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Both the maximum velocity and the Michaelis constant of the oxygenation of N,N-dimethylaniline with the pig liver microsomal FAD-containing monooxygenase (EC 1.14.13.8) to N,N-dimethylaniline N-oxide appear 1.7 folds greater in aqeous buffer solution of pH 7.4 than those in deuterium oxide buffer solution of pD 7.4.

1. The presence and properties of flavin monooxygenase (FMO) in liver of the marine teleost, turbot (Scophthalmus maximus) were examined in relation to organic xenobiotic metabolism and osmoregulation. 2. Hepatic microsomes of sexually mature fish contained NADPH-dependent FMO as evidenced by the conversion of N,N-dimethylaniline (DMA) to DMA-N-oxide, and immunorecognition of single bands (approximate apparent molecular weight of 55 kDa) by antibodies to mammalian FMO 1 and FMO 2. Additionally, Northern analysis using a full-length cDNA probe to mammalian FMO 1 revealed a single hybridizing band of approximately 2.5 kb. 3. No significant differences were seen between male and female turbot FMO with respect to DMA N-oxidase activity, levels of immunoreactive protein (with anti-FMO 1 or anti-FMO 2) and gene expression (hybridizing mRNA). 4. Hepatic microsomal DMA N-oxidase activity was inhibited by methimazole (an FMO substrate) and trimethylamine (TMA), but not by piperonyl butoxide (a P450 inhibitor). Inhibition by TMA is indicative of a role for FMO in osmoregulation, catalysing the conversion of TMA to TMA N-oxide. DMA N-oxidase activity was optimal at pH 8.8 and 25°C, and displayed Michaelis-Menten kinetics with respect to DMA (apparent Km = 88 μM).

A highly efficient and selective oxidation of primary and tertiary amines employing SO2F2/H2O2/base system was described. Anilines were converted to the corresponding azoxybenzenes, while primary benzylamines were transformed into nitriles and secondary benzylamines were rearranged to amides. For tertiary amine substrates quinolines, isoquinolines and pyridines, their oxidation products were the corresponding N-oxides. The reaction conditions are very mild and just involve SO2F2, amines, 30% aqueous H2O2 solution, and inorganic base at room temperature. One unique advantage is that this oxidation system is just composed of inexpensive inorganic compounds without the use of any metal and organic compounds.

An inexpensive, mild, and highly efficient epoxidation protocol has been developed involving bubbling SO2F2 gas into a solution of olefin, 30% aqueous hydrogen peroxide, and 4 N aqueous potassium carbonate in 1,4-dioxane at room temperature for 1 h with the formation of the corresponding epoxides in good to excellent yields. The novel SO2F2/H2O2/K2CO3 epoxidizing system is suitable to a variety of olefinic substrates including electron-rich and electron-deficient ones.

The reaction of p-cyano-N,N-dimethylaniline N-oxide, an O-atom donor, with different copper(I) complexes (at room temperature and in acetone) indicates the formation via O-atom transfer of a high-valent copper oxyl species, CuII-O?, a putative key intermediate in the catalytic cycle of copper-containing monooxygenases. The formation of p-cyano-N-hydroxymethyl-N-methylaniline and p-cyano-N-methylaniline as the main products of the reaction highlight the capability of this species to hydroxylate strong C-H bonds (bond dissociation energy ～90 kcal/mol). A plausible mechanism for the reactivity of this catalytic system is proposed.

Azobenzenes are extensively used to dye textiles and leather and by tuning the substituent in the ring, vivid colours are obtained. Here, we report preparation of a large number of azobenzenes in good yield from commercially available anilines using sodium perborate (SPB) and catalytic amount of Na2MoO4 under mild conditions. Glacial acetic acid is the solvent of choice and the aniline to azobenzene conversion is zero, first and first orders with respect to SPB, Na2MoO4 and aniline, respectively. Based on the kinetic orders, UV–visible spectra and cyclic voltammograms, the conversion mechanism has been suggested. The reaction rates of about 50 anilines at 20–50?°C and their energy and entropy of activation conform to the isokinetic or Exner relationship and compensation effect, respectively. However, the reaction rates, deduced by the so far adopted method, fail to comply with the Hammett correlation. The specific reaction rates of molecular anilines, obtained through a modified calculation, conform to the Hammett relationship. Thus, this work presents a convenient inexpensive non-hazardous method of preparation of a larger number of azobenzenes, and shows the requirement of modification in obtaining the true reaction rates of anilines in acetic acid and the validity of Hammett relationship in the conversion process, indicating operation of a common mechanism.

Oxido-alcoholato- and oxido-thiolato-molybdenum(VI) complexes bearing two ene-1,2-dithiolate ligands (cyclohexene-1,2-dithiolate) are prepared as synthetic models of molybdenum(VI) reaction centers of dimethyl sulfoxide reductase family of molybdenum enzymes. These complexes are prepared by oxygen atom transfer from tertiary amine N-oxide (trimethylamine N-oxide and N,N-dimethylaniline N-oxide) to the five-coordinate alcoholato- and thiolato-molybdenum(IV) complexes, and are characterized by UV–vis, cold-spray-ionization mass, resonance Raman, and 1H NMR spectroscopies. The oxygen atom transfer reactions are studied kinetically at a low temperature (?40 °C) to demonstrate that the reactivity of the thiolato-molybdenum(IV) complex is higher than that of alcoholato-molybdenum(IV) complex by about 7 times, and that the oxygen atom transfer reactivity increases with increasing the electron withdrawing ability of the p-substituent of N,N-dimethylaniline N-oxide derivatives. Mechanistic details are discussed based on the reactivity studies.

A general and facile method to prepare unquaternized C-bound boron enolates by a ligand-controlled O-to-C isomerization is reported. Using this protocol, C-bound pinacolboron enolates have been isolated in pure form for the first time, and have been fully characterized by NMR spectroscopy and X-ray crystallography. In contrast to the general perception, such C-boron enolates are stable without coordinative saturation at the boron. Moreover, C-boron enolates present reactivities that are distinct from the O-boron enolates, and their applications in C-O and C-C bond formations are demonstrated.

A molybdenum-catalyzed deoxygenation of pyridine N-oxides and N-hydroxybenzotriazoles, as well as other azole N-oxides, has been developed using pinacol as an environmentally friendly oxo-acceptor. The only by-products are acetone and water making the process a convenient alternative to established protocols in terms of waste generation. The reaction is highly chemoselective and a variety of functional groups are tolerated. The processes are usually very clean allowing the isolation of the pure deoxygenated products after a simple extraction in most cases. (Figure presented.).

Three new arylboronate ester protected amino acids and their on-resin deprotection methods have been developed. These useful building blocks were found to exhibit favorable chemical properties that are fully compatible with Fmoc strategy solid-phase peptide synthesis. Furthermore, the formation of over-oxidation side-product methionine was minimized by using N-methyl-N-phenylaniline N-oxide as the oxidizing reagent. Effective application of the three new amino acids for the synthesis of different types of peptidomimetics has been demonstrated by high-quality preparation of lipidated peptide MP-196 C-C8, on-resin head-to-tail cyclization of desotamide B, and lactam bridging of hPTHrP-(11–19) through a facile and metal-free procedure by standard Fmoc solid-phase peptide synthesis.

Low cost renewable waste rice husks (RH) have been used as a support for grafting of an oxo-vanadium Schiff base via covalent attachment for the oxidation of tertiary amines to N-oxide. The synthesis of the desired RH grafted oxo-vanadium complex involves prior functionalization of the RH support with amino-propyltrimethoxysilane (APTMS) followed by its reaction with salicylaldehyde to get an RH-functionalized Schiff base which subsequently reacted with vanadyl sulphate to get the targeted oxo-vanadium catalyst. The synthesized catalyst was found to be an efficient heterogeneous catalyst and afforded an excellent yield of corresponding N-oxides via oxidation of tertiary amines with hydrogen peroxide as an oxidant. Furthermore, the synthesized catalyst was found to be quite stable and showed consistent activity for five runs without any loss in activity.

In this work, a lipase-glucose oxidase system has been designed and proven to be an efficient system for the oxidation of N-heteroaromatic compounds and tertiary amines. This dual-enzyme system not only displays environmental friendliness, but also demonstrates its huge potential in industrial applications.

The oxovanadium(IV)-salen ion catalyzed H2O2 oxidation of N,N-dimethylaniline forms N-oxide as the product of the reaction. The reaction follows Michaelis-Menten kinetics and the rate of the reaction is accelerated by electron donating groups present in the substrate as well as in the salen ligand. This peculiar substituent effect is accounted for in terms of rate determining bond formation between peroxo bond of the oxidant and the N-atom of the substrate in the transition state. Trichloroacetic acid (TCA) shifts the λmax value of the oxidant to the red region and catalyzes reaction enormously. The cleavage of N￡O bond by vanadium complex leads to moderate yield of the product. But the percentage yield of the product becomes excellent in the presence of TCA.

Pyridine functionalized carbon nanofibers (Py-CNFs) were synthesized, characterized and used for the grafting of oxo-rhenium complex i.e., methyltrioxorhenium (MTO) via acid-base ionic interaction. The grafting of MTO to Py-CNFs was confirmed by FTIR, UV-vis, SEM, TEM and TGA analyses. The determination of rhenium content by ICP-AES further suggested the successful immobilization of MTO to the support. The developed heterogeneous material i.e., MTO@Py-CNFs was found to be an efficient catalyst for the oxidation of various secondary as well as tertiary amines to corresponding nitrones or N-oxides, respectively by using hydrogen peroxide. The developed catalyst was readily recovered by centrifugation and reused for subsequent ten runs without any significant loss in catalytic activity.

Ultrafine ruthenium oxide nanoparticles (RuO2NPs) with an average diameter of 1.3 nm were anchored on graphene nanoplatelets (GNPs) using a Ru(acac)3 precursor by a very simple dry synthesis method. The resultant material (GNPs-RuO2NPs) was used as a heterogeneous catalyst for the N-oxidation of tertiary amines for the first time. The transmission electron microscopy (TEM) images of the GNPs-RuO2NPs showed the excellent attachment of RuO2NPs on GNPs. The loading of Ru in GNPs-RuO2NPs was 2.68 wt%, as confirmed by scanning electron microscope-energy dispersive spectroscopy (SEM-EDS). The X-ray photoelectron spectrum (XPS) and the X-ray diffraction pattern (XRD) of GNPs-RuO 2NPs revealed that the chemical state of Ru on GNPs was +4. After the optimization of reaction conditions for N-oxidation of triethylamine, the scope of the reaction was extended to various aliphatic, alicyclic and aromatic tertiary amines. The GNPs-RuO2NPs showed excellent catalytic activity in terms of yields even at a very low amount of Ru catalyst (0.13 mol%). The GNPs-RuO2NPs was heterogeneous in nature, chemically as well as physically, very stable and could be reused up to 5 times. The Royal Society of Chemistry 2014.

A variety of tertiary and secondary amines were efficiently oxidized to their corresponding N-oxides and nitrones, respectively, using the trichloroacetonitrile-hydrogen peroxide system. The in situ generated trichloromethylperoxyimidic acid is the active reagent for the oxidation processes.

A simple set of protocols for the controlled elaboration of anilines is reported allowing access to a diverse array of aminophenols, aminoarylsulfonates, alkylated anilines, and aminoanilines in 29-95% yield in a single laboratory operation from easily isolable, bench-stable N,N-dialkylaniline N-oxides. The introduction of new C-O, C-C, and C-N bonds on the aromatic ring is made possible by a temporary increase in oxidation level and excision of a weak N-O bond.

The intrinsic reactivity of a manganese(V)-oxo porphyrin complex, a typically fleeting intermediate in catalytic oxidation reactions in solution, has been elucidated in a study focused on its gas-phase ion-chemistry. The naked high-valent MnV-oxo porphyrin intermediate 1 ([(tpfpp)Mn VO]+; tpfpp=meso-tetrakis(pentafluorophenyl)porphinato dianion), has been obtained by controlled treatment of [(tpfpp)Mn III]Cl (2-Cl) with iodosylbenzene in methanol, delivered in the gas phase by electrospray ionization and assayed by FT-ICR mass spectrometry. A direct kinetic study of the reaction with selected substrates, each containing a heteroatom X (X=S, N, P) including amines, sulfides, and phosphites, was thus performed. Ionic products arising from electron transfer (ET), hydride transfer (HT), oxygen-atom transfer (OAT), and formal addition (Add) may be observed, with a predominance of two-electron processes, whereas the product of hydrogen-atom transfer (HAT), [(tpfpp)MnIVOH]+, is never detected. A thermochemical threshold for the formation of the product radical cation allows an evaluation of the electron-transfer ability of a Mn V-oxo complex, yielding a lower limit of 7.85 eV for the ionization energy of gaseous [(tpfpp)MnIVO]. Linear free-energy analyses of the reactions of para-substituted N,N-dimethylanilines and thioanisoles indicate that a considerable amount of positive charge is developed on the heteroatom in the oxidation transition state. Substrates endowed with different heteroatoms, but similar ionization energy display a comparable reaction efficiency, consistent with a mechanism initiated by ET. For the first time, the kinetic acidity of putative hydroxo intermediates playing a role in catalytic oxidations, [(tpfpp)FeIVOH]+ and [(tpfpp)Mn IVOH]+, has been investigated with selected reference bases, revealing a comparatively higher basicity for the ferryl, [(tpfpp)Fe IVO], with respect to the manganyl, [(tpfpp)MnIVO], unit. Finally, the neat association reaction of 2 has been studied with various ligands showing that harder ligands are more strongly bound.

The mechanism of N-dealkylation mediated by cytochrome P450 (P450) has long been studied and argued as either a single electron transfer (SET) or a hydrogen atom transfer (HAT) from the amine to the oxidant of the P450, the reputed iron-oxene. In our study, tertiary anilinic N-oxides were used as oxygen surrogates to directly generate a P450-mediated oxidant that is capable of N-dealkylating the dimethylaniline derived from oxygen donation. These surrogates were employed to probe the generated reactive oxygen species and the subsequent mechanism of N-dealkylation to distinguish between the HAT and SET mechanisms. In addition to the expected N-demethylation of the product aniline, 2,3,4,5,6-pentafluoro-N,N-dimethylaniline N-oxide (PFDMAO) was found to be capable of N-dealkylating both N,N-dimethylaniline (DMA) and N-cyclopropyl-N-methylaniline (CPMA). Rate comparisons of the N-demethylation of DMA supported by PFDMAO show a 27-fold faster rate than when supported by N,N-dimethylaniline N-oxide (DMAO). Whereas intermolecular kinetic isotope effects were masked, intramolecular measurements showed values reflective of those seen previously in DMAO- and the native NADPH/O2-supported systems (2.33 and 2.8 for the N-demethylation of PFDMA and DMA from the PFDMAO system, respectively). PFDMAO-supported N-dealkylation of CPMA led to the ring-intact product N-cyclopropylaniline (CPA), similar to that seen with the native system. The formation of CPA argues against a SET mechanism in favor of a P450-like HAT mechanism. We suggest that the similarity of KIEs, in addition to the formation of the ring-intact CPA, argues for a similar mechanism of Compound I (Cpd I) formation followed by HAT for N-dealkylation by the native and N-oxide-supported systems and demonstrate the ability of the N-oxide-generated oxidant to act as an accurate mimic of the native P450 oxidant.

This work presents the spectroscopic characterization and reaction studies of a FeIII-complex (2) of a tetraamido macrocyclic ligand (1, 15,15-dimethyl-5,8,13,17-tetrahydro-5,8,13,17-tetraaza-dibenzo[a,g] cyclotridecene-6,7,14,16-tetraone). 2 was characterized primarily by means of EPR. In agreement with the magnetic moment (μeff = 3.87 BM), EPR spectroscopy of 2 shows signals consistent with S = 3/2 intermediate-spin ferric-iron. Besides EPR, mass spectrometry, UV/vis spectroscopy and cyclic voltammetry were used to further characterize 2. 2 is soluble in water and activates hydrogen peroxide under ambient conditions. 2 catalytically bleaches dyes, pulp and paper effluents and oxidizes several amines to their corresponding N-oxides with high turnover number and good yields.

A variety of tertiary amines were efficiently and selectively oxidized to the corresponding N-oxides by bromamine-T using ruthenium trichloride as catalyst in alkaline (pH8.4) acetonitrile/water (1:1) at 80°C.

Cyclohexanone monooxygenase from Acinetobacter calcoaceticus catalyzed the oxidation of tertiary and secondary amines to N-oxides and nitrones, respectively. The formation of a hydroxylamine intermediate was involved with secondary amines as starting substrates.

Novel biomimetic, aerobic oxidation with an organocatalyst was performed. The oxidations of organic substrates such as sulfides, secondary amines, N-hydroxylamines, and tertiary amines with molecular oxygen (1 atm) or even in air in the presence of 5-ethyl-3-methyllumiflavinium perchlorate catalyst and hydrazine monohydrate in 2,2,2-trifluoroethanol occur highly efficiently to give the corresponding oxidized compounds in excellent yields along with water and molecular nitrogen, which are environmentally benign. The TON of the oxidation of sulfides amounts to 19000. Copyright

A variety of tertiary, secondary and primary organonitrogen compounds have been efficiently and selectivity oxidized to their corresponding N-oxides, nitrones, and nitro compounds with molecular oxygen using methyltrioxorhenium as catalyst.

A simple system, simple workup, and excellent yields make the new method for the oxidation of tertiary nitrogen compounds described in Equation (1) an attractive, environmentally acceptable synthetic tool. Molecular oxygen serves as the oxygen source and no sacrificial agents are required.

A variety of tertiary nitrogen compounds have been efficiently oxidized to their corresponding N-oxides in excellent yields with molecular oxygen as a sole oxidant and ruthenium trichloride as catalyst.

The synthesis of novel hydroperoxy sultams 1b-d and their potential as renewable chemoselective electrophilic oxidants for a wide range of nitrogen, sulfur, and phosphorus heteroatoms in nonaqueous media is described. Reactions of 1b,c with secondary amines 10f,g yielded the hydroxysultams 2b,c and nitrone 11f or radical 11g depending on the substrate and stoichiometry, while tertiary amines 10a-d gave amine oxides 11a-d. Compounds 1c,d oxidized various thioethers 12a-g to sulfoxides 13a-g smoothly that were isolated by chromatography in nearly quantitative yields. 1c was regenerated from 2c by treatment of the latter with acidified H2O2. Kinetic studies of the reaction of 1c with 1,4-thioxane 12f suggest that the reaction follows the second-order kinetics, first order in substrate and first order in oxidant with the second-order rate constant several orders of magnitude larger than that of the corresponding reaction with hydrogen peroxide and tert-butyl hydroperoxide without the need for any acid or heavy metal catalysts. The phosphines 14a,b were also oxidized by 1c to the respective phosphine oxides 15a,b readily in quantitative yields. The reactions may be conducted at ambient temperature or lower and appear to proceed via a nonradical mechanism. Reactions are sensitive to steric as well as electronic factors.

The rate of oxidation of tertiary amines by aqueous hydrogen peroxide is increased in the presence of acetonitrile due to the formation of a reactive intermediate. The active oxidant, presumably peroxyacetimidic acid, was quantified by a photometric method. Activation parameters of the acetonitrile-assisted and non-assisted oxidations are given in the temperature range 20 to 40 °C. The increased rate of the assisted oxidation is explained by the low enthalpy of activation although the entropy of activation is more negative due to a highly ordered transition state.

A variety of tertiary nitrogen compounds have been oxidized to corresponding N-oxides in near quantitative yields by molecular oxygen/2-methylpropanal system in the absence of metal catalyst.

Electrospray ionization in combination with tandem mass spectrometric techniques has been employed to study the formation of oxomanganese-salen complexes upon oxidation of [MnIII(salen)]+ cations as well as the properties and reactions of the oxidized species in the gas phase. Two species could be characterized as the principal oxidation products: the oxomanganese(V) complex, [Mn=O(salen)]+, which is the actual oxygen-transfer agent in epoxidation reactions, and the dinuclear, μ-oxo bridged [L(salen)Mn-Q-Mn-(salen)L]2+ with two terminal ligands L; the latter acts as a reservoir species. The effects of various substituents in the 5-and 5′-positions, respectively, of the salen ligand on the reactivity of the epoxidation catalyst were determined quantitatively from CID (collision-induced dissociation) experiments and B3LYP density functional calculations. Accordingly, the effect of axial donor ligands on the reactivity of the epoxidation catalyst was studied. Electron-withdrawing substitutents on the salen ligand and additional axial ligands decrease the stability and thus enhance the reactivity of the Mn=O moiety, while electron-donating salen substituents have a strong stabilizing effect. WILEY-VCH Verlag GmbH, 2001.

Heterocyclic N-oxides have been synthesized in very high yields over redox molecular sieve catalysts in the presence of H2O2.

Oxidation of tertiary amines to tertiary amine N-oxides was achieved in moderate to high yields, by using Fe2O3 as catalyst, with molecular oxygen in the presence of isovaleraldehyde under mild conditions.

Relative rates of dimethyldioxirane oxidation of a number of para-substituted N,N-dimethylanilines in acetone at 5°C are compared with those of reactions with methyl iodide and other oxidants. The reactions with dimethyldioxirane followed the Hammett relationship with a ρ value of -1.0. Measurement of the second order rate constants for the dimethyldioxirane reactions in aqueous acetonitrile containing potassium nitrate at 21°C, showed better correlation with the Hammett relationship (ρ = 0.89) than with the Okamoto-Brown model (ρ+ = 0.56). The reaction rates are accelerated greatly in the presence of water such that the respective pseudo first order rate constants for the oxidation of N,N-dimethyl-4-nitroaniline in acetone and water are 6.3 × 10-3 and 5.86 s-1, respectively. All of the data are consistent with a concerted electrophilic mechanism and there is no evidence of free radical or electron transfer reactions.

The title compound was prepared and characterized by conventional methods. Its uses as stoichiometric oxidizing agent for a variety of organic compounds are described. With this reagent alcohols are converted to the corresponding carbonyl compounds. With 1,2-dioles C-C bond cleavage occurs. Decarboxylation of α-hydroxy acids proceeds quantitatively. Also thiols are converted to disulfides, hydroxy phenols to quinones, benzylamines to carbonyl compounds, tertiaryamines to the N-oxides, phosphines to phosphine oxides, sulfides to sulfoxides, and anthracene and phenanthrene to quinones. Deprotection of oximes and oxidative deprotection of silyl ethers proceed easily.

The reaction of heterocyclic aromatic amines, anilines and tertiary amines with dimethyldioxirane (DMD) was examined. Treatment of heterocyclic aromatic amines and anilines with a slight excess of DMD at 0°C afforded the corresponding N-oxides in quantitative conversion yields. In addition, the oxidation was chemoselective in the presence of carbon-carbon double bonds. On the other hand, most of the tertiary amines assayed did afford also quantitative yields of the corresponding N. oxides, although reaction conditions, in particular regarding the amount of DMD required, depended on each substrate. Additional studies carried out on selected substrates suggested that certain N-oxides derived from tertiary amines deactivate DMD.

We have investigated the p-toluenesulfonic peracid (2) generated in situ in the oxidation of different types of compounds containing nitrogen and/or sulfur. The sulfonic peracid 2 shows a remarkable chemoselectivity characterized by a preferred oxidation of sulfides to the sulfones in the presence of amines or olefins and a strong dependence on the nature of the amine in the competitive oxidation of olefins and amines.

The oxidation of anilines by hydrogen peroxide in methanol is catalyzed by methylrhenium trioxide, CH3ReO3.The major product of the oxidation of aniline at room temperature is nitrosobenzene.For 4-substituted N,N-dimethylanilines, the N-oxide is the only product.The rate constants for the oxidation of 4-substituted N,N-dimethylanilines follow a linear Hammett relationship with ρ = -1.19.The rate constants for the reaction between CH3Re(O)2(O2), referred to as A, and 4-XC6H4-NMe2 are as follows: 4-Me, 24.5; 4-H, 18.4; 4-F, 12.7; 4-Br, 8.7; and 4-NO2, 1.0 L mol-1 s-1.This shows that electron-withdrawing substituents inhibit the reaction.The corresponding rate constant for the oxidation of aniline is 2.04 +/- 0.11 L mol-1 s-1, whereas it is 178 +/- 11 L mol-1 s-1 for the oxidation of N-phenylhydroxylamine to nitrosobenzene.A mechanism has been assigned on the basis of the kinetics and product yields.The data are consistent with the attack of the nucleophilic nitrogen atom on one of the peroxidic oxygen atom of A.The kinetics of the reaction of CH3ReO3 and hydrogen peroxide in methanol were also investigated.The formation of the 1:1 peroxide compound A is characterized by an equilibrium constant K1 = 261 +/- 6 L mol-1.The equilibration occurs rapidly: k1 = 1150 +/- 60 L mol-1 s-1 and k-1 = 4.4 +/- 0.4 s-1 at 25.0 deg C.The bisperoxide compound, CH3Re(O)(O2)2(H2O), B, forms more slowly.The rate constant is k2 = 308 +/- 16 L mol-1 s-1, and the equilibrium constant is K2 = 814 +/- 14 L mol-1 at 25.0 deg C in methanol.B reacts with the anilines, but much more slowly than A.

Ascorbic acid (AscH-), commonly known as vitamin C, is an antioxidant and radical scavenger present in many human and animal tissues. There is much current interest in the protective roles of antioxidants against degenerative tissue damage associated with aging and chronic diseases. We demonstrate that ascorbic acid mediates the facile N-deoxygenation and N-dealkylation of N,N-dimethylaniline N-oxide (DMAO) at room temperature to produce N,N-dimethylaniline (DMA), N-methylaniline (MA), and formaldehyde, respectively. The relative rates of N-dealkylation and N-deoxygenation were found to be dependent on both DMAO and AscH- concentrations in the reaction medium, and N-deoxygenation was somewhat faster than N-dealkylation under standard reaction conditions. Quantitative analysis of the products from DMAO/AscH- reaction mixtures indicated that the rate of N-deoxygenation is identical to the rate of AscH- consumption for at least the first 60 min of the reaction. Trapping experiments with mercaptoethanol and N,N,N',N'-tetramethylphenylenediamine (TMPD) provided evidence that the AscH--mediated N-deoxygenation and N-dealkylation of DMAO is initiated by a single electron transfer process. A chemical mechanism for the AscH--mediated N-deoxygenation and N-dealkylation of DMAO is proposed, which entails initial formation of a nitrogen cation radical and a subsequently-formed carbon-centered radical species. Steady state kinetic studies were carried out, and the kinetic results support the proposed mechanism. The possible physiological significance of these reactions with regard to the metabolism of xenobiotic aromatic amines as well as the biological role of vitamin C in normal and disease states is discussed.

The Oxaziridinium salt 1 derived from dihydroisoquinolin is an oxygen transfer reagent to primary amines leading to nitrosoderivatives (if R = Alkyl) or nitro compounds (if R = Aryl), to tertiary amines leading to N-oxides, and to secondary amines and imines leading to the corresponding nitrone.

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Unlike the real enzyme, FAD-containing monooxygenase, 4a-FlEt-OOH, oxidizes most of common primary, secondary and tertiary water-soluble amines, such as N-methylmorpholine and n-octylamine.Both kinetic rates and products of the oxidation were obtained.The plots of rates vs. pKa values gave three different correlations lines depending upon the types of amines.

The previous belief that the persulfate oxidation of aromatic amines gives the o-sulfate exclusively is untrue; substantial quantities of the para isomer are produced.Kinetic studies on 2,4- and 2,6-disubstituted aromatic amines show that the rate of reaction with persulfate is nearly the same for both isomers.The probable intermediate in this reaction is the arylhydroxylamine-O-sulfonate.This was demonstrated by showing that the reaction between N,N-dimethylaniline N-oxide and the sulfur trioxide-pyridine complex gives material which rearranges to a mixture of N,N-dimethyl aniline o- and p-sulfates in the same ratio as is given by the persulfate oxidation of N,N-dimethylaniline.The ortho-para ratio is unaffected by dilution.This leads to the conclusion that the degreee of intramolecularity of the rearrangement is the same for the formation of both the ortho and para isomers.

A new and versatile synthetic intermediate, α-siloxy amine was prepared in situ by the base-promoted rearrangement of a siloxyammonium salt obtained by treatment of a tertiary amine N-oxide with trialkylsilyl trifluoromethanesulfonate.The best combination of the base and silylating reagent was found to be methyllithium and t-butyldimethylsilyl trifluoromethanesulfonate.The reactions of α-siloxy amines with acyl halides and haloformates gave the corresponding amides and carbamates in moderate to good yields, respectively.Treatment of α-siloxy amines with acetic acid resulted in a direct dealkylation to free secondary amines.Fluoride induced alkylation of α-siloxy amines using alkyl halides as electrophiles leading to tertiary amines was also examined and demonstrated to be a new transalkylation method of amines.

Amine oxides, 1, 5, 10, 15, 21, 23, when treated by lithium diisopropylamide undergo deprotonation.Monodeprotonation gives rise either to secondary amines and benzaldehyde resulting from the hydrolysis of an intermediate immonium (I) or to hydroxylamines via a Stevens-like rearrangement observed for the first time on an amine oxide.Double deprotonation gives an immonium ylid (Y) which, depending upon the structure of the initial tertiary amine yields either "head to head" piperazines (biradical-like behavior of (DD)) or aziridines.The immonium ylid (Y5) derived from trimethylamine oxide, whose formation and reactivity are reported for the first time, has remarkable property of undergoing cycloaddition reactions with unactivated olefins, leading to a new and efficient synthesis of various pyrrolidines.

Tertiary amines have been found to react directly with molecular oxygen under high O2 pressures to give in an unexpected result the corresponding N-oxide in high yields.

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In the oxidation of the title compounds, 5-ethyl-4a-hydroperoxy-3-methyl-lumiflavin (4a-FlEt-OOH), was found to be an electrophilic oxidant similar to m-chloroperoxybenzoic acid.However, the stereoselectivity of the oxidation of cyclic sulfides to the corresponding sulfoxides by 4a-FlEt-OOH was less pronounced than that of the oxygenation with flavin-containing monooxygenase.

The reaction of 3-bromo-4,5-dihydro-5-hydroperoxy-4,4-dimethyl-3,5-diphenyl-3H-pyrazole with tertiary amines and sulfides produced amine oxides and sulfoxides in high yield with k2s for amines similar to those reported for reaction of amines with a 4a-hydroperoxyflavin.

Mixing with equimolar solutions of pyridine N-oxide or its homologs and SbCl5 in CCl4 deposited 1:1 complexes as colorless crystals in high yield.On thermolysis, these complexes underwent intramolecular oxygen transfer to give selectively the corresponding 2-pyridone derivatives.N,N-Dimethylaniline N-oxide and SbCl5 also gave a crystalline 1:1 complex which on termolysis yield o-dimethylaminophenol in good yield.

Kinetic and product studies have been carried out for the reaction of 12 tertiary amines, secondary amines, and secondary hydroxylamines with the 4a-hydroperoxide of N5-ethyl-3-methyllumiflavin (4a-FlEtOOH).All reactions were found to be first order in 4a-FlEtOOH and amine in t-BuOH solvent.Transfer from t-BuOH to the aprotic solvent dioxane decreases the second-order rate constant by ca. threefold, but does not change the kinetic order in reactants (i.e., no external proton source is required).The reactions with the secondary and tertiary amines are quantitative, yielding secondary hydroxylamines and tertiary amine oxides along with the flavin pseudobase (4a-FlEtOH).Secondary hydroxylamines yield with 4a-FlEtOOH nitrones and 4a-FlEtOH.The free radical trap 2,6-di-tert-butyl-4-methylphenol does not influence the rate constants or product yields.This finding, along with the observation that rate constants are not related to the stability of cation radicals derived from amine, establishes that free radical processes are not involved in the N-oxidation reactions.The N-oxidation reactions are best explained as occurring through nucleophilic attack of amine nitrogen upon the terminal oxygen of the 4a-FlEtOOH molecule with back donation of the hydroperoxy hydrogen to the internal peroxy oxygen.Comparison of the second-order rate constants ( on the basis of the amine pKa's in H2O) provides the nucleophilic order secondary hydroxylamines > tertiary amines > secondary amines.The disappearance of 4a-FlEtOOH from solution in the presence of primery amines is much slower than with secondary amines and the reaction does not follow a simple rate law nor is 4a-FlEtOH a major product.In t-BuOH the spontaneous first-order rate constant for decomposition of 4a-FlEtOOH exceeds that for the decomposition of H2O2 by more than 400-fold while the second-order rate constant for N-oxidation of N,N-dimethylbenzylamine by 4a-FlEtOOH exceeds that for N-oxidation by H2O2 by 36000-fold (and N-oxidation by t-BuOOH by > 400000).These results are discussed in terms of the involvement of 4a-hydroperoxyflavin cofactor in the metabolism of amines by the hepatic flavoprotein microsomal oxidase.