Synthesis of substituted azaoxindoles for the preparation of aza-tenidap analogs

The preparation of a set of eight azaoxindoles bearing substituents on the aromatic nucleus is outlined. These compounds were required for the preparation of aza-analogs of the anti-inflammatory oxindole tenidap. Two methods of synthesis were used, the first involving the addition of malonate to 2-chloro-3-nitropyridine derivatives followed by nitro group reduction and one-pot cyclization/hydrolysis/decarboxylation. The second method, utilizing the vicarious nucleophilic substitution (VNS) reaction of nitropyridine derivatives (followed by nitro group reduction and one-pot cyclization/hydrolysis), constitutes a novel route to azaoxindoles.     

Synthesis of novel nitro-substituted triaryl pyrazole derivatives as potential estrogen receptor ligands

Novel tetrasubstituted pyrazole derivatives bearing a nitro substituent on their A-phenol ring were synthesized and their binding affinity towards the estrogen receptor (ER) subtypes ERalpha and ERbeta was determined. Among compounds tested, the 2-nitrophenol derivative 5c was found to bind satisfactorily to both estrogen receptor subtypes (RBAalpha=5.17 and RBAbeta=3.27). In general, the introduction of a nitro group into the A ring of these compounds was found to benefit their ERbeta binding abilities.     

Synthesis of nitro and amino N-heterocycles via ring transformation of 2-methyl-3-nitrochromone

2-Methyl-3-nitrochromone ( 1 ) reacted with acid hydrazides, S-methylisothiourea, hydroxylamine and ethyl aminoethanoate to give the nitro derivatives of pyrazole 2 , pyrimidine 6 , isoxazole 11 and pyrrole 13 , respectively. These nitro compounds were reduced by catalytic hydrogenation to the corresponding amino derivatives. In the case of 2 , a rearrangement of the acyl group took place during the reduction. Substitution reactions of the 2-methylthio group in 6 were also described.     

Synthesis of p-Nitro-stilbene Derivatives with Different Linking Bonds:An Attempt to Tune Spectroscopy of Dyes with Molecular Engineering

The synthesis, characterization and spectroscopy of a range of novel substituted p‐nitro‐stilbene derivatives with different bridging bonds were presented. The molecular structure characterization was carried out with ¹H NMR, ¹³C NMR and elemental analysis. The ultraviolet/visible spectroscopy and photoluminescence of the compounds were investigated in various solvents. The maximal absorption wavelength of the nitro‐stilbene derivatives with an ether bond exhibited approximate 30 to 40 nm bathochromic shift compared to that of nitro‐stilbene dyes with an ester bond. Furthermore, the nitro‐stilbene derivatives with an ether bond displayed obvious photoluminescence, while the nitro‐stilbene derivatives with an ester bond showed weak fluorescence emission. The detection of the cyclic voltammograms of the nitro‐stilbene derivatives showed that the nitro‐stilbene compounds with different linking bonds exhibited different redox proceses at various scan rates. The theroretical calculations of HOMO and LUMO energy of nitro‐stilbene derivatives showed that the energy gaps between HOMO and LUMO of 3 and 4 were lower than those of 1 and 2 . The electron density of the frontier orbitals of nitro‐stilbene derivatives was observed to be affacted by the linking bonds, which thus made it possible to tune the spectroscopy of these dyes with chemical strategy. The differential scanning calorimetry and thermogravimetry showed that the thermal stabilities of these dyes were not much affected by the linking bond. The results presented in this paper would be great interest in development of ideal nitro‐stilbene derivatives for special purposes.     

N-（4＇-取代嘧啶-2＇-基）-取代苯氧基磺酰脲的合成及除草活性

光谱;N-（4＇-取代嘧啶-2＇-基）-取代苯氧基磺酰脲的合成及除草活性     

Computational study on energetic properties of nitro derivatives of furan substituted azoles

Density functional theory has been used to investigate geometries, heats of formation (HOFs), C-NO₂ bond dissociation energies (BDEs), and relative energetic properties of nitro derivatives of azole substituted furan. HOFs for a series of molecules were calculated by using density functional theory (DFT) and Møller–Plesset (MP2) methods. The density is predicted using crystal packing calculations; all the designed compounds show density above 1.71 g/cm³. The calculated detonation velocities and detonation pressures indicate that the nitro group is very helpful for enhancing the detonation performance for the designed compounds. Thermal stabilities have been evaluated from the bond dissociation energies. Charge on the nitro group was used to assess the impact sensitivity in this study. According to the results of the calculations, tri- and tetra-nitro substituted derivatives reveal high performance with better thermal stability.     

Characterisation of Plasmodium falciparum aspartic protease inhibition by piperidine derivatives

Piperidine derivatives are reported to exhibit a variety of pharmacological activities. In this article, synthesis and aspartic protease inhibitory activity of three nitrophenacyl derivatives of N-methyl-4-hydroxy piperidine are reported. Enzyme assays showed that the attachment of a nitro group in the benzene ring plays an important role in the inhibition of plasmepsin-II of Plasmodium falciparum. The compound 1-methyl-1-(4'-nitrophenacyl)-4-hydroxypiperidinium bromide (3), consisting of a nitro group at the para position, was the most active at the concentration of 1.0?μM. The activity of the compounds was evaluated through the observed orientation and diagrammatic representation of nitrophenacyl derivatives of 4-hydroxy piperidine.     

Palladium-catalyzed intramolecular α-arylation of aliphatic ketone, formyl, and nitro groups

Intramolecular arylation of properly designed substrates bearing a ketone, formyl, or nitro terminating group was achieved by use of a PdCl₂(Ph₃P)₂-Cs₂CO₃ reaction system to form a variety of carbocyclic compounds. Arylation in ketone compounds afforded benzene-annulated bridged or spirocycloalkanone derivatives, depending on the structure of the cyclization precursors. Arylation in formyl compounds occurred at the α-position (α-arylation) or at the carbonyl carbon (carbonyl-arylation) depending on the structure of the cyclization precursors and on the reaction solvent. An α-arylated secondary nitro group was partially transformed to ketone in the manner of the Nef reaction, whereas a tertiary nitro group was partially eliminated to afford a styrene-type olefin.     

One-pot preparation of azobenzenes from nitrobenzenes by the combination of an indium-catalyzed reductive coupling and a subsequent oxidation

We demonstrated how a reduction step with a reducing system comprised of In(OTf)₃ and Et₃SiH and a subsequent oxidation that occurred under an ambient (oxygen) atmosphere allowed the highly selective and catalytic conversion of aromatic nitro compounds into symmetrical or unsymmetrical azobenzene derivatives. This catalytic system displayed a tolerance for the functional groups on a benzene ring: an alkyl group, a halogen, an acetyl group, an ester, a nitrile group, an acetyl group, an ester moiety, and a sulfonamide group.     

BER催化还原一些含氮功能基化合物的研究

用强碱性阴离子交换树脂制备了硼氢阴离子交换树脂还原剂(BER),使其在氯化铜等金属化合物的催化下还原一些芳香硝基、氰基、氮氮双键等含氮功能基化合物.还研究了BER的制备条件:如温度、溶剂、不同金属化合物对还原反应的影响,并初步探讨其反应机理.     

吡啶硝化衍生物的合成及应用

综合评述了吡啶类化合物的硝化合成方法及近年来的研究进展，对其中较重要的氮氧化－硝化法进行了讨论，并介绍了该类衍生物在农药、医药、有机合成等方面的应用情况。     

Synthesis of Oxidized Nitro-Polycyclic Aromatic Hydrocarbons

A series of phenolic and cis-dihydrodiol derivatives of 6-nitrobenzo[a] pyrene and 7-nitrobenz[a]anthracene were synthesized. The common structural feature of these compounds is that their nitro groups are perpendicular or near perpendicular to the aromatic moieties. From the synthesis of these compounds, it was found that an acetoxy group does not affect the regioselectivity of electrophilic nitration to a polycyclic aromatic hydrocarbon (PAH) and that a nitro substituent can substantially reduce the concerted electrophilic 1,2-addition of osmium tetroxide to the most olefinic aromatic double bond of a PAH.     

Palladium-catalysed transfer hydrogenation of aromatic nitro compounds — an unusual chain elongation

Aromatic nitro compounds are reduced via transfer hydrogenation in the presence of palladium on magnesium-lanthanum mixed oxide support in ethanol yielding the corresponding amines. With several acetophenone derivatives, the reduction was accompanied by chain elongation whilst the carbonyl group remained intact.     

New Adamantane Derivatives with NO-Generating Fragment

An approach to the synthesis of adamantane derivatives with NO-generating fragment containing nitroxy group has been developed. 1-Aminoadamantane, memantine, and adamantanecarboxylic acid have been used as initial compounds. The prepared compounds have shown ability to generate nitric oxide in a system mimicking biological reactions of nitro group reduction.     

ESR and electrochemical study of 5-nitroindazole derivatives with antiprotozoal activity

The electrochemistry of 3-alkoxy- and 3-hydroxy-1-[omega-(dialkylamino)alkyl]-5-nitroindazole derivatives were characterized using cyclic voltammetry in DMSO. The nitro reduction process was studied and this was affected by the acid moieties present in these compounds. A nitro anion self-protonation process was observed. This phenomenon was studied by cyclic voltammetry in presence of increasing amount of NaOH. The reactivity of the nitro anion radical of these derivatives with glutathione was also studied by cyclic voltammetry. The oxidizing effect of glutathione is supported by the parallel decrease of the anodic peak current and increase of the cathodic peak in the cyclic voltammograms, corresponding to the wave of the nitro anion radical from uncharged species with the addition of glutathione. Nitro anion radicals obtained by electrolytic reduction of these derivatives were measured and analyzed in DMSO using electron spin resonance spectroscopy.     

The proton magnetic resonance spectra of some disubstituted acetophenones

An accurate measurement of the chemical shifts and the coupling constants of some disubstituted acetophenones has been made. The acetophenones studied contained nitro, bromo or amino groups substituted in either the 3,4 or 2,5 positions. For compounds with no substituent adjacent to the acetyl group, the chemical shifts and the coupling constants estimated by the simple additivity of the substituent increments were found to be in reasonable agreement with the experimental values. The two nitro, bromo derivatives substituted in positions 2 and 5 probably prefer the conformer in which the proton H-6 is adjacent to the acetyl methyl group whilst the 3,4-disubstituted bromo, nitro and bromo, amino derivatives prefer the conformer in which the H-6 proton is adjacent to the carbonyl group.     

Electrochemical reduction of nitrotetralones

The electrochemical reduction of three nitrotetralone derivatives by tast and differential pulse polarography and cyclic voltammetry in a wide pH range was studied. In aqueous media, the reduction of mono- and dinitrotetralone follows the general pattern of reduction of aromatic nitro compounds: the nitro group is reduced in a four-electron step to a hydroxylamine group. However, in mixed media this reduction differs from that of other nitrobenzenes, due to the fact that the formation of the nitroradical anion was not observed. The reduction of the acetoxy derivative was studied only at alkaline pH, because it suffered acid hydrolysis. The ionization pK of the protonatable groups were polarographically obtained.     

1-苯基-3-甲基-6-N,N-二正丁基胺-2(1H)-喹喔啉-2-酮的全合成

报道了2(1H)-喹喔啉类衍生物——1-苯基-3-甲基-6-N,N-二正丁基胺-2(1H)-喹喔啉-2-酮的全合成.该化合物及其中间体1-苯基-3-甲基-6-胺基-2(1H)-喹喔啉-2-酮和1-苯基-3-甲基-6-硝基-2(1H)-喹喔啉-2-酮均为新化合物,文中给出了它们的重要的分析数据,简要讨论了溶剂在关环反应以及N-烷基化反应中的重要影响,偶然发现以水作溶剂时关环主产物为1-苯基-3-甲基-5-硝基-苯并咪唑.这类化合物可应用于药物,如用作N-甲基-D-天冬氨酸(NMDA)受体及α-氨基羟甲基异噁唑丙酸(AMMPA)受体拮抗剂、杀菌剂等;还可用作植物生长抑制剂、荧光探针以及作为新型功能染料中间体等诸多领域.     

Quantum-chemical parameters of 2-substituted 5-nitrofuran derivatives

Quantum-chemical parameters of molecules of 2-substituted 5-nitrofuran derivatives were calculated using the GAMESS software package and their correlation with the antibacterial activity of the compounds was analyzed. Regression analysis technique was employed to find linear relationships between the logarithm of the average inhibiting concentration of 5-nitrofuran derivatives and the quantum-chemical parameters. The largest correlation coefficient (0.932) was found for the dependence of the antibacterial activity on the amount of charge on the nitrogen atom of the nitro group. The results obtained are in agreement with modern concepts about the nature of the antibacterial activity of 2-substituted 5-nitrofuran derivatives.     

Desoxy-nitrozucker. 2. Mitteilung Herstellung geschützter 1-Desoxy-1-nitroaldosen

Synthesis of Protected 1-Deoxy-1-nitroaldoses The direct oxidation of the oxime 1 with t-butyl hydroperoxide and vanadyl acetylacetonate yielding the nitro derivative 2 (54%, Scheme 1) could not be applied to other oximes. Diastereoselective bromination of the aldonolactone oxims 7 and 10–12 according to known procedures gave the corresponding bromonitroso compounds which were oxidized to the bromonitro compounds 9, 14, 18 and 22 , respectively. Oxidation of the bromonitroso compound in the D-mannopyranose series proved difficult, but the corresponding chloronitro derivative 23 was easily obtained according to Corey & Estreicher (Scheme 2 and 3). The structure of the bromonitro compound 9 was determined by an X-ray analysis, and the configurations of the bromonitro compounds 14, 18 and 22 were deduced from their molecular rotations. Reduction of the bromonitro compounds gave the protected 1-deoxy-l-nitroaldoses 2 , 15/16 , 19/20 , and 24/25 , respectively, in good overall yields. The ribose derivatives 15 and 16 were detritylated to give the nitro compound 4 , and the mannose derivative 2 was partially deprotected to give the monoisopropylidene compound 26 . The nitro group shows a normal anomeric effect which is reflected in the IR . spectra of the pyranose derivatives 19 and 20 , and 24 and 25 .