Reaction Of Nitroalkanes Research Articles

New Method for the Reaction of Nitroalkanes with Unsaturated Esters

New Method for the Reaction of Nitroalkanes with Unsaturated Esters

ChemInform Abstract: Anti‐Selective Michael Addition of Thiols and Their Analogues to Nitro Olefins.

The reaction of nitro olefins with thiolate anions followed by protonation at −78 o C gives anti-β-nitro sulfides. This procedure can be applied to the anti-selective preparation of β-nitro ethers and β-nitro selenides. The reaction of cyclic nitro olefins with aryl thiol gives cis-β-nitro sulfide in excellent selectivity. The conjugate addition of alkylaluminum reagents to phenylthio β-nitro olefins followed by protonation at −78 o C also results in selective formation of anti-β-nitro sulfides. Theoretical calculations show that the methylthio group on the β-position covers the one side of the nitronate plane effectively to give the anti isomer in a stereoselective way

ChemInform Abstract: Reaction of Nitroalkenes with Iodotrimethylsilane: A New Method for the Conversion of Vinyl Nitro Steroids to Keto Steroids.

AbstractTreatment of the nitrocholestane derivatives (I) with sodium iodide and trimethylsilyl chloride results in predominant formation of the keto steroids (II).

Anti-selective Michael addition of thiols and their analogs to nitro olefins

The reaction of nitro olefins with thiolate anions followed by protonation at −78 o C gives anti-β-nitro sulfides. This procedure can be applied to the anti-selective preparation of β-nitro ethers and β-nitro selenides. The reaction of cyclic nitro olefins with aryl thiol gives cis-β-nitro sulfide in excellent selectivity. The conjugate addition of alkylaluminum reagents to phenylthio β-nitro olefins followed by protonation at −78 o C also results in selective formation of anti-β-nitro sulfides. Theoretical calculations show that the methylthio group on the β-position covers the one side of the nitronate plane effectively to give the anti isomer in a stereoselective way

Reaction of nitro-alkenes with iodotrimethylsilane: a new method for the conversion of vinyl nitrosteroids to ketosteroids

Iodotrimethylsilane generated in situ from chlorotrimethylsilane and sodium iodide effects the reduction of nitro-alkenes (1a–e) and (5) at –5 to 0 °C to furnish the ketones (2a–e) and (6) respectively as the major products.

ChemInform Abstract: Alumina‐Supported Potassium‐Fluoride‐Promoted Reaction of Nitroalkanes with Electrophilic Alkenes: Synthesis of 4,5‐Dihydrofurans and Isoxazoline N‐Oxides.

ChemInform Abstract: Alumina‐Supported Potassium‐Fluoride‐Promoted Reaction of Nitroalkanes with Electrophilic Alkenes: Synthesis of 4,5‐Dihydrofurans and Isoxazoline N‐Oxides.

ChemInform Abstract: Synthesis and a Novel Fragmentation of 6‐Alkoxy‐5,6‐dihydro‐4H‐1,2‐oxazine 2‐Oxide.

An electron-deficient nitro olefin, methyl α,p-dinitrocinnamate, reacts with vinyl ethers to give cyclic nitronic esters, which are stable as compared with those produced by reactions of nitro olefins with enamines. Stability of the cyclic nitronate depends on the properties of the substituents at 4- and 6-positions of the ring. The adducts undergo fragmentation by a catalytic amount of base to β,γ-unsaturated α-hydroxyimino esters.

ChemInform Abstract: Novel Addition of Nitroalkanes to o‐Quinones.

AbstractThe fused ortho‐benzoquinones (I), (IV), (VI), and (VIII) react with the branched nitroalkanes (II) to produce the 1,3‐dioxoles (III), (V), (VII), and (IX).

Synthesis and a Novel Fragmentation of 6-Alkoxy-5,6-dihydro-4H-1,2-oxazine 2-Oxide

Abstract An electron-deficient nitro olefin, methyl α,p-dinitrocinnamate, reacts with vinyl ethers to give cyclic nitronic esters, which are stable as compared with those produced by reactions of nitro olefins with enamines. Stability of the cyclic nitronate depends on the properties of the substituents at 4- and 6-positions of the ring. The adducts undergo fragmentation by a catalytic amount of base to β,γ-unsaturated α-hydroxyimino esters.

Synthesis of Fragrance Compounds, 4-Oxononanal and Methyl Jasmonate by the Michael Reaction of Nitroalkane with Acrolein Catalyzed with Tertiary-phosphine

4-Oxoaldehydes, which are important intermediates for the syntheses of terpenoids and jasmonoids, are prepared from the reaction of nitroalkane with acrolein catalyzed by tertiary-phosphine as tributylphosphine, tricyclohexylphosphine or triphenylphosphine, followed by Nef reaction of the resulting 4-nitro aldehyde ethylene acetals. The Michael reaction of nitroethane (1 a) with acrolein was carried out using a variety of tertiary-phosphines as catalysts in benzene at room temperature. Acetalization in situ gave 1, 1-ethylenedioxy-4-nitropentane (2a) in 68% yields. In the reaction of nitroalkane (1 b) (1g) with acrolein, 4-nitro ethylene acetals (2b) (2g) were obtained in 62-70% yields. 4-Nitroethylene acetals (2e), (2f) were subjected to an electrochemical oxidative Nef reaction to give 4-oxoaldehydes (4e), (4f). These compounds were converted respectively to 4-oxononanal and 2- hydroxy-5-pentyltetrahydrofuran, the latter being an essential oil found in watermelon. Dihydro- and cis-methyl jasmonate (7) were prepared from 4-oxoaldehydes (4).

High‐Pressure Syntheses: The Henry Reaction

High yields of nitro alcohols in the reaction of nitroalkanes with ketones (Henry reaction) could, until now, only be obtained in a limited number of special cases. However, use of high pressure and n-Bu4NF as catalyst considerably extends the range of application of the Henry reaction.

Reaction of nitroolefins with raney nickel and sodium hypophosphite. A mild method for converting nitroolefins into ketones (or aldehydes).

Nitroolefins are converted into the corresponding saturated ketones or aldehydes in high yield by treatment with Raney nickel and sodium hypophosphite in aqueous ethanol at pH 5.

Nitroalkylation of aromatic hydrocarbons promoted by manganese(III) acetate

Additional mechanistic and synthetic details concerning the formation of nitroalkylated aromatic products from the reaction of nitroalkanes with manganese(III) acetate and an aromatic compounds are presented. A large isotope effect (k/sub H//k/sub D/ = 4.02-4.20) was found for both manganese(III)-and cerium(IV)-promoted nitromethylations with nitromethane-d/sub 3/ while no isotope effect (k/sub H//k/sub D/ = 1.05) was observed with benzene-d/sub 6/. This indicated that deprotonation (most likely from an aci radical cation) to the nitromethyl radical is the slow step while subsequent rearomatization of a sigma-radical complex occurs rapidly. Somewhat more convenient methods of activating the manganese(III) acetate promotor were found. However, attempts to find cooxidants or other additives which could improve this process met with only limited success. The reaction of either toluene or benzene with nitroethane or the nitropropanes and manganese(III) acetate in refluxing acetic acid gave much poorer fields (3 to 8%) of the corresponding nitroalkylated products. Incorporation of sodium acetate into these systems completely elimiated the aromatic substituttion products and formed ..cap alpha..-nitroalkyl acetates instead. Implications of this finding on the mechanism for the generation of nitroalkyl radicals are discussed.

A new synthesis of olefins. Conversion of nitroolefins into olefins by reductive elimination

A nitro group in nitroolefins is displaced by hydrogen giving the corresponding olefins in good yields by the reaction of nitroolefins with sodium sulfide in the presence of benzenethiol. It proceeds rapidly at room temperature.

Reactions of nitroalkenes with ynamines; synthesis of stable four-membered cyclic nitrones and X-ray crystal structure of 2-(NN-diethylcarbamoyl)-2,4-dimethyl-3-phenyl-2,3-dihydroazete 1-oxide

2,3-Dihydroazete 1-oxides (3b–e), the first examples of crystalline, ‘stable’, four-membered cyclic nitrones, are formed by reaction of 1-nitroalkenes with ynamines, and other products are 3-nitrocyclobutenes; the structure of the cyclic nitrone (3b) has been determined by X-ray crystallography.

Importance of C4a- and N5-covalent adducts in the flavin oxidation of carbanions.

The reaction of nitroalkanes, furoin, and phenacyl alcohol with 7- and 8-cyano-3,10-dimethylisoalloxazine (7-CNFlox, 8-CNFlox), 5-ethyl-3-methyllumiflavinium ion (Flox+Et), and 2.6-dichloroindophenol (DCI) have been studied. Nitromethane anion forms an adduct on reaction with Flox +Et. The condensation reaction has been shown (nuclear magnetic resonance) to occur through addition of the methylene carbon of the nitromethane anion to the 4a position of Flox+Et. This adduct undergoes spontaneous dissociation to its components in acid. It does not undergo conversion in base to reduced flavin (1,5-F1EtH), NO2-, and CH2O. For this reason one may conclude that nitroalkane anion oxidation by flavin does not involve the intermediacy of a 4a-covalent intermediate. Oxidation of nitroalkane anion through formation of an N5-flavin adduct is discussed in terms of the peculiar requirements of the substrate when compared with carbanions derived from normal flavoenzyme substrates. It is concluded that the mechanism of nitroalkane oxidation by flavin must bear no relationship to the flavin oxidation of normal substrates. Furoin and phenacyl alcohol (compounds containing the-CH(OH)--CO-functionality) are oxidized by 8-CNFlOX, 7-CNFlOX, DCI and by the N5-blocked flavin Flox+Et. These reactions are found to be zero order in oxidant at the concentrations of oxidants (approximately 1.0 X 10(-5) M) and reductant (approximately 10(-3) to 10(-4) M) employed. This finding, and that of an 1H/2H kinetic isotope effect of 3.5, as well as certain equalities of the determined rate constants establish the rate-determining step in all these oxidations to be carbanion formation. That the N5-blocked flavin (Flox+Et) serves just as well as an oxidant as do substituted and unsubstituted isoalloxazines provides evidence that the flavin oxidation of carbanions of general structure (-C-(OH)--CO-) does not require the formation of an intermediate N5-flavin adduct. This conclusion when taken with the fact that the N5-flavin adduct formed on reaction of dihydroflavin with -C(=O)--CO-is not an intermediate in the reduction of -C(=O)--CO-to -CH(OH)--CO- by dihydroflavin shows that N5 adducts do not arise as intermediates in these oxidations. Remaining mechanisms (4a addition and radical pair formation) are discussed. 4a addition of carbanions to Flox+Et is shown to be subject to considerable steric strain by the instability of the nitroethane adduct and the inability to observe the formation of the 2-nitropropane adduct.

ChemInform Abstract: THE NITROALKANE ANOMALY

The effect of substituents on the reaction of nitroalkanes with base is analyzed in terms of two interactions which influence both rate and equilibrium constants and two others which affect the rat...

The Nitroalkane Anomaly

The effect of substituents on the reaction of nitroalkanes with base is analyzed in terms of two interactions which influence both rate and equilibrium constants and two others which affect the rates alone. The results of these calculations serve to explain the Brønsted relation with negative exponent given by data for the series nitromethane, nitroethane, and 2-nitropropane reacting with hydroxide ion, and also the Brønsted exponents greater than unity recently observed for the reactions of aryl-substituted nitroalkanes with hydroxide ion and other bases.

The di-(2-alkyl-2-nitroethyl)-methylamines from reactions of nitroalkanes with formaldehyde and methylamine

Di-(2-alkyl-2-nitroethyl)-methylamines obtained from reactions of nitroalkanes with formaldehyde and methylamine were separated in diastereoisomers. NMR assignments of meso and racemic forms, and conformations are discussed. Partial separation of racemates into enantiomers was carried out by liquid-solid chromatography, on an optically-active adsorbent.

Reactions of nitroalkanes in the gas phase. Part 1.—Pyrolysis of nitromethane

The pyrolysis of nitromethane has been studied between 305 and 440°C. The reaction is pressure dependent. Above 150 mm, it is approximately first order, k= 1014.1 exp (–55,200/RT) sec–1. The principal products are methane, carbon monoxide, nitrogen, nitric oxide, hydrogen cyanide and water. The results are explained by considering the reactions of methyl: CH3·+ CH3NO2→ CH4+·CH2NO2, CH3·+ NO2→ CH3NO2, CH3·+ NO2→ CH3O·+ NO, CH3·+ NO → CH3NO The product distribution depends on the relative concentrations of nitric oxide and nitrogen dioxide in the system, and this is confirmed by studying the ratio of products formed on addition of excess formaldehyde and nitrogen dioxide.