- Visible-light photoredox-catalyzed selective carboxylation of C(sp3)?F bonds with CO2
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It is highly attractive and challenging to utilize carbon dioxide (CO2), because of its inertness, as a nontoxic and sustainable C1 source in the synthesis of valuable compounds. Here, we report a novel selective carboxylation of C(sp3)?F bonds with CO2 via visible-light photoredox catalysis. A variety of mono-, di-, and trifluoroalkylarenes as well as α,α-difluorocarboxylic esters and amides undergo such reactions to give important aryl acetic acids and α-fluorocarboxylic acids, including several drugs and analogs, under mild conditions. Notably, mechanistic studies and DFT calculations demonstrate the dual role of CO2 as an electron carrier and electrophile during this transformation. The fluorinated substrates would undergo single-electron reduction by electron-rich CO2 radical anions, which are generated in situ from CO2 via sequential hydride-transfer reduction and hydrogen-atom-transfer processes. We anticipate our finding to be a starting point for more challenging CO2 utilization with inert substrates, including lignin and other biomass.
- Bo, Zhi-Yu,Chen, Lin,Gao, Tian-Yu,Jing, Ke,Lan, Yu,Liu, Shi-Han,Luo, Shu-Ping,Yan, Si-Shun,Yu, Bo,Yu, Da-Gang
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p. 3099 - 3113
(2021/11/16)
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- METHOD FOR MANUFACTURING AROMATIC NITRILE COMPOUND
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The present invention provides a method for industrially producing a highly pure aromatic nitrile compound and a highly pure aromatic carboxylic acid compound safely and highly efficiently at low costs. Compound (2) is subjected to Willgerodt reaction in the presence of an additive as necessary, and the obtained amide compound (3) is hydrolyzed and neutralized to give carboxylic acid compound (4). Carboxylic acid compound (4) is reacted with a halogenating agent in the presence of a catalyst as necessary in an organic solvent, and further reacted with an amidating agent, and the obtained amide compound (5) or (6) is reacted with a dehydrating agent to give nitrile compound (1). Alternatively, carboxylic acid compound (4) is reacted with a halogenating agent and a compound represented by the formula R6SO2R7 in the presence of a catalyst as necessary in an organic solvent to give nitrile compound (1). Np is a naphthyl group optionally having substituent(s), R5 is an alkylene group having 1-3 carbon atoms, and other symbols are as described in the DESCRIPTION.
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- Method for preparing carboxylic acid by one-pot method
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The invention discloses a method for preparing carboxylic acid by a one-pot method, which comprises the steps of carrying out a Corey-Fuchs process on 1,1-dibromo olefin under the action of n-butyllithium, reacting with isopropanol pinacol borate, quenching with hydrogen chloride, oxidizing with an oxidant, separating and purifying to obtain carboxylic acid. The method disclosed by the invention is a one-pot preparation method, is simple and convenient to operate, does not need to use metal catalysis, uses cheap and easily available reagents for reaction, is green and environment-friendly, hasmild reaction conditions and wide substrate applicability, and provides a new way for rapidly preparing a series of carboxylic acids containing different functional groups.
- -
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Paragraph 0066-0070
(2021/01/29)
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- Pd(OH)2/C, a Practical and Efficient Catalyst for the Carboxylation of Benzylic Bromides with Carbon Monoxide
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A simple, efficient, cheap, and broadly applicable system for the carboxylation of benzylic bromides with carbon monoxide and water is reported. Upon simple reaction with only 2.5 wt % of Pearlman's catalyst and 10 mol % of tetrabutylammonium bromide in tetrahydrofuran at 110 °C for 4 h, a range of benzylic bromides can be smoothly converted to the corresponding arylacetic acids in good to excellent yields after simple extraction and acid-base wash. The reaction was found to be broadly applicable, scalable, and could be successfully extended to the use of ex situ-generated carbon monoxide and applied to the synthesis of the nonsteroidal anti-inflammatory drug diclofenac.
- Wakuluk-Machado, Anne-Marie,Dewez, Damien F.,Baguia, Hajar,Imbratta, Miguel,Echeverria, Pierre-Georges,Evano, Gwilherm
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p. 713 - 723
(2020/02/04)
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- Method for converting benzyl borate compounds into phenylacetic acid and derivatives thereof by carbon dioxide
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The invention discloses a method for converting benzyl borate compounds into phenylacetic acid and derivatives thereof by carbon dioxide. The method comprises the steps: dissolving the benzyl borate compounds and an alkali in an organic solvent in the absence of a metal catalyst, introducing carbon dioxide into the reaction system, carrying out a reaction at the temperature of 50-150 DEG C for 3-72 hours, and acidifying to obtain phenylacetic acid or the derivatives thereof. The method is a green, simple and efficient method for synthesizing phenylacetic acid and the derivatives thereof, greenhouse gas carbon dioxide is used as a carbon source in the reaction, no transition metal catalyst is used, and the method is environmentally friendly, economical and high in efficiency.
- -
-
Paragraph 0028-0029
(2020/03/06)
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- BF3·OEt2-promoted tandem Meinwald rearrangement and nucleophilic substitution of oxiranecarbonitriles
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Tandem Meinwald rearrangement and nucleophilic substitution of oxiranenitriles was realized. Arylacetic acid derivatives were readily synthesized from 3-aryloxirane-2-carbonitriles with amines, alcohols, or water in the presence of boron trifluoride under microwave irradiation, and the designed synthetic strategy includes introducing a cyano leaving group into arylepoxides and capturing the in situ generated toxic cyanide with boron trifluoride, making the reaction efficient, safe, and environmentally benign. The reaction occurs through an acid-promoted Meinwald rearrangement, producing arylacetyl cyanides, followed by an addition-elimination process with nitrogen or oxygen-containing nucleophilic amines, alcohols or water. The current method provides a new application of the tandem Meinwald rearrangement.
- Xu, Chuangchuang,Xu, Jiaxi
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p. 127 - 134
(2019/12/26)
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- Design and evolution of an enzyme with a non-canonical organocatalytic mechanism
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The combination of computational design and laboratory evolution is a powerful and potentially versatile strategy for the development of enzymes with new functions1–4. However, the limited functionality presented by the genetic code restricts the range of catalytic mechanisms that are accessible in designed active sites. Inspired by mechanistic strategies from small-molecule organocatalysis5, here we report the generation of a hydrolytic enzyme that uses Nδ-methylhistidine as a non-canonical catalytic nucleophile. Histidine methylation is essential for catalytic function because it prevents the formation of unreactive acyl-enzyme intermediates, which has been a long-standing challenge when using canonical nucleophiles in enzyme design6–10. Enzyme performance was optimized using directed evolution protocols adapted to an expanded genetic code, affording a biocatalyst capable of accelerating ester hydrolysis with greater than 9,000-fold increased efficiency over free Nδ-methylhistidine in solution. Crystallographic snapshots along the evolutionary trajectory highlight the catalytic devices that are responsible for this increase in efficiency. Nδ-methylhistidine can be considered to be a genetically encodable surrogate of the widely employed nucleophilic catalyst dimethylaminopyridine11, and its use will create opportunities to design and engineer enzymes for a wealth of valuable chemical transformations.
- Burke, Ashleigh J.,Lovelock, Sarah L.,Frese, Amina,Crawshaw, Rebecca,Ortmayer, Mary,Dunstan, Mark,Levy, Colin,Green, Anthony P.
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p. 219 - 223
(2019/06/13)
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- Optimizing the Pharmacological Profile of New Bifunctional Antihyperlipidemic/Antioxidant Morpholine Derivatives
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Among the causal risk factors directly promoting the development of coronary and peripheral atherosclerosis are reactive oxygen species and elevated low-density lipoprotein plasma levels. We hereby designed new potent squalene synthase (SQS) inhibitors that may simultaneously tackle the oxidative stress induced by lipid peroxidation. Using previously developed morpholine derivatives as a starting point, we conducted extensive structural changes by either substituting or modifying the morpholine ring, aiming at an optimal SQS-antioxidant pharmacological profile. Compounds 2, 3, and 7 emerged as the most potent bifunctional analogues, displaying IC50 values for SQS inhibition of 0.014, 0.16, and 0.51 μM, respectively, and further significantly decreasing lipid peroxidation of hepatic microsomal membranes. The aforementioned activities were also confirmed in vivo since the most promising derivative 2 exhibited a remarkable antihyperlipidemic and antioxidant effect. In conclusion, rational drug design accompanied by structure-activity relationship studies led to compounds combining improved antioxidant and antihyperlipidemic activity that may serve as multifunctional agents against atherosclerosis.
- Matralis, Alexios N.,Kourounakis, Angeliki P.
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- A General, Activator-Free Palladium-Catalyzed Synthesis of Arylacetic and Benzoic Acids from Formic Acid
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A new catalyst for the carboxylative synthesis of arylacetic and benzoic acids using formic acid (HCOOH) as the CO surrogate was developed. In an improvement over previous work, CO is generated in situ without the need for any additional activators. Key to success was the use of a specific system consisting of palladium acetate and 1,2-bis((tert-butyl(2-pyridinyl)phosphinyl)methyl)benzene. The generality of this method is demonstrated by the synthesis of more than 30 carboxylic acids, including non-steroidal anti-inflammatory drugs (NSAIDs), under mild conditions in good yields.
- Wang, Lin,Neumann, Helfried,Beller, Matthias
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supporting information
p. 6910 - 6914
(2018/06/04)
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- Ruthenium-catalyzed umpolung carboxylation of hydrazones with CO2
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The first ruthenium-catalyzed umpolung carboxylation of hydrazones with CO2 to generate important aryl acetic acids is reported. Besides aldehyde hydrazones, a variety of ketone hydrazones, which have not been successfully applied in previous umpolung reactions with other reactive electrophiles, also show high reactivity and selectivity under mild conditions. Moreover, this operationally simple protocol features good functional group tolerance, is readily scalable, and offers easy derivation of important structures, including bioactive felbinac and adiphenine. Computational studies reveal that this umpolung reaction proceeds through the generation of a Ru-nitrenoid followed by concerted [4 + 2] cycloaddition with CO2.
- Yan, Si-Shun,Zhu, Lei,Ye, Jian-Heng,Zhang, Zhen,Huang, He,Zeng, Huiying,Li, Chao-Jun,Lan, Yu,Yu, Da-Gang
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p. 4873 - 4878
(2018/06/07)
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- Synthetic method of fatty acid containing nitrogen heterocycle
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The invention discloses a synthetic method of fatty acid containing nitrogen heterocycle. The synthetic method comprises the following steps: (S1) adding a heterocyclic compound with substitution of chloromethyl groups, a catalyst and a solvent DMF into a reaction kettle; (S2) introducing carbon dioxide to lead the pressure in the kettle to be 2-4MPa, adjusting and reacting for 10-16 hours at thetemperature of 40-50 DEG C; (S3) adding diluted hydrochloric acid into the reaction kettle to carry out acidification, using ethyl acetate for extraction, combining organic phases, carrying out rotaryevaporation to remove liquid, and further carrying out vacuum drying, thus obtaining the fatty acid containing nitrogen heterocycle. The synthetic method disclosed by the invention has the beneficialeffects that a one-pot method is adopted, the raw materials are easy to obtain, price is low, aftertreatment of products is also simpler, the universality for a substrate is also very high, and the promotion and application are easy.
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-
Paragraph 0042
(2018/07/30)
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- Visible-Light-Driven External-Reductant-Free Cross-Electrophile Couplings of Tetraalkyl Ammonium Salts
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Cross-electrophile couplings between two electrophiles are powerful and economic methods to generate C-C bonds in the presence of stoichiometric external reductants. Herein, we report a novel strategy to realize the first external-reductant-free cross-electrophile coupling via visible-light photoredox catalysis. A variety of tetraalkyl ammonium salts, bearing primary, secondary, and tertiary C-N bonds, undergo selective couplings with aldehydes/ketone and CO2. Notably, the in situ generated byproduct, trimethylamine, is efficiently utilized as the electron donor. Moreover, this protocol exhibits mild reaction conditions, low catalyst loading, broad substrate scope, good functional group tolerance, and facile scalability. Mechanistic studies indicate that benzyl radicals and anions might be generated as the key intermediates via photocatalysis, providing a new direction for cross-electrophile couplings.
- Liao, Li-Li,Cao, Guang-Mei,Ye, Jian-Heng,Sun, Guo-Quan,Zhou, Wen-Jun,Gui, Yong-Yuan,Yan, Si-Shun,Shen, Guo,Yu, Da-Gang
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p. 17338 - 17342
(2019/01/04)
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- Mutagenicity of N-acyloxy-N-alkoxyamides as an indicator of DNA intercalation part 1: Evidence for naphthalene as a DNA intercalator
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N-Acyloxy-N-alkoxyamides are direct-acting mutagens in S. typhimurium TA100 with a linear dependence upon log P that maximises at log P0 = 6.4. Eight N-acyloxy-N-alkoxyamides (2-9) bearing a naphthalene group on any of the three side-chains and with log P0 6.4 have been demonstrated to be significantly and uniformly more mutagenic towards S. typhimurium TA100 than 50 mutagens without naphthalene. The activity enhancement of 2-9 is likely due to intercalative binding of naphthalene to bacterial DNA as a number are also active in TA98, a frame-shift strain of S. typhimurium, which is modified by intercalators. DNA damage profiles for naphthalene-bearing mutagens confirm enhanced reactivity with DNA when naphthalene is incorporated and a different binding mode when compared to mutagens without naphthalene. The effect is independent of whether the naphthalene is attached to an electron-donating alkyl or electron-withdrawing acyl group, alkyl tether length or, in the case of 6 and 7, the point of attachment to naphthalene. A new quantitative structure activity relationship has been constructed for all 58 congeners incorporating log P and an indicator variable, I, for the presence (I = 1) or absence (I = 0) of naphthalene and from which the activity enhancing effect of a naphthalene has been quantified at between three and four log P units. Contrary to conventional views, simple naphthalene groups could target molecules to DNA through intercalation.
- Banks, Tony M.,Clay, Samuel F.,Glover, Stephen A.,Schumacher, Rhiannon R.
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p. 3699 - 3714
(2016/05/09)
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- Nickel-Catalyzed Carboxylation of Benzylic C-N Bonds with CO2
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A user-friendly Ni-catalyzed reductive carboxylation of benzylic C-N bonds with CO2 is described. This procedure outperforms state-of-the-art techniques for the carboxylation of benzyl electrophiles by avoiding commonly observed parasitic pathways, such as homodimerization or β-hydride elimination, thus leading to new knowledge in cross-electrophile reactions.
- Moragas, Toni,Gaydou, Morgane,Martin, Ruben
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supporting information
p. 5053 - 5057
(2016/04/26)
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- A high-throughput screening method for determining the substrate scope of nitrilases
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Nitrile compounds are intermediates in the synthesis of pharmaceuticals such as atorvastatin. We have developed a chromogenic reagent to screen for nitrilase activity as an alternative to Nessler's reagent. It produces a semi-quantifiable blue colour and hydrolysis of 38 nitrile substrates by 23 nitrilases as cell-free extracts has been shown. This journal is
- Black, Gary W.,Brown, Nicola L.,Perry, Justin J. B.,Randall, P. David,Turnbull, Graeme,Zhang, Meng
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supporting information
p. 2660 - 2662
(2015/03/05)
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- Palladium-Catalyzed Carboxylation of Benzyl Chlorides with Atmospheric Carbon Dioxide in Combination with Manganese/Magnesium Chloride
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An efficient direct carboxylation of a series of benzyl chlorides with CO2 catalyzed by Pd(OAc)2/dicyclohexyl (2′,6′-dimethoxy-[1,1′-biphenyl]-2-yl)phosphine (SPhos) was developed to afford the corresponding phenylacetic acids in combination with Mn powder as a reducing reagent and MgCl2 as an indispensable additive. The reaction proceeded smoothly under 1 atm CO2. The application of Mn powder instead of a sensitive reducing reagent represents an operationally simple access to phenylacetic acids. Notably, MgCl2 is able to stabilize the (SPhos)2PdII(Bn)(Cl)(η1-CO2)(MgCl2) adduct and thus facilitates CO2 insertion into the PdII-C bond, which is supported by a DFT study. Specific effect: MgCl2 facilitates the direct insertion of CO2 into the PdII-C bond by stabilizing the PdII-CO2 adduct. With MgCl2 as an indispensable additive, the Pd-catalyzed carboxylation of various benzyl chlorides proceeded smoothly under 1 atm CO2, and the application of Mn powder instead of a sensitive reducing reagent makes this protocol an operationally simple access to phenylacetic acids.
- Zhang, Shuai,Chen, Wei-Qiang,Yu, Ao,He, Liang-Nian
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p. 3972 - 3977
(2016/01/26)
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- Ni-catalyzed carboxylation of C(sp2)- and C(sp3)-O bonds with CO2
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In recent years a significant progress has been made for the carboxylation of aryl and benzyl halides with CO2, becoming convenient alternatives to the use of stoichiometric amounts of well-defined metal species. Still, however, most of these processes require the use of pyrophoric and air-sensitive reagents and the current methods are mostly restricted to organic halides. Therefore, the discovery of a mild, operationally simple alternate carboxylation that occurs with a wide substrate scope employing readily available coupling partners will be highly desirable. Herein, we report a new protocol that deals with the development of a synergistic activation of CO2 and a rather challenging activation of inert C(sp2)-O and C(sp3)-O bonds derived from simple and cheap alcohols, a previously unrecognized opportunity in this field. This unprecedented carboxylation event is characterized by its simplicity, mild reaction conditions, remarkable selectivity pattern and an excellent chemoselectivity profile using air-, moisture-insensitive and easy-to-handle nickel precatalysts. Our results render our method a powerful alternative, practicality and novelty aside, to commonly used organic halides as counterparts in carboxylation protocols. Furthermore, this study shows, for the first time, that traceless directing groups allow for the reductive coupling of substrates without extended π-systems, a typical requisite in many C-O bond-cleavage reactions. Taking into consideration the limited knowledge in catalytic carboxylative reductive events, and the prospective impact of providing a new tool for accessing valuable carboxylic acids, we believe this work opens up new vistas and allows new tactics in reductive coupling events.
- Correa, Arkaitz,Leon, Thierry,Martin, Ruben
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p. 1062 - 1069
(2014/02/14)
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- Structural characterization and function determination of a nonspecific carboxylate esterase from the amidohydrolase superfamily with a promiscuous ability to hydrolyze methylphosphonate esters
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The uncharacterized protein Rsp3690 from Rhodobacter sphaeroides is a member of the amidohydrolase superfamily of enzymes. In this investigation the gene for Rsp3690 was expressed in Escherichia coli and purified to homogeneity, and the three-dimensional structure was determined to a resolution of 1.8 ? The protein folds as a distorted (β/α)8-barrel, and the subunits associate as a homotetramer. The active site is localized to the C-terminal end of the β-barrel and is highlighted by the formation of a binuclear metal center with two manganese ions that are bridged by Glu-175 and hydroxide. The remaining ligands to the metal center include His-32, His-34, His-207, His-236, and Asp-302. Rsp3690 was shown to catalyze the hydrolysis of a wide variety of carboxylate esters, in addition to organophosphate and organophosphonate esters. The best carboxylate ester substrates identified for Rsp3690 included 2-naphthyl acetate (kcat/Km = 1.0 × 105 M-1 s-1), 2-naphthyl propionate (k cat/Km = 1.5 × 105 M-1 s -1), 1-naphthyl acetate (kcat/Km = 7.5 × 103 M-1 s-1), 4-methylumbelliferyl acetate (kcat/Km = 2.7 × 103 M-1 s-1), 4-nitrophenyl acetate (kcat/Km = 2.3 × 105 M-1 s-1), and 4-nitrophenyl butyrate (kcat/Km = 8.8 × 105 M -1 s-1). The best organophosphonate ester substrates included ethyl 4-nitrophenyl methylphosphonate (kcat/Km = 3.8 × 105 M-1 s-1) and isobutyl 4-nitrophenyl methylphosphonate (kcat/Km = 1.1 × 104 M-1 s-1). The (SP)-enantiomer of isobutyl 4-nitrophenyl methylphosphonate was hydrolyzed 10 times faster than the less toxic (RP)-enantiomer. The high inherent catalytic activity of Rsp3690 for the hydrolysis of the toxic enantiomer of methylphosphonate esters make this enzyme an attractive target for directed evolution investigations.
- Xiang, Dao Feng,Kumaran, Desigan,Swaminathan, Subramanyam,Raushel, Frank M.
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p. 3476 - 3485
(2014/06/23)
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- PROCESS FOR SYNTHESIZING PHENYLACETIC ACID BY CARBONYLATION OF TOLUENE
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A production process for substituted phenylacetic acids or ester analogues thereof is disclosed. In this process toluene or toluene substituted with various substituents, an alcohol, an oxidant and carbon monoxide are used as raw materials to obtain compounds comprising structure of phenylacetic acid ester or analogues thereof by catalysis of the complex catalyst formed from transition metal and ligand, and such compounds are hydrolyzed to obtain various substituted phenylacetic acid based compounds. This type of compounds and their derivatives serve as important fine chemicals used widely in the industries of pharmaceuticals, pesticides, perfume and the like.
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- An efficiently cobalt-catalyzed carbonylative approach to phenylacetic acid derivatives
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A highly efficient cobalt-catalyzed carbonylative approach to phenylacetic acid derivatives under one atmosphere pressure is reported. This methodology represents a useful extension of benzimidazole used as ligand in metal catalysis, and the catalytic mechanism has been proved by computer simulation. Notably, this new cobalt precatalyst, which promotes the carbonylation reaction dramatically and has already been used for scale-up experiment of phenylacetic acid derivatives.
- She, Meng-Yao,Xiao, Da-Wei,Yin, Bing,Yang, Zheng,Liu, Ping,Li, Jian-Li,Shi, Zhen
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p. 7264 - 7268
(2013/08/23)
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- Ni-catalyzed direct carboxylation of benzyl halides with CO2
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A novel Ni-catalyzed carboxylation of benzyl halides with CO2 has been developed. The described carboxylation reaction proceeds under mild conditions (atmospheric CO2 pressure) at room temperature. Unlike other routes for similar means, our method does not require well-defined and sensitive organometallic reagents and thus is a user-friendly and operationally simple protocol for assembling phenylacetic acids.
- León, Thierry,Correa, Arkaitz,Martin, Ruben
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supporting information
p. 1221 - 1224
(2013/03/14)
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- One-pot synthesis of trichloromethyl carbinols from primary alcohols
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Versatile trichloromethyl carbinols can be prepared in one pot from primary alcohols by treatment with Dess-Martin periodinane (DMP) in CHCl3 followed by introduction of commercially available 1,5,7-triazabicyclo[4.4.0] dec-5-ene (TBD). A modification of the method was used to convert chiral primary alcohol (R)-(-)-2,2-dimethyl-1,3-dioxolane-4-methanol to the corresponding trichloromethyl carbinol with complete stereochemical fidelity, despite the reactant proceeding through a base-sensitive aldehyde intermediate.
- Gupta, Manoj K.,Li, Zhexi,Snowden, Timothy S.
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experimental part
p. 4854 - 4860
(2012/07/30)
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- Palladium-catalyzed cyanomethylation of aryl halides through domino Suzuki coupling-isoxazole fragmentation
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A one-pot protocol for the cyanomethylation of aryl halides through a palladium-catalyzed reaction with isoxazole-4-boronic acid pinacol ester was developed. Mechanistically, the reaction proceeds through (1) Suzuki coupling, (2) base-induced fragmentation, and (3) deformylation as shown by characterization of all postulated intermediates. Under optimized conditions (PdCl2dppf, KF, DMSO/H2O, 130 °C) a broad spectrum of aryl bromides could be converted into arylacetonitriles with up to 88% yield.
- Velcicky, Juraj,Soicke, Arne,Steiner, Roland,Schmalz, Hans-Guenther
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supporting information; scheme or table
p. 6948 - 6951
(2011/06/19)
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- 2-(Trimethylsilyl)-1,3-dithiane 1-oxide as a convenient reagent for the transformation of aldehydes and ketones into homologous carboxylic acids
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Aldehydes and ketones were converted into the corresponding homologous carboxylic acids in two steps by treatment with 2-(trimethylsilyl)-1,3-dithiane 1-oxide. A modified Peterson olefination of the carbonyl compounds gave ketene thioacetal sulfoxides that were readily cleaved in acidic acetonitrile to give the required carboxylic acids. Georg Thieme Verlag Stuttgart New York.
- Krohn, Karsten,Cludius-Brandt, Stephan
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experimental part
p. 2616 - 2620
(2010/09/10)
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- General and practical conversion of aldehydes to homologated carboxylic acids
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(Chemical Equation Presented) The reaction of aldehydes with trichloromethide followed by sodium borohydride or sodium phenylseleno(triethyl) borate under basic conditions affords homologated carboxylic acids in high yields. This operationally simple procedure provides a practical, efficient alternative to other homologation protocols. The approach is compatible with sensitive aldehydes including enals and enolizable aldehydes. It also offers convenient access to α-monodeuterated carboxylic acids.
- Cafiero, Lauren R.,Snowden, Timothy S.
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supporting information; experimental part
p. 3853 - 3856
(2009/07/01)
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- The green and effective oxidation of alcohols to carboxylic acids with molecular oxygen via biocatalytic reaction
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A clean and effective alcohol oxidizing system using three enzymes has been developed. Regeneration of NAD+ by NADH oxidase with molecular oxygen enabled to oxidize alcohols to carboxylic acids in good yield under mild conditions (25 °C, 1 atm).
- Hirano, Jun-ichiro,Miyamoto, Kenji,Ohta, Hiromichi
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p. 1217 - 1219
(2008/09/17)
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- A facile synthesis of phenylacetic acids via Willgerodt-Kindler reaction under PTC condition
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Phenylacetic acids are efficiently synthesized from acetophenones via thiomorpholides under Phase Transfer Catalytic (PTC) condition. The reaction proceeds efficiently by using triethyl benzyl ammonium chloride (TEBA) as PTC and the reaction time decreased dramatically upto 1/5th (24-5) to afford pure products in good to excellent yield.
- Alam, Mujahid,Adapa, Srinivas R.
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- Chemo-enzymatic synthesis of enantiomerically pure (R)-2-naphthylmethoxyacetic acid
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Enantiomerically pure (R)-2-naphthylmethoxyacetic acid (2-NMA) was synthesized from 2-naphthaldehyde via an integrated chemo-enzymatic procedure. The one-pot, successive use of SnBr2-TMSCN and AcBr worked effectively to give a racemic cyanohydrin acetate. Lipase from Burkholderia cepacia then mediated the highly enantioselective hydrolysis of the (S)-enantiomer of the racemate, leaving the (R)-acetate with an e.e. of >99.9%. The resulting product of this enzyme-catalyzed hydrolysis, an (S)-cyanohydrin, spontaneously decomposed into naphthaldehyde, the starting material of this synthetic route, which could be recycled. The hydration of nitrile to amide as well as the hydrolysis of the acetate was performed with a microorganism, Rhodococcus rhodochrous, under very mild conditions without any loss of the enantiomeric purity. The amide group was hydrolyzed with nitrosylsulfuric acid, and the product was isolated as an α-hydroxy ester. The α-hydroxyl group was methylated with diazomethane-silica gel and the final task, hydrolysis of the ester, was accomplished under conditions as mild as neutral pH with an esterase from Krebsiella oxytoca to give enantiomerically pure 2-NMA.
- Kimura, Mayumi,Kuboki, Atsuhito,Sugai, Takeshi
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p. 1059 - 1068
(2007/10/03)
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- A stereospecific '2-aza-divinylcyclopropane' rearrangement
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The stereochemical course of the thermal 2-aza-Cope rearrangement of the optically pure acyl azide (-)-(1S)-5 was investigated by determination of the absolute configuration of the rearrangement product (1R,8S)-9. The reaction proceeds by a sequence of stereospecific steps from 5 to an equilibrating mixture of exo- and endo-isocyanates 6 and 7. The endo-isomer 7 undergoes Cope rearrangement to the putative intermediate 8, which is trapped and characterized as the adduct 9b of butan-1-ol. The absolute configuration of 9b was determined by its reduction to the amide 20, and determination of the X-ray structure of the N-camphanoylamide 21 derived from camphanic acid of known absolute configuration.
- Mueller, Paul,Toujas, Jean-Louis,Bernardinelli, Gerald
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p. 1525 - 1534
(2007/10/03)
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- Quinolones as gonadotropin releasing hormone (GnRH) antagonists: Simultaneous optimization of the C(3)-aryl and C(6)-substituents
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A series of 3-arylquinolones was prepared and evaluated for their ability to act as gonadotropin releasing hormone (GnRH) antagonists. A variety of substitution patterns of the 3-aryl substituent are described. The 3,4,5-trimethylphenyl substituent (23h) was found to be optimal. (C) 2000 Elsevier Science Ltd. All rights reserved.
- Young, Jonathan R.,Huang, Song X.,Chen, Irene,Walsh, Thomas F.,DeVita, Robert J.,Wyvratt Jr., Matthew J.,Goulet, Mark T.,Ren, Ning,Lo, Jane,Yang, Yi Tien,Yudkovitz, Joel B.,Cheng, Kang,Smith, Roy G.
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p. 1723 - 1727
(2007/10/03)
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- Direct Carbonylation of Benzyl Alcohol and Its Analogs Catalyzed by Palladium and HI in Aqueous Systems and Mechanistic Studies
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Carbonylation of benzyl alcohol, benzyl formate, dibenzyl ether, and benzyl phenylacetate catalyzed by palladium complexes and promoted by hydrogen iodide gives phenylacetic acid in moderate to excellent yields in aqueous systems. Application of the carbonylation process to other arylmethanol analogs provides convenient means to prepare 2-naphthaleneacetic acid, 3-isochromanone, 1,4-benzenediacetic acid, and o-hydroxybenzeneacetic acid. A mechanism for the catalytic reaction is proposed, which involves (1) formation of benzyl iodide by the reaction of benzyl alcohol with HI in situ, (2) oxidative addition of benzyl iodide to palladium(0) to form a benzylpalladium iodide species. (3) CO insertion into the Pd-benzyl bond to form a (phenylacetyl)palladium iodide species. (4) reductive elimination of phenylacetyl iodide, and (5) its hydrolysis into phenylacetic acid. Evidence supporting the mechanism was obtained by examining the properties of benzyl- and (phenylacetyl)palladium iodide and chloride complexes. Formation of benzyl(carbonyl)palladium species and migratory insertion of the benzyl group to CO was confirmed by means of NMR at low temperature under high pressure.
- Lin, Yong-Shou,Yamamoto, Akio
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p. 723 - 734
(2007/10/03)
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- An in-depth study of the biotransformation of nitriles into amides and/or acids using Rhodococcus rhodochrous AJ270
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A variety of aliphatic, aromatic and heterocyclic nitriles have been readily hydrolysed into the corresponding amides and/or acids under very mild conditions using Rhodococcus sp. AJ270. The nitrile hydratase involved in this novel nitrile-hydrolysing microorganism efficiently hydrates most nitriles tested, irrespective of the electronic and steric effects of the substituents, to form the amides. Conversion of amides into acids catalysed by the associated amidase is rapid and efficient in most cases. Substrates bearing an adjacent substituent (which may be an ortho substituent on an aromatic nitrile, an adjacent heteroatom in a heterocyclic ring or a geminal substituent in an α,β-unsaturated nitrile) undergo slow hydrolysis of the amides allowing efficient amide isolation. The scope, limitations and reaction mechanism of this enzymatic process have been systematically studied. A molecular size of >7 A diameter and the presence of functions capable of metal complexation near to the nitrile inhibit hydrolysis.
- Meth-Cohn, Otto,Wang, Mei-Xiang
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p. 1099 - 1104
(2007/10/03)
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- Palladium-catalyzed carbonylation of benzyl alcohol and its analogs promoted by HI in aqueous systems
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Carbonylation of benzyl alcohol catalyzed by a palladium(0) complex and promoted by hydrogen iodide gives phenylacetic acid in excellent yields in aqueous systems. The catalysis is proposed to proceed through a benzylpalladium species formed by the oxidative addition of benzyl iodide, produced in situ by the interaction of benzyl alcohol with HI, to a Pd(0) species. Application of the carbonylation process to other arylmethanol analogs provided convenient means to prepare 3-isochromanone, 1,4-benzenediacetic acid, 2-hydroxybenzeneacetic acid and 2-naphthaleneacetic acid.
- Lin, Yong-Shou,Yamamoto, Akio
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p. 3747 - 3750
(2007/10/03)
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- Ligand exchange reaction of sulfoxides in organic synthesis: A versatile procedure for one-carbon homologation of methylesters to esters, thioesters, carboxylic acids and amides
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A novel two-step procedure for one-carbon homologation of methylesters to esters, thioesters, carboxylic acids and amides is described. Methylesters are reacted with lithium carbanion of chloromethyl phenyl sulfoxide to give α-chloro α-sulfinyl ketones in 70 to 90% yields. Potassium enolate of the α-chloro α-sulfinyl ketone was treated with tert-butyllithium at -78°C to give alkynolate via alkylidene carbenoid. This intermediate was treated with alcohols, thioles, 5% aqueous NaOH, and amine hydrochlorides to afford one-carbon homologated esters, thioesters, carboxylic acids and amides, respectively, in good to excellent yields.
- Satoh, Tsuyoshi,Unno, Hideaki,Mizu, Yasuhiro,Hayashi, Yasumasa
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p. 7843 - 7854
(2007/10/03)
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- Catalytic carbonylation of benzylic and allylic bromides by a rhodium zwitterionic complex under phase transfer catalysis conditions
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The zwitterionic rhodium complex, (COD)Rh(η6-C6H5BPh3) (1), can catalyze the carbonylation of benzylic and allylic bromides in the presence of 5 N NaOH and CH2Cl2 at atmospheric pressure and 40 deg C, with (C6H13)4N+ HSO4- as the phase transfer catalyst, to give carboxylic esters as the major products. Keywords: Rhodium; Carbonylation; Zwitterionic complex; Phase transfer catalysis
- Amaratunga, Shiyamalie,Alper, Howard
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- New Allyl Group Acceptors for Palladium Catalyzed Removal of Allylic Protections and Transacylation of Allyl Carbamates.
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Key words: allylic protecting groups, palladium catalysis, transacylation, phenyltrihydrosilane, N-methyl-N-(trimethylsilyl)trifluoroacetamide.Allyl carboxylates, carbamates and phenoxides may be cleaved or transacylated in the presence of palladium catalyst and either phenyltrihydridosilane or N-methyl-N-(trimethylsilyl)trifluoroacetamide.These reactions are totally compatible with the presence of Boc and, as far as phenyltrihydrosilane is concerned, Fmoc protections.
- Dessolin, Michele,Guillerez, Marie-George,Thieriet, Nathalie,Guibe, Francois,Loffet, Albert
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p. 5741 - 5744
(2007/10/02)
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- Ligand exchange reaction of sulfoxides in organic synthesis: A new method for one-carbon homologation of esters to carboxylic acids and esters via α- chloro α-sulfinyl ketones
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Reaction of the Carbanion of chloromethyl phenyl sulfoxide with esters gave α-chloro α-sulfinyl ketones, which were treated with KH followed by t- BuLi to afford one-carbon homologated acids and esters in good to excellent yields.
- Satoh,Mizu,Hayashi,Yamakawa
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p. 133 - 134
(2007/10/02)
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- Generation of Radical-cations from Naphthalene and Some Derivatives, both by Photoionization and Reaction with SO4-.: Formation and Reactions Studied by Laser Flash Photolysis
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Radical-cations from naphthalene and some derivatives have been generated in aqueous acetonitrile both by direct photolysis (with λ 248 nm light via biphotonic ionization) and via reaction with SO4-..The radical-cation reacts rapidly with the parent substrate (k ca. 1E8 dm3 mol-1 s-1) and with nucleophiles (e. g. with N3- k = 4.2*1E9 dm3 mol-1 s-1 or with water, k 4*1E4 s-1 ).The radical-cation from 1-naphthylethanoic acid undergoes rapid decarboxylation (k 5*1E5 s-1).The radical cations from 4-methyl- and 4-methoxy-phenylethanoic acid also rapidly decarboxylate to yield the corresponding benzyl radicals.
- Steenken, Steen,Warren, Cathryn J.,Gilbert, Bruce C.
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p. 335 - 342
(2007/10/02)
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- Lanthanide-Promoted and Nickel Cyanide Catalyzed Carbonylation Reactions under Phase-Transfer Conditions
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The nickel cyanide and phase transfer catalyzed carbonylation of benzyl chlorides is promoted by lanthanide salts .This simple reaction is sensitive to the concentration of the lanthanide compound, sodium hydroxide, quaternary ammonium salt, and nickel catalyst.The nature of the organic phase and phase transfer agent also influences the reaction rate.The acceleration of the reaction may be a consequence of coordination of a nickel cyanide nitrogen lone pair to the lanthanide salt.
- Amer, Ibrahim,Alper, Howard
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p. 927 - 930
(2007/10/02)
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- INTER- AND INTRA-MOLECULAR PHOTOCYCLOADDITION OF ENOL ETHERS TO NAPHTHALENE
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The isomeric non-conjugated naphthyl enol ether bichromophores (6) and (7) display markedly different photoreactivities.The former undergoes ? + 2?> cycloaddition from the S1 state whereas the latter is relatively photostable.The two cyano derivatives (4) and (5) both yield intramolecular cycloadducts but the orientation of the addition is the opposite of that predicted from the reported intermolecular cyanonaphthalene-enol ether photoreactions. 2,3-Dihydrofuran undergoes specific "head to head" endo photoaddition to naphthalene but in contrast the major adducts from 2,3-dihydrofuran and this arene have "head to head" exo and "head to tail" endo structures.The adduct (18) undergoes a facile 1,3-shift to yield the (4? + 2?) endo adduct (19).The reactivities of the bichromophores and the regiochemistries of the additions are considered in relation to the relative charge densities at the 1- and 2-positions of the S1 arene.
- Gilbert, Andrew,Heath, Peter,Kashoulis-Koupparis, Annoula,Ellis-Davies, Graham C. R.,Firth, Susan M.
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- A FACILE O-ALKYL CLEAVAGE OF ESTERS WITH SODIUM HYDROGEN SELENIDE
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Sodium hydrogen selenide generated in the dipolar aprotic solvent DMF is shown to be effectively selective reagent for the dealkylation of esters to give the corresponding carboxylic acids in good yields.
- Kong, Fangming,Chen, Jian,Zhou, Xunjun
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p. 801 - 804
(2007/10/02)
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- IRON PENTACARBONYL MEDIATED COUPLING OF BENZYL HALIDES TO KETONES UNDER MILD PHASE TRANSFER CONDITIONS.
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In a two-phase system (saturated aqueous calcium hydroxide, tetrabutylammonium sulfate, dichloromethane, iron pentacarbonyl) benzyl bromides are readily carbonylated to dibenzyl ketones ; α-α' dibromoorthoxylene yields the o-quinodimethane iron tricarbonyl cmplex 8.It is inferred that the reactions proceed through transient generation of the tetracarbonyl ferrate dianion.
- Tanguy, Guy,Weinberger, Bernd,Abbayes, Hevre des
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p. 5529 - 5532
(2007/10/02)
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- CATALYTIC PHASE TRANSFER CARBONYLATION OF BENZYL HALIDES WITH IRON PENTACARBONYL.
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Benzyl halides are readily carbonylated to arylacetic acids in a two-phase system (aqueous sodium hydroxide (1M), tetrabutylammonium sulfate ; organic phase (CH2Cl2 or C6H6 or C6H5CH3)), using a catalytic amount of the cheap, easy to handle iron pentacarbonyl under carbon monoxide atmosphere.
- Tanguy, Guy,Weinberger, Berndt,Abbayes, Herve des
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p. 4005 - 4008
(2007/10/02)
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- Esters of α-Arylalkanoic Acids from 'Masked' α-Halogenoalkyl Aryl Ketones and Silver Salts: Synthetic, Kinetic, and Mechanistic Aspects
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A method for the synthesis of alkyl esters of α-arylalkanoic acids is given based on silver-ion-assisted (AgBF4, AgOSO2CF3, AgSbF6, AgNO3) solvolysis of alkyl acetals of primary and secondary α-halogenoalkyl aryl ketones (Hal = I, Br, Cl) in an alcoholic medium (methanol, ethanol).The reaction is quite selective and alkyl esters are the only reaction products; ethers, which are possible substitution products, are not found.The importance of masking the carbonyl as the acetal is emphasised.The reaction is found to be first-order in AgBF4 and in the primary α-halogeno acetal.A three-point Hammett correlation (ρ = -3.29) between ?+ and the rate constants suggests a large cationic contribution as well as strong aryl participation in the transition state.The role payed by the oxygen of the acetal group in the specificity of the reaction is discussed in comparison with the reactivity of analogous compounds with saturated skeletons and of α-halogenoalkyl aryl ketones.
- Giordano, Claudio,Castaldi, Graziano,Casagrande, Francesco,Belli, Aldo
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p. 2575 - 2582
(2007/10/02)
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- Process for preparing esters of arylacetic acids from alpha-halo-alkylarylketones
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Esters of arylacetic acids, more particularly lower alcohol esters of arylacetic acids, including those substituted on the methylene group, are prepared by rearrangement of the corresponding alpha-halo-alkylarylketones with Ag compounds in lower alcohols and in an acid medium. From the alkyl esters so prepared, their respective free acids can be obtained, if desired, by various means such as hydrolysis or the shift with mineral acids of the alkaline salts prepared by reaction with alkali, etc.
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- PHASE TRANSFER CATALYSIS USING COBALT TRICARBONYL NITROSYL
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The first example of the use a mononuclear cobalt complex in a phase-transfer catalyzed process is described.The carbonylation of halides catalyzed by cobalt tricarbonyl nitrosyl gives, depending on the organic substrate, appreciably different results as compared with dicobalt octacarbonyl.
- Gambarotta, Sandro,Alper, Howard
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p. C23 - C26
(2007/10/02)
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