Pyridine-acetic Acid Research Articles

The Fe(III)-catalyzed functionalization of saturated hydrocarbons by tert-butyl hydroperoxide: Mechanistic studies on the role of dioxygen

The Fe(III)-catalyzed ketonization of saturated hydrocarbons by tert-butyl hydroperoxide (TBHP) in pyridine-acetic acid or acetonitrile solution follows the reaction pathway alkane → alkyl hydroperoxide → ketone or alcohol. Dioxygen (O 2) is the precursor of the oxygen atoms in the alkyl hydroperoxide, the alcohol, and the ketone.

Porphyrins with exocyclic rings. 1. Chemistry of 4,5,6,7-tetrahydro-1H-indoles: synthesis of acetoxy derivatives, dihydroindoles, and novel porphyrins with four exocyclic rings

A variety of 4,5,6,7-tetrahydro-1H-indoles (THI's) and 4-oxo-4,5,6,7-tetrahydro-1H-indoles (4-oxoTHIs) have been synthesized from cyclohexanone and 1,3-cyclohexanedione, respectively. The THI's reacted regioselectively with lead tetraacetate in acetic acid to give the 7-acetoxy derivatives. The isomeric 4-acetoxyTHI's were prepared by first reducing the corresponding 4-oxoTHI's with sodium borohydride and then reacting the resulting hydroxyTHI's with acetic acid-pyridine

Car☐ylation of saturated hydrocarbons by gif systems (Fe 0/CO/O 2, and CU 0/CO/O 2 in pyridine-acetic acid)

Saturated hydrocarbons are transformed into the corresponding homologous car☐ylic acid by treatment with Fe 0/CO/O 2 or Cu 0/CO/O 2 in pyridine/acetic acid. Mechanistic studies support a reaction pathway involving the insertion of CO into a carbon-iron or carbon-copper bond.

The functionalisation of saturated hydrocarbons. Part XXI. The Fe(III)-catalyzed and the Cu(II)-catalyzed oxidation of saturated hydrocarbons by hydrogen peroxide: a comparative study

The selective functionalisation of saturated hydrocarbons catalyzed by copper or iron salts are compared. In addition to further studies on the homogeneous oxidation by Cu(II)-H 2O 2 is pyridine-acetic acid ( GoChAgg system), we introduce a heterogeneous Gif III-analog based on Cu 0 and dioxygen in pyridine-acetic acid. Both Cu-based systems display Gif-type reactivity. The intermediacy of alkyl hydroperoxides in the Cu(II)-catalyzed reaction has been proven spectroscopically (following the reaction on [1- 13C]-cyclohexane by 13C-N.M.R. spectroscopy) and chemically (quenching the reaction with triphenylphosphine to reduce the hydroperoxide to alcohol). The same holds for Cu 0/O 2 system, as shown by the effect of triphenylphosphine added to the reaction mixture. Thus, both reactions follow the pathway alkane → alkyl hydroperoxide → alcohol or ketone. Experiments running the GoChAgg reaction (H 2O 2-based) under an 18O 2-atmosphere showed the incorporation of 18O 2 into the hydroperoxide and the alcohol (which derives itself from the alkyl hydroperoxide). The relative reactivity of this Cu(II) system was studied for a series of cycloalkanes. The participation of another reaction intermediate ( A) has also been demonstrated. However, some important differences are presented, that show that the chemical properties of the Cu-A and the Fe-A intermediates are different. Thus, Gif-type reactivity is metal-dependent and involves two chemically different non-radical species.

The functionalization of saturated hydrocarbons. Part XIX. Oxidation of alkanes by H 2O 2 in pyridine catalyzed by copper(II) Complexes. A Gif-Type Reaction.

The Cu II-catalyzed oxidation of saturated hydrocarbons by hydrogen peroxide proceeds in pyridine-acetic acid solutions affording mainly ketones as the reaction product. The conversion of hydrocarbon is about 20–30 %. This system (called GoChAgg) shares with the Fe III-catalyzed system (GoAgg II) its unusual chemical characteristics.

Concerning the mechanism of ‘Gif’ oxidations of cycloalkanes

The oxygen atom of cyclodecanone, formed by oxidation of cyclodecane using FeCl3–H2O2 in pyridine–acetic acid, is largely derived from molecular oxygen: taken in conjunction with results of radical-trapping experiments, this supports a free-radical mechanism for the hydrocarbon activation.

An unprecedented chemical transformation: the oxidation of alkanes to alkyl dimethyl phosphates

Treatment of alkanes under Gif IV conditions [FedCl 2.4H 2O (cat.), Zn 0, and O 2 in pyridine-acetic acid] in the presence of trimethylphosphite afforded alkyl dimethyl phosphates; 13C-NMR experiments showed that the phosphates are formed from the reaction between the intermediate alkyl hydroperoxide and trimethyl phosphite in the presence of an iron catalyst.

The oxidation of progesterone under GoAggIII conditions

The oxidation of pregn-4-ene-3,20-dione (progesterone) by the GoAggIII system (aqueous hydrogen peroxide, ferric chloride, picolinic acid in pyridine-acetic acid solution) has been investigated. Two tri-keto derivatives were isolated and identified as pregn-4-ene-3,6,20-trione and pregn-4-ene-3,12,20-trione. The third major product isolated was identified as the unstable 5α-formyl-A-nor-pregnane-3,20-dione, which deformylated spontaneously to A-nor-5β-pregnane-3,20-dione. A mechanism for the A-ring contraction is proposed, based upon the participation of a carbon-Fe(V) intermediate.

Highly conjugated π-electron donors for organic metals: synthesis and redox chemistry of new 1,3-dithiole and 1,3-selenathiole derivatives

The bis(1,3-dithiolium) dication salts 8a–c have been synthesised in three steps (31–51% overall yields) starting from 1,4-bis(bromomethyl)naphthalene, 9,10-bis(chloromethyl)anthracene and 4,4′-bis(chloromethyl)biphenyl, respectively. The bis(halogenomethyl) compounds 5 were converted into the dipiperidiniumbis(dithiocarboxylate) salts 6, which on alkylation with 3-chlorobutane-2-one yielded bis(dithioesters)7; cyclisation of 7 occurred on treatment with concentrated sulphuric acid to give dication salts 8. Dimethyl 1,3-dithiol-2-ylphosphonate 20, dimethyl 4,5-dimethyl-1,3-dithiol-2-ylphosphonate 21 and dimethyl 1,3-selenathiol-2-ylphosphonate 22 were treated with butyllithium in the presence of a range of carbonyl compounds and quinones, e.g., cyclopentanone, cyclohexanone, benzophenone, acetophenone, benzaldehyde, thioxanthen-9-one, anthraquinone, bianthrone and naphthacene-5,12-quinone to yield Wittig–Horner products, e.g., alkenes 26–34 and the anthracenediylidene derivatives 35, 36, 40–43 and 53. Unsymmetrical derivatives 37–39 were prepared in two steps as follows: anthrone reacted with 2-methylthio-1,3-dithiolium iodides 45 and 46 in pyridine-acetic acid to yield ketones 48 and 49 which were then treated with the Wittig–Horner reagents 23–25. Cyclic voltammetric data for the new tetrathiafulvalene, selenatrithiafulvalene and diselenadithiafulvalene derivatives 35–43and 53, show that these systems undergo two-electron redox behaviour which is observed as a single wave. Complexes of these donors with electron acceptors, e.g. 7,7,8,8-tetracyano-p-quinodimethane (TCNQ), have been obtained, some of which are organic semiconductors.

口腔細菌叢の解糖作用を促進する唾液物質の分離

The supernatant of human whole saliva separated by centrifugation contains low-molecular weight, thermostable, water-soluble and ninhydrin positive substances, which promote glycolysis of the salivary sediment and pure culture ofStr. mutans6715, Str. faecalisATCC 9790 andLact. caseiATCC 4646. These substances are reported by some investigators to be peptides or amino acids. We fractionated these substances by ion exchange chromatography, which is widely used for fractionation of peptides, using pyridine-acetic acid buffer, and examined their glycolytic-enhancing activity. Whole saliva was centrifuged at 26, 000×g for 20min. and separated into supernatant and sediment. The supernatant was dialyzed against distilled water through a cellophane membrane, and the dialysate was gel filtrated through a Sephadex G-25 column eluted with 0.2M acetic acid solution (pH 2.7). The ninhydrin positive fraction was chromatographed on the ion exchange resin Dowex 50W and eluted at the incremental pyridine concentration gradient of 0.2M pyridine-acetic acid (pH 3.1), 2M pyridineacetic acid (pH 5.0) and 4M pyridine-acetic acid (pH 5.6). Peptides and amino acids were assayed in the elute by the ninhydrin method after alkaline hydrolysis. A total of 15 fractions were obtained by Dowex 50W ion exchange chromatography. Glycolytic-enhancing activity was observed in fractions eluted at pH 3-4, which contained L-glutamine, L-glutamic acid, L-serine and L-proline. These individual amino acids did not promote glycolysis.

Unusual host properties. X-Ray structures of three salt-like crystalline aggregates of 1,1′-binaphthyl-8,8′-dicarboxylic acid

In contrast with 1,1′-binaphthyl-2,2′-dicarboxylic acid (1), isomeric 1,1′-binaphthyl-8,8′-dicarboxylic acid (2) does not form inclusion compounds with aprotic or proton-donor organic molecules. Instead, salt-like associations of (2) with basic components such as pyridine, derivatives of pyridine, or related heterocycles are readily obtained, and recrystallization of (2) from pyridine in the presence of other non-basic solvents, including cyclic ethers, dipolar aprotic compounds, and acids, gives, crystalline ternary complexes. Crystal structures of the two-component aggregates (2)·pyridine (1:1) and (2)·3-(hydroxymethyl)pyridine, (1:1) and of the ternary crystal aggregate of (2)·pyridine-acetic acid (1:1:1) have been studied by X-ray diffraction. In the crystals of (2)·pyridine (1:1) and (2)·pyridine·acetic acid (1:1:1), the structures are built up from finite blocks of H-bonded (2)·pyridine and (2)·pyridine·acetic acid associations. In the case of (2)·3-(hydroxymethyl)pyridine (1:1) the side-chain hydroxy group of the pyridine moiety acts as a proton donor to the carboxyl group of a neighbouring molecule of (2), thus forming infinite undulating chains in the crystallographic c-direction. A characteristic feature of these structures is the intramolecular H bond between the carboxylic groups of (2), which works against the net bulkiness of the molecule and thus seems to result in the modest clathrate-forming ability of this host. Crystal data for (2)·pyridine (1:1): monoclinic (P21), a= 8.080(1), b= 17.254(2), c= 7.715(1)A, β= 106.28(3)°, R= 0.049 for 1 860 reflections; for (2)·3-(hydroxymethyl)pyridine (1:1): orthorhombic: (Pbca), a= 15.426 7(4), b= 21.189 5(6), c= 13.372 7(4)A, R= 0.049 for 2 085 reflections; and for (2)·pyridine·acetic acid (1:1:1): triclinic (P), a= 14.525(6), b= 10.481(4), c= 8.862(4)A, α= 105.69(4), β= 111.10(6), γ= 86.37(6)°, R= 0.053 for 2 686 observations.

Characterization of monoclonal nonspecific suppressor factor (MNSF) with the use of a monoclonal antibody.

The secretion of immunoglobulin (Ig) from cultured mononuclear cells by lipopolysaccharide (LPS) stimulation is inhibited by monoclonal nonspecific suppressor factor (MNSF), a lymphokine produced by murine T cell hybridoma. In an attempt to develop a murine monoclonal antibody (MAb) with specific reactivity against MNSF, a cell fusion technique that incorporated immune murine splenocytes and HAT-sensitive murine myeloma cells was used. Cross-reactivity experiments confirmed that the MAb (MO6) does not bind to unrelated proteins such as bovine serum albumin, mouse IgG, and murine interferon-gamma (IFN-gamma). There are no effects when anti-IFN-gamma antibodies are used with MNSF. As far as biological activity is concerned, MO6 inhibits in vitro the activity of MNSF in terms of the Ig secretion from cultured lymphocytes. By using MO6, affinity chromatography and immunoblotting were performed. The MNSF on the SDS-PAGE showed a band with m.w. of approximately 70,000, indicating the formation of an aggregate in saline; but after treatment with 0.4 M pyridine-acetic acid buffer, separate bands of 24,000 and 16,000 daltons were evident. Therefore MO6 recognizes 70,000 and both 24,000 and 16,000 daltons. Thus we confirmed by using this MAb and affinity chromatography, the existence of human counterpart, human nonspecific suppressor factor (hNSF), in supernatant from concanavalin A-stimulated T cells. When hNSF was fractionated by high pressure liquid chromatography (HPLC), the activity was found in a region corresponding to 70,000 daltons. However, when fractionated in pyridine-acetic acid buffer, hNSF activity was distributed in a slightly wider range of 15,000 to 30,000 daltons. Physicochemical analysis showed that the purified hNSF is resistant to either heating at 56 degrees C or to 2-mercaptoethanol treatment; however, it is labile to acidification at pH 2.0 and is also sensitive to protease treatment, the characteristics of which were similar to those of murine MNSF. Thus MO6 was confirmed to be a pertinent tool for isolation of hNSF, as well as for murine MNSF.

High Performance Liquid Chromatography of Fluorescein Isothiocyanate Isomers and Intermediate Products

Fluorescein isothiocyanate (FITC) isomers and the intermediate products have been separated by reversed phase high performance liquid chromatography (HPLC), using a linear gradient formed from acetone and 0.01 M sodium phosphate buffer (pH 7.0) or an isocratic elution of 40% acetone in 0.1M pyridine-acetic acid (pH 7.0). This HPLC system was used to evaluate commercial FITC products. A method for the purification of the FITC product by HPLC was also described.

ChemInform Abstract: 4,4′,4“‐TRIS(LEVULINOYLOXY)TRITYL AS A NEW TYPE OF PRIMARY HYDROXYL PROTECTING GROUP

AbstractDie Titelschutzgruppe [A30], die sich mit dem wie angegeben zugänglichen Reagens (IIIb) in Nucleoside, wie z.B. (V), einführen läßt, ist gegenüber Säuren genügend stabil und kann leicht durch Hydrazinolyse und anschließendes Erwärmen auf 50°C in Py/ Essigsäure ohne Beeinträchtigung anderer Schutzgruppen [z.B. ‐Ac bzw. ‐Dmt in (VIIa) bzw. (VIIb), deren Darstellung beschrieben wird] entfernt werden.

4,4′,4″-Tris(levulinoyloxy)trityl as a New Type of Primary Hydroxyl Protecting Group

Abstract The 4,4′,4″-tris(levulinoyloxy)trityl (TLTr) group was introduced selectively on the 5′-oxygen of thymidine by use of in situ generated 4,4′,4″-tris(levulinoyloxy)trityl bromide. The TLTr group was found to be sufficiently stable to acids and readily removed by hydrazinolysis followed by warming to 50 °C in pyridine–acetic acid without damage of other protecting groups such as the O-acetyl and 4,4′-dimethoxytrityl groups. The utility of this new protecting group was demonstrated by the successful synthesis of thymidylyl(3′–5′)-thymidine where the TLTr group was employed as the 5′-hydroxyl-protecting group.

Nature of manganese complexes in manganese accumulator plant ‐Acanthopanax sciadophylloides

Abstract The chemical nature of manganese complexes was investigated in a Mn‐hyperaccumulator plant, Acanthopanax sciadophylloides growing under natural conditions in the forest of central Japan. The concentration of Mn in various cell fractions was in the order: supernatant > cell wall and cell debris > mitochondria > ribosome > chloroplast. Supernatant (105000 x g) was subjected to gel filteration on sephadex G‐10 column. Molecular weight of the major peak of Mn was estimated to be approximately 145 indicating that it was not a protein complex. Mn rich fractions of the major peak were analyzed for organic acids by the use of high performance liquid chromatography. Oxalic acid was the only organic acid detected in these fractions. Paper electrophoresis of the Mn rich fractions of the major peak as well as that of water extracts of the leaves was performed in two ways: 1) paper was treated with pyridineacetic acid buffer (pH 6.5) prior to the application of samples 2) paper was treated with different concentrations of oxalate solutions (0.5, 1, 2 and 5 mM) prior to the sample application. The results indicated that Mn was mostly chelated with oxalic acid having a very low stability constant. We suggest that oxalate functions as a “terminal acceptor”; for Mn. Chelation of Mn by oxalate, therefore, appears to be an essentially detoxification mechanism whereby excess Mn is rendered inactive.

Selective oxidation of saturated hydrocarbons at secondary positions

The selectivity in the oxidation of saturated hydrocarbons by oxygen in pyridine-acetic acid in presence of an iron catalyst and zinc is strongly dependant on the oxygenation of the reaction mixture; using air and slow stirring, it is possible to attack adamantane and trans -1,4-dimethylcyclohexane almost exclusively at the secondary positions.

Chemical nature of manganese in the leaves of manganese accumulator plants

Abstract The chemical nature of Mn in the leaves of Acanthopanax seiadophylloides, Ilex crenata var. paludosa and Kalopanax pictus was investigated. Successive extraction of freeze-dried and fresh leaf sam pies with various solvents showed that the major portion of Mn (>90%) was extractable with water and 0.2 M HCl. Electron probe X-ray microanalysis was performed with the fresh leaf tissues of Mn hyper accumulator A. seiadophylloides, before and after shaking with distilled water, 80% methanol and 1 M HCl. Water removed large parts of Mn in the tissue as a whole except in the region of the epidermis. A negligible amount of Mn was removed by 80% methanol; on the other hand, 1 M HCl removed almost all of the Mn in the tissues. Paper electrophoretic experiments conducted with water and 0.2 M HCl extracts using pyridine-acetic acid buffer (pH 6.5) indicated that Mn in the extracts behaved similarly to Mn2+, presumably due to the labile nature of Mn components in the tissues.

Regioselective O-deacylation of fully acylated glycosides and 1,2- O-isopropylidenealdofuranose derivatives with hydrazine hydrate

On hydrazinolysis in 1:4 acetic acid-pyridine, and in pyridine, partial O-deacylation of fully acylated methyl glycosides and some other glycosyl compounds (23 compounds) was found to be induced, to give, in good yields, products bearing one free hydroxyl group; the results obtained indicated that, among the primary and secondary O-acyl groups, the 2- O-acyl groups were, in general, the most labile toward the nucleophile (hydrazine). Hydrazinolysis of 1,2- O-isopropylidenealdofuranose acylates (3 compounds), on the other hand, gave, in high yield, the corresponding monoacyl derivatives having the protecting group on their primary hydroxyl group. The factors possibly involved in the regioselectivity of the hydrazinolysis were discussed.

Structure of ferric pseudobactin, a siderophore from a plant growth promoting Pseudomonas.

Both plant growth promoting Pseudomonas B10 and its yellow-green, fluorescent iron transfer agent (siderophore) pseudobactin enhance the growth of the potato and control certain phytopathogenic microorganisms. The structure of the little compound has been determined by single-crystal X-ray diffraction methods using counter data. The structure consisted of a linear hexapeptide, L-Lys-D-threo-beta-OH-Asp-L-Ala-D-allo-Thr-L-Ala-D-N delta-OH-Orn, in which the N delta-OH nitrogen of the ornithine was cyclized with the C-terminal carboxyl group, and the N epsilon-amino group of the lysine was linked via an amide bond to a fluorescent quinoline derivative. The iron-chelating groups consisted of a hydroxamate group derived from N delta-hydroxyornithine, an alpha-hydroxy acid derived from beta-hydroxyaspartic acid, and an o-dihydroxy aromatic group derived from the quinoline moiety. The combination of metal-chelating ligands and the alternating L- and D-amino acids was unusual. The little compound crystallized as a single coordination isomer with the lambda absolute configuration. The present study is the first structural determination of a fluorescent siderophore. In the crystal structure, ferric pseudobactin formed a dimer, which constituted the asymmetric unit. The asymmetric unit also contained 26 water molecules. The molecules in the dimer were related by a pseudo-2-fold symmetry axis. Red-brown crystals of ferric pseudobactin (C42H57N12O16Fe . 13H2O), obtained from pyridine-acetic acid buffer solution equilibrated with water, conformed to space group I2 with a = 29.006 (23) A, b = 14.511 (13) A, c = 28.791 (21) A, and beta = 96.06 (5) degrees at -135 (2) degrees C. For eight molecules per unit cell, the calculated density was 1.38 g/cm3; the observed density was 1.40 g/cm3. The structure was refined by least-squares methods with anisotropic thermal parameters for all nonhydrogen atoms to a final R factor of 0.08 (8989 observed reflections).