Reactions of the carbanion of chloromethyl methyl sulfone with aldehydes and ketones

Addition of the carbanion of chloromethyl methyl sulfone to aldehydes and ketones proceeds faster than its degradation via the Ramberg-Baecklund reaction. Chlorohydrins and oxiranes produced from aldehydes treated with an excess of base undergo the Ramberg-Baecklund reaction giving allylic alcohols, whereas the reaction of ketones gives the oxiranes.     

芳香族硝基化合物与苯硫酚钠盐的亲核取代反应: 自由基IPSO取代机理

作者通过苯硫酚钠盐与对硝基苯甲酸甲酯(1), 对硝基苯甲酸苯酯(2), 间硝基苯甲酸甲酯(3), 3,5-二硝基苯甲酸甲酯(4)和对二硝基苯(5)反应研究, 用自旋捕获技术检测到苯硫基自由基; 同时, 从产物混合物中分离到二苯基二硫化物PhSSPh。提出苯硫基自由基与芳香族硝基化合物1,2,3,4和5反应的自由基IPSO亲核取代机理。     

Reduction of aromatic nitro compounds with phosphine

The reduction of 1- and 2-nitronaphthalene and of some mono- and dinitro-biphenyls with phosphine was carried out under the conditions described by Buckler.¹ Reduction of 1-nitro-naphthalene did not yield any crystalline product while reduction of 2-nitronaphthalene yielded benzo[f]naphtho[2,1-c]cinnoline-N-oxide together with 2,2′-azoxynaphthalene. The mononitro-biphenyls and 4,4′-dinitrobiphenyl were readily reduced to azoxy compounds, while reduction of 2,2′-dinitrobiphenyl gave benzo[c]cinnoline-N,N′-dioxide.     

Regioselectivity in SNH reactions of some 3-nitro-1,8-naphthyridines with chloromethyl phenyl sulfone

A number of 2-X-3-nitro-1,8-naphthyridines (X= H,D,OH,Cl,NH₂, OEt) react with the anion of chloromethyl phenyl sulfone exclusively into 2-X-3-nitro-4-(phenylsulfonylmethyl)-1,8-naphthyridines in high yield. The reaction is found by quantum chemical calculations to be controlled by the interactions of the HOMO of the nucleophile with the LUMO of the substrate, and not by charge.     

Low-temperature copper hydrosilicates: catalysts for reduction of aromatic nitro compounds with molecular hydrogen

Russian Chemical Bulletin - The catalytic reduction of aromatic nitro compounds with hydrogen was carried out for the first time over low-temperature copper hydrosilicates synthesized at...     

Intramolecular aromatic nucleophilic substitution of the benzimidazole-activated nitro group

A wide range of 2-(2-nitrophenyl)-1H-benzimidazoles undergo high-yielding intramolecular S(N)Ar of nitrite with N-pendant alkoxides under mild conditions (DMF, rt). When this operationally simple process is carried out at elevated temperatures in the presence of excess NaH, the initially formed S(N)Ar products are converted to the corresponding N-vinyl-substituted 2-(2-hydroxyphenyl)-1H-benzimidazoles via base-catalyzed isomerization. [reaction: see text]     

Spectrophotometric determination of reducing sugars with aromatic nitro compounds

Summary It has been found that mononitro-aromatic compounds can be used as quite sensitive reagents for determination of reducing sugars, and use of 2-, 3- and 4-nitrobenzoic and 3-nitrobenzenesulphonic acids has been investigated. Reduction of these reagents with sugars gives a yellow product which can be determined spectrophotometrically. The sugar (0.5–7 mg) is heated with fixed concentrations of reagent, base and sodium potassium tartrate for a prescribed time, at 100° C. The method can also be used for determination of the number-average molecular weight of dextran fractions if the molecular weight is not too high.

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Spektrophotometrische Bestimmung reduzierender Zucker mit aromatischen Nitroverbindungen

Zusammenfassung Aromatische Mononitroverbindungen lassen sich als ziemlich empfindliche Reagenzien zur Bestimmung reduzierender Zucker verwenden. 2-, 3-und 4-Nitrobenzoesäure und 3-Nitrobenzolsulfonsäure wurden zu diesem Zweck verwendet. Die Reduktion dieser Reagenzien durch Zucker gibt eine Gelbfärbung, die spektrophotometrisch ausgewertet werden kann. Der Zucker (0,5-7 mg) wird mit einer bestimmten Menge Reagens sowie mit einer Base und Seignettesalz für eine bestimmte Zeit auf 100° C erhitzt. Das Verfahren kann auch für die Bestimmung des durchschnittlichen Molekulargewichtes von Dextranfraktionen verwendet werden, soferne diese nicht zu hochmolekular sind.

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Presented at the 8th International Microchemical Symposium, Graz, August 25–30, 1980.     

Lewis acid catalyzed substitution of allylic nitro compounds with cyanotrimethylsilane

The nitro group in allylic nitro compounds is replaced by cyano group on treatment with cyanotrimethylsilane in the presence of Lewis acid.     

Charge-transfer complexes of pyrimidine Schiff bases with aromatic nitro compounds

Charge-transfer (CT) complexes of pyrimidine Schiff bases, derived from condensation of 2-aminopyrimidine and substituted benzaldehydes, with some aromatic polynitro compounds were prepared and investigated using IR, UV, visible and (1)H NMR spectroscopy. For all solid complexes, the main interaction between the donor and acceptor molecules takes place through the π-π* interaction. Strong and some weak acidic acceptors, in addition interact through proton transfer from the acceptor molecule to the basic centre of the electron donor. Also, an n-π* transition was detected in some complexes.     

(2-Pyridyl)phenyl methanol: a new reagent for metal-free reduction of nitro aromatic compounds

As previously reported for 1-(2-pyridyl)-2-propen-1-ol, (2-pyridyl)phenyl methanol is able to react as hydrogen donor towards nitro aromatic and heteroaromatic compounds. Operating in the presence of methyl acrylate as an aza-Michael acceptor, a domino process involving reduction and conjugate addition steps allows the one pot formation of β-amino esters. The crucial role of the pyridine nucleus in making this purely thermal reactivity of carbinols possible has been shown.     

Pd/C-catalyzed transfer hydrogenation of aromatic nitro compounds using methanol as a hydrogen source

We describe the selective transfer hydrogenation of aromatic nitro compounds to anilines using Pd/C as a heterogeneous catalyst with methanol as a green reductant. Nitroarenes bearing both electron-releasing and electron-deficient groups are amenable to this method and enable the synthesis of corresponding arylamines in moderate to good selectivities including the synthesis of butamben, a local anesthictic drug molecule. This new concise protocol is simple, ligand-free and does not require the supply of external molecular hydrogen.     

Ammonia in the ion source. II. Clustering with aromatic nitro compounds

Under positive ion chemical ionization conditions with ammonla at relatively low pressure, aromatic nitro compounds do not form [M + H]⁺ ions but often form ionic clusters [M + NH₄]⁺ and [M + N₂H₇]⁺. Nitrobenzene forms a cluster [2M + NH₄]⁺ and aniline, formed by nucleophilic substitution, leads to a cluster [anilinium ion + nitrobenzene]⁺. The dinitrobenzenes form [M + NH₄]⁺ clusters and show evidence of nitroaniline formation and clustering. 1,3,5-Trinitrobenzene gives little indication of clustering or of substitution. The six isomers of trinitrotoluene appear to be stabilized by the methyl group and form clusters up to [M + N₃H₁₀]⁺. Nucleophilic substitution leads to dinitrotoluidines, which also form clusters with ammonium ions.     

Preparation of SF5 aromatics by vicarious nucleophilic substitution reactions of nitro(pentafluorosulfanyl)benzenes with carbanions

Vicarious nucleophilic substitutions (VNS) of hydrogen in 1-nitro-4-(pentafluorosulfanyl)benzene with carbanions provide 2-substituted 1-nitro-4-(pentafluorosulfanyl)benzenes in good to high yields. VNS of 1-nitro-3-(pentafluorosulfanyl)benzene gives a mixture of 6- and 4-substituted 1-nitro-3-(pentafluorosulfanyl)benzenes in 85:15 to >98:2 ratio and good to high yields. In basic media, the VNS reactions lead to the formation of carbanions that can be alkylated by alkyl halides affording the corresponding alkylated products in moderate yields. Transformation of primary products to substituted (pentafluorosulfanyl)anilines and 3- or 4-substituted (pentafluorosulfanyl)benzenes is also described.     

Uncatalyzed polymerization of bistriazolinediones with electron-rich aromatic compounds via electrophilic aromatic substitution

The reaction of 4-substituted-1,2,4-triazoline-3,5-diones(4R-TD's), i.e., MeTD(4-methyl substituted) and PhTD(4-Phenyl substituted) with electron rich aromatic compounds were investigated. N,N-Dimethylaniline undergoes reaction instantaneously with MeTD and PhTD. Electrophilic aromatic substitution occurred at room temperature at the para position without use of any catalyst. N,N,N′,N′-tetramethyl-m-phenylenediamine (TMPDA) undergoes reaction with 2 mol of PhTD and MeTD which lead to the formation of 2:1 adducts in high yields. These compounds were fully characterized by IR, ¹³C-NMR, ¹H-NMR and elemental analysis and were used as model compounds. The reaction of bistriazolinediones with TMPDA was performed in dimethylformamid at room temperature. The reactions are exothermic, fast, and gave novel polymer structures via electrophilic aromatic substitution. Some physical properties and structural characterization of these new polymers have been studied, and will be reported.     

Ultrathin platinum nanowire catalysts for direct C-N coupling of carbonyls with aromatic nitro compounds under 1 bar of hydrogen

Traditionally important in the pharmaceutical, agrochemical, and synthetic dye industries, C-N coupling has proved useful for the preparation of a number of valuable organic compounds. Here, a new method for the direct one-pot reductive C-N coupling from carbonyl and aromatic nitro compounds is described. Employing ultrathin platinum nanowires as the catalyst and hydrogen as the reducing agent, N-alkylamines were achieved in high yields. Debenzylation products were not detected after prolonged reaction times. Time-dependent analysis, ReactIR spectroscopy and DFT calculations revealed that the C-N coupling proceeded through a different mechanism than traditional "reductive amination." N-Alkylamines were directly obtained by intermolecular dehydration over platinum nanowires under a hydrogen atmosphere, instead of intramolecular water elimination and imine hydrogenation.     

Small ring compounds—XXX : Homolytical aromatic substitution and hydrogen abstraction reaction with cyclopropyl radical

Homolytic aromatic substitution and hydrogen abstraction reactions with cyclopropyl radical were carried out to determine the reactivity and ionic character of cyclopropyl radical by examination of the orientation effect, partial rate factor and influence of substituents. By thermal decomposition of biscyclopropaneformyl peroxide in a series of substituted benzenes, the corresponding cyclopropylated benzene derivatives (the mixture of ortho, meta and para isomers) were obtained in moderate yield. In view of the orientation effect and the partial rate factor, the cyclopropyl radical seems to be fairly free from polar effect, and to resemble the phenyl radical more than the common alkyl radical although the cyclopropyl radical has a slightly higher reactivity than the phenyl radical. The relative reactivity of the 2-phenylcyclopropyl radical in the hydrogen abstraction reaction toward the benzylic position of ring-substituted toluenes gave good Hammett's correlation with the slope of + 0·20 suggesting little ionic character in the transition state. This result was in good agreement with the conclusion obtained from homolytic aromatic substitution reaction and with the chemical reactivity to be expected from the non-planar nearly sp²-hybridized conformation of the cyclopropyl radical.