- Regiodivergent Reductive Opening of Epoxides by Catalytic Hydrogenation Promoted by a (Cyclopentadienone)iron Complex
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The reductive opening of epoxides represents an attractive method for the synthesis of alcohols, but its potential application is limited by the use of stoichiometric amounts of metal hydride reducing agents (e.g., LiAlH4). For this reason, the corresponding homogeneous catalytic version with H2 is receiving increasing attention. However, investigation of this alternative has just begun, and several issues are still present, such as the use of noble metals/expensive ligands, high catalytic loading, and poor regioselectivity. Herein, we describe the use of a cheap and easy-To-handle (cyclopentadienone)iron complex (1a), previously developed by some of us, as a precatalyst for the reductive opening of epoxides with H2. While aryl epoxides smoothly reacted to afford linear alcohols, aliphatic epoxides turned out to be particularly challenging, requiring the presence of a Lewis acid cocatalyst. Remarkably, we found that it is possible to steer the regioselectivity with a careful choice of Lewis acid. A series of deuterium labeling and computational studies were run to investigate the reaction mechanism, which seems to involve more than a single pathway.
- De Vries, Johannes G.,Gandini, Tommaso,Gennari, Cesare,Jiao, Haijun,Pignataro, Luca,Stadler, Bernhard M.,Tadiello, Laura,Tin, Sergey
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p. 235 - 246
(2022/01/03)
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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.
-
supporting information
p. 8013 - 8017
(2021/10/25)
-
- Selective Cross-Dehydrogenative C(sp3)-H Arylation with Arenes
-
Selective C(sp3)-C(sp2) bond construction is of central interest in chemical synthesis. Despite the success of classic cross-coupling reactions, the cross-dehydrogenative coupling between inert C(sp3)-H and C(sp2)-H bonds represents an attractive alternative toward new C(sp3)-C(sp2) bonds. Herein, we establish a selective inter-and intramolecular C(sp3)-H arylation of alcohols with nondirected arenes that thereby provides a general pathway to access a wide range of β-arylated alcohols, including tetrahydronaphthalen-2-ols and benzopyran-3-ols, with high to excellent chemo-and regioselectivity.
- Hao, Hong-Yan,Mao, Yang-Jie,Xu, Zhen-Yuan,Lou, Shao-Jie,Xu, Dan-Qian
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supporting information
p. 2396 - 2402
(2020/03/13)
-
- CATALYST FOR PREPARING PROPYLENE GLYCOL PHENYL ETHER AND METHOD FOR SYNTHESIZING PROPYLENE GLYCOL PHENYL ETHER
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Disclosed is a method for preparing propylene glycol phenyl ether, comprising carrying out a polymerization reaction of phenol and a propylene oxide in the presence of a quaternary phosphonium salt compound as a catalyst. Preferably, the method comprises mixing phenol and a quaternary phosphonium salt compound, and then adding propylene oxide under oxygen-free conditions, wherein the phenol is polymerized with the propylene oxide to produce the propylene glycol phenyl ether. The propylene glycol phenyl ether thus prepared has few impurities and contains no metal ions, such as potassium and sodium, and does not require subsequent operations to remove metal ions and perform rectification separation, thereby reducing the costs and allowing same to be directly applied to high-standard industrial production.
- -
-
Paragraph 0022-0049
(2020/06/08)
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- Ruthenium-Catalyzed Selective Hydrogenation of Epoxides to Secondary Alcohols
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A ruthenium(II)-catalyzed highly selective Markovnikov hydrogenation of terminal epoxides to secondary alcohols is reported. Diverse substitutions on the aryl ring of styrene oxides are tolerated. Benzylic, glycidyl, and aliphatic epoxides as well as diepoxides also underwent facile hydrogenation to provide secondary alcohols with exclusive selectivity. Metal-ligand cooperation-mediated ruthenium trans-dihydride formation and its reaction involving oxygen and the less substituted terminal carbon of the epoxide is envisaged for the origin of the observed selectivity.
- Thiyagarajan, Subramanian,Gunanathan, Chidambaram
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supporting information
p. 9774 - 9778
(2019/12/02)
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- PROCESS FOR MAKING FORMIC ACID UTILIZING LOWER-BOILING FORMATE ESTERS
-
Disclosed is a process for recovering formic acid from a formate ester of a C3 to C4 alcohol. Disclosed is also a process for producing formic acid by carbonylating a C3 to C4 alcohol, hydrolyzing the formate ester of the alcohol, and recovering a formic acid product. The alcohol may be dried and returned to the reactor. The process enables a more energy efficient production of formic acid than the carbonylation of methanol to produce methyl formate.
- -
-
Paragraph 00177; 00178
(2019/02/15)
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- Iridium-catalyzed efficient reduction of ketones in water with formic acid as a hydride donor at low catalyst loading
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A highly efficient and chemoselective transfer hydrogenation of ketones in water has been successfully achieved with our newly developed catalyst. Simple ketones, as well as α- or β-functionalized ketones, are readily reduced. Formic acid is used as a traceless hydride source. At very low catalyst loading (S/C = 10:000 in most cases; S/C = 50:000 or 100:000 in some cases), the iridium catalyst is impressively efficient at reducing ketones in good to excellent yields. The TOF value can be as high as up to 26:000 mol mol-1 h-1. A variety of functional groups are well tolerated, for example, heteroaryl, aryloxy, alkyloxy, halogen, cyano, nitro, ester, especially acidic methylene, phenol and carboxylic acid groups.
- Liu, Ji-Tian,Yang, Shiyi,Tang, Weiping,Yang, Zhanhui,Xu, Jiaxi
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supporting information
p. 2118 - 2124
(2018/05/24)
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- Unveiling the Hidden Performance of Whole Cells in the Asymmetric Bioreduction of Aryl-containing Ketones in Aqueous Deep Eutectic Solvents
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In this contribution, we report the first successful baker's yeast reduction of arylpropanones using deep eutectic solvents (DESs) as biodegradable and non-hazardous co-solvents. The nature of DES [e.g. choline chloride/glycerol (2:1)] and the percentage of water in the mixture proved to be critical for both the reversal of selectivity and to achieve high enantioselectivity on going from pure water (up to 98:2 er in favour of the S-enantiomer) to DES/aqueous mixtures (up to 98:2 er in favour of the R-enantiomer). As a result, both enantiomers of valuable chiral alcohols of pharmaceutical interest were prepared from the same biocatalyst by simply switching the solvent. The possible inhibition of some (S)-oxidoreductases making part of the genome of such a wild-type whole cell biocatalyst when DESs are used as co-solvents may pave the way for an anti-Prelog reduction. The scope and limitations of this kind of biotransformations for a range of aryl-containing ketones are also discussed. (Figure presented.).
- Vitale, Paola,Abbinante, Vincenzo Mirco,Perna, Filippo Maria,Salomone, Antonio,Cardellicchio, Cosimo,Capriati, Vito
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supporting information
p. 1049 - 1057
(2017/03/31)
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- Copper-catalyzed/mediated borylation reactions of epoxides with diboron reagents: access to β-hydroxyl boronic esters
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We report the first copper-catalyzed/mediated borylative ring opening reaction of epoxides. This process represents a direct borylative C(sp3)-O bond cleavage of terminal epoxide substrates with commercially available diboron reagents. A wide range of epoxides with different functional groups are involved, and were subsequently converted to the corresponding β-hydroxyl boronic esters smoothly. Moreover, the ring opening product β-pinacol boronate alcohol provided a more beneficial approach for the formation of C-C and C-N bonds.
- Ahmed, Ebrahim-Alkhalil M. A.,Lu, Xi,Gong, Tian-Jun,Zhang, Zhen-Qi,Xiao, Bin,Fu, Yao
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supporting information
p. 909 - 912
(2017/01/17)
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- Synthesis of supported Ru-nanoparticles for selective hydrogenation of carbonyl compounds
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Ru nanoparticles were successfully supported on molecular sieves and it was further characterized by sophisticated analytical methods such as transmission electron microscopy, energydispersive X-ray spectroscopy and nitrogen adsorption techniques. Transmission electron microscopy data confirmed, indicated the formation of metal oxide nanoparticles (4.5±2 nm) on the external surface of molecular sieves. Ru supported molecular sieves were applied as a catalyst for the hydrogenation of carbonyl compounds. Aldehydes as well as ketones were successfully hydrogenated in good yield and selectivity. Easy synthesis of air/moisture stable catalyst, hassle free reaction protocol (no requirement of aqueous work-up), 7 times catalyst recycling and additive free approach were the promising outcomes of the proposed work.
- Upadhyay, Praveenkumar,Srivastava, Vivek
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p. 528 - 533
(2015/10/05)
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- First example of borirane synthesis by α-olefins reaction with BCl3·SMe2 Catalyzed with (η5-C5H5)2TiCl2
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New method was developed of the synthesis of 2-phenyl(alkyl, benzyl, phenoxy)-1-chloroboriranes via reaction of α-olefins with BCl3·SMe2 catalyzed by Cp2TiCl2. The method is based on the boracyclopropanes (boriranes) formation resulting from transmetallation of titanacyclopropanes arising from the reaction of α-olefins with Cp2TiCl2. The calculations were fulfilled of thermodynamic and activation parameters of possible reaction routes.
- Khusainova,Khafizova,Tyumkina,Dzhemilev
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p. 1517 - 1523
(2015/12/30)
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- Photocatalytic hydrogenolysis of epoxides using alcohols as reducing agents on TiO2 loaded with Pt nanoparticles
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Photoexcitation (λ > 300 nm) of TiO2 loaded with Pt particles promotes selective hydrogenolysis of epoxides using alcohols as reducing agents.
- Hirakawa, Hiroaki,Shiraishi, Yasuhiro,Sakamoto, Hirokatsu,Ichikawa, Satoshi,Tanaka, Shunsuke,Hirai, Takayuki
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supporting information
p. 2294 - 2297
(2015/02/05)
-
- Versatile iridicycle catalysts for highly efficient and chemoselective transfer hydrogenation of carbonyl compounds in water
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Cyclometalated iridium complexes are shown to be highly efficient and chemoselective catalysts for the transfer hydrogenation of a wide range of carbonyl groups with formic acid in water. Examples include α-substituted ketones (α-ether, α-halo, α-hydroxy, α-amino, α-nitrile or α-ester), α-keto esters, β-keto esters and α,β-unsaturated aldehydes. The reduction was carried out at substrate/catalyst ratios of up to 50000 at pH 4.5 and required no organic solvent. The protocol provides a practical, easy and efficient way for the synthesis of β-functionalised secondary alcohols, such as β-hydroxyethers, β-hydroxyamines and β-hydroxyhalo compounds, which are valuable intermediates in pharmaceutical, fine chemical, perfume and agrochemical synthesis. Water wonder: Iridicycle catalysts are versatile and allow the highly efficient and chemoselective transfer hydrogenation of a variety of carbonyl compounds, including problematic and challenging ones, with formate in neat water (see scheme).
- Talwar, Dinesh,Wu, Xiaofeng,Saidi, Ourida,Salguero, Noemí Poyatos,Xiao, Jianliang
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supporting information
p. 12835 - 12842
(2015/03/30)
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- Straightforward heterogeneous palladium catalyzed synthesis of aryl ethers and aryl amines via a solvent free aerobic and non-aerobic dehydrogenative arylation
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Aryl ethers have been prepared from cyclohexanone derivatives and various alcohols in the presence of a catalytic amount of palladium on charcoal. The formation of an enol ether followed by an aerobic or non-aerobic dehydrogenation reaction, seem to be the key steps of this transformation. In addition, this new method was also adapted for the synthesis of arylamines.
- Sutter, Marc,Sotto, Nicolas,Raoul, Yann,Metay, Estelle,Lemaire, Marc
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supporting information
p. 347 - 352
(2013/03/28)
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- Heterogeneous palladium-catalyzed synthesis of aromatic ethers by solvent-free dehydrogenative aromatization: Mechanism, scope, and limitations under aerobic and non-aerobic conditions
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Starting from cyclohexanone derivatives and alcohols, both non-aromatic precursors, aryl ethers could be synthesized in good yields and with good selectivities in the presence of a catalytic amount of Pd/C, in one step, without added solvent, in a reaction vessel open to air. For less reactive substrates, the addition of 1-octene in a closed system under non-aerobic conditions improved the conversion. In addition, the catalyst could be recycled several times with no decrease in the yield of the aryl ether. The process was also used with tetralone derivatives and polyols. Several reactions were performed to propose a mechanism for this transformation. The formation of an enol ether followed by a dehydrogenation reaction seem to be the key steps of this reaction. Aryl ethers were prepared in good yields and with good selectivities in a solvent-free and heterogeneous catalytic dehydrogenative alkylation of cyclohexanones with various alcohols. Three different complementary routes were used, and for the first time, non-aerobic, safe conditions could be used. Moreover, the catalyst could be recycled several times with no decrease in the yield of the aryl ether. Copyright
- Sutter, Marc,Lafon, Romain,Raoul, Yann,Metay, Estelle,Lemaire, Marc
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supporting information
p. 5902 - 5916
(2013/09/23)
-
- An efficient catalyst for ring opening of epoxides with phenol and thiophenol under solvent-free conditions
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An efficient and rapid procedure for ring opening reaction of various epoxides with phenol and thiophenol derivatives was developed. The procedure can be obtained at room temperature under solvent-free condition in presence of (C4H12N2)2[BiCl6] Cl·H2O (1 mol %). This catalyst can be reused several times without significant loss of activity.
- Lu, Hong-Fei,Zhou, Jun-Tao,Cheng, He-Long,Sun, Lei-Lei,Yang, Fei-Fei,Wu, Run-Ze,Gao, Yu-Hua,Luo, Zhi-Bin
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p. 11174 - 11184
(2014/01/06)
-
- Silicate anion-stabilized layered magnesium-aluminium hydrotalcite
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Layered magnesium-aluminum hydrotalcite (HT) were completely intercalated and stabilized with silicate anions. The silicate anion-stabilized HT retained the layered structure and possessed a high surface area of 530-540 m2 g-1 with needle-like particles 60 nm × 4 nm in dimension. The findings of FT-IR, powder XRD, TGA, DSC and 29Si MAS-NMR revealed that silicate anions were intercalated and coated on the surface of layered HTs with the formation of a solid solution of magnesium silicate and HT. The resultant silicate-anion-intercalated materials are found to be promising catalysts for the synthesis of 1-phenoxy-2-propanol using phenol with propylene oxide. The Royal Society of Chemistry 2013.
- Baskaran, Thangaraj,Kumaravel, Raju,Christopher, Jayaraj,Sakthivel, Ayyamperumal
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p. 16392 - 16398
(2013/09/23)
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- One-pot synthesis of aryloxypropanediols from glycerol: Towards valuable chemicals from renewable sources
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Glycerol offers an easy and green route for the synthesis of aryloxypropanediols of known pharmacological activity. Glycerol is selectively converted to aryloxypropanediols in a one-pot reaction, through in situ formed glycerol carbonate, under benign and solvent-free conditions. Catalyst and unreacted reagent can be recycled.
- Truscello, Ada M.,Gambarotti, Cristian,Lauria, Mirvana,Auricchio, Sergio,Leonardi, Gabriella,Shisodia, Suresh U.,Citterio, Attilio
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supporting information
p. 625 - 628
(2013/03/29)
-
- Ruthenium-catalysed transfer hydrogenation reactions with dimethylamine borane
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Dimethylamine-borane adduct has been used as the hydrogen source for the reduction of carbonyl compounds, imines, oximes, nitriles, nitroarenes and alkenes using [Ru(p-cymene)Cl2]2 as the catalyst.
- Nixon, Tracy D.,Whittlesey, Michael K.,Williams, Jonathan M.J.
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supporting information; experimental part
p. 6652 - 6654
(2012/01/03)
-
- Screening on the use of Kluyveromyces marxianus CBS 6556 growing cells as enantioselective biocatalysts for ketone reductions
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The versatility of Kluyveromyces marxianus CBS 6556 growing cells in the enantioselective reduction of ketone functionalities to the corresponding alcohols was exploited. In particular, methyl ketones were reduced to (S)-alcohols with ees of up to 96%. Longer chain alkyl ketones afforded, under the same experimental condition, (R)-alcohols with an ee of up to 84%. Interestingly, carbon-carbon double and the triple bonds can also be reduced in the presence of Kluyveromyces marxianus CBS 6556 yeast. A cyclic ketone, such as 2-tetralone, was also quantitatively reduced to its corresponding (S)-alcohol with ee = 76%.
- Vitale, Paola,Perna, Filippo Maria,Perrone, Maria Grazia,Scilimati, Antonio
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body text
p. 1985 - 1993
(2012/03/22)
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- An atom-economic reaction for synthesis of 1-phenoxy-2-propanol over Al2O3/MgO
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Al2O3/MgO materials with various Mg/Al molar ratios were prepared and characterized by XRD, FT-IR, SEM and BET analysis. These materials were used as catalysts for synthesis of 1-phenoxy-2-propanol (1-PhP) from phenol and propylene oxide as compared with some oxides, i.e. MgO, CaO, ZnO and Al2O3, etc. Al2O3/MgO with Al/Mg molar ratio of 1.5% exhibited outstanding catalytic performance with 98.2% conversion and 99.3% selectivity to 1-PhP at 120 °C for 5 h. This catalyst can be easily recovered and reused due to its heterogeneous catalytic nature.
- Zhang, Yongbo,Lu, Bin,Wang, Xiaoguang,Zhao, Jingxiang,Cai, Qinghai
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experimental part
p. 125 - 129
(2012/05/04)
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- Immobilization of β-cyclodextrin onto Dowex resin as a stationary microvessel and phase transfer catalyst
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In this study, immobilization of β-cyclodextrin onto commercial Dowex resin by covalent bond was reported. The efficiency of this biocatalyst system as a stationary microvessel and new solid-liquid phase transfer catalyst in reduction of epoxides by NaBH4 was studied.
- Kiasat, Ali Reza,Sayyahi, Soheil
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scheme or table
p. 484 - 486
(2010/12/19)
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- One-pot alkoxylation of phenols with urea and 1,2-glycols
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A one-pot epoxide-free alkoxylation process has been developed for phenolic compounds. The process involves heating phenols and urea in 1,2-glycols at 170-190 °C using Na2CO3/ZnO as co-catalysts under atmospheric conditions. During the course of this new alkoxylation reaction, a five-membered ring cyclic carbonate intermediate, ethylene carbonate (EC) or propylene carbonate (PPC), was produced in-transit as the key intermediate and was subsequently consumed by phenols to form alkoxylated ether alcohols as final products in excellent yields. For instance, phenol, bisphenol A (BPA), hydroquinone and resorcinol were converted into their respective mono-alkoxylated ether alcohols on each of their phenolic groups in 80-95% isolated yields. In propoxylation of phenols, this approach shows great product selectivity favoring production of high secondary alcohols over primary alcohols in isomeric ratios of nearing 95/5. Since ammonia (NH3) and carbon dioxide (CO2) evolving from the reaction can be re-combined in theory into urea for re-use, the overall net-alkoxylation by this approach can be regarded as a simple condensation reaction of phenols with 1,2-glycols giving off water as its by-product. This one-pot process is simple, safe and environmentally friendlier than the conventional alkoxylated processes based on ethylene oxide (EO) or propylene oxide (PO). Moreover, this process is particularly well-suited for making short chain-length alkoxyether alcohols of phenols.
- Lin, Hsing-Yo,Dai, Shenghong A.
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experimental part
p. 167 - 173
(2011/04/19)
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- First use of HEH in oxazine synthesis: Hydroxy-substituted 2 H-1,4-benzoxazine derivatives
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The synthesis of 2H-1,4-benzoxazine derivatives from 1,2-epoxy-3-(2- nitroaryloxy)propanes in the presence of Hantzsch 1,4-dihydropyridine (HEH) and Pd/C as a catalyst was achieved. The nitro group was reduced before the epoxide functionality, leading to attack of the amino group on the epoxide moiety in a 6-exo-fashion. By introducing a methyl group at the 1-position, the 7-endo ring-closed product could also be formed. Georg Thieme Verlag Stuttgart - New York.
- Meng, Qing-Yuan,Liu, Qiang,Li, Jing,Xing, Rui-Guang,Shen, Xiao-Xia,Zhou, Bo
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scheme or table
p. 3283 - 3286
(2010/03/04)
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- Asymmetric reduction and oxidation of aromatic ketones and alcohols using W110A secondary alcohol dehydrogenase from Thermoanaerobacter ethanolicus
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An enantioselective asymmetric reduction of phenyl ring-containing prochiral ketones to yield the corresponding optically active secondary alcohols was achieved with W110A secondary alcohol dehydrogenase from Thermoanaerobacter ethanolicus (W110A TESADH) in Tris buffer using 2-propanol (30%), v/v) as cosolvent and cosubstrate. This concentration of 2-propanol was crucial not only to enhance the solubility of hydrophobic phenyl ring-containing substrates in the aqueous reaction medium, but also to shift the equilibrium in the reduction direction. The resulting alcohols have S-configuration, in agreement with Prelog's rule, in which the nicotinamide-adenine dinucleotide phosphate (NADPH) cofactor transfers its pro-R hydride to the re face of the ketone. A series of phenyl ring-containing ketones, such as 4-phenyl-2-butanone (1a) and 1-phenyl-1,3-butadione (2a), were reduced with good to excellent yields and high enantioselectivities. On the other hand, 1-phenyl-2-propanone (7a) was reduced with lower ee than 2-butanone derivatives. (R)-Alcohols, the anti-Prelog products, were obtained by enantiospecific oxidation of (S)-alcohols through oxidative kinetic resolution of the rac-alcohols using W110A TESADH in Tris buffer/acetone (90:10, v/v).
- Musa, Musa M.,Ziegelmann-Fjeld, Karla I.,Vieille, Claire,Zeikus, J. Gregory,Phillips, Robert S.
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- Magnetically separable Pd catalyst for highly selective epoxide hydrogenolysis under mild conditions
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A magnetically separable palladium catalyst was synthesized simply through a sol-gel process incorporating palladium nanoparticles and superparamagnetic iron oxide nanoparticles in aluminum oxyhydroxide matrix, which is highly active and selective for epoxide hydrogenolysis at room temperature under 1 atm H 2. The catalyst was recycled for 25 times without loss of the activity.
- Kwon, Min Serk,Park, In Soo,Jang, Jum Suk,Lee, Jae Sung,Park, Jaiwook
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p. 3417 - 3419
(2008/02/12)
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- A new and efficient epoxide ring opening via poor nucleophiles: Indole, p-nitroaniline, borane and O-trimethylsilylhydroxylamine in lithium perchlorate
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Highly regioselective ring opening of 2,3-dimethyloxirane, 2-epoxyphenylether and allyl(2-epoxymethyl) ether are observed through reactions with poor nucleophiles such as indole, borane, O-trimethylsilylhydroxylamine, p-nitroaniline and sterically hindered tert-butylamine in the presence of 5.0 M lithium perchlorate-Et2O solution. These reactions are fast, convenient, with rather high yields and are carried out at ambient temperatures.
- Heydari, Akbar,Mehrdad, Morteza,Maleki, Aziz,Ahmadi, Nafiseh
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p. 1563 - 1565
(2007/10/03)
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- Aromatic ethers and process for producing aromatic ethers
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According to a production process, aromatic ethers are producible by reacting phenols with an oxirane compound with use of an anion exchange resin as a catalyst. According to another production process, aromatic ethers having an alcoholic hydroxyl group are producible by a crystallization-purification step of using a solvent having a solubility parameter ranging from 7.5 to 12.5 for purification by crystallization. Further, according to still another production process, producible are aromatic ethers having an alcoholic hydroxyl group, wherein the content of a metal in the aromatic ethers is less than 100 ppm by mass, and the content of a halogen element in the aromatic ethers is less than 100 ppm by mass.
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- Water-resistant solid Lewis acid catalysts: Meerwein-Ponndorf-Verley and Oppenauer reactions catalyzed by tin-beta zeolite
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The catalytic activity of Sn-beta zeolite in the Meerwein-Pondorf-Verley reduction of carbonyl compounds with secondary alcohols as reductants and Oppenauer oxidation of alcohols were performed with quantitative yields to the corresponding product. The catalyst had an excellent activity and selectivity even after four catalytic recycles, and good stereoselectivities to the thermodynamic less favorable cis-alcohol isomer when alkyl-cyclohexanones were used as substrates. A prochiral ketone was reduced within an enantiomeric excess close to 50% when using a chiral alcohol as the reducing reactant. IR studies using cyclohexanone as probe molecule over beta zeolites showed that the more specific Lewis acid sites in the framework of Sn-beta were responsible for its better catalytic activity with respect to Ti- or Al-beta. The order of hydrophobicity of the samples was Ti-beta > Sn-beta > Al-beta. Ti-beta and Sn-beta retained a higher percentage of catalytic activity when water was present in the reaction media. Even with ~ 4 wt % of H2O (0.2 g) in the media, Sn-beta yielded a higher turnover number than Ti- or Al-beta when working in the absence of water.
- Corma, Avelino,Domine, Marcelo E.,Valencia, Susana
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p. 294 - 304
(2007/10/03)
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- Process for preparing optically active secondary alcohols having nitrogenous or oxygenic functional groups
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A process for preparing optically active secondary alcohols of the general formula (3), [wherein R1 is linear lower alkyl, an aromatic ring group, or the like; A is CH2NR2R3 or the like; n is an integer of 0 to 2; and * represents an asymmetric carbon atom] by asymmetrically hydrogenating a ketone compound of the general formula (1) having nitrogenous or oxygen functional group at any of the a-, β- and γ-positions, with selectivity among functional groups by the use of a ruthenium/optically active bidentate phosphine/diamine complex as the catalyst in the presence of hydrogen alone or together with a base. The optically active secondary alcohols obtained by the process are useful as drugs and intermediates for the preparation of drugs.
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- Reduction of aliphatic and aromatic cyclic ketones to sec-alcohols by aqueous titanium trichloride/ammonia system. Steric course and mechanistic implications
-
In contrast to the dissolved metal and metal hydride reductions, the reduction of cyclic ketones by the aqueous TiCl3/NH3 system favours the formation of the less thermodynamically stable axial alcohol. The ammonium ion formed in situ is essential for the reduction to proceed because it behaves as a mild Br?nsted acid in basic medium and favours the protonation of the intermediate ketyl. The corresponding α-hydroxy radical is then rapidly reduced under conditions where the first electron transfer to the substrate takes place. We suggest that the stereoselectivity is determined by the second reduction step, which occurs through the less hindered transition state, regardless of whether the radical to be reduced is thermodynamically favoured or not.
- Clerici, Angelo,Pastori, Nadia,Porta, Ombretta
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p. 2235 - 2243
(2007/10/03)
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- 4-substituted piperidine analogs and their use as subtype selective NMDA receptor antagonists
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PCT No. PCT/US96/20872 Sec. 371 Date Sep. 16, 1998 Sec. 102(e) Date Sep. 16, 1998 PCT Filed Dec. 20, 1996 PCT Pub. No. WO97/23216 PCT Pub. Date Jul. 3, 1997Novel 4-substituted piperidine analogs, pharmaceutical compositions containing the same and the method of using 4-substituted piperidine analogs are selective active antagonists of N-methyl-D-aspartate (NMDA) receptor subtypes for treating conditions such as stroke, cerebral ischemia, central nervous system trauma, hypoglycemia, psychosis, anxiety, migraine headaches, glaucoma, CMV retinitis, aminoglycoside antibiotics-induced hearing loss, convulsions, chronic pain, opioid tolerance or withdrawal, urinary incontinence or neurodegenerative disorders, such as lathyrism, Alzheimer's Disease, Parkinsonism and Huntington's Disease are described.
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- Pd/C(en)-catalyzed regioselective hydrogenolysis of terminal epoxides to secondary alcohols
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Various terminal epoxides, such as 1,2-epoxyalkanes, glycidyl ethers and glycidol, were hydrogenolyzed to give secondary alcohols with high regioselectivity using a 10% Pd/C-ethylenediamine complex as a catalyst under entirely neutral conditions.
- Sajiki, Hironao,Hattori, Kazuyuki,Hirota, Kosaku
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p. 1041 - 1042
(2007/10/03)
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- The enantiomer ratio strongly depends on the alkyl part of the acyl donor in transesterification with lipase B from Candida antarctica
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Three secondary alcohols, 1-phenoxy-, 1-phenylmethoxy- and 1-(2-phenylethoxy)-2-propanol, have been resolved by transesterification with the acyl donors 2-chloroethyl butanoate, 2,2,2-trichloroethyl butanoate, vinyl butanoate and butanoic anhydride using lipase B from Candida antarctica as catalyst in hexane. The enantiomer rate E, which was calculated on the basis of a ping-pong bi-bi mechanism, was highest when 2-chloroethyl butanoate was used as acyl donor, however the reaction was reversible. It was shown that the E-value increased when the amount of 2,2,2-trichloroethyl butanoate was reduced. It is also indicated that butanoic anhydride and vinyl butanoate make the lipase less specific probably by acylation. Copyright (C) Elsevier Science Ltd.
- Hoff, Bard H.,Anthonsen, Henrik W.,Anthonsen, Thorleif
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p. 3187 - 3192
(2007/10/03)
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- Chemo- and Regioselective Reductions of Functionalized Epoxides by Bu3SnH/Bu3SnI-Phosphine Oxide
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A novel reagent, Bu3SnH/Bu3SnI-phosphine oxide, reduced functionalized epoxides to the corresponding alcohols in high chemo- and regioselectivities.
- Kawakami, Takayo,Tanizawa, Daisuke,Shibata, Ikuya,Baba, Akio
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p. 9357 - 9360
(2007/10/02)
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- Modified Borohydride Agents, 1-Benzyl-4-aza-1-azoniabicyclooctane Tetrahydroborate (BAAOTB) versus Tetrabutylammonium Tetrahydroborate (TBATB). Efficient, Selective, and Versatile Reducing Agents
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1-Benzyl-4-aza-1-azoniabicyclooctane tetrahydroborate (BAAOTB) and tetrabutylammonium tetrahydroborate (TBATB) are used for the selective reductions of aldehydes, ketones, α,β-unsaturated carbonyl compounds, acid chlorides, azides, epoxides, and disulfides in t-BuOH and hexane/chloroform.ABBOAB with its rigid and bulky structure reacts more selectively than its analogue TBATB.
- Firouzabadi, Habib,Afsharifar, Gholam Reza
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p. 2595 - 2602
(2007/10/03)
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- Pd-catalysed regiospecific reductive ring opening of epoxides and glycidic esters
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The regiospecific ring opening of epoxides was achieved by Pd-catalysed transfer hydrogenolysis using ammonium formate as hydrogen source.
- Varghese,Sudalai,Iyer
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p. 2267 - 2273
(2007/10/02)
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- Method for purification of alcohols
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A method for the purification of alcohols from organic soluble impurities has been discovered comprising treating the crude alcohol with a cyclic anhydride followed by an aqueous base and extracting the corresponding half-ester into aqueous solution leaving the impurities in organic solution. This method is particularly useful for the separation of chiral, nonracemic alcohols from the corresponding antipodal ester (the mixture resulting from an enzymatic kinetic resolution) because the separation is non-chromatographic and the enantiomeric integrity of the products is maintained.
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- STRUCTURE OF THE PRODUCT OF THE REACTION OF ELEMENTAL PHOSPHORUS, PROPYLENE OXIDE, PHENOL, AND TRIETHYLAMINE
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The composition and structure of an oligomer has been studied, formed in the reaction of elemental phosphorus (P4) with propylene oxide, phenol, and triethylamine in the ratio 1:5:0.8:1.It has been found by using mass spectrometry, IR and 31P NMR spectrometry, chromatography and ebulliometry that the oligomer represents a chain consisting of fragments of isopropylphosphonous acid.Products of side reactions have been identified.
- Ivanov, B. E.,Fridland, N. S.,Krokhina, S. S.,Sharafutdinova, D. R.,Efremov, Yu. Ya.
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p. 2062 - 2065
(2007/10/02)
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- OXIRANE RINGS: STUDIES AND APPLICATIONS OF A NEW CHEMO AND REGIO SELECTIVE REDUCTIVE OPENING OF EPOXIDES
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The straightforward reductive opening of 1,2 epoxides to alcohols was studied and applied to several significant compounds.The reaction, which proceeds via the nucleophilic opening of the oxirane ring and the subsequent free radical dehalogenation, shows an excellent chemical yield as well as chemo and regioselectivity.This reaction was also applied to a chiral α,β-epoxyester.
- Bonini, Carlo,Fabio, Romano Di,Sotgiu, Giovanni,Cavagnero, Silvia
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p. 2895 - 2904
(2007/10/02)
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- SODIUM HYDROGEN TELLURIDE AS A USEFUL NUCLEOPHILIC REAGENT FOR THE CLEAVAGE OF EPOXIDES AND OF QUATERNARY AMMONIUM SALTS
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Sodium hydrogen telluride opens many epoxides cleanly by an SN2 process to give telluro-alcohols, which by reduction with nickel boride afford alcohols.An intermediate telluro-alcohol was converted to olefin in high yield by treatment with p-toluene-sulphonyl chloride in pyridine.Quaternary ammonium salts are also cleaved efficiently by sodium hydrogen telluride.
- Barton, Derek H. R.,Fekih, Abdelwaheb,Lusinchi, Xavier
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p. 6197 - 6200
(2007/10/02)
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- Conversion of One Hydroxy Group in a Diol to a Phenyl Ether with Triphenylbismuth Diacetate, a New Glycol Reaction Showing Strong Axial Preference in Six-Membered Rings
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After being refluxed for a few hours, a dichloromethane solution of a diol with triphenylbismuth diacetate gave in most cases excellent yields of a monophenyl ether.No diphenylated products were found.Tertiary hydroxy groups were only phenylated in bis tertiary diols, and then in poor yield.Increasing the distance between the hydroxy groups up to six carbon atoms decreased the speed of the reaction which nevertheless was still preparatively useful.Diols in flexible rings behaved like their acyclic counterparts.The course of the reaction was also examined with someconformationally rigid molecules: trans-4-tert-butyl-cis-2-hydroxycyclohexanol, trans-4-tert-butyl-trans-2-hydroxycyclohexanol, cholestane-2α,3α-diol, cholestane-2α,3β-diol, and pyranoside derivatives with the α-D-gluco, α-D-manno, α-D-galacto, and α-D-allo configurations.The phenylations of cis-diols were strongly regioselective for axial epimers, while those of trans, bis equatorial diols were undiscriminate and often much slower.A feasible general mechanism is proposed to explain these results.
- David, Serge,Thieffry, Annie
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p. 441 - 447
(2007/10/02)
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- SYNTHESIS OF ARYL MONOETHERS OF POLYOXYPROPYLENE GLYCOLS
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The synthesis is described of aryl monoethers of polyoxypropylene glycols.
- Chlebicki, Jan
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p. 983 - 989
(2007/10/02)
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- SELECTIVE PHENYLATION IN MILD CONDITIONS OF ONE HYDROXY GROUP IN GLYCOLS WITH TRIPHENYLBISMUTH DIACETATE: A NEW SPECIFIC GLYCOL REACTION.
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Refluxing for 4-5 h a dichloromethane solution of diol in the presence of an equimolecular quantity of triphenylbismuth diacetate gave the monophenyl ether in good to excellent yield.
- David, Serge,Thieffry, Annie
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p. 5063 - 5066
(2007/10/02)
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- Piperazine alkanols
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This invention relates to variously substituted piperazine derivatives. S compounds possess therapeutically useful vasodilator properties.
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