Aliphatic Nitro Compounds Research Articles

Inhibition of LDL oxidation and inflammasome assembly by nitroaliphatic derivatives. Potential use as anti-inflammatory and anti-atherogenic agents

We have previously shown the antioxidant and anti-inflammatory properties of several para-substituted arylnitroalkenes. Since oxidative stress and inflammation are key processes that drive the initiation and progression of atherosclerosis, in the present work the antioxidant, anti-inflammatory and anti-atherogenic properties of an extended library of aryl-nitroaliphatic derivatives, including several newly designed nitroalkanes, was explored. The antioxidant capacity of the nitroaliphatic compounds, measured using the oxygen radical absorbance capacity assay (ORAC) showed that the p-methylthiophenyl-derivatives were about three times more effective than Trolox to prevent fluorescein oxidation, independently of the presence or the absence of the double bond next to the nitro group. The peroxyl radical scavenger capacity of the p-dimethylaminophenyl-derivatives was even higher, being the reduced form of these compounds even more active. In fact, while the antioxidant capacity of 1-dimethylamino-4-(2-nitro-1Z-ethenyl)benzene and 1-dimethylamino-4-(2-nitro-1Z-propenyl)benzene was 4.2 ± 0.1 and 5.4 ± 0.1 Trolox Eq/mol, respectively; ORAC values obtained with the ethyl and the propyl derivatives were 10 ± 1 and 13 ± 2 Trolox Eq/mol, respectively. The p-dimethylamino-derivatives, especially the nitroalkanes, were also able to prevent LDL oxidation mediated by peroxyl radicals. Oxygen consumption due to the oxidation of fatty acids was delayed in the presence of the dimethylamino substituted compounds, only the alkanes interrupted the chain of lipid oxidations decreasing the rate of oxygen consumption. Although the formation of foam cells in the presence of oxidized-LDL (oxLDL) remained unaffected, the molecules containing the dimethylamino moiety were able to decrease the expression of IL-1β in LPS/INF-γ challenged macrophages.

O2‐Mediated Oxidation of Aminoboranes through 1,2‐N Migration

In analogy to the classical reaction of C-B bonds with peroxides, the first oxidative functionalization of aminoboranes through a 1,2-N migration was realized. Readily available aliphatic nitro compounds are thereby transformed into N- and O-functionalized hydroxylamines in a single synthetic operation. Addition of hazardous peroxides is avoided. Instead, the insertion of O2 , as the terminal oxidant, into Zn-C bonds provides the necessary peroxides. The required zinc organyls, in turn, are formed through a boron-to-zinc exchange, from an organoboronic ester byproduct of the nitro-to-aminoborane transformation.

O2‐Mediated Oxidation of Aminoboranes through 1,2‐N Migration

AbstractIn analogy to the classical reaction of C−B bonds with peroxides, the first oxidative functionalization of aminoboranes through a 1,2‐N migration was realized. Readily available aliphatic nitro compounds are thereby transformed into N‐ and O‐functionalized hydroxylamines in a single synthetic operation. Addition of hazardous peroxides is avoided. Instead, the insertion of O2, as the terminal oxidant, into Zn−C bonds provides the necessary peroxides. The required zinc organyls, in turn, are formed through a boron‐to‐zinc exchange, from an organoboronic ester byproduct of the nitro‐to‐aminoborane transformation.

Direct Reductive N-Functionalization of Aliphatic Nitro Compounds.

The first general protocol for the direct reductive N-functionalization of aliphatic nitro compounds is presented. The nitro group is partially reduced to a nitrenoid, with a mild and readily available combination of B2 pin2 and zinc organyls. Thereby, the formation of an unstable nitroso intermediate is avoided, which has so far severely limited reductive transformations of aliphatic nitro compounds. The reaction is concluded by an electrophilic amination of zinc organyls.

Efficient and Selective N-Methylation of Nitroarenes under Mild Reaction Conditions.

Herein, we report a straightforward protocol for the preparation of N,N-dimethylated amines from readily available nitro starting materials using formic acid as a renewable C1 source and silanes as reducing agents. This tandem process is efficiently accomplished in the presence of a cubane-type Mo3 PtS4 catalyst. For the preparation of the novel [Mo3 Pt(PPh3 )S4 Cl3 (dmen)3 ]+ (3+ ) (dmen: N,N'-dimethylethylenediamine) compound we have followed a [3+1] building block strategy starting from the trinuclear [Mo3 S4 Cl3 (dmen)3 ]+ (1+ ) and Pt(PPh3 )4 (2) complexes. The heterobimetallic 3+ cation preserves the main structural features of its 1+ cluster precursor. Interestingly, this catalytic protocol operates at room temperature with high chemoselectivity when the 3+ catalyst co-exists with its trinuclear 1+ precursor. N-heterocyclic arenes, double bonds, ketones, cyanides and ester functional groups are well retained after N-methylation of the corresponding functionalized nitroarenes. In addition, benzylic-type as well as aliphatic nitro compounds can also be methylated following this protocol.

Catalytic Reductions and Tandem Reactions of Nitro Compounds Using in Situ Prepared Nickel Boride Catalyst in Nanocellulose Solution.

A mild and efficient method for the in situ reduction of a wide range of nitroarenes and aliphatic nitrocompounds to amines in excellent yields using nickel chloride/sodium borohydride in a solution of TEMPO-oxidized nanocellulose in water (0.01 wt %) is described. The nanocellulose has a stabilizing effect on the catalyst, which increases the turnover number and enables low loading of nickel catalyst (0.1-0.25 mol % NiCl2). In addition, two tandem protocols were developed in which the in situ formed amines were either Boc-protected to carbamates or further reacted with an epoxide to yield β-amino alcohols in excellent yields.

Greener Synthesis of Reduced Graphene Oxide‐Nickel Nanocomposite: Rapid and Sustainable Catalyst for the Reduction of Nitroaromatics

AbstractAn efficient one‐pot method for the preparation of reduced graphene oxide‐nickel nanocomposite (RGO−Ni) has been developed using L‐ascorbic acid as a greener reducing agent, which simultaneously reduces both graphene oxide and NiII. The nanocomposite was characterized using various analytical techniques such as Fourier Transform Infrared Spectroscopy (FT‐IR), Powder X‐Ray Diffraction analysis(PXRD), Raman, Inductively Coupled Plasma‐Optical Emission Spectroscopy (ICP‐OES), Energy Dispersive X‐ray Spectroscopy (EDS), Scanning Electron Microscopy (SEM), High‐Resolution Transmission Electron Microscopy (HRTEM), X‐ray Photoelectron Spectroscopy (XPS) and surface area measurements. ICP‐OES confirms the presence of 19.7% nickel loading and TEM shows the average size of the particles to be 10 nm. Subsequently, RGO−Ni nanocomposite was used as a sustainable catalyst for the reduction of nitroaromatics to the corresponding amines using NaBH4 in an aqueous methanol medium. A series of aromatic and aliphatic nitro compounds are chemoselectively reduced to amines over other reducible functionalities. RGO−Ni nanocomposite is highly stable, and can be recovered by magnetic separation and recycled for at least five consecutive cycles. The present catalytic system has achieved the dual requirements for reactivity and selectivity in a nitro reduction in short reaction time with minimum nickel load in greener media.

Hexafluoro-2-propanol-assisted quick and chemoselective nitro reduction using iron powder as catalyst under mild conditions

Hexafluoro-2-propanol as the promoter for the quick nitro reduction using a combination of iron powder and 2N HCl aqueous solution is reported. This methodology has several positive features, as it is of room temperature, remarkably short reaction time. A wide range of substrates including those bearing reducible functional groups such as aldehyde, ketone, acid, ester, amide, nitrile, halogens, even allyl, propargyl and heterocycles are chemoselectively reduced in good to excellent yields, even on gram scale. Notably, the highly selective reduction of 3-nitrophenylboronic acid is achieved quantitatively. The reduction is also tolerant of common protecting groups, and aliphatic nitro compound, 1-nitrooctane can be reduced successfully.

Aliphatic nitroalkanes: Evaluation of thermochemical data with complementary experimental and computational methods

Thermochemical properties of aliphatic nitroalkanes available in the literature are scarce and inconsistent. New standard molar enthalpies of vaporization and sublimation of 2-nitropropane, 2-methyl-2-nitropropane, and 2,3-dimethyl-2,3-dinitrobutane were derived from the vapor pressure temperature dependence measured by the transpiration method. Thermodynamic data on linear and branched aliphatic mono- and di-nitroalkanes available in the literature were combined with own experimental results and evaluated with help of empirical and theoretical methods aiming at recommendation of the sets of vaporization and formation enthalpies for aliphatic nitroalkanes as the reliable benchmark properties for further thermochemical calculations. Gas phase standard molar enthalpies of formation of aliphatic nitro-compounds derived by high-level quantum-chemical method G4 were found in a good agreement with the evaluated and recommended experimental data. Group-additivity procedure for calculation of vaporization and formation enthalpies have been developed and tested.

Tandem Transformation of Nitro Compounds into N-Methylated Amines: Greener Strategy for the Utilization of Methanol as a Methylating Agent.

A simple air- and moisture-stable, highly efficient ruthenium NNN pincer complex is reported for the first time to catalyze the tandem transformation of various aromatic and aliphatic nitro compounds into the corresponding N-methylated amines in up to 98 % yield by using methanol as a green methylating agent. Gram-scale reactions of challenging nitro substrates demonstrated the practical application aspects of this catalytic system. Importantly, the N-methylamine moiety could be smoothly introduced to various complex molecular structures without using any expensive palladium/phosphine/amine-based cross-coupling reactions.

English

Rauwolfia vomitoria Aftzel belong to the family of Apocynacea with a common name serpent wood and Igbo name as akanta. It is used traditionally to treat hypertension and rheumatoid arthritis. The present study deals with GC-MS determination and FT-IR analysis of methanolic root extract of the named plant. Exactly thirty phytochemical constituents have been identified by comparing the chromatogram peek values of unknown compounds with entries in NIST database. The major bioactive compounds were 2-Formyl-9-[b-d-ribofuranosyl]hypoxanthine (8.63%), 5-Cyclopropylcarbonyloxypenta-decane (5.58%), 1,2,5-Oxadiazol-3-carboxamide-4,4’-azobis-2,2’-dioxide (4.47%), 1-(5-Bicylco[2.2.1]heptyl)ethylamine (3.66%), 1-Adamantanemethylamine,a-methyl- (2.22%), Diphenylephrine (1.26%), Imidazole,2-amino-5-[(2-carboxy)vinyl]- (0.85%), Spiro[androst-5-ene-17,1’-Cyclobutan]-2’-one,3-hydroxy-,(3b,17b)- (0.82, and Cyclohexan-1,4,55-triol-3-one-1-carboxylic acid (0.65%). The FTIR spectrum confirmed the presence of alkyl halides, alcohols, phenols, secondary alcohols, tertiary alcohols, aromatic ethers, aldehydes, ketones, aliphatic nitro compound, aromatic organophosphorus compounds, aromatic compounds, carboxylic acid derivatives, alkenes, saturated ketones, and alkanes. Hence, this study offers bases of employing R. vomitoria as herbal alternative for the treatment of various diseases. Key words: Fourier transform infrared spectrometry (FTIR), gas chromatography-mass spectrometry (GC-MS), phytochemical, Rauwolfia vomitoria Aftzel.

New insights into the catalytic reduction of aliphatic nitro compounds with hypophosphites under ultrasonic irradiation

This work proposes an efficient process allowing the reduction of nitro compounds to the corresponding amines in water, at 70 °C with a quantitative conversion and a maximal yield in only 15 min thanks to the ultrasonic activation.

ChemInform Abstract: B(C6F5)3‐Catalyzed Reduction of Aromatic and Aliphatic Nitro Groups with Hydrosilanes.

AbstractA transition‐metal‐free, B(C6F5)3‐catalyzed deoxygenation of aromatic and aliphatic nitro compounds by Et3SiH affords the corresponding amines.

Selective reductive coupling of nitro aliphatic compounds with aldehydes in hydrogen using gold catalyst

Nitrones were synthesized in good yields directly from nitro aliphatic compounds, aldehydes, and H2 using highly dispersed gold nanoparticles on titania. The high selectivity for nitrone synthesis contrasts with the platinum supported on carbon and corresponds to an increase from roughly 50% to 90%. The catalytic performance is tuned by precise control of the structure of the active sites, the characteristics of the support and reaction conditions.

The toxicology mechanism of endophytic fungus and swainsonine in locoweed.

Locoweed is a perennial herbaceous plant included in Astragalus spp. and Oxytropis spp. that contains the toxic indolizidine alkaloid swainsonine. The livestock that consume locoweed can suffer from a type of toxicity called locoism. There are aliphaticnitro compounds, selenium, selenium compounds, and alkaloids in locoweed. The toxic component in locoweed has been identified as swainsonine, an indolizidine alkaloid. Swainsonine inhibits lysosomal a-mannosidase and mannosidase II, resulting in altered oligosaccharide degradation and incomplete glycoprotein processing. Corresponding studies on endophytic fungi producing swainsonine have been isolated from a variety of locoweed, and these endophytic fungi and locoweed have a close relationship. Endophytic fungi can promote the growth of locoweed and increase swainsonine production. As a result, livestock that consume locoweed exhibit several symptoms, including dispirited behavior, staggering gait, chromatopsia, trembling, ataxia, and cellular vacuolar degeneration of most tissues by pathological observation. Locoism results in significant annual economic losses. Therefore, in this paper, we review the current research on locoweed, including that on locoweed species distribution in China, endophyte fungus in locoweed, the toxicology mechanism of locoweed, and the swainsonine effect on reproduction.

Catalytic Hydrogenation of Aliphatic Nitro Compounds with Polysilane/Bone Charcoal‐Supported Palladium Catalysts under Continuous‐Flow Conditions

AbstractHydrogenation of aromatic nitro compounds has been widely studied, however, the catalytic hydrogenation of aliphatic nitro compounds remains a challenging topic. Herein, a polysilane/bone charcoal‐supported Pd catalyst with excellent catalyst activity for the hydrogenation of aliphatic nitro compounds under continuous‐flow conditions is described. The catalyst was synthesized by a simple procedure and analyzed by STEM and energy dispersive X‐ray spectroscopy (EDX) measurements. This polysilane/bone charcoal‐supported Pd catalyst demonstrated higher catalyst activity than conventional Pd/C, and a wide substrate scope including secondary and tertiary nitro compounds was achieved. Furthermore, no catalyst deactivation was observed during 120 h of continuous‐flow reaction without leaching of Pd.

Recent Developments in the Reduction of Aromatic and Aliphatic Nitro Compounds to Amines

The reduction of the nitro group represents a powerful and widely used transformation that allows to introducing an amino group in the molecule. New synthetic strategies for complex functionalized molecular architectures are deeply needed, including highly efficient and selective nitro reduction methods, tolerant of a diverse array of functional moieties and protecting groups. Since chiral amino groups are ubiquitous in a variety of bioactive molecules such as alkaloids, natural products, drugs, and medical agents, the development of reliable catalytic methodologies for the nitro group reduction is attracting an increasing interest also in the preparation of enantiomerically pure amines. In this context, the modern reduction methods should be chemoselective and respectful of the stereochemical integrity of the stereogenic elements of the molecule. The review will offer an overview of the different possible methodologies available for this fundamental transformation, with special attention on the most rece...

Reliable method for safety assessment of melting points of energetic compounds

This work presents a widely applicable model for the prediction of melting points of energetic compounds including organic peroxides, organic azides, organic nitrates, polynitro arenes, polynitro heteroarenes, acyclic and cyclic nitramines, nitrate esters and nitroaliphatic compounds. This method is based on the elemental composition of an energetic compound and the contribution of some specific polar groups/structural moieties as additive and non-additive functions, respectively. The new model was applied for 288 different energetic compounds including complex molecular structures. The average and maximum deviations of the suggested method are 6.8 and 21.1, respectively, which are much lower than the predicted values of two well-known different methods.

B(C6F5)3‐Catalyzed Reduction of Aromatic and Aliphatic Nitro Groups with Hydrosilanes

A transition‐metal‐free method for the hydrosilane reduction of aromatic and aliphatic nitro compounds to the corresponding amines is reported. Et3SiH is found to be the optimal reductant in this B(C6F5)3‐catalyzed deoxygenation. The functional‐group tolerance is, however, moderate.

ChemInform Abstract: Novel Approaches to Pharmacology‐Oriented and Energy Rich Organic Nitrogen—Oxygen Systems

AbstractReview: [79 refs.