- Phosphate monoester hydrolysis in cyclohexane
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(Chemical Equation Presented) The hydrolysis of simple phosphate monoesters is among the most difficult reactions that are subject to catalysis by enzymes, and it has been suggested that extraction of the substrates from solvent water may contribute to th
- Stockbridge, Randy B.,Wolfenden, Richard
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Read Online
- The hydrolysis of phosphate diesters in cyclohexane and acetone
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The hydrolysis of phosphate diesters is one of the most difficult reactions known. Here we show that in acetone or cyclohexane, at 25°C, phosphodiesters undergo hydrolysis 5 × 105 and 2 × 109-fold more rapidly than in water, respecti
- Stockbridge, Randy B.,Wolfenden, Richard
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Read Online
- (Hexamethylbenzene)Ru catalysts for the Aldehyde-Water Shift reaction
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The Aldehyde-Water Shift (AWS) reaction uses H2O as a benign oxidant to convert aldehydes to carboxylic acids, producing H2, a valuable reagent and fuel, as its sole byproduct. (Hexamethylbenzene)RuIIcomplexes are demonstrated to have higher activity and selectivity (up to 95%) for AWS over disproportionation than previously reported catalysts.
- Phearman, Alexander S.,Moore, Jewelianna M.,Bhagwandin, Dayanni D.,Goldberg, Jonathan M.,Heinekey, D. Michael,Goldberg, Karen I.
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supporting information
p. 1609 - 1615
(2021/03/09)
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- Catalytic enantioselective addition of alkylzirconium reagents to aliphatic aldehydes
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A catalytic methodology for the enantioselective addition of alkylzirconium reagents to aliphatic aldehydes is reported here. The versatile and readily accessible chiral Ph-BINMOL ligand, in the presence of Ti(OiPr)4 and a zinc salt, facilitates the reaction, which proceeds under mild conditions and is compatible with functionalized nucleophiles. The alkylzirconium reagents are conveniently generated in situ by hydrozirconation of alkenes with the Schwartz reagent. This work is a continuation of our previous work on aromatic aldehydes.
- Carter, Nicholas,González-Soria, María José,Maciá, Beatriz,Vaccari, Jade
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- 1-D manganese(ii)-terpyridine coordination polymers as precatalysts for hydrofunctionalisation of carbonyl compounds
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Reductive catalysis with earth-abundant metals is currently of increasing importance and shows potential in replacing precious metal catalysis. In this work, we revealed catalytic hydroboration and hydrosilylation of ketones and aldehydes achieved by a structurally defined manganese(ii) coordination polymer (CP) as a precatalyst under mild conditions. The manganese-catalysed methodology can be applied to a range of functionalized aldehydes and ketones with turnover numbers (TON) of up to 990. Preliminary results on the regioselective catalytic hydrofunctionalization of styrenes by the Mn-CP catalyst are also presented.
- Johnson, Jahvon,Li, Sihan,Mo, Zixuan,Neary, Michelle C.,Zeng, Haisu,Zhang, Guoqi,Zheng, Shengping
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p. 2610 - 2615
(2020/03/05)
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- Selective hydrogenation of primary amides and cyclic di-peptides under Ru-catalysis
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A ruthenium(II)-catalyzed selective hydrogenation of challenging primary amides and cyclic di-peptides to their corresponding primary alcohols and amino alcohols, respectively, is reported. The hydrogenation reaction operates under mild and eco-benign conditions and can be scaled-up.
- Subaramanian, Murugan,Sivakumar, Ganesan,Babu, Jessin K.,Balaraman, Ekambaram
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supporting information
p. 12411 - 12414
(2020/10/30)
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- Catalytic Hydrogenation of Thioesters, Thiocarbamates, and Thioamides
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Direct hydrogenation of thioesters with H2 provides a facile and waste-free method to access alcohols and thiols. However, no report of this reaction is documented, possibly because of the incompatibility of the generated thiol with typical hydrogenation catalysts. Here, we report an efficient and selective hydrogenation of thioesters. The reaction is catalyzed by an acridine-based ruthenium complex without additives. Various thioesters were fully hydrogenated to the corresponding alcohols and thiols with excellent tolerance for amide, ester, and carboxylic acid groups. Thiocarbamates and thioamides also undergo hydrogenation under similar conditions, substantially extending the application of hydrogenation of organosulfur compounds.
- Luo, Jie,Rauch, Michael,Avram, Liat,Ben-David, Yehoshoa,Milstein, David
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supporting information
p. 21628 - 21633
(2021/01/11)
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- Method for preparing alcoholic compound from aliphatic carboxylic acid without catalytic reaction
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The invention discloses a method for preparing an alcoholic compound from an aliphatic carboxylic acid without the catalytic reaction. In an inert gas atmosphere, 4,4,5,5-tetramethyl-1,3,2-dioxa-borolane and the carboxylic acid are evenly stirred and mixed in a dehydration and deoxidization reaction flask, and react for 8-10 hours to obtain a boric acid ester; and the carboxylic acid is acetic acid, caproic acid, valeric acid, heptylic acid, trimethylacetic acid, adipic acid and the like. The aliphatic carboxylic acid efficiently is used to react with borane to implement hydroboration withouta catalyst for the first time, and a novel scheme is provided for the preparation of the boric acid ester through hydroboration of a carbonyl compound and the borane and the further hydrolysis of theboric acid ester into an alcohol.
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Paragraph 0022
(2019/04/04)
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- N-butyl lithium based fatty alcohol preparation method
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The invention relates to an n-butyl lithium based fatty alcohol preparation method. In an inert gas atmosphere, borane and aliphatic carboxylic acid are mixed, then n-butyl lithium taken as the catalyst is added to carry out hydroboration reactions; and after the hydroboration reactions, silica gel and methanol are added to carry out hydrolysis reactions to obtain the fatty alcohols. N-butyl lithium can efficiently catalyze the hydroboration reactions between carboxylic acids and borane at a room temperature, the used catalyst only accounts for 0.2 mol% of the carboxylic acids, compared with aconventional catalyst system, a commercial catalyst namely n-butyl lithium is adopted, the reaction conditions are mild, and the yield of fatty alcohols with different substitutes under restricted conditions is high.
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Paragraph 0023
(2019/05/08)
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- Interplay between Substrate and Proton Donor Coordination in Reductions of Carbonyls by SmI2-Water Through Proton-Coupled Electron-Transfer
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The reduction of a carbonyl by SmI2-water is the first step in a range of reactions of synthetic importance. Although the reduction is often proposed to proceed through an initial stepwise electron-transfer-proton-transfer (ET-PT), recent work has shown that carbonyls and related functional groups are likely reduced though proton-coupled electron-transfer (PCET). In the present work, the reduction of an activated ester, aldehyde, a linear and cyclic ketone, and related sterically demanding carbonyls by SmI2-H2O was examined through a series of mechanistic experiments. Kinetic studies demonstrate that all substrates exhibit significant increases in the rate of reduction by SmI2 as [H2O] is increased. Under identical conditions, ketones and an aldehyde containing a methyl adjacent to the carbonyl are reduced slower than an unsubstituted variant by an order of magnitude, demonstrating the importance of substrate coordination. In the case of unactivated substrates, rates of reduction show excellent correlation with the calculated bond dissociation free energy of the O-H bond of the intermediate ketyl and the calculated free energy of intermediate ketyl radical anions derived from unhindered substrates: findings consistent with concerted PCET. Activated esters derived from methylbenzoate are likely reduced through stepwise or asynchronous PCET. Overall, this work demonstrates that the combination of the coordination of substrate and water to Sm(II) provides a configuration uniquely suited to a coupled electron- and proton-transfer process.
- Chciuk, Tesia V.,Anderson, William R.,Flowers, Robert A.
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supporting information
p. 15342 - 15352
(2018/11/30)
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- Selective hydrogenation of amides to alcohols in water solvent over a heterogeneous CeO2-supported Ru catalyst
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CeO2-supported Ru (Ru/CeO2) worked as an effective and reusable heterogeneous catalyst for the selective dissociation of the C-N bond in amides, particularly primary amides, with H2 in water solvent at low reaction temperature of 333 K, and high yields of the corresponding alcohols were obtained from primary amides.
- Tamura, Masazumi,Ishikawa, Susumu,Betchaku, Mii,Nakagawa, Yoshinao,Tomishige, Keiichi
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p. 7503 - 7506
(2018/07/13)
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- Selective Hydrogenation of Carboxylic Acids to Alcohols or Alkanes Employing a Heterogeneous Catalyst
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The chemoselective hydrogenation of carboxylic acids to either alcohols or alkanes is reported, employing a heterogeneous bimetallic catalyst consisting of rhenium and palladium supported on graphite. α-Chiral carboxylic acids were hydrogenated without loss of optical purity. The catalyst displays a reverse order of reactivity upon hydrogenation of different carboxylic functions with esters being less reactive than amides and carboxylic acids. This allows for chemoselective hydrogenation of an acid in the presence of an ester or an amide function.
- Ullrich, Johannes,Breit, Bernhard
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p. 785 - 789
(2018/02/14)
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- Robust cobalt oxide catalysts for controllable hydrogenation of carboxylic acids to alcohols
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The selective catalytic hydrogenation of carboxylic acids is an important process for alcohol production, while efficient heterogeneous catalyst systems are still being explored. Here, we report the selective hydrogenation of carboxylic acids using earth-abundant cobalt oxides through a reaction-controlled catalysis process. The further reaction of the alcohols is completely hindered by the presence of carboxylic acids in the reaction system. The partial reduction of cobalt oxides by hydrogen at designated temperatures can dramatically enhance the catalytic activity of pristine samples. A wide range of carboxylic acids with a variety of functional groups can be converted to the corresponding alcohols at a yield level applicable to large-scale production. Cobalt monoxide was established as the preferred active phase for the selective hydrogenation of carboxylic acids.
- Song, Song,Wang, Dong,Di, Lu,Wang, Chuanming,Dai, Weili,Wu, Guangjun,Guan, Naijia,Li, Landong
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p. 250 - 257
(2018/02/20)
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- Ruthenium-Catalyzed Deoxygenative Hydroboration of Carboxylic Acids
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An efficient deoxygenative hydroboration of carboxylic acids to alkyl boronate esters under mild reaction condition is reported. Both aromatic and aliphatic carboxylic acids exhibited excellent reactivities with minimal catalyst load of 0.1 mol% and reactions occurred under neat conditions. This catalytic transformation selectively provides alkyl boronate esters, which can be conveniently hydrolyzed to obtain the corresponding alcohols. Remarkably, this reduction reaction proceeds with the liberation of molecular hydrogen.
- Kisan, Sesha,Krishnakumar, Varadhan,Gunanathan, Chidambaram
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p. 4772 - 4776
(2018/06/08)
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- REACTIONS OF STANNYL CATIONS
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The present invention relates to a method of reducing, cleaving and/or coupling at least one C=O, C-O, C=C or C=N bond of a compound, using a reagent comprising a stannyl cation.
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Page/Page column 18; 19
(2018/01/17)
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- Rhenium-Loaded TiO2: A Highly Versatile and Chemoselective Catalyst for the Hydrogenation of Carboxylic Acid Derivatives and the N-Methylation of Amines Using H2 and CO2
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Herein, we report a heterogeneous TiO2-supported Re catalyst (Re/TiO2) that promotes various selective hydrogenation reactions, which includes the hydrogenation of esters to alcohols, the hydrogenation of amides to amines, and the N-methylation of amines, by using H2 and CO2. Initially, Re/TiO2 was evaluated in the context of the selective hydrogenation of 3-phenylpropionic acid methyl ester to afford 3-phenylpropanol (pH2 =5 MPa, =5 MPa, T=180 °C), which revealed a superior performance over other catalysts that we tested in this study. In contrast to other typical heterogeneous catalysts, hydrogenation reactions with Re/TiO2 did not produce dearomatized byproducts. DFT studies suggested that the high selectivity for the formation of alcohols in favor of the hydrogenation of aromatic rings is ascribed to the higher affinity of Re towards the COOCH3 group than to the benzene ring. Moreover, Re/TiO2 showed a wide substrate scope for the hydrogenation reaction (19 examples). Subsequently, this Re/TiO2 catalyst was applied to the hydrogenation of amides, the N-methylation of amines, and the N-alkylation of amines with carboxylic acids or esters.
- Toyao, Takashi,Siddiki,Morita, Yoshitsugu,Kamachi, Takashi,Touchy, Abeda S.,Onodera, Wataru,Kon, Kenichi,Furukawa, Shinya,Ariga, Hiroko,Asakura, Kiyotaka,Yoshizawa, Kazunari,Shimizu, Ken-Ichi
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supporting information
p. 14848 - 14859
(2017/10/27)
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- Novel method for industrially preparing neopentyl alcohol
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The invention relates to and provides a novel method for industrially preparing neopentyl alcohol. The method comprises steps as follows: a substrate, namely, trimethylacetic acid, a solution of a borane solvent A and a solvent A react at a certain temperature, a quenching reaction is conducted after the reaction ends, filtration is performed, a filtrate is subjected to reduced pressure concentration, the solvent A is removed, later, water and a solvent B are added for extraction of a crude product of neopentyl alcohol, reduced pressure concentration is performed after water washing and drying, and neopentyl alcohol is obtained. With the cheap and easily available raw material, namely, trimethylacetic acid, as an initiator, the solution of the borane solvent A as a reducer and the solvent A as a solvent system, the substrate, namely, trimethylacetic acid, is directionally reduced under the normal-temperature condition, no side reactions are produced, special equipment and catalysts are not required in the reaction process, high-purity neopentyl alcohol can be obtained through ordinary distillation, the raw material conversion rate reaches 99% or above, the yield reaches 86% or above, the purity of the neopentyl alcohol product reaches 99% or above, and industrial amplified production is facilitated.
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Paragraph 0022-0023
(2017/07/22)
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- METHOD FOR PRODUCING ALCOHOL COMPOUND
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PROBLEM TO BE SOLVED: To provide a novel production method that reduces a carboxylic acid derivative to an alcohol compound under a mild reaction condition by using inexpensive copper complex catalysts instead of expensive ruthenium complex catalysts. SOLUTION: An method for producing an alcohol compound comprises a step (2) for reducing a carboxylic acid ester compound with hydrogen in the presence of a copper complex obtained by the reaction of an imidazolium salt (A), a copper compound (B) and a base (C). SELECTED DRAWING: None COPYRIGHT: (C)2017,JPOandINPIT
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Paragraph 0075; 0076; 0078
(2017/04/28)
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- Improved Catalytic Activity and Stability of a Palladium Pincer Complex by Incorporation into a Metal-Organic Framework
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A porous metal-organic framework Zr6O4(OH)4(L-PdX)3 (1-X) has been constructed from Pd diphosphinite pincer complexes ([L-PdX]4- = [(2,6-(OPAr2)2C6H3)PdX]4-, Ar = p-C6H4CO2-, X = Cl, I). Reaction of 1-X with PhI(O2CCF3)2 facilitates I-/CF3CO2- ligand exchange to generate 1-TFA and I2 as a soluble byproduct. 1-TFA is an active and recyclable catalyst for transfer hydrogenation of benzaldehydes using formic acid as a hydrogen source. In contrast, the homogeneous analogue tBu(L-PdTFA) is an ineffective catalyst owing to decomposition under the catalytic conditions, highlighting the beneficial effects of immobilization.
- Burgess, Samantha A.,Kassie, Abebu,Baranowski, Sarah A.,Fritzsching, Keith J.,Schmidt-Rohr, Klaus,Brown, Craig M.,Wade, Casey R.
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supporting information
p. 1780 - 1783
(2016/03/01)
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- Ligand, metal complex containing ligand, and reaction using metal complex containing ligand
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A hydrogen transfer reaction may be more efficiently promoted by using a metal complex represented by Formula (2): (wherein, R1 to R8 are the same or different, and each represents a hydrogen atom, a substituted or unsubstituted alkyl group or the like; or wherein; R1 and R2, R2 and R3, R3 and R4, R4 and R5, and R5 and R6 are respectively bonded to each other to form a bivalent hydrocarbon group; R9 are the same or different, and each represents an alkyl group or cycloalkyl group; M is ruthenium (Ru) or the like; X is a ligand; and n is 0, 1 or 2). More specifically, the metal complex enables a hydrogenation reaction of various substrates having a stable carbonyl group or the like to be advanced with a high yield under mild conditions.
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Page/Page column 46-50
(2016/10/31)
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- METAL COMPLEX INCLUDING TRIDENTATE AMINODICARBENE LIGAND AND HYDROGENATION REDUCTION METHOD USING SAME
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The use of a metal complex containing a ruthenium ion or an osmium ion, and a tridentate aminodicarbene ligand, the tridentate aminodicarbene ligand having one secondary amino group and two specific heterocyclic carbene groups sandwiching the amino group, enables hydrogenation reduction of carbonyl compounds, such as ketones, carboxylic acid esters, lactones, carboxylic acid amides, and lactams, and imine compounds under relatively mild conditions to produce corresponding alcohols, amines, and the like in a high yield with high catalytic efficiency. The metal complex is obtained by a method comprising steps of reacting a specific metal compound with a specific aminodicarbene precursor and subsequently reacting a specific compound. Reduction of a carbonyl compound or an imine compound in the presence of this metal complex using a hydrogen donor makes it possible to reduce the carbonyl compound or imine compound by hydrogenation.
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Paragraph 206; 207
(2016/06/13)
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- METHOD FOR PRODUCING OXIDE
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PROBLEM TO BE SOLVED: To provide a method for producing an oxide capable of easily producing an oxide excellent in substrate selectivity with a high yield, which allows the reaction to proceed without using a solvent under moderate conditions at 100°C or less. SOLUTION: There is provided a method for producing an oxide by oxidizing a substrate (A) in the presence of a compound selected from oxygen, ozone and a radical generator to obtain a corresponding oxide. The radical generator preferably includes at least one compound selected from a nitroxy-based radical generator and an azo-based radical generator. In addition, the oxidation reaction is preferably carried out in the presence of a metal compound containing at least one metal element selected from cobalt, manganese, zirconium and molybdenum. SELECTED DRAWING: None COPYRIGHT: (C)2016,JPO&INPIT
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Paragraph 0090; 0096
(2018/10/16)
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- Base-Free Iridium-Catalyzed Hydrogenation of Esters and Lactones
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Half-sandwich iridium bipyridine complexes catalyze the hydrogenation of esters and lactones under base-free conditions. The reactions proceed with a variety of ester and lactone substrates. Mechanistic studies implicate a pathway involving rate-limiting hydride transfer to the substrate at high pressures of H2 (≥50 bar).
- Brewster, Timothy P.,Rezayee, Nomaan M.,Culakova, Zuzana,Sanford, Melanie S.,Goldberg, Karen I.
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p. 3113 - 3117
(2016/07/06)
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- Highly efficient, general hydrogenation of aldehydes catalyzed by PNP iron pincer complexes
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A general protocol for the synthetically and industrially important hydrogenation of aldehydes to alcohols is reported. The reactions are catalyzed by well-defined iron pincer complexes that are capable of hydrogenation of aliphatic and aromatic aldehydes selectively and efficiently under mild conditions, with unprecedented turnover numbers.
- Zell, Thomas,Ben-David, Yehoshoa,Milstein, David
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p. 822 - 826
(2015/02/19)
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- Synthesis, structure, and bonding properties of ruthenium complexes possessing a boron-based pbp pincer ligand and their application for catalytic hydrogenation
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In addition to our previous works for PBP-pincer metal complexes, four PBP-pincer Ru complexes, [PBP]Ru(Cl)(CO) (2), [PBP]Ru(CO)(2-BH4) (3), [PBP](-H)2Ru(OAc-2O) (4), and [PBP](-H)2Ru(2-BH4) (5) were synthesized. All the obtained complexes were characterized by NMR and IR spectroscopy, X-ray crystallography, elemental analysis, and DFT calculation with AIM analysis. Through the structural analysis, two types of interaction between boron atoms and ruthenium atoms in 3-5 were revealed. One is the typical two-center-two-electron bond between the boron atom of the PBP ligand and the Ru atom, associated with bridging hydride ligand(s) on the Ru(IV) center. The other is an ionic interaction between the Ru fragment and the tetrahydroborate anion. On comparison of the structural features, vibrational analysis, NBO analysis, and AIM analysis of the obtained compounds with those of the previously reported complexes having "similar" interactions among B, H, and Ru atoms, the interactions in 4 and 5 were proven to be different from that previously reported. The obtained complexes 3-5 were applied as catalysts for the hydrogenation of aldehyde. Complex 5 showed the highest catalytic activity and widest range of substrate scope. Two mechanisms for the catalytic cycle were proposed with an initial dissociation of BH3 or anionic ligand, according to the control experiments.
- Miyada, Takuma,Huang Kwan, Enrique,Yamashita, Makoto
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p. 6760 - 6770
(2015/02/19)
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- PROMOTED RUTHENIUM CATALYST FOR THE IMPROVED HYDROGENATION OF CARBOXYLIC ACIDS TO THE CORRESPONDING ALCOHOLS
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The invention relates to ruthenium-rhenium-tin and ruthenium-rhenium catalysts effective for the reduction of carboxylic acids to the corresponding alcohols and processes for the reduction of carboxylic acids to the corresponding alcohols using the ruthenium-rhenium-tin and ruthenium-rhenium catalysts.
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Paragraph 0088
(2014/05/08)
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- Gallium-catalyzed reductive chlorination of carboxylic acids with copper(II) chloride
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Described herein is the direct chlorination of carboxylic acids using copper(II) chloride via a gallium(III)-catalyzed reduction in the presence of a hydrosiloxane. During this reductive chlorination, the counteranions of CuCl2 functioned as a chloride source.
- Sakai, Norio,Nakajima, Takumi,Yoneda, Shinichiro,Konakahara, Takeo,Ogiwara, Yohei
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p. 10619 - 10623
(2015/02/19)
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- Catalytic hydrogenation of unactivated amides enabled by hydrogenation of catalyst precursor
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A general method for catalytic hydrogenation of unactivated amides was achieved. During the catalyst induction period, a novel structural change was observed involving full hydrogenation of the interior unsaturated bonds of the pyridines of the Ru-containing catalyst precursor. Based on this observation, the mechanism of amide hydrogenation may involve a two-step pathway, wherein the Ru catalyst having an H-Ru-N-H functionality is generated in the first step, followed by the amide carbonyl group interacting with the outer, rather than the inner, sphere of the Ru catalyst.
- Miura, Takashi,Held, Ingmar E.,Oishi, Shunsuke,Naruto, Masayuki,Saito, Susumu
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supporting information
p. 2674 - 2678
(2013/06/26)
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- Ester hydrogenation catalyzed by a ruthenium(II) complex bearing an N-heterocyclic carbene tethered with an "nH2" group and a DFT study of the proposed bifunctional mechanism
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A ruthenium(II) catalyst containing an NHC-amine (NHC = Nheterocyclic carbene) ligand (C-NH2) catalyzes the H2-hydrogenation of various esters and lactones at 50 °C and 25 bar of H2 pressure, mild reaction conditions compared with other reported catalysts. A maximum turnover frequency of 1510 h-1 for the hydrogenation of phthalide with a conversion of 96% is achieved in 4 h. DFT calculations suggest a concerted, asynchronous bifunctional mechanism for homogeneous ester hydrogenation; a proton transfer step from the N-H group of a ruthenium hydride-amine complex to the carbonyl group has the largest energy barrier in the catalytic cycle. A surprising observation is that methyl pivalate ( tBuCOOCH3) is hydrogenated much more rapidly than is tert-butyl acetate (CH3COOtBu). This is explained by the energetics of the rate-determining step of the proposed Ru-H/N-H bifunctional mechanism.
- O, Wylie W.N.,Morris, Robert H.
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- Formation of an alkyne during degradation of metal-alkylidyne complexes
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The compound [(Ot-Bu)3WCt-Bu] (1) (t-Bu = C(CH3) 3) decomposes upon contact with water and several organic products are formed, including di-tert-butylacetylene, t-BuCCt-Bu. This process is reminiscent of the degradation of trinuclear metal-alkylidyne complexes in which free carbynes are ejected into solution, couple and form alkynes along with many other products. The reactivity pattern of the resulting t-BuC carbynes that includes extensive hydrogen abstraction, cleavage of alkynes and lack of reactivity towards alkenes is indicative of a quartet (S = 3/2) spin state. A similar spin state was assigned to other RC (R = alkyl) species that were produced by degrading M3-alkylidyne (M = transition metal) complexes in water. t-BuCCt-Bu is also produced during thermal decomposition of solid 1. In 1977 Fischer and co-workers reported a very similar process in which solids of Br(CO)4CrCR1 and Br(CO)4CrCR2 were co-thermolyzed to produce R1CCR2, R 1CCR1, and R2CCR2. Fischer had considered the involvement of free carbynes in the making of the alkynes but later resorted to other explanations. The current results suggest that his original proposal is indeed valid.
- Levy, Ophir,Musa, Sanaa,Bino, Avi
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p. 12248 - 12251
(2013/09/02)
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- Versatile approach to α-alkoxy carbamate synthesis and stimulus-responsive alcohol release
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A series of α-alkoxy carbamates that cleave under mild conditions to release alcohols has been synthesized through a multicomponent process. The relationship between structural features in these compounds and the rate of alcohol release in the presence of basic hydrogen peroxide has been studied. The preparation of carbamates that cleave under other conditions has been demonstrated.
- Mosey, R. Adam,Floreancig, Paul E.
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supporting information
p. 7980 - 7985
(2013/06/27)
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- Catalytic proficiency: The extreme case of S-O cleaving sulfatases
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As benchmarks for judging the catalytic power of sulfate monoesterases, we sought to determine the rates of spontaneous hydrolysis of unactivated alkyl sulfate monoesters by S-O bond cleavage. Neopentyl sulfate proved to be unsuitable for this purpose, since it was found to undergo hydrolysis by a C-O bond cleaving mechanism with rearrangement of its carbon skeleton. Instead, we examined the temperature dependence of the spontaneous hydrolyses of aryl sulfate monoesters, which proceed by S-O cleavage. Extrapolation of a Bronsted plot [log(k25N) = (-1.81 ± 0.09) pKaLG + (3.6 ± 0.7)] based on the rate constants at 25 °C for hydrolysis of a series of sulfate monoesters to a pKaLG value of 16.1, typical of an aliphatic alcohol, yields k25N = 3 × 10 -26 s-1. Comparison of that value with established k cat values of bacterial sulfatases indicates that these enzymes produce rate enhancements (kcat/kuncat) of up to 2 × 1026-fold for the hydrolysis of sulfate monoesters. These rate enhancements surpass by several orders of magnitude the ～10 21-fold rate enhancements that are generated by phosphohydrolases, the most powerful biological catalysts previously known. The hydrolytic rates of phosphate and sulfate monoesters are compared directly, and the misleading impression that the two classes of ester are of similar reactivity is dispelled.
- Edwards, David R.,Lohman, Danielle C.,Wolfenden, Richard
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supporting information; experimental part
p. 525 - 531
(2012/03/07)
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- Selective hydrogenation of amides using ruthenium/ molybdenum catalysts
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Recyclable, heterogeneous bimetallic ruthenium/molybdenum catalysts, formed in situ from triruthenium dodecacarbonyl [Ru3(CO)12] and molybdenum hexacarbonyl [Mo(CO)6], are effective for the selective liquid phase hydrogenation of cyclohexylcarboxamide (CyCONH2) to cyclohexanemethylamine (CyCH2NH2), with no secondary or tertiary amine by-product formation. Variation of Mo:Ru composition reveals both synergistic and poisoning effects, with the optimum combination of conversion and selectivity at ca. 0.5, and total inhibition of catalysis evident at ≥1. Good amide conversions are noted within the reaction condition regimes 20100 bar hydrogen and 145-160°C. The order of reactivity of these catalysts towards reduction of different amide functional groups is primary > tertiary ? secondary. In situ HP-FT-IR spectroscopy confirms that catalyst genesis occurs during an induction period associated with decomposition of the organometallic precursors. Ex situ characterisation, using XRD, XPS and EDX-STEM, for active Mo:Ru compositions, has provided evidence for intimately mixed ca. 2.5-4 nm particles that contain metallic ruthenium, and molybdenum (in several oxidation states, including zero).
- Beamson, Graham,Papworth, Adam J.,Philipps, Charles,Smith, Andrew M.,Whyman, Robin
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experimental part
p. 869 - 883
(2010/07/05)
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- Indium triiodide catalyzed direct hydroallylation of esters
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The InI3-catalyzed hydroallylation of esters by using hydroand allysilanes under mild conditions has been accomplished. Many significant groups such as alkenyl, alkynyl, cyano, and nitro ones survive under these conditions. This reaction system, provided routes to both homoallylic alcohols and ethers, in which either elimination of the alkoxy moiety or of the carbonyl oxygen atom could be freely selected by changing the substituents on the alkoxy moiety and on the hydrosilane. In addition, the hydroallylation of lactones took place without ring cleavage to produce the desired cyclic ethers in high yields.
- Nishimoto, Yoshihiro,Inamoto, Yoshihiro,Saito, Takahiro,Yasuda, Makoto,Baba, Akio
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supporting information; experimental part
p. 3382 - 3386
(2010/08/19)
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- Platinum-triethylamine-catalyzed hydrogenation of aldehydes and cyclohexanones
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The first hydrogenation of aldehydes and chemoselective hydrogenation of cyclohexanones catalyzed by PtO2-Et3N are presented. An additionally attractive feature of this hydrogenation is being applicable to the complicated molecules. Three equivalent of triethylamine and 0.05 equiv of PtO2 in 95% ethanol are found to be the optimal condition.
- Gao, Feng,Chen, Qiao-Hong,Wang, Feng-Peng
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supporting information; experimental part
p. 5270 - 5273
(2009/12/24)
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- Formation of secondary or tertiary aliphatic amines in aqueous media
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Secondary and tertiary amines can be easily obtained from primary and secondary amines, respectively, in completely aqueous media, in the presence of a bicatalytic system formed of cheap commercial aluminum (Al) powder and 5% rhodium (Rh) or ruthenium (Ru) deposed on charcoal.
- Marieta Simion, Alina,Arimura, Takashi,Miyazawa, Akira,Simion, Cristian,Surya Prakash,Olah, George A.,Tashiro, Masashi
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scheme or table
p. 2859 - 2865
(2009/12/03)
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- EXTERNALLY MASKED NEOPENTYL SULFONYL ESTER CYCLIZATION RELEASE PRODRUGS OF ACAMPROSATE, COMPOSITIONS THEREOF, AND METHODS OF USE
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Masked nitrogen-substituted and oxygen-substituted neopentyl sulfonyl ester prodrugs of acamprosate, pharmaceutical compositions comprising such prodrugs, and methods of using such prodrugs and compositions thereof for treating diseases are disclosed. In particular, acamprosate prodrugs exhibiting enhanced oral bioavailability and methods of using acamprosate prodrugs to treat neurodegenerative disorders, psychotic disorders, mood disorders, anxiety disorders, somatoform disorders, movement disorders, substance abuse disorders, binge eating disorder, cortical spreading depression related disorders, tinnitus, sleeping disorders, multiple sclerosis, and pain are disclosed.
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Page/Page column 37
(2009/04/24)
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- A convenient and general iron-catalyzed hydrosilylation of aldehydes
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A general and highly chemoselective hydrosilylation of aldehydes using iron catalysts is reported. Fe(OAc)2 in the presence of tricyclohexylphosphine as ligand and polymethylhydrosiloxane (PMHS) as an economical hydride source forms an efficient catalyst system for the hydrosilylation of a variety of aldehydes. Aryl, heteroaryl, alkyl and α,β-unsaturated aldehydes are successfully reduced to the corresponding primary alcohols. Broad substrate scope and high tolerance against several functional groups make the process synthetically useful.
- Shaikh, Nadim S.,Junge, Kathrin,Beller, Matthias
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p. 5429 - 5432
(2008/09/19)
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- On water and in air: Fast and highly chemoselective transfer hydrogenation of aldehydes with iridium catalysts
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(Chemical Equation Presented) Water as solvent: A fast, selective, and high-yielding transfer hydrogenation of a wide range of aldehydes is achieved using IrIII catalysts containing simple ethylene-diamine (en) ligands (see scheme; Ts = p-toluenesulfonyl, TOF = turnover frequency). This procedure is suitable for aldehydes with a wide range of functional groups.
- Wu, Xiaofeng,Liu, Jianke,Li, Xiaohong,Zanotti-Gerosa, Antonio,Hancock, Fred,Vinci, Daniele,Ruan, Jiwu,Xiao, Jianliang
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p. 6718 - 6722
(2007/10/03)
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- Copper(I)-catalyzed enantio- and diastereoselective tandem reductive aldol reaction
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(Chemical Equation Presented) An efficient method for the enantioselective tandem reductive aldol reaction of methyl acrylate with aldehydes is reported. By using a copper-(I) precursor and a proper diphosphane ligand, high reactivities can be reached, with TOF up to 40 000 h-1. Taniaphos-based ligands lead to enantioselectivities of up to 97% in the case of the major syn diastereoisomer.
- Chuzel, Olivier,Deschamp, Julia,Chausteur, Christophe,Riant, Olivier
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p. 5943 - 5946
(2007/10/03)
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- Practical syntheses of neopentyl alcohol and sec-butyl ethyl ether using Marukasol as a solvent
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By using Marukasol, neopentyl alcohol and sec-butyl ethyl ether have been obtained in good yields with easy operations. Thus, neopentyl alcohol was obtained from tert-butylmagnesium chloride and paraformaldehyde in 76% isolated yield with >99% purity using Marukasol as an effective extraction solvent On the other hand, sec-butyl ethyl ether was obtained from sodium sec-butoxide with ethyl iodide in Marukasol in 67% yield with >99% purity.
- Yuasa, Yoshifumi,Kato, Yasushi
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p. 825 - 826
(2012/12/26)
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- Exploring SmBr2-, SmI2-, and YbI2-mediated reactions assisted by microwave irradiation
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The use of microwave heating in lanthanide(II) halide (LnX2 = SmBr2, SmI2, and YbI2) mediated reduction and coupling reactions has been investigated for a variety of functional groups including α,β-unsaturated esters, aldehydes, ketones, imines, and alkyl halides. Good to quantitative transformations were obtained within a few minutes without the addition of any co-solvents, such as hexamethyl phosphoramide (HMPA). The redox potential of YbI2 in tetrahydrofuran (THF) has been determined as -1.02± 0.05 V (versus Ag/AgNO3) by cyclic voltammetry. A large selectivity difference in various reactions was observed depending on the redox potential of the LnX2 reagent. The more powerful reductant, SmBr2, afforded mainly pinacol-coupling products of ketones whereas the weaker reductant YbI2 afforded mainly reduction products. The results indicate that the reducing power of LnX 2 has a large impact on not only the pinacol coupling/reduction product ratio of ketones but also on other substrates in which there are competing coupling and reduction reactions. The use of in situ generated LnX2 has also been explored and proven useful in many of these reactions.
- Dahlen, Anders,Prasad, Edamana,Flowers II, Robert A.,Hilmersson, Goeran
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p. 3279 - 3284
(2007/10/03)
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- A pentanuclear yttrium hydroxo cluster as an oxidation catalyst. Catalytic oxidation of aldehydes in the presence of air
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The air- and moisture-stable pentanuclear yttrium cluster H 5[Y5(μ4-O)(μ3-O) 4(μ-η2-Ph2acac) 4(η2-Ph2acac)6] (Ph 2acac = dibenzoylmethanide) has been used as a homogenous catalyst for the oxidation of aldehydes to the corresponding carboxylic acids in the presence of air.
- Roesky, Peter W.,Canseco-Melchor, Graciela,Zulys, Agustino
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p. 738 - 739
(2007/10/03)
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- Reduction of carbonyl compounds with polyethylsiloxane in the presence of titanium compounds
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Reduction of carbonyl compounds with polyethylsiloxane in the presence of titanium alkoxides gives the corresponding alcohols in high yields.
- Kozhukhova,Yatluk,Suvorov,Koryakova
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p. 759 - 762
(2007/10/03)
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- An amino alcohol ligand for highly enantioselective addition of organozinc reagents to aldehydes: Serendipity rules
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(matrix presented) Amino alcohol 4 (or its enantiomer) is prepared in two simple steps. Commercial (1R,2S)-2-amino-1,2-diphenylethanol is dialkylated with bis(2-bromoethyl) ether. Subsequent hydrogenation over 5% Rh on alumina in the presence of morpholine unexpectedly stops at the hexahydro derivative 4. Amino alcohol 4 promotes the enantioselective addition of diethylzinc to aldehydes at room temperature in up to 99% enantiomeric excess.
- Nugent, William A.
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p. 2133 - 2136
(2007/10/03)
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- Reduction of aldehydes using trialkylboranes in ionic liquids
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Non-aqueous ionic liquids, molten salts, have been found to enhance organoboron mediated reductions of aldehydes.
- Kabalka,Malladi
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p. 2191 - 2191
(2007/10/03)
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- The autoxidation of aliphatic esters. Part 2. The autoxidation of neopentyl esters
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The autoxidation of six esters, neopentyl butanoate, 2,2-dimethylpropanoate, 3,3-dimethylbutanoate, 2,2-dimethylbutanoate, 2-methylbutanoate and 1,1-[2H2]-neopentyl butanoate, has been studied at 438 K. The reaction products were determined for each system and key reactions leading to the formation and further reactions of the primary products have been identified. Primary products include a range of hydroperoxides which lead to the formation of keto- and hydroxy-esters. Large amounts of neopentanol and the parent carboxylic acid are formed from each ester. It is shown that these are principally oxidation, and not hydrolysis, products. The relative rates of autoxidation of the first five esters mirror the relative rates of attack that occur on reaction with alkoxyl radicals; the sites of attack are on both the alkyl and acyl groups, with the α-alkyl hydrogen atoms on the ester showing particular vulnerability compared to the acyl hydrogen atoms. The analysis of products from the deuterated ester supports this conclusion.
- Lindsay Smith, John R.,Nagatomi, Eiji,Waddington, David J.
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p. 2248 - 2258
(2007/10/03)
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- Selective reduction of acid chloride with a catalytic amount of an indium compound
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Indium hydride generated from tributyltin hydride and indium trichloride was coordinated by a phosphine to reduce acid chlorides to the corresponding aldehydes selectively. This reaction was achieved by a catalytic amount of indium trichloride.
- Inoue, Katsuyuki,Yasuda, Makoto,Shibata, Ikuya,Baba, Akio
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p. 113 - 116
(2007/10/03)
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- Reduction of carboxylic acids by tetraalkyl ammonium borohydride
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Tetraalkylammonium borohydride reduces carboxylic acids to the corresponding alcohols in good yields utilizing only stoichiometric quantities of hydride and also in the absence of any Lewis acids.
- Narasimhan,Swarnalakshmi,Balakumar
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p. 941 - 946
(2007/10/03)
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- Preparation of a novel indium hydride and application to practical organic synthesis
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Dichloroindium hydride was first generated using the transmetalation between indium trichloride and tributylstannane at - 78 °C, and the generation was confirmed by IR and NMR measurements. The resulting hydride is considerably stable even at ambient temperature due to the coordination of THF, such that it is applicable to practical reduction of carbonyls and halides.
- Miyai, Takashi,Inoue, Katsuyuki,Yasuda, Makoto,Shibata, Ikuya,Baba, Akio
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p. 1929 - 1932
(2007/10/03)
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