefficients of 0.999-0.953 (histidine), MS limit of detection (LOD) reaching 0.03 pmol at proline to nearly 20 pmol at glutamic acid, plus electron impact (EI) spectra and diagnostic SIM fragment ions of the derivatives are reported. The novel method is simple, robust and rapid, enabling to treat amino acids in aqueous environment and to analyze them in <15 min.     

Hydrophobic “pocket” on photosynthesizing membrane near photosystem II

Studies concerning the effect of 2-alkyl pyridine N-oxides with different substituents on electron transfer, phosphorylation, and light-dependent proton transport in photosynthesizing membranes of chloroplasts were conducted. It is determined that 2-alkyl pyridine N-oxides with short alkyl chains stimulate the Hill reaction and light-dependent proton transport inside chloroplasts. Compounds having alkyl residues with 6-10 carbon atoms in the chain inhibit electron transport, ADP phosphorylation, and reduction of ferrocyanide in thylakoids. A conclusion is drawn on the presence of the hydrophobic “pocket,” which is of importance for organization of the electron-transport chain of chloroplasts, near photosystem II.     

Ruthenium-mediated regio- and stereoselective alkenylation of pyridine

A novel alkenylation reaction of pyridine is developed. Heating a cationic ruthenium vinylidene complex [CpRu(=C=CHR)(PPh(3))(2)]PF(6) in pyridine at 100-125 degrees C for 24 h affords (E)-2-alkenylpyridine. Initially, pyridine coordinates to ruthenium by displacement of one of the phosphine ligands. Then, [2 + 2] heterocycloaddition occurs to form a four-membered ruthenacyclic complex. Deprotonation of the beta-hydrogen affords a neutral pi-azaallyl complex. Protonolysis furnishes the product. As a result, a vinylidene group is inserted into the alpha C-H bond of pyridine. The alkenylation reaction is made catalytic in ruthenium by the use of (alkyn-1-yl)silane as the vinylidene source. Treatment of (alkyn-1-yl)trimethylsilane with pyridine in the presence of a cationic ruthenium complex [CpRu(PPh(3))(2)]PF(6) affords the corresponding (E)-2-alkenylpyridine in good yield in a regio- and stereoselective manner.     

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.     

Synthesis and structure of nitrogen bridged calix[5]- and -[10]-pyridines and their complexation with fullerenes

Azacalix[5]pyridine, a heteroatom bridged calixaromatic with an odd number of arene units, and azacalix[10]pyridine, a giant molecular belt, were selectively synthesized based on a 2 + 3 macrocyclic coupling strategy; both novel macrocyclic hosts formed strong 1 : 1 complexes with fullerenes C60 and C70 in a size-selective manner with association constants up to 1.3 x 10(5) +/- 0.03 x 10(5) M(-1).     

Pyridine-based coordination polymeric hydrogel with Cu2+ ion and its encapsulation of a hydrophobic molecule

We report the formation of a coordination polymeric hydrogel of a pyridine derivative with Cu(2+) and its efficiency as a delivery system for curcumin as a model hydrophobic drug.     

Catalytic Hydrolysis of Phosphate Diester with Metal Complexes of Macrocyclic Tetraamine in Comicellar Solution

Four novel pyridine or benzene ring‐containing pendant macrocyclic dioxotetraamines 2,6‐dixo‐l,4,7,10‐tetraazacyclododecane ligands have been synthesized. Their metal complexes have been investigated as catalysts for the hydrolysis of bis(p‐nitrophenyl) phosphate (BNPP) in aqueous comicellar solution. The results indicate mat the hydrophobic interaction between substrate and metal complex, the nature of transition metal ion, and the micellar microenvironment are important factors for the hydrolysis of BNPP. Large rate enhancement (up to over two‐three orders of magnitude) employing 5 has been observed.     

Design,Synthesis, and Insecticidal Activity of Novel Diacylhydrazine Derivatives Containing an Isoxazole Carboxamide or a Pyridine Carboxamide Moiety

Russian Journal of General Chemistry - In this study, two series of novel diacylhydrazine derivatives containing an isoxazole carboxamide or a pyridine carboxamide moiety have been synthesized and...     

Host-guest complexes of a water soluble cucurbit[6]uril derivative with some dications of 1,ω-alkyldipyridines: <Superscript>1</Superscript>H NMR and X-ray structures

Interactions between a symmetrical tetramethyl-substituted cucurbit[6]uril (host: TMeQ[6]) and 1,ω-alkylenedipyridine (ω = 2, 4, 6, 8, 10) dicationic guests were investigated using ¹H NMR spectroscopy and single crystal X-ray crystallography. In these inclusion complexes, combined cavity and portal binding in TMeQ[6] were observed, and the length of the bridged alkylene was found to play an important role not only in balancing the overall hydrophilic/hydrophobic interaction between the host and the guest, but also in defining the structure of the resulting inclusion complexes. For the guest 1,2-ethylenedipyridine (Edpy), TMeQ[6] includes a positively charged pyridine ring of Edpy to form an unsymmetrical inclusion complex; for the guest 1,4-butylenedipyridine (Bdpy), TMeQ[6] includes a positively charged pyridine ring of Bdpy, but the different competitive interactions in and between the related inclusion complexes could lead to a fast exchange between the hosts and guests. For the guests with longer bridge chains, such as 1,6-hexamethylenedipyridine (Hdpy) or 1,8-octylenedipyridine (Odpy), a stable pseudorotaxane inclusion complex is formed by combining the hydrophobic cavity and the outer portal dipole-ion interactions. However, for 1,10-decatylenedipyridine (Ddpy), the two TMeQ[6] host molecules include the two end pyridine rings of Ddpy and form a dumbbell inclusion complex. Supported by the National Natural Science Foundation of China (Grant Nos. 20662003 & 20767001), the International Collaborative Project of Guizhou Province (Grant No. 2007400108), the Science Technology Fund of Guizhou Province (Grant No. J-2008-2012) and the Natural Science Youth Foundation of Guizhou University (Grant No. 2007-005)     

Smiles rearrangement for the synthesis of 5-amino-substituted [1]benzothieno[2,3-b]pyridine

The Smiles rearrangement was successfully applied to 4-hydroxybenzo[b]thiophene furnishing a facile entry to the 4-amino derivative. The rearrangement was extended to 5-methoxy-4-methoxycarbonyl[1]benzothieno[2,3-b]pyridine obtained via aza-Wittig/electrocyclization reaction of novel N-(4-methoxybenzothiophen-2-yl)iminomethyldiphenylphosphorane with methyl trans-4-oxo-2-pentenoate. The preparation of a novel 5-amino-4-methoxycarbonyl[1]benzothieno[2,3-b]pyridine, which is of interest as a potential secondary peptide structure mimic, was successfully achieved.     

Synthesis of novel 1,2,3-triazole-containing pyridine–pyrazole amide derivatives based on one-pot click reaction and their evaluation for potent nematicidal activity against Meloidogyne incognita

Research on Chemical Intermediates - In order to find a novel, leading nematicide compound, a series of pyridine–pyrazole amide derivatives containing 1,2,3-triazoles were synthesized via...     

新型吡啶双亚胺铁催化乙烯聚合反应

合成与表征了一种新型吡啶双亚胺铁烯烃聚合催化剂2,6-二[1-(4-羟基-2,6-二甲基苯胺)乙基]吡啶氯化铁（1a）。结果表明,在亚胺环的对位引入羟基,可同时提高催化剂的活性和聚合物的分子量。在改性甲基铝氧烷(MMAO)的活化下,该催化剂引发乙烯聚合的活性（以单位时间（h）mol Fe引发乙烯聚合的PE质量（g）来表征）可达到6.78×10⁶ g/（mol•h）,明显高于已知催化剂2,6-二[1-(2,6-二甲基苯胺)乙基]吡啶氯化铁（1b）,且能得到更高分子量的聚乙烯。     

Synthesis of a new pyridine-containing diamine and related polyimide

<正>A new kind of aromatic diamine monomer containing pyridine unit,2,6-bis[4-(4-aminophenoxy)phenoxy]pyridine(BAPP),was synthesized in three steps,using hydroquinone as starting material.A novel pyridine-containing polyimide was prepared from the resulting diamine BAPP with 4,4'-oxydiphthalic anhydride(ODPA) via a conventional two-step thermal imidization method.The resulting polyimide exhibits excellent solubility,film-forming capability and high thermal resistance.     

Expeditious microwave-assisted synthesis and bio-evaluation of novel bis (trifluoromethyl) phenyl-triazole-pyridine hybrid analogues by the click chemistry approach

Research on Chemical Intermediates - A series of novel 1,2,3-triazole-2,4-bis(trifluoromethyl) phenyl pyridine hybrids 7a–n were efficiently synthesized by the click chemistry approach. The...     

Synthesis and biological evaluation of 1,3,4-oxadiazole fused pyridine derivatives as antibacterial and antifungal agents

Russian Journal of General Chemistry - A series of novel 1,3,4-oxadiazole fused pyridine derivatives were synthesized 11a–11f and their structures confirmed by IR, 1H NMR and Mass spectral...     

Utilization of potassium carbonate for the synthesis of 2-(organylsulfonyl)thieno[2,3-b]pyridine derivatives

Russian Chemical Bulletin - A novel preparative method for the synthesis of 2-(organylsulfonyl)thieno[2,3-b]pyridine derivatives has been developed, which allows one to obtain the desired products...     

Eosin Y catalysed visible-light mediated aerobic oxidation of tertiary amines

A mild and efficient one-pot visible light-induced method has been developed for the aerobic oxidation of saturated carbon conjugated with pyridine moiety with an important conversion in medicinal and synthetic organic chemistry. This eosin Y based organic transformations, exhibit a novel approach towards site selective functionalization of pyridine with enhance integrity and capability. This novel synthetic route may hold great potential for diverse functionalization of a wide range of pyridine moiety with an economical and sustainable manner.     

Synthesis,Characterization, Self‐Assembly,Gelation, Morphology and Computational Studies of Alkynylgold(III) Complexes of 2,6‐Bis(benzimidazol‐2′‐yl)pyridine Derivatives

A novel class of alkynylgold(III) complexes of the dianionic ligands derived from 2,6‐bis(benzimidazol‐2′‐yl)pyridine (H₂bzimpy) derivatives has been synthesized and characterized. The structure of one of the complexes has also been determined by X‐ray crystallography. Electronic absorption studies showed low‐energy absorption bands at 378–466 nm, which are tentatively assigned as metal‐perturbed π–π* intraligand transitions of the bzimpy^2? ligands. A computational study has been performed to provide further insights into the nature of the electronic transitions for this class of complexes. One of the complexes has been found to show gelation properties, driven by π–π and hydrophobic–hydrophobic interactions. This complex exhibited concentration‐ and temperature‐dependent ¹H NMR spectra. The morphology of the gel has been characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM).