- Non-Heme-Type Ruthenium Catalyzed Chemo- and Site-Selective C?H Oxidation
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Herein, we developed a Ru(II)(BPGA) complex that could be used to catalyze chemo- and site-selective C?H oxidation. The described ruthenium complex was designed by replacing one pyridyl group on tris(2-pyridylmethyl)amine with an electron-donating amide ligand that was critical for promoting this type of reaction. More importantly, higher reactivities and better chemo-, and site-selectivities were observed for reactions using the cis-ruthenium complex rather than the trans-one. This reaction could be used to convert sterically less hindered methyne and/or methylene C?H bonds of a various organic substrates, including natural products, into valuable alcohol or ketone products.
- Doiuchi, Daiki,Nakamura, Tatsuya,Hayashi, Hiroki,Uchida, Tatsuya
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supporting information
p. 762 - 765
(2020/03/05)
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- Method for synthesizing tertiary alcohol by catalytically oxidizing benzyl tertiary C-H bonds of aromatic hydrocarbon through metalloporphyrin
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The invention discloses a method for synthesizing tertiary alcohol by catalytically oxidizing benzyl tertiary C-H bonds of aromatic hydrocarbon through metalloporphyrin. The method comprises the following steps: dispersing metalloporphyrin (1*10-1%, mol/mol) into aromatic hydrocarbon; sealing the reaction system, heating to 40-120 DEG C while stirring, introducing an oxidant (0.10-1.0 MPa), keeping the set temperature and pressure, carrying out reactions for 3.0-24.0 hours under stirring, and carrying out after-treatment on the reaction solution to obtain the product aromatic benzyl tertiary alcohol. The method has the advantages of shortest conversion path, highest atom economy, lower reaction temperature, lower environmental influence and the like, and the selectivity of aromatic benzyl tertiary alcohol is high. In addition, the content of aromatic hydrocarbon hydroperoxide is low, and the safety coefficient is high. The invention provides an efficient, feasible and safe method for synthesizing aromatic benzyl tertiary alcohol through selective catalytic oxidation of benzyl tertiary C-H bonds of aromatic hydrocarbon.
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Paragraph 0066-0067
(2020/09/30)
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- Fluoro-Substituted Methyllithium Chemistry: External Quenching Method Using Flow Microreactors
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The external quenching method based on flow microreactors allows the generation and use of short-lived fluoro-substituted methyllithium reagents, such as fluoromethyllithium, fluoroiodomethyllithium, and fluoroiodostannylmethyllithium. Highly chemoselective reactions have been developed, opening new opportunities in the synthesis of fluorinated molecules using fluorinated organometallics.
- Colella, Marco,Degennaro, Leonardo,Higuma, Ryosuke,Ishikawa, Susumu,Luisi, Renzo,Nagaki, Aiichiro,Takahashi, Yusuke,Tota, Arianna
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p. 10924 - 10928
(2020/05/08)
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- Efficient and selective oxidation of tertiary benzylic C[sbnd]H bonds with O2 catalyzed by metalloporphyrins under mild and solvent-free conditions
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The direct and efficient oxidation of tertiary benzylic C[sbnd]H bonds to alcohols with O2 was accomplished in the presence of metalloporphyrins as catalysts under solvent-free and additive-free conditions. Based on effective inhibition on the unselective autoxidation and deep oxidation, systematical investigation on the effects of porphyrin ligands and metal centers, and apparent kinetics study, the oxidation system employing porphyrin manganese(II) (T(2,3,6-triCl)PPMn) with bulkier substituents as catalyst, was regarded as the most promising and efficient one. For the typical substrate, the conversion of cumene could reach up to 57.6% with the selectivity of 70.5% toward alcohol, both of them being higher than the current documents under similar conditions. The superiority of T(2,3,6-triCl)PPMn was mainly attributed to its bulkier substituent groups preventing metalloporphyrins from oxidative degradation, its planar structure favoring the interaction between central metal with reactants, and the high efficiency of Mn(II) in the catalytic transformation of hydroperoxides to alcohols.
- Hu, Meng-Yun,Liu, Lei,Qi, Bei,She, Yuan-Bin,Shen, Hai-Min,Ye, Hong-Liang
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- COMPOUNDS FOR THE REDUCTION OF THE DELETERIOUS ACTIVITY OF EXTENDED NUCLEOTIDE REPEAT CONTAINING GENES
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Aspects of the present disclosure include methods of reducing the deleterious impact of a target gene in a cell, such as the deleterious activity of a mutant extended nucleotide repeat (NR) containing target gene in a cell by contacting the cell with an effective amount of a tetrahydrocarbazole compound. The deleterious activity (e.g., toxicity and/or dis-functionality of products encoded thereby) of a mutant extended NR containing target gene may be reduced, e.g., by reducing (and in some instances differentially, including selectively, reducing) the production or activity of toxic expression products (e.g., RNA or protein) encoded by the target gene. Kits and compositions for practicing the subject methods are also provided.
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Page/Page column 62; 94
(2020/07/14)
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- A 2 - hydroxy isopropyl substituted preparation method of acetophenone (by machine translation)
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The invention relates to a method for synthesizing 2 - hydroxy isopropyl substituted acetophenone method, it includes S1: in the 130 - 140 °C temperature, will be acetyl benzoic acid methyl ester and ethylene glycol in the organic solvent and the presence of a catalyst under the conditions of the reaction, generating comprises intermediate reaction mixture 1st; S2: the 1st reaction mixture is cooled to room temperature, the reaction mixture purification 1st, get midbody; S3: in - 5 to 0 °C temperature, in an inert atmosphere environment, the intermediate of the tetrahydrofuran solution dripped into methyl bromide in tetrahydrofuran solution of the magnesium oxide, the method comprises generating the 2 - hydroxy isopropyl substituted acetophenone 2nd reaction mixture; and S4: purifying the 2nd reaction mixture, to obtain the 2 - hydroxy isopropyl substituted acetophenone; wherein said alkali comprises acyl benzoic acid methyl ester 4 - acetyl benzoic acid methyl ester or 3 - acetyl-benzoic acid methyl ester. The methods of the invention and is simple, preparation procedure is simple and convenient, high yield, small pollution to the environment. (by machine translation)
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- Ruthenium-Catalyzed C-H Hydroxylation in Aqueous Acid Enables Selective Functionalization of Amine Derivatives
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The identification, optimization, and evaluation of a new catalytic protocol for sp3 C-H hydroxylation is described. Reactions are performed in aqueous acid using a bis(bipyridine)Ru catalyst to enable oxidation of substrates possessing basic amine functional groups. Tertiary and benzylic C-H hydroxylation is strongly favored over N-oxidation for numerous amine derivatives. With terpene-derived substrates, similar trends in reactivity toward tertiary and benzylic C-H bonds are observed. Hydroxylation of chiral tertiary centers is enantiospecific in spite of the ionizing strength of the reaction medium. Preliminary kinetics experiments show a marked difference in reactivity between isomeric cis- and trans-Ru catalysts suggesting that the catalyst is configurationally stable under the reaction conditions.
- Mack, James B. C.,Gipson, John D.,Du Bois,Sigman, Matthew S.
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supporting information
p. 9503 - 9506
(2017/07/24)
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- Effect of Substituents and Stability of Transient Aluminum-Aminals in the Presence of Nucleophiles
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Disubstituted hydroxylamines are synthesized and used to form aluminum-amide complexes. These reagents mask carbonyl groups in situ via nucleophilic addition. The stability and utility of the aluminum-aminals are presented in the context of selectively controlling nucleophilic addition on substrates with multiple carbonyl groups.
- Barrios, Francis J.,Springer, Brannon C.,Hazlitt, Robert A.,Colby, David A.
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p. 175 - 180
(2015/05/05)
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- SELECTIVE OCTAHYDRO-CYCLOPENTA[C] PYRROLE NEGATIVE MODULATORS OF NR2B
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Compounds that selectively negatively modulate NMDA receptors containing an NR1/NR2B subunit, pharmaceutical compositions comprising the compounds, and methods of treating a disease using the compounds are disclosed. Such diseases include, without limitation, neurological dysfunction such as Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, multiple sclerosis, and seizure disorders; emotional disorders; depression; bipolar disorder; obsessive-compulsive disorder; and other anxiety disorders.
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Paragraph 0154
(2015/04/15)
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- Asymmetric hydrogenation of α,β-unsaturated nitriles with base-activated iridium N,P ligand complexes
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Although many chiral catalysts are known that allow highly enantioselective hydrogenation of a wide range of olefins, no suitable catalysts for the asymmetric hydrogenation of α,β-unsaturated nitriles have been reported so far. We have found that Ir N,P ligand complexes, which under normal conditions do not show any reactivity towards α,β-unsaturated nitriles, become highly active catalysts upon addition of N,N- diisopropylethylamine. The base-activated catalysts enable conjugate reduction of α,β-unsaturated nitriles with H2 at low catalyst loadings, affording the corresponding saturated nitriles with high conversion and excellent enantioselectivity. In contrast, alkenes lacking a conjugated cyano group do not react under these conditions, making it possible to selectively reduce the conjugated C=C bond of an α,β-unsaturated nitrile, while leaving other types of C=C bonds in the molecule intact.
- Mueller, Marc-Andre,Pfaltz, Andreas
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p. 8668 - 8671
(2014/08/18)
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- Methodology for in situ protection of aldehydes and ketones using trimethylsilyl trifluoromethanesulfonate and phosphines: Selective alkylation and reduction of ketones, esters, amides, and nitriles
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A methodology for selective transformations of ketones, esters, Weinreb amides, and nitriles in the presence of aldehydes has been developed. The use of a combination of PPh3-trimethylsilyl trifluoromethanesulfonate (TMSOTf) promotes selective transformation of aldehydes to their corresponding, temporarily protected, O,P-acetal type phosphonium salts. Because, hydrolytic work-up following ensuing reactions of other carbonyl moieties in the substrates liberates the aldehyde moiety, a sequence involving aldehyde protection, transformation of other carbonyl groups, and deprotection can be accomplished in a one-pot manner. Furthermore, the use of PEt3 instead of PPh 3 enables ketones to be converted in situ to their corresponding O,P-ketal type phosphonium salts and, consequently, selective transformations of esters, Weinreb amides, and nitriles in the presence of ketones can be performed. This methodology is applicable to various dicarbonyl compounds, including substrates that possess heteroaromatic skeletons and hydroxyl protecting groups.
- Yahata, Kenzo,Minami, Masaki,Yoshikawa, Yuki,Watanabe, Kei,Fujioka, Hiromichi
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p. 1298 - 1307
(2014/01/06)
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- Control of transient aluminum-aminals for masking and unmasking reactive carbonyl groups
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A new reagent, the dimethylaluminum N,O-dimethylhydroxylamine complex, is effective at masking reactive carbonyl groups in situ from nucleophilic addition. This reagent allows chemoselective addition of reducing reagents, Grignard reagents, organolithiums, Wittig reagents, and enolates into substrates with multiple carbonyl groups. Moreover, the trapped carbonyl group, a stable aminal, can be unmasked in situ for additional synthetic manipulations.
- Barrios, Francis J.,Springer, Brannon C.,Colby, David A.
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supporting information
p. 3082 - 3085
(2013/07/26)
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- Cyanocuprates convert carboxylic acids directly into ketones
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Carboxylic acids were converted directly in 56-99% yields into methyl, n-butyl, and isopropyl ketones using excess cyanocuprates R2CuLi 3 LiCN. A substrate with a stereocenter α to the carboxylic acid was converted into ketones with very little loss of enantiomeric purity. A variety of functional groups were tolerated including aryl bromides. This direct transformation of a carboxylic acid into ketone with minimal tertiary alcohol formation is proposed to involve a relatively stable copper ketal tetrahedral intermediate.
- Genna, Douglas T.,Posner, Gary H.
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scheme or table
p. 5358 - 5361
(2011/12/15)
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- Reversing the reactivity of carbonyl functions with phosphonium salts: Enantioselective total synthesis of (+)-centrolobine
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Step saver: Carbonyl groups with lower reactivities can be transformed in the presence of more reactive ones by treatment with PPh3 (or PEt3) and TMSOTf prior to the reaction (see scheme; TMS=trimethylsilyl, Tf=trifluoromethanesulfonyl). This methodology can be applied to reduction and alkylation reactions, and enabled the short asymmetric total synthesis of (+)-centrolobine with the highest overall yield reported to date.
- Fujioka, Hiromichi,Yahata, Kenzo,Kubo, Ozora,Sawama, Yoshinari,Hamada, Tomohito,Maegawa, Tomohiro
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supporting information; experimental part
p. 12232 - 12235
(2012/01/30)
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- Dialkylaluminum N, O -dimethylhydroxylamine complex as a reagent to mask reactive carbonyl groups in situ from nucleophiles
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Aluminum complexes of N,O-dimethylhydroxylamine are effective reagents to mask carbonyl groups in situ from nucleophilic addition by organolithiums, Grignard reagents, and borohydrides. The utility of this process by selectively adding nucleophiles into carbonyl groups on a variety of structures as well as distinguishing between carbonyl groups on a sensitive natural product is demonstrated. 1H NMR analysis supports the in situ masking of the more reactive carbonyl group.
- Barrios, Francis J.,Zhang, Xuechao,Colby, David A.
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supporting information; experimental part
p. 5588 - 5591
(2011/02/23)
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- Kinetics and mechanism of acid catalysed hydration of α- methylstyrenes
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Twelve para-substituted α-methylstyrenes with substituents H, CH 3, CF3, CH3O, CH3S, F, Cl, Br, CH3CO, CH3SO2, CN a NO2 were synthesised; additionally, the acid catalysed hydration kinetics of these compounds were measured in sulfuric acid in a concentration range c from 0.017 to 9.58 mol l-1, at 25.0°C. The observed rate constants obtained were used to construct the kinetic acidity function and calculate the catalytic rate constants. Based on the evaluation of the acidity function kinetic dependence on acid medium concentration, and the substituent effects of acid catalysed hydration of α-methylstyrenes on the catalytic rate constants, the mechanism of acid catalysed hydration was verified. The mechanism involves the addition of a proton to the double bond of α-methylstyrene in the rate-limiting reaction step denoted as A-SE2. No evident difference was found between the effects of the acid medium on the acid catalysed hydration of styrenes and α-methylstyrenes, which indicates very similar activity coefficients of the reactants, and of the transition state of both substrates. The substituent effects evaluation shows that the rate-limiting step of the reaction consists in the addition of a proton to the substrate. The carbocation formation in the transition state of this reaction step proceeds roughly half-way compared with the extent of the carbocation formation by cumyl chloride hydrolysis. The obtained carbocation is in particular stabilised by the substituents with +M effect, while the influence of the substituents with -M and I effects is significantly smaller.
- Pytela, Oldrich,Trlida, Bronislav
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p. 1025 - 1036
(2008/09/19)
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- Linear Free Energy Relationship Studies of the Dimethyldioxirane C-H Bond Insertion Reaction
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The relative rates of reaction of a series of p-substituted cumenes with dimethyldioxirane have been studied.The products are the corresponding cumyl alcohols.Treatment of the rate data with the Hammett substituent constants reveals that the insertion reaction is an electrophilic process with ρ = -2.76.Similar tretment of the data with the Brown-Okamoto substituent constants gives ρ+ = -1.61.The second-order rate constants for the reaction of a series of substituted adamantanes with dimethyldioxirane were also determined.Again, the products are the corresponding adamantanols.The rate constants were correlated with several types of substituent constants.The best correlations were obtained with the Taft ?* and ?I constants which gave ρ* = -1.08 and ρI = -2.39, respectively.Thus, the insertion reaction in this aliphatic system is also electrophilic.
- Murray, Robert W.,Gu, Hong
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p. 5673 - 5677
(2007/10/03)
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- SINGLE-PARAMETER VERSUS DUAL-PARAMETER CORRELATION FOR RADICAL REACTIONS. ADDITION OF BROMINE ATOMS TO α-METHYLSTYRENES
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A rigorous procedure was developed for measuring the relative rates of addition of bromine atoms to eleven substituted α-methylstyrenes (1-Y, with Y = CF3, NO2, F, CN, Cl, Br, CO2Me, Me, COMe, OMe and SMe).The reaction was run in tetrahydrofuran in the presence of HBr, O2 and dibutyl peroxyoxalate at 30 deg C.All products were derived from the YC6H4CMeCH2Br adduct radicals, which were immediately intercepted by O2.Correlation analysis of all the data confirmed the proposition that in the absence of measurable steric effects, the relative rates for radical additions can be correlated only by a dual-parameter equation and not by a single parameter equation.Among various combiations of ?* and ξx, the (?JJ* + ?mb) combination yields the best correlation.
- Jiang, Xi-Kui,Liu, Wayne Wei-Zhong,Wu, Shi-Hui
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- 6-(1-ACYL-1-HYDROXYMETHYL)PENICILLANIC ACID DERIVATIVES
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6-(1-Acyl-1-hydroxymethyl)penicillanic acid derivatives are useful as antibacterials and/or beta-lactamase inhibitors.
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- 4-(1-HYDROPEROXY-1-METHYLETHYL)-1,3-CYCLOPENTADIENYL METHYL KETONE: ITS FORMATION FROM α-TERPINEOL AND BEHAVIOR AS A DIMETHYLFULVENE EPOXIDE.
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Ozonolysis of α-terpineol (1) then steam distillation in presence of acid gives the known 4-isopropylidenecyclopentenyl methyl ketone (4).This is oxidized in air to 4-(1-hydroperoxy-1-methylethyl)-1,3-cyclopentadienyl methyl ketone (10), a compound frequently reacting as if it were one of the elusive dimethylfulvene epoxides.It is converted by silica gel to two dimers (12, 13) of 2-acetyl-6,6-dimethylfulvene epoxide (19).Catalytic reduction of the dimers occurs mostly by exo addition of hydrogen to the conjugated double bond, and thermolysis of the dimers yields 4-acetyl-6,6-dimethylcyclohexa-2,4-dienone (20).With triphenylphosphine the hydroperoxide (10) yields two dimers of 2-acetyl-6,6-dimethylfulvene (26).This is the first reported isolation of dimers of a fulvene.The hydroperoxide (10) adds diazomethane to give an unstable pyrazoline (28); this pyrazoline loses nitrogen to yield a single isomer o' 5-acetyl-3',3'-dimethylbicyclohex-3-ene-2-spiro-2'-oxirane (29).Catalytic hydrogenation of the latter involves ring opening of the epoxide.
- Thomas, Alan F.,Perret, Celia
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p. 3311 - 3322
(2007/10/02)
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