Showing papers on "Oxime published in 1997"
TL;DR: Among these compounds, compound 20 (LB20304) showed the best in vivo efficacy and pharmacokinetic profile in animals, as well as good physical properties, and was selected as a candidate for further evaluation.
Abstract: New pyrrolidine derivatives, which bear an alkyloxime substituent in the 4-position and an aminomethyl substituent in the 3-position of the pyrrolidine ring, have been synthesized and coupled with various quinolinecarboxylic acids to produce a series of new fluoroquinolone antibacterials. These fluoroquinolones were found to possess potent antimicrobial activity against both Gram-negative and Gram-positive organisms, including methicillin resistant Staphylococcus aureus (MRSA). Variations at the C-8 position of the quinolone nucleus included fluorine, chlorine, nitrogen, methoxy, and hydrogen atom substitution. The activity imparted to the substituted quinolone nucleus by the C-8 substituent was in the order F (C5-NH2) > F (C5-H) > naphthyridine > Cl = OMe = H against Gram-positive organisms. In the case of Gram-negative strains, activity was in the order F (C5-NH2) > naphthyridine = F (C5-H) > H > Cl > OMe. The advantages provided by the newly introduced oxime group of the quinolones were clearly demonstrated by their comparison to a desoximino compound 30. In addition, the oxime moiety greatly improved the pharmacokinetic parameters of the novel quinolones. Among these compounds, compound 20 (LB20304) showed the best in vivo efficacy and pharmacokinetic profile in animals, as well as good physical properties. The MICs (microgram/mL) of LB20304, compound 30, and ciprofloxacin against several test organisms are as follows: S. aureus 6538p (0.008, 0.031, and 0.13), methicillin resistant S. aureus 241 (4, 16, and 128), Streptococcus epidermidis 887E (0.008, 0.016, and 0.13), methicillin resistant S. epidermidis 178 (4, 32, and 128), Enterococcus faecalis 29212 (0.063, 0.13, and 1), Pseudomonas aeruginosa 1912E (0.25, 0.5, and 0.13), Escherichia coli 3190Y (0.008, 0.016, and 0.008), Enterobacter cloacae P99 (0.008, 0.031, and 0.008), Actinobacter calcoaceticus 15473 (0.063, 0.13, and 0.25). On the basis of these promising results, LB20304 was selected as a candidate for further evaluation.
147 citations
TL;DR: In this article, the authors investigated the influence of chemical structure on the formation of NH4+ and NO3− ions from the view of adsorption behaviors of substrates onto the TiO2 surface.
Abstract: Nitrogen-containing substrates such as amino acids, amides, succinimide, imidazole, hydroxylamine and urea were photodegraded in illuminated TiO2 suspensions, and the temporal course of formation of NH4+ and NO3− ions was monitored. The hydroxylated nitrogen moiety in a molecule was predominantly converted to NO3− ions, whereas a primary amine and/or an amide were exclusively transformed to NH4+ ions under the prevailing conditions. Heterocyclic nitrogen groups in imidazole were converted to both NH4+ and NO3− ions via the intermediates whose structures were the primary amine and hydroxylamine, respectively. The influence of chemical structure on formation of NH4+ and NO3− ions is discussed from the view point of adsorption behaviours of substrates onto the TiO2 surface.
123 citations
TL;DR: Substituent and solvent effects on the reaction pathway of the Beckmann rearrangement were studied in this article, where energy surfaces of the isolated gas phase systems were mapped out using ab initio MO calculations at the MPn and QCISD(T) levels with basis sets ranging from 6-31G(d,p) to 6-311++G(2df,2p) in the simplest gas phase system.
Abstract: Substituent and solvent effects on the reaction pathway of the Beckmann rearrangement were studied Energy surfaces of the isolated gas phase systems were mapped out using ab initio MO calculations at the MPn and QCISD(T) levels with basis sets ranging from 6-31G(d,p) to 6-311++G(2df,2p) In the simplest gas phase system, the most favored path is as follows: protonation of formaldehyde oxime → N-protonated species → O-protonated species → fragmentation products, in which the 1,2-H-shift connecting both protonated isomers is rate-determining While both methyl and formyl substituents on C and O of the oxime have only a small effect on the rate-controlling energy barrier, they significantly modify the barrier to fragmentation The bulk solvent effect which is treated by a polarizable continuum model does affect only marginally the activation parameters with respect to the gas phase values A combination of both quantum and statistical mechanics was also used to probe the solvent effect In order to investi
93 citations
TL;DR: The intramolecular reductive coupling of a series of simple or polyoxygenated oxime ethers δ- or e-functionalized with bromide, α,β-unsaturated ester, aldehyde, or ketone groups is reported and provides a selective entry to enantiomerically pure aminocyclitols of varying regio- and stereochemistry.
Abstract: The intramolecular reductive coupling of a series of simple or polyoxygenated oxime ethers δ- or e-functionalized with bromide, α,β-unsaturated ester, aldehyde, or ketone groups is reported. The cyclization of a nitrile-tethered aldehyde is also studied. These reductive couplings are promoted by tributyltin hydride or samarium diiodide. The reactions proceed under mild conditions, in good chemical yield, and with high stereoselectivity. When applied to highly functionalized substrates derived from carbohydrates, this approach provides a selective entry to enantiomerically pure aminocyclitols of varying regio- and stereochemistry. In particular, the reductive coupling reaction of carbonyl-tethered oxime ethers promoted by samarium diiodide can be performed in a one-pot sequence, following a Swern oxidation step, allowing the direct transformation of hydroxyl-tethered oxime ethers into the corresponding aminocyclitols. Moreover, the resultant O-benzylhydroxylamine products of these cyclizations can be furth...
66 citations
TL;DR: The results suggested that tyramine was sequentially N-oxygenated in the presence of pig and human liver microsomes and cDNA-expressed FMO3 to the hydroxylamine and then to the di-N-hydroxylamine that was spontaneously dehydrated to the trans oxime, which may be facilitated by FMO through a nondissociative substrate-enzyme interaction.
Abstract: In the presence of pig or adult human liver microsomes, tyramine was metabolized to the corresponding trans oxime through the intermediacy of the hydroxylamine. The requisite intermediate, (4-hydroxyphenethyl)hydroxylamine, was retroreduced to tyramine or converted stereoselectively to the trans oxime in the presence of pig or adult human liver microsomes. Studies of the effect of metabolic inhibitors suggested that formation of the trans oxime and retroreduction of the hydroxylamine were largely dependent on NADPH and the flavin-containing monooxygenase (FMO) and cytochrome P450, respectively. The conclusion that FMO was predominantly responsible for trans oxime formation in human liver microsomes was based on the effect of incubation conditions on tyramine N-oxygenation and the observation that cDNA-expressed human FMO3 also N-oxygenated tyramine to give exclusively the trans oxime. The synthetic hydroxylamine and oxime metabolites of tyramine were examined for affinity to human and animal dopamine and serotonin receptors and the human dopamine transporter. For all of the receptors and for the transporter examined, the avidity of the hydroxylamine and oximes was greater than 10 microM and beyond the effective concentration for physiological relevance. The results suggested that tyramine was sequentially N-oxygenated in the presence of pig and human liver microsomes and cDNA-expressed FMO3 to the hydroxylamine and then to the di-N-hydroxylamine that was spontaneously dehydrated to the trans oxime. This may be facilitated by FMO through a nondissociative substrate-enzyme interaction. Based on the biogenic amine receptor or transporter affinity for the hydroxylamine and oxime metabolites of tyramine, N-oxygenation of tyramine by pig or human liver FMO may represent a detoxication reaction that terminates the pharmacological activity of tyramine.
61 citations
TL;DR: In this paper, the role of the hydrogen bond in NiH−1L2 species was investigated and it was shown that the hydrogen link stabilizes the cis coordination of two ligands in a planar complex.
55 citations
TL;DR: In this article, two crystallographically independent molecules of cis-[PtCl(Me2CNO)(Me2CNOH)2] and excess 2-propanone oxime were characterized by X-ray diffraction.
Abstract: Heating cis-[PtCl2(Me2COH)2] in molten 2-propanone oxime affords the cationic complex [PtCl(Me2CNOH)3]Cl. This compound reacts with 1 equiv of NaOH to give the neutral complex cis-[PtCl(Me2CNO)(Me2CNOH)2] (1). Further, the reaction of [PtCl(Me2CNOH)3]Cl with 2 equiv of AgNO3 and successive addition of excess oxime and NaSbF6 afford the chloride-free cationic complex [Pt(Me2CNO)(Me2CNOH)3](SbF6). When a solution of NaOH, instead of NaSbF6, was added to the reaction mixture, the neutral compound [Pt(Me2CNO)2(Me2CNOH)2]·2H2O (2) was isolated. The homoleptic complex [Pt(Me2CNOH)4]Cl2 (3) was prepared both by addition of excess HCl to [Pt(Me2CNO)2(Me2CNOH)2] (87% yield) and by prolonged heating of [PtCl(Me2CNOH)3]Cl and excess 2-propanone oxime, although in the latter case the conversion of the starting complex did not exceed 5−10%. 1−3 were characterized by X-ray diffraction. All three compounds display interesting hydrogen-bonding modes. In 1, two crystallographically independent molecules of cis-[PtCl(Me2CN...
54 citations
TL;DR: In this paper, a zeolite catalysts for the vapor phase Beckmann rearrangement of cyclohexanone oxime have been proposed, and they have a smaller pore window size than cycloencoder oxime and very weak acid sites.
48 citations
Patent•
8 Apr 1997
TL;DR: In this paper, an oximesulfonate compound of the formula was obtained by subjecting an oxime group-containing compound to esterification reaction with a sulfonic chloride groupcontaining compound in an organic solvent such as tetrahydrofuran in the presence of a basic catalyst such as pyridine.
Abstract: PROBLEM TO BE SOLVED: To obtain the subject new compound useful as an acid generator for a resist, having high transparency to active light used for light exposure and high in strength of generated acid and especially excellent in solubility to resist solvent. SOLUTION: This acid generator is an oximesulfonate compound of the formula (R and R are each a nonaromatic hydrocarbon or a halogenated nonaromatic hydrocarbon), e.g. α-(methylsulfonyloxyimino)-1 cyclopentenylacetronitrile. In the compound of the formula, preferably, R is a cycloalkenyl and R is an alkyl, especially preferably, R is a cyclopentenyl or a cyclohexenyl and R is a 1-4C lower alkyl. Furthermore, the compound of the formula is obtained by subjecting, e.g. an oxime group-containing compound to esterification reaction with a sulfonic chloride group-containing compound in an organic solvent such as tetrahydrofuran in the presence of a basic catalyst such as pyridine.
47 citations
TL;DR: In this paper, the structure of the Pt(C-N)Cl3(SMe2) complex was established on the basis of analytical and 1H NMR data and confirmed by an X-ray diffraction analysis of the platinated ferrocenyl methyl ketone oxime.
Abstract: Acetophenone, benzamide, ferrocenyl methyl ketone and ferrocenecarboxamide oximes reacted with cis-[PtCl2(dmso)2] (dmso = dimethyl sulfoxide) in refluxing methanol to afford the expected platina(II)cycles N,S-trans-[Pt(C–N)Cl(dmso)], where C–N stands for the corresponding cycloplatinated organic ligand. The highest yield of 51% was observed in the case of the acetophenone oxime complex. The structures of the complexes were established on the basis of analytical and 1H NMR data, and confirmed by an X-ray diffraction analysis of the platinated ferrocenyl methyl ketone oxime. A cyclic voltammetry study of the latter indicated that cyclometallation decreases the redox potential of the ferrocene unit by ca. 200 mV. The reaction of a bulkier analog of acetophenone oxime, viz. 2-methyl-1-phenylbutan-1-one oxime, resulted in the formation of the unexpected platinum(IV) complex fac-[Pt(C–N)Cl3(SMe2)] revealing a unique combination of oxidative cycloplatination and dmso-deoxygenation processes which occur under rather mild conditions. The composition of the platinum(IV) compound was established by X-ray crystallography. The Pt–Cl bond distance trans to the phenyl carbon [2.464(4) A] is rather large. As a result, the trans chloro ligand undergoes rapid solvolysis in aqueous solution, causing a pH drop. The deoxygenation of dimethyl sulfoxide that occurs within the metal co-ordination sphere can be viewed as a model of the action of the metal-dependent redox enzyme dimethyl sulfoxide reductase.
47 citations
TL;DR: In this paper, the tributyltin hydride-mediated cycloisomerization of allene-tethered oxime ethers or hydrazones is shown to be a convenient method for the preparation of (vinylstannyl)cyclop...
Abstract: In this work, we have shown that the tributyltin hydride-mediated cycloisomerization of allene-tethered oxime ethers or hydrazones is a convenient method for the preparation of (vinylstannyl)cyclop...
TL;DR: In this paper, the heterogeneous catalyzed ammoximation of cyclohexanone on titanium silicalite catalyst has been studied and the organic by-products formed in the reaction have been identified.
Abstract: The heterogeneous catalyzed ammoximation of cyclohexanone on titanium silicalite catalyst has been studied. Cyclohexanone oxime is formed by reaction of cyclohexanone with ammonia and hydrogen peroxide. The organic by-products formed in the reaction have been studied and the following products were identified: nitrocyclohexane, cyclohexenylcyclohexanone, cyclohexenone oxime and cyclohexanone azine. The effect of some reaction parameters on by-products formation have been investigated. Experiments have been performed to verify if these by-products are due to side or consecutive reactions and derive from non-catalyzed or catalyzed reactions.
TL;DR: Heating 2,3:5,6- O -dicyclohexylidene-L-gulose oxime with methyl glyoxylate hemiacetal followed by treatment of the resulting mixture with allyl alcohols in the presence of catalytic amounts of titanium tetrachloride and molecular sieves 4A caused tandem nitrone formation, transesterification, E, Z -isomerization and diastereofacial selective intramolecular cycloaddition to provide stereocontrolled polycyclic compounds in one step as discussed by the authors
Journal Article•
TL;DR: The results suggest that the biogenic amine phenethylamine is efficiently sequentially N-oxygenated in the presence of human liver microsomes or cDNA-expressed FMO (form 3) to phenethyl hydroxylamine and then to oximes that are pharmacologically inactive and serve to terminate biological activity.
Abstract: The biogenic amine phenethylamine has been shown to be N-oxygenated by human flavin-containing monooxygenase (FMO) (form 3) and human liver microsomes and, to a much lesser extent, N-oxygenated by porcine liver FMO1 and porcine liver microsomes but not by rabbit FMO2. Adult human liver microsomes catalyze the NADPH-dependent N-oxygenation of phenethylamine to the corresponding trans-oxime through the intermediacy of phenethyl hydroxylamine. In addition to trans-oxime formation, phenethyl hydroxylamine is retroreduced to phenethylamine in the presence of human or porcine liver microsomes. Studies on the biochemical mechanism of N-oxygenation suggested that trans-oxime formation was dependent on the human FMO (form 3) and that retroreduction was stimulated by superoxide and dependent on a cytochrome P-450 system. These conclusions are based on studies examining the effects of incubation conditions on phenethylamine N-oxygenation and the effect of reactive oxygen species on phenethyl hydroxylamine retroreduction, respectively. The pharmacological activity of synthetic phenethyl hydroxylamine and phenethyl oxime with a number of biogenic amine receptors and transporters was examined in vitro. In all cases examined, the affinity of phenethyl hydroxylamine and the corresponding oxime for a biogenic transporter or receptors was very poor. The results suggest that the biogenic amine phenethylamine is efficiently sequentially N-oxygenated in the presence of human liver microsomes or cDNA-expressed FMO (form 3) to phenethyl hydroxylamine and then to oximes that are pharmacologically inactive and serve to terminate biological activity. N-Oxygenation of phenethylamine to the corresponding trans-oxime is a detoxication process that abrogates pharmacological activity.
TL;DR: Aminodecanoic acid and 11-AMNylon-12 precursors for nylon-12 and nylon-11 have been synthesized from vernolic (cis-12,13-epoxy-cis 9-octadecenoic) acid via a reaction sequence that includes the formation of 12-oxodecaneic acid oxime, which was catalytically reduced to give 12-AMC with a yield greater than 85% and a melting point of 184-186°C.
Abstract: 12-Aminododecanoic acid and 11-aminoundecanoic acid, monomer precursors for nylon-12 and nylon-11, respectively, have been synthesized from vernolic (cis-12,13-epoxy-cis-9-octadecenoic) acid via a reaction sequence that includes the formation of 12-oxododecanoic acid oxime. Saponification of vernonia oil, followed by a low-temperature recrystallization at −20°C, gave 51% vernolic acid (97% purity, m.p. 23–25°C). Hydrogenation afforded cis-12,13-epoxystearic acid (m.p. 52–54°C, lit. m.p. 52–54°C), which upon oxidation with periodic acid in tertiary butyl alcohol gave 12-oxododecanoic acid with an isolated yield of 71.0%. Reaction of the oxoacid with hydroxylamine hydrochloride gave 12-oxododecanoic acid oxime, which was catalytically reduced to give 12-aminododecanoic acid with a yield greater than 85% and a melting point of 184–186°C (lit. m.p. 185–187°C). 11-Aminoundecanoic acid was prepared from the 12-oxododecanoic acid oxime via a three-step reaction sequence that involved a Beckmann rearrangement, Hofmann degradation, and hydrolysis. Thus, the aldoxime acid was hydrolyzed in the presence of nickel acetate tetrahydrate to give 11-carbamoylundecanoic acid (48% yield, m.p. 129–131°C, lit. m.p. 129–130°C). The amide was then treated with a solution of sodium methoxide and bromine at 70–80°C to give 11-(methoxycarbonylamino)undecanoic acid at 75% yield (m.p. 84–86°C; elemental analysis, calculated for C13H25NO4: C, 60.19; H, 9.73; N, 5.40; O, 24.68%; found C, 60.02; H, 9.81; N, 5.26; O, 24.91%), which upon alkaline hydrolysis and subsequent neutralization gave 11-aminoundecanoic acid at 34% yield (m.p. 189–192°C, lit. m.p. 190°C). Mass spectrometric and 13C nuclear magnetic resonance data of the previously unreported 11-(methoxycarbonylamino)undecanoic acid is provided.
TL;DR: In this paper, the reaction of α-bromoketone oximes with isocyanides and sodium carbonate leads to a new formation of 5-aminoisoxazole derivatives.
TL;DR: In this paper, a simple synthetic pathway for the preparation of oxime and Schiff base-containing aza- and diazacrown ethers is reported, which can be used for simultaneous binding of soft transition and hard alkali or alkaline earth metal ions in one molecule.
TL;DR: In this paper, the mechanism of the Beckmann rearrangement of formaldehyde oxime in concentrated sulfuric acid or in oleum solution was investigated, and it was shown that a specific interaction between solvent molecules and substrates seems to be the dominant factor in reducing the energy barrier to 1,2-H-shift.
Abstract: Ab initio calculations have been performed to probe
the mechanism of the Beckmann rearrangement of formaldehyde oxime in
concentrated sulfuric acid or in oleum solution
(H2SO4 + S2O7
). In the gas phase, the most favoured reaction path is: protonation of
oxime → N-protonated
oxime → O-protonated
oxime → fragmentation products, in which the
1,2-H-shift connecting both protonated forms constitutes the
rate-determining step. Reaction field calculations using two different
models [Onsager self-consistent reaction field (SCRF) and polarizable
continuum model (PCM)] indicate that the non-specific interaction of the
solvent exerts only a small effect on both the energetic and geometrical
parameters of the considered reaction path. Formation of the sulfate
ester, H2CN–O–SO3H,
also appears to play a negligible role in marginally affecting the
1,2-H-shift. In contrast, a specific interaction between solvent
molecules and substrates seems to be the dominant factor in reducing
substantially the energy barrier to 1,2-H-shift. Using a neutral
H2SO4 molecule as a simple model for solvent
molecules, MP2/6-311G(d,p) energy calculations based on
HF/6-31G(d)-geometries of the supermolecule reveal that the barrier to
1,2-H-shift is decreased by 115 kJ mol-1 with respect
to the gas phase value, when a H2SO4 molecule
interacts specifically with the protonated oxime and thereby assists the
hydrogen migration. The calculated results thus suggest a strong case of
active solvent participation in which the solvent molecules exert a
catalytic effect.
TL;DR: X-ray crystallographic and solution studies have revealed the first examples of complexes of Cu============ 2+672====== and Ni============ 1+672 2+676====== with an oxime======¯¯ derivative in which completely deprotonated ligand molecules bind in======trans position because of the lack of a hydrogen bond between the============hydroxyl oxygens which usually stabilises the cis======positioning.
Abstract: X-Ray crystallographic and solution studies have revealed the first
examples of complexes of Cu
2+
and Ni
2+
with an oxime
derivative in which completely deprotonated ligand molecules bind in
trans position because of the lack of a hydrogen bond between the
hydroxyl oxygens which usually stabilises the cis
positioning.
TL;DR: Bis(acetonitrile) palladium (II) chloride (10 mol %) effects cyclization of δ-alkenyl oximes to nitrones which undergo in situ 1,3-dipolar cycloaddition reactions with suitable dipolarophiles to afford a range of complex isoxazolidine derived heterocycles in high yield as discussed by the authors.
Patent•
27 Feb 1997
TL;DR: A process of preparing 9-oxime erythromycin A using acetic acid and isopropanol is described in this article, which is used in this paper.
Abstract: A process of preparing 9-oxime erythromycin A using acetic acid and isopropanol is provided
TL;DR: Acid-sensitive terpene alcohols such as linalool were successfully acetylated by the present method to give acetyl linalools in quantitative yield and enables an alternative acylation of tertiary alcohols under acid-free conditions.
Abstract: An efficient method for the acylation of tertiary alcohols with isopropenyl acetate (1) by the use of an oxime and Cp*2Sm(thf)2 as catalyst was developed. Thus, various types of tertiary alcohols could be acylated with 1 in the presence of a catalytic amount of cyclohexanone oxime acetate (2) and Cp*2Sm(thf)2 under mild conditions to form the corresponding acetates in excellent yields. Acid-sensitive terpene alcohols such as linalool were successfully acetylated by the present method to give acetyl linalool in quantitative yield. This method enables an alternative acylation of tertiary alcohols under acid-free conditions.
TL;DR: In this article, methyl octadepsipeptides attached to an oxime resin were cyclized by heating them in refluxing ethyl acetate for two days to give cyclooctadepipeptide PF1022A analogs.
TL;DR: In this article, the synthesis and characterization of a new solid acid, tungsten oxide/silica gel, is described and different procedures for its preparation compared, including the combined calorimetric and adsorption isotherm analysis, cal-ad, providing equilibrium constants, enthalpies and amounts of different acid sites on the solid.
Abstract: The synthesis and characterization of a new solid acid, tungsten oxide/silica gel, is described and different procedures for its preparation compared. Characterization includes the combined calorimetric and adsorption isotherm analysis, cal-ad, providing equilibrium constants, enthalpies and amounts of the different acid sites on the solid. The solid acid is shown to catalyze the Beckmann rearrangement of cyclohexanone oxime to -caprolactam. Competing pathways that depend on strength and the industrial significance of this intermediate for Nylon 6, make this an ideal reaction to show the relationship between acid catalysis and solid acidity. The utility of the cal-ad procedure in probing catalytic reactivity is illustrated by comparing the acidity of the original catalyst, the regenerated catalyst and a catalyst prepared by conventional means. The strength and number of acid sites correlate to selectivity and activity.
TL;DR: In this article, the open chain oxime ligand N,N′-bis(2-hydroxyimino-propionyl)propane-1,3-diamine and its complexes with NiII and CuII ions were studied.
Abstract: Potentiometric spectroscopic and X-ray studies of the open chain oxime ligand, N,N′-bis(2-hydroxyimino-propionyl)propane-1,3-diamine and its complexes with NiII and CuII ions showed a very high efficacy of the ligand studied in the co-ordination of both CuII and NiII ions. The metal complexes are very stable and square-planar with four nitrogens involved in metal-ion binding. These complexes may be additionally stabilised by hydrogen bonds between two oxime oxygen atoms.
TL;DR: In this article, Vicinal carbonyl-oxime and oxime-imine ligands were used in the synthesis of new RuIII oxime complexes and the isolated chelates were characterized by elemental analysis, electrical conductance and magnetic moment measurements.
Abstract: Vicinal carbonyl-oxime and oxime-imine ligands were used in the synthesis of new RuIII oxime complexes and the isolated chelates were characterized by elemental analysis, electrical conductance and magnetic moment measurements. I.r., u.v.–vis. and e.s.r. spectroscopic analysis methods were also employed. The spectral data were utilized to compute the important ligand field parameters B, β and Dq. The carbonyl-oxime ligand coordinates through the nitrogen of =N-OH to form a five-membered chelate ring. Replacement of the C=O group by C=N-NH2 induces the =N-OH group to coordinate through the oxygen, forming thereby a six-membered chelate ring. The quadridentate tetraaza ligand (L7) coordinates with RuIII through its nitrogen donors in the equatorial position with loss of one of the oxime protons and concomitant formation of an intramolecular hydrogen bond. The spectral and magnetic results suggest a slightly distorted octahedral environment around the RuIII ion. The superoxide dismutase (SOD) mimetic activity of the prepared complexes was assessed for their ability to inhibit the reduction of nitroblue tetrazolium (NBT). The results demonstrate that most of the complexes have promising SOD-mimetic activity. A probable mechanism for the catalytic scavenging of O2− by RuIII oximes is proposed.
TL;DR: In this paper, a new type of cyclolignans with an isoxazoline ring fused to the core has been prepared from 7-ketolignanolides by reaction with hydroxylamine.
TL;DR: In this article, a new enantioselective synthesis of a-amino acids is described in which the key step is the enanti-selective reduction of E, and Z furyl ketone oxime ethers with chiral boron complexes.
Abstract: A new enantioselective synthesis of a- amino acids are described in which the key step is the enantioselective reduction of E, and Z furyl ketone oxime ethers with chiral boron complexes. The chirality of amino acid is fully controlled by appropriate choice of geometrical isomer of the oxime ether. Optically active a-amino acids constitue important materials in all disciplines of biology, medicine, biochemistry, and chemistry. Many attempts have been made to develop asymmetric syntheses of a- amino acids: asymmetric derivatization of glycine, homologation of the P-carbon, electrophilic amination of enolates, nucleophilic amination of a-substituted acids, asymmetric Strecker synthesis, asymmetric hydrogenation of dehydroamino acids, and enzymatic syntheses of a-amino acids'. In this paper, we report a highly enantioselective , simple method for the synthesis of a-amino acids starting from furyl ketones via enantioselective reduction of furyl ketone oxime ethers.
TL;DR: The reaction between RuBr3·xH2O and benzaldehyde oxime in aqueous 6 M HBr results in facile metal-assisted dehydration of the oxime and concomitant partial reduction of ruthenium(III) to produce the mixed-valence RUThenium (III)-ruthenia(II) compound [RuBr(NCPh)5] as mentioned in this paper.
TL;DR: Beckmann rearrangement of O-4-pentenyl oxime derivatives proceeds in good yield under mild conditions through the formation of a cationic tetrahydrofuranium intermediate in the halocyclization reaction with N-bromosuccinimide.
Abstract: Beckmann rearrangement of O-4-pentenyl oxime derivatives proceeds in good yield under mild conditions through the formation of a cationic tetrahydrofuranium intermediate in the halocyclization reaction with N-bromosuccinimide.