- PNO ligand containing planar chiral ferrocene and application thereof
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The invention discloses a PNO ligand containing planar chiral ferrocene and application thereof. The PNO ligand containing planar chiral ferrocene is a planar chiral ferrocene-containing and phenol-containing PNO ligand as shown in a general formula (I) or (II) which is described in the specification, or a planar chiral ferrocene-containing and aryl-phosphoric-acid-containingPNO ligand containing as shown in a general formula (III) or (IV) which is described in the specification, or a planar chiral ferrocene-containing and carbon-chiral-phenol-containingPNO ligand as shown in a general formula (V) or (VI) which is described in the specification. The invention provides tridentate PNO ligands and processes for their complexation with transition metal salts or transition metal complexes; the introduction of salicylaldehyde and derivatives thereof, which are simple and easy to obtain, enables the ligands to have a bifunctionalization effect, and -OH in a formed catalyst has stronger acidity and is beneficial to combination with N/O in polar double bonds. Therefore, due to the bifunctionalization effect of the catalyst, the interaction between the catalyst and a substrate can be greatly improved, so a reaction can obtain higher catalytic activity and stereoselectivity.
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Paragraph 0114-0118
(2021/06/21)
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- Primary Alcohols via Nickel Pentacarboxycyclopentadienyl Diamide Catalyzed Hydrosilylation of Terminal Epoxides
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The efficient and regioselective hydrosilylation of epoxides co-catalyzed by a pentacarboxycyclopentadienyl (PCCP) diamide nickel complex and Lewis acid is reported. This method allows for the reductive opening of terminal, monosubstituted epoxides to form unbranched, primary alcohols. A range of substrates including both terminal and nonterminal epoxides are shown to work, and a mechanistic rationale is provided. This work represents the first use of a PCCP derivative as a ligand for transition-metal catalysis.
- Lambert, Tristan H.,Steiniger, Keri A.
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supporting information
p. 8013 - 8017
(2021/10/25)
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- Stabilization of NaBH4 in Methanol Using a Catalytic Amount of NaOMe. Reduction of Esters and Lactones at Room Temperature without Solvent-Induced Loss of Hydride
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Rapid reaction of NaBH4 with MeOH precludes its use as a solvent for large-scale ester reductions. We have now learned that a catalytic amount of NaOMe (5 mol %) stabilizes NaBH4 solutions in methanol at 25 °C and permits the use of these solutions for the reduction of esters to alcohols. The generality of this reduction method was demonstrated using 22 esters including esters of naturally occurring chiral γ-butyrolactone containing dicarboxylic acids. This method permits the chemoselective reductions of esters in the presence of cyano and nitro groups and the reductive cyclization of a pyrrolidinedione ester to a fused five-membered furo[2,3-b]pyrrole and a (-)-crispine A analogue in high optical and chemical yields. Lactones, aliphatic esters, aromatic esters containing electron-withdrawing groups, and heteroaryl esters are reduced more rapidly than aryl esters containing electron-donating groups. The 11B NMR spectrum of the NaOMe-stabilized NaBH4 solutions showed a minor quartet due to monomethoxyborohydride (NaBH3OMe) that persisted up to 18 h at 25 °C. We postulate that NaBH3OMe is probably the active reducing agent. In support of this hypothesis, the activation barrier for hydride transfer from BH3(OMe)- onto benzoic acid methyl ester was calculated as 18.3 kcal/mol.
- Prasanth,Joseph, Ebbin,Abhijith,Nair,Ibnusaud, Ibrahim,Raskatov, Jevgenij,Singaram, Bakthan
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p. 1431 - 1440
(2018/02/09)
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- Cobalt- and Iron-Catalyzed Isomerization-Hydroboration of Branched Alkenes: Terminal Hydroboration with Pinacolborane and 1,3,2-Diazaborolanes
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The synthesis and characterization of a series of structurally varied N-phosphinoamidinate-ligated cobalt complexes is described, along with the successful application of these and a related iron complex as precatalysts in the isomerization-hydroboration of terminal, geminal, and internal alkenes. These reactions proceed under mild conditions (23-65 °C), at relatively low base-metal loadings (1-5 mol %), typically without cosolvent, and with high terminal hydroboration selectivity across a broad spectrum of branched alkenes. With some of the alkene substrates examined, the N-phosphinoamidinate-ligated precatalysts employed herein are shown to provide alternative terminal selectivity versus other previously reported precatalyst classes for such transformations. Reports of terminal-selective metal-catalyzed alkene isomerization-hydroboration disclosed thus far in the literature employ pinacolborane (HBPin); while effective in the system herein, we also report the first examples of such transformations employing either 1,3-dimethyl-1,3-diaza-2-boracyclopentane or benzo-1,3,2-diazaborolane. The application of these 1,3,2-diazaborolanes in place of HBPin in some instances enables novel terminal selectivity in the isomerization-hydroboration of branched alkenes.
- Ogawa, Takahiko,Ruddy, Adam J.,Sydora, Orson L.,Stradiotto, Mark,Turculet, Laura
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supporting information
p. 417 - 423
(2017/04/26)
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- Isotope-Labeling Studies Support the Electrophilic Compound i Iron Active Species, FeO3+, for the Carbon-Carbon Bond Cleavage Reaction of the Cholesterol Side-Chain Cleavage Enzyme, Cytochrome P450 11A1
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The enzyme cytochrome P450 11A1 cleaves the C20-C22 carbon-carbon bond of cholesterol to form pregnenolone, the first 21-carbon precursor of all steroid hormones. Various reaction mechanisms are possible for the carbon-carbon bond cleavage step of P450 11A1, and most current proposals involve the oxoferryl active species, Compound I (FeO3+). Compound I can either (i) abstract an O-H hydrogen atom or (ii) be attacked by a nucleophilic hydroxy group of its substrate, 20R,22R-dihydroxycholesterol. The mechanism of this carbon-carbon bond cleavage step was tested using 18O-labeled molecular oxygen and purified P450 11A1. P450 11A1 was incubated with 20R,22R-dihydroxycholesterol in the presence of molecular oxygen (18O2), and coupled assays were used to trap the labile 18O atoms in the enzymatic products (i.e., isocaproaldehyde and pregnenolone). The resulting products were derivatized and the 18O content was analyzed by high-resolution mass spectrometry. P450 11A1 showed no incorporation of an 18O atom into either of its carbon-carbon bond cleavage products, pregnenolone and isocaproaldehyde. The positive control experiments established retention of the carbonyl oxygens in the enzymatic products during the trapping and derivatization processes. These results reveal a mechanism involving an electrophilic Compound I species that reacts with nucleophilic hydroxy groups in the 20R,22R-dihydroxycholesterol intermediate of the P450 11A1 reaction to produce the key steroid pregnenolone.
- Yoshimoto, Francis K.,Jung, I-Ji,Goyal, Sandeep,Gonzalez, Eric,Guengerich, F. Peter
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p. 12124 - 12141
(2016/10/03)
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- Synthesis of (R)-(-)-muscone from (R)-5-bromo-4-methylpentanoate: A chiron approach
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A synthesis of (R)-muscone (1), a valuable musk odorant, is presented. The stereogenic center of muscone was introduced from methyl (R)-5-bromo-4-methylpentanoate (5), a chiral pool molecule developed in our group, and the macrocyclic ring was prepared by ring-closing metathesis (RCM) reaction. Using methyl (R)-5-bromo-4-methylpentanoate, we have accomplished a synthesis of (R)-muscone, a natural macrocyclic musk, based on chiral pool strategy.
- Shen, Junwei,Shi, Yong,Tian, Weisheng
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p. 683 - 687
(2015/06/25)
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- Amino acid motifs in natural products: Synthesis of O-acylated derivatives of (2S,3S)-3-hydroxyleucine
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(2S,3S)-3-Hydroxyleucine can be found in an increasing number of bioactive natural products. Within the context of our work regarding the total synthesis of muraymycin nucleoside antibiotics, we have developed a synthetic approach towards (2S,3S)-3- hydroxyleucine building blocks. Application of different protecting group patterns led to building blocks suitable for C- or N-terminal derivatization as well as for solid-phase peptide synthesis. With respect to according motifs occurring in natural products, we have converted these building blocks into 3-O-acylated structures. Utilizing an esterification and cross-metathesis protocol, (2S,3S)-3-hydroxyleucine derivatives were synthesized, thus opening up an excellent approach for the synthesis of bioactive natural products and derivatives thereof for structure activity relationship (SAR) studies.
- Ries, Oliver,Bueschleb, Martin,Granitzka, Markus,Stalke, Dietmar,Ducho, Christian
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supporting information
p. 1135 - 1142
(2014/06/09)
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- Facile microwave-assisted synthesis of monodispersed ball-like Ag@AgBr photocatalyst with high activity and durability
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We reported a rapid one-step microwave-assisted approach to synthesize a plasmonic photocatalyst of ball-like AgBr nanoparticles (ca. 290 nm in average diameter) with a small amount of metal Ag anchored on the surface. The obtained Ag@AgBr nanocomposites were characterized by means of X-ray diffraction, scanning electron microscopy, Transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and UV-visible diffuse reflectance spectroscopy. The shape, size, and compositions of the Ag@AgBr photocatalysts could be controlled by tuning the microwave irradiation time and the concentrations of polyvinylpyrrolidone (PVP) in the reaction solution. The as-prepared Ag@AgBr plasmonic photocatalysts show excellent visible-light photocatalytic performance and good reusability for decomposing organic pollutant of Rhodamine B (RhB) due to the surface plasmon resonance (SPR) effect of Ag nanoparticles. Meanwhile, the possible degradation pathways of RhB and a mechanism of the plasmonic photocatalytic process were also proposed.
- Xu, Xiang,Shen, Xiaoping,Zhou, Hu,Qiu, Dezhou,Zhu, Guoxing,Chen, Kangmin
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p. 183 - 192
(2013/05/21)
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- From olefins to alcohols: Efficient and regioselective ruthenium-catalyzed domino hydroformylation/reduction sequence
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Exploring the alternatives: Ruthenium imidazoyl phosphine complexes catalyze the domino hydroformylation/reduction of alkenes to alcohols in good yields and with good selectivities (see scheme). Linear aliphatic alcohols are synthesized under reaction conditions typically used in industrial hydroformylations. Copyright
- Fleischer, Ivana,Dyballa, Katrin Marie,Jennerjahn, Reiko,Jackstell, Ralf,Franke, Robert,Spannenberg, Anke,Beller, Matthias
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supporting information
p. 2949 - 2953
(2013/04/10)
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- Improved syntheses of high hole mobility phthalocyanines: A case of steric assistance in the cyclo-oligomerisation of phthalonitriles
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It has been shown that the base-initiated cyclo-oligomerisation of phthalonitriles is favoured by bulky α-substituents making it possible to obtain the metal-free phthalocyanine directly and in high yield. The phthalocyanine with eight α-isoheptyl substituents gives a high time-of-flight hole mobility of 0.14 cm2·V -1·s-1 within the temperature range of the columnar hexagonal phase, that is 169-189 °C.
- Tate, Daniel J.,Anemian, Remi,Bushby, Richard J.,Nanan, Suwat,Warriner, Stuart L.,Whitaker, Benjamin J.
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supporting information; experimental part
p. 120 - 128
(2012/02/14)
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- PROCESS AND APPARATUS FOR THE PRODUCTION OF ALCOHOLS
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A process utilising the gases carbon monoxide, carbon dioxide and hydrogen to produce alcohols directly, comprises the steps of bringing a fluid mixture comprising carbon monoxide, carbon dioxide and hydrogen into contact with the surfaces of a supported tubular porous catalyst membrane having a range of pore sizes including micropores, mesopores and macropores, controlling the temperature of the said catalyst membrane, maintaining a pressure over said catalyst membrane of from 88 to 600 kPa, and recovering alcohol containing product formed by contact of the fluid mixture with said catalyst membrane.
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Page/Page column 4
(2010/09/05)
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- Properties and tissue distribution of a novel aldo-keto reductase encoding in a rat gene (Akr1b10)
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A recent rat genomic sequencing predicts a gene Akr1b10 that encodes a protein with 83% sequence similarity to human aldo-keto reductase (AKR) 1B10. In this study, we isolated the cDNA for the rat AKR1B10 (R1B10) from rat brain, and examined the enzymatic properties of the recombinant protein. R1B10 utilized NADPH as the preferable coenzyme, and reduced various aldehydes (including cytotoxic 4-hydroxy-2-hexenal and 4-hydroxy- and 4-oxo-2-nonenals) and α-dicarbonyl compounds (such as methylglyoxal and 3-deoxyglucosone), showing low Km values of 0.8-6.1μM and 3.7-67μM, respectively. The enzyme also reduced glyceraldehyde and tetroses (Km=96-390μM), although hexoses and pentoses were inactive and poor substrates, respectively. Among the substrates, 4-oxo-2-nonenal was most efficiently reduced into 4-oxo-2-nonenol, and its cytotoxicity against bovine endothelial cells was decreased by the overexpression of R1B10. R1B10 showed low sensitivity to aldose reductase inhibitors, and was activated to approximately two folds by valproic acid, and alicyclic and aromatic carboxylic acids. The mRNA for R1B10 was expressed highly in rat brain and heart, and at low levels in other rat tissues and skin fibroblasts. The results suggest that R1B10 functions as a defense system against oxidative stress and glycation in rat tissues.
- Endo, Satoshi,Matsunaga, Toshiyuki,Kuragano, Tsukasa,Ohno, Satoshi,Kitade, Yukio,Tajima, Kazuo,El-Kabbani, Ossama,Hara, Akira
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experimental part
p. 230 - 237
(2011/10/30)
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- METHOD OF SYNTHESIZING HIGHER-MOLECULAR ALCOHOL
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A clean process for efficiently producing, from ethanol as a raw material, higher-molecular alcohols having an even number of carbon atoms, such as 1-butanol, hexanol, octanol, and decanol and a mixture of these. The higher-molecular alcohols are yielded from ethanol as a starting material with the aid of a calcium phosphate compound, e.g., hydroxyapatite Ca10(PO4)6(OH)2, tricalcium phosphate Ca3(PO4)2, calcium monohydrogen phosphate CaHPO4·(0-2)H2O, calcium diphosphate Ca2P2O7, octacalcium phosphate Ca8H2(PO4)6·5H2O, tetracalcium phosphate Ca4(PO4)2O, or amorphous calcium phosphate Ca3(PO4)2·nH2O, preferably hydroxyapatite, as a catalyst, the contact time being 0.4 seconds or longer.
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Page/Page column 7-10
(2008/06/13)
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- Synthesis of disparlure analogues, using resolution on microcrystalline cellulose triacetate-I
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The gypsy moth, Lymantria dispar, uses a chiral epoxide, (+)-(7R,8S)-2-methyl-7,8-epoxyoctadecane, (+)-disparlure, as its main sex attractant. The moths can detect both enantiomers of disparlure and respond differently to each one. In an effort to understand the structure-activity relationships of the gypsy moth olfactory system, we prepared the analogues of (+)- and (-)-disparlure. The key intermediate in route to the analogues was 2-epoxytridecan-1-ol. Herein we report the resolution of 2-epoxytridecan-1-yl esters on microcrystalline cellulose triacetate and the synthesis of 5-oxa and (5Z)-ene analogues of (+)- and (-)-disparlure. An effort to make 5-aza analogues resulted in the formation of anti-5-(1-hydroxy-1-undecyl)-3-(3-methylbutyl) oxazolidin-2-one. The analogues were tested for their electroantennogram responses and for their ability to bind to pheromone-binding protein 1 (PBP1). We found that the 5-oxa analogues gave strong responses and that the antenna and the PBP1 no longer distinguish the enantiomers of the 5-oxa analogues. The analogues all bound the PBP1 with similar affinity to (-)-disparlure.
- Inkster, James A. H.,Ling, Ivy,Honson, Nicolette S.,Jacquet, Loic,Gries, Regine,Plettner, Erika
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p. 3773 - 3784
(2007/10/03)
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- Photochemically-Removable Silyl Protecting Groups
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(Hydroxystyryl)dimethylsilyl (HSDMS) and (hydroxystyryldiisopropylsilyl (HSDIS) reagents have been developed that readily protect primary and secondary alcohols and can be removed on irradiation with short wavelength light in polar solvent.
- Pirrung, Michael C.,Lee, Yong Rok
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p. 6961 - 6963
(2007/10/02)
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- The Reduction of Nitrile with 2-Propanol over Hydrous Zirconium Oxide
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The vapor-phase reduction of nitriles with 2-propanol proceeded efficiently over hydrous zirconium oxide to give the corresponding alcohols in high yields.
- Takahashi, Kyoko,Shibagaki, Makoto,Matsushita, Hajime
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p. 311 - 314
(2007/10/02)
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- ACTIVATION OF REDUCING AGENTS. SODIUM HYDRIDE CONTAINING COMPLEX REDUCING AGENTS 21. REGIOSELECTIVE REDUCTION OF ALKENE OXIDES
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It is shown that epoxides are reduced by ZnCRA and NiCRA.Interestingly, the simple change in the nature of the metal included in the reagent, changes the regiochemistry of the reduction.
- Fort, Yves,Vanderesse, Regis,Caubere, Paul
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p. 3111 - 3114
(2007/10/02)
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- An Oxidative Ether Cleavage with p-Nitroperbenzoic Acid
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The reaction of p-nitroperbenzoic acid in chloroform with alkyl ethers (1a, 2a) leads by selective attack at C - H bonds in α-position to the ether oxygen to hemiacetals, which decompose to aldehydes and alcohols, yielding carboxylic acids.Secondary alkoxy groups as in 3a, 4a furnish Baeyer-Villiger oxidation products of initially formed ketones. Kinetic measurements with substituted benzyl methyl ethers show a Hammett reaction constant ρ = -0.9, which is in accordance with the observed relatively small discrimination between secondary and tertiary C - H bonds.The results are compared with similar hydroxylations of alkanes and with monooxygenase reactions and point to oxenoid transition states.Radical reactions as found with some alkanes are not observed, which is shown by the small amounts of nitrobenzene ( 10percent) formed during the reaction. 13C-NMR shifts of several ethers and oxidation products are reported.
- Schneider, Hans-Joerg,Ahlhelm, Alfred,Mueller, Walter
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p. 3297 - 3302
(2007/10/02)
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- METHOD FOR DETERMINATION OF ENANTIOMERIC COMPOSITION AND ABSOLUTE CONFIGURATION OF 2,3-DEUTERATED 3-ALKYLPROPANOLS
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Assignments were made for diastereotopic methylene protons on C-2 and C-3 of 1-phenyl-3-alkylpropanols in Eu(fod)3-enhanced 1H-NMR spectra to develope a generally applicable method to determine enantiomeric composition and absolute configuration of 2 and/or 3-deuterated 3-alkylpropanols.
- Furukawa, Jun,Iwasaki, Shigeo,Okuda, Shigenobu
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p. 5257 - 5260
(2007/10/02)
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