- Synthesis of novel chiral heterometallic terpene oximates: Unusual generation of an aluminium enolate by a cooperative effect
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Al-K heterometallic terpene oximate derivatives with uncommon structural features are reported. These species react with an aryl ketone leading to heterometallic enolates via an unusual route. Isolation of a remarkable heterometallic Al-K enolate confirms the cooperative mechanism proposed by DFT calculations, where the oximate ligand has a prominent role. From these enolates the formation of new C-C bonds is straightforward.
- Fernández-Millán, María,Temprado, Manuel,Cano, Jesús,Cuenca, Tomás,Mosquera, Marta E.G.
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Read Online
- Experimental and Computational Studies of Palladium-Catalyzed Spirocyclization via a Narasaka-Heck/C(sp3or sp2)-H Activation Cascade Reaction
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The first synthesis of highly strained spirocyclobutane-pyrrolines via a palladium-catalyzed tandem Narasaka-Heck/C(sp3 or sp2)-H activation reaction is reported here. The key step in this transformation is the activation of a δ-C-H bond via an in situ generated σ-alkyl-Pd(II) species to form a five-membered spiro-palladacycle intermediate. The concerted metalation-deprotonation (CMD) process, rate-determining step, and energy barrier of the entire reaction were explored by density functional theory (DFT) calculations. Moreover, a series of control experiments was conducted to probe the rate-determining step and reversibility of the C(sp3)-H activation step.
- Wei, Wan-Xu,Li, Yuke,Wen, Ya-Ting,Li, Ming,Li, Xue-Song,Wang, Cui-Tian,Liu, Hong-Chao,Xia, Yu,Zhang, Bo-Sheng,Jiao, Rui-Qiang,Liang, Yong-Min
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supporting information
p. 7868 - 7875
(2021/05/27)
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- Competitive Desulfonylative Reduction and Oxidation of α-Sulfonylketones Promoted by Photoinduced Electron Transfer with 2-Hydroxyaryl-1,3-dimethylbenzimidazolines under Air
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Desulfonylation reactions of α-sulfonylketones promoted by photoinduced electron transfer with 2-hydroxyarylbenzimidazolines (BIH-ArOH) were investigated. Under aerobic conditions, photoexcited 2-hydroxynaphthylbenzimidazoline (BIH-NapOH) promotes competitive reduction (forming alkylketones) and oxidation (producing α-hydroxyketones) of sulfonylketones through pathways involving the intermediacy of α-ketoalkyl radicals. The results of an examination of the effects of solvents, radical trapping reagents, substituents of sulfonylketones, and a variety of hydroxyaryl- and aryl-benzimidazolines (BIH-ArOH and BIH-Ar) suggest that the oxidation products are produced by dissociation of α-ketoalkyl radicals from the initially formed solvent-caged radical ion pairs followed by reaction with molecular oxygen. In addition, the observations indicate that the reduction products are generated by proton or hydrogen atom transfer in solvent-caged radical ion pairs derived from benzimidazolines and sulfonylketones. The results also suggest that arylsulfinate anions arising by carbon-sulfur bond cleavage of sulfonylketone radical anions act as reductants in the oxidation pathway to convert initially formed α-hydroperoxyketones to α-hydroxyketones. Finally, density functional theory calculations were performed to explore the structures and properties of radical ions of sulfonylketones as well as BIH-NapOH.
- Hasegawa, Eietsu,Nakamura, Shyota,Oomori, Kazuki,Tanaka, Tsukasa,Iwamoto, Hajime,Wakamatsu, Kan
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p. 2556 - 2569
(2021/02/27)
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- Palladium-Catalyzed Synthesis of α-Methyl Ketones from Allylic Alcohols and Methanol
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One-pot synthesis of α-methyl ketones starting from 1,3-diaryl propenols or 1-aryl propenols and methanol as a C1 source is demonstrated. This one-pot isomerization-methylation is catalyzed by commercially available Pd(OAc)2 with H2O as the only by-product. Mechanistic studies and deuterium labelling experiments indicate the involvement of isomerization of allyl alcohol followed by methylation through a hydrogen-borrowing pathway in these isomerization-methylation reactions.
- Biswal, Priyabrata,Chandrasekhar, Vadapalli,Meher, Sushanta Kumar,Samser, Shaikh,Venkatasubbaiah, Krishnan
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supporting information
(2021/11/01)
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- External-oxidant-free amino-benzoyloxylation of unactivated alkenes of unsaturated ketoximes with: O -benzoylhydroxylamines
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A new copper-catalyzed two-component amino-benzoyloxylation of unactivated alkenes of unsaturated ketoximes with O-benzoylhydroxylamines as the benzoyloxy sources is developed. Chemoselectivity of this method toward amino-benzoyloxylation or oxy-benzoyloxylation of alkenyl ketoximes relies on the position of the tethered olefins, and provides an external-oxidant-free alkene difunctionalization route that directly utilizes O-benzoylhydroxylamines as the benzoyloxy radical precursors and internal oxidants for the divergent synthesis of cyclic nitrones and isoxazolines.
- Chen, Jiangfei,Zhu, Yan-Ping,Li, Jin-Heng,Wang, Qiu-An
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supporting information
p. 5215 - 5218
(2021/05/31)
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- Rhenium(I)-Catalyzed C-Methylation of Ketones, Indoles, and Arylacetonitriles Using Methanol
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A ReCl(CO)5/MeC(CH2PPh2)3 (L2) system was developed for the C-methylation reactions utilizing methanol and base, following the borrowing hydrogen strategy. Diverse ketones, indoles, and arylacetonitriles underwent mono-and dimethylation selectively up to 99% yield. Remarkably, tandem multiple methylations were also achieved by employing this catalytic system.
- Shee, Sujan,Kundu, Sabuj
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p. 6943 - 6951
(2021/05/29)
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- Iron-Catalyzed Cleavage Reaction of Keto Acids with Aliphatic Aldehydes for the Synthesis of Ketones and Ketone Esters
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The radical–radical coupling reaction is an important synthetic strategy. In this study, the iron-catalyzed radical–radical cross-coupling reaction based on the decarboxylation of keto acids and decarbonylation of aliphatic aldehydes to obtain valuable aryl ketones is reported for the first time. Remarkably, when tertiary aldehydes were used as carbonyl sources, ketone esters were selectively obtained instead of ketones. The gram-scale preparation of aryl ketone through this strategy was easily achieved by using only 3 mol % of the iron catalyst. As a proof-of-concept, the bioactive molecule flurprimidol was synthesized in two steps by using this strategy.
- Zhou, Fangyuan,Li, Lesong,Lin, Kao,Zhang, Feng,Deng, Guo-Jun,Gong, Hang
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supporting information
p. 4246 - 4250
(2020/03/11)
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- Method for preparing aryl ketone based on iron-catalyzed free radical-free radical coupling reaction such as ketonic acid decarboxylation and fatty aldehyde de-carbonylation
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The invention discloses a method for preparing an aryl ketone derivative based on a free radical-free radical cross-coupling reaction such as ketonic acid decarboxylation and fatty aldehyde de-carbonylation. The method comprises the following steps: reacting aryl-substituted ketonic acid with fatty aldehyde under the catalytic action of ferric triacetylacetonate to generate an aryl ketone derivative; the gram-grade reaction can be realized by the method only by using 3mol% of an iron catalyst; and the method has the advantages of no need of consumption of a large amount of a Lewis acid catalyst or a stoichiometric organic metal reagent, mild reaction conditions, one-step reaction, few by-products, wide substrate application range and scalable reaction, and overcomes the defects of large catalyst consumption, insufficient functional group tolerance, many by-products and the like in the prior art.
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Paragraph 0047-0048
(2020/05/05)
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- One-Pot Conversion of Allylic Alcohols to α-Methyl Ketones via Iron-Catalyzed Isomerization-Methylation
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A one-pot iron-catalyzed conversion of allylic alcohols to α-methyl ketones has been developed. This isomerization-methylation strategy utilized a (cyclopentadienone)iron(0) carbonyl complex as precatalyst and methanol as the C1 source. A diverse range of allylic alcohols undergoes isomerization-methylation to form α-methyl ketones in good isolated yields (up to 84% isolated yield).
- Latham, Daniel E.,Polidano, Kurt,Williams, Jonathan M. J.,Morrill, Louis C.
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supporting information
p. 7914 - 7918
(2019/10/16)
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- Enamines as Surrogates of Alkyl Carbanions for the Direct Conversion of Secondary Amides to α-Branched Ketones
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A direct transformation of secondary amides into α-branched ketones with enamines as soft alkylation reagents was developed. In this reaction, enamines serve as surrogates of alkyl carbanions, rather than the conventional enolates equivalents in the Stork's reactions, which allowed for the easy introduction of alkyl groups with electrophilic functional groups. In the presence of 4 ? molecular sieves, the method can be extended to the one-pot coupling of secondary amides with aldehydes to yield ketones. (Figure presented.).
- Liu, Yong-Peng,Wang, Shu-Ren,Chen, Ting-Ting,Yu, Cun-Cun,Wang, Ai-E,Huang, Pei-Qiang
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supporting information
p. 971 - 975
(2019/01/25)
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- Silver-promoted cascade radical cyclization of γ,δ-unsaturated oxime esters with P(O)H compounds: synthesis of phosphorylated pyrrolines
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A cascade radical cyclization was realized for the first silver-promoted imino-phosphorylation of γ,δ-unsaturated oxime esters, which provided a step-economical and redox-neutral route to access a variety of phosphorylated pyrrolines in good to excellent yields. Moreover, a new bulky trivalent phosphine ligand with a pyrroline motif was obtained through a deoxidation process.
- Chen, Chen,Bao, Yinwei,Zhao, Jinghui,Zhu, Bolin
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supporting information
p. 14697 - 14700
(2019/12/11)
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- Catalytic C1 Alkylation with Methanol and Isotope-Labeled Methanol
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A metal-catalyzed methylation process has been developed. By employing an air- and moisture-stable manganese catalyst together with isotopically labeled methanol, a series of D-, CD3-, and 13C-labeled products were obtained in good yields under mild reaction conditions with water as the only byproduct.
- Sklyaruk, Jan,Borghs, Jannik C.,El-Sepelgy, Osama,Rueping, Magnus
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supporting information
p. 775 - 779
(2019/01/04)
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- Naphthyridine-based iridium complexes: Structures and catalytic activity on alkylation of aryl ketones
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Iridium(III) complexes containing a designed ligand, 2-amino-7-(2-pyridinyl)-1,8-naphthyridine derivative, were prepared and all complexes were characterized using spectroscopic and crystallographic methods. These new Ir(III) complexes are able to act as catalysts for the C-alkylation of aryl alkyl ketones with the use of alcohols as the alkylating agent. Typically, acetophenone undergoes alkylation with methanol and ethanol to yield isobutyrophenone and butyrophenone, respectively.
- Chen, Po-Hao,Liu, Yi-Hung,Liu, Shiuh-Tzung
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p. 972 - 981
(2019/05/24)
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- α-Methylation of Ketones with Methanol Catalyzed by Ni/SiO2-Al2O3
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α-Methylation of ketones with methanol catalyzed by a cheap and easy to handle Ni/SiO2-Al2O3 was explored. After optimization of the reaction between propiophenone and methanol, the desired product was obtained in 95 % isolated yield. A wide range of ketones was methylated under the optimized conditions (16 examples). This procedure was extended to a three-component cross-benzylation-methylation of acetophenone.
- Charvieux, Aubin,Duguet, Nicolas,Métay, Estelle
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supporting information
p. 3694 - 3698
(2019/06/13)
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- Synthesis of Halomethyl Isoxazoles/Cyclic Nitrones via Cascade Sequence: 1,2-Halogen Radical Shift as a Key Link
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A novel iminoxyl radical-promoted dichotomous regioselective 5-exo-trig cyclization onto vinylic halogen/1,2-halogen radical shift sequence is developed for the synthesis of halomethyl isoxazoles/cyclic nitrones using β-halo-β,?- and ?-halo-?,?-unsaturated ketoximes as the substrates and PhI(OAc)2/TEMPO as the oxidation system. DFT calculations reveal that a halogen-bridged three-membered ring transition state is involved in the 1,2-Cl-/Br-atom shift, while the 1,2-I atom migration can be taken into account with an elimination/readdition mechanism. The migration ability was indicated to be ranked in the following order: I > Br > Cl.
- Chen, Hong-Lei,Wei, Dian,Zhang, Jian-Wu,Li, Cheng-Lin,Yu, Wei,Han, Bing
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supporting information
p. 2906 - 2910
(2018/05/28)
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- C -Methylation of Alcohols, Ketones, and Indoles with Methanol Using Heterogeneous Platinum Catalysts
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A versatile, selective, and recyclable heterogeneous catalytic method for the methylation of C-H bonds in alcohols, ketones, and indoles with methanol under oxidant-free conditions using a Pt-loaded carbon (Pt/C) catalyst in the presence of NaOH is reported. This catalytic system is effective for various methylation reactions: (1) the β-methylation of primary alcohols, including aryl, aliphatic, and heterocyclic alcohols, (2) the α-methylation of ketones, and (3) the selective C3-methylation of indoles. The reactions are driven by a borrowing-hydrogen mechanism. The reaction begins with the dehydrogenation of the alcohol(s) to afford aldehydes, which subsequently undergo a condensation reaction with the nucleophile (aldehyde, ketone, or indole), followed by hydrogenation of the condensation product by Pt-H species to yield the desired product. In all of the methylation reactions explored in this study, the Pt/C catalyst exhibits a significantly higher turnover number than other previously reported homogeneous catalytic systems. Moreover, it is demonstrated that the high catalytic activity of Pt can be rationalized in terms of the adsorption energy of hydrogen on the metal surface, as revealed by density functional theory calculations on different metal surfaces.
- Siddiki, S. M. A. Hakim,Touchy, Abeda S.,Jamil, Md. A. R.,Toyao, Takashi,Shimizu, Ken-Ichi
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p. 3091 - 3103
(2018/04/14)
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- Methylation of Amines and Ketones with Methanol Catalyzed by an Iridium Complex Bearing a 2-Hydroxypyridylmethylene Fragment
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Reaction of complex [Cp?Ir(HOC5H3CH2C5H3OH)Cl][Cl] (1) with AgOTf generated the product [Cp?Ir(HOC5H3CH2C5H3OH)(H2O)][OTf]2 (2), which was further transformed to the complex [Cp?Ir(OC5H3CH2C5H3O)(H2O)] (3) in the presence of t-BuONa via -OH deprotonation. Complexes 1-3 exhibited high activity for the methylation of amines and ketones. These C-C and C-N coupling reactions proceeded in air with 1 mol % catalyst loading in the presence of K2CO3.
- Deng, Danfeng,Hu, Bowen,Yang, Min,Chen, Dafa
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p. 3353 - 3359
(2018/09/25)
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- Iron-Catalyzed Methylation Using the Borrowing Hydrogen Approach
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A general iron-catalyzed methylation has been developed using methanol as a C1 building block. This borrowing hydrogen approach employs a Kn?lker-type (cyclopentadienone)iron carbonyl complex as catalyst (2 mol %) and exhibits a broad reaction scope. A variety of ketones, indoles, oxindoles, amines, and sulfonamides undergo mono- or dimethylation in excellent isolated yields (>60 examples, 79% average yield).
- Polidano, Kurt,Allen, Benjamin D. W.,Williams, Jonathan M. J.,Morrill, Louis C.
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p. 6440 - 6445
(2018/07/25)
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- Study on the design, synthesis and structure-activity relationships of new thiosemicarbazone compounds as tyrosinase inhibitors
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52 Structure-based thiosemicarbazone compounds bearing various substituted-lipophilic part, including substituted-benzaldehyde, substituted-phenylalkan-1-one and their biphenyl-type thiosemicarbazone analogs, were designed, synthesized and evaluated as new tyrosinase inhibitors. The results demonstrated that 22 compounds have potent inhibitory activities against tyrosinase with the IC50 value of lower than 1.0 μM. On the basis of the obtained experimental data, the structure-activity relationships (SARs) were rationally derived. Besides, the inhibition mechanism and the inhibitory kinetics of selected compounds 3d and 6e were investigated, revealing that such type of compounds were belonged to the reversible and competitive tyrosinase inhibitors. To verify the safety of these developed thiosemicarbazone compounds, four randomly selected compounds 3d, 4e, 6a and 9a were also tested in 293T cell line for the evaluation of the cytotoxicity. Interestingly, all these compounds almost did not perform any toxicity to 293T cells even at a high concentration of 1000 μmol/L. Taken together, these results suggested that such compounds could serve as the highly efficient and more safe candidates for the treatment of tyrosinase-related disorders.
- Song, Senchuan,You, Ao,Chen, Zhiyong,Zhu, Guoxun,Wen, Huan,Song, Huacan,Yi, Wei
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p. 815 - 825
(2017/09/05)
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- Cu/Mn bimetallic catalysis enables carbonylative Suzuki-Miyaura coupling with unactivated alkyl electrophiles
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A bimetallic system consisting of Cu-carbene and Mn-carbonyl co-catalysts was employed for carbonylative C-C coupling of arylboronic esters with alkyl halides, allowing for the convergent synthesis of ketones. The system operates under mild conditions and exhibits complementary reactivity to Pd catalysis. The method is compatible with a wide range of arylboronic ester nucleophiles and proceeds smoothly for both primary and secondary alkyl iodide electrophiles. Preliminary mechanistic experiments corroborate a hypothetical catalytic mechanism consisting of co-dependent cycles wherein the Cu-carbene co-catalyst engages in transmetallation to generate an organocopper nucleophile, while the Mn-carbonyl co-catalyst activates the alkyl halide electrophile by single-electron transfer and then undergoes reversible carbonylation to generate an acylmanganese electrophile. The two cycles then intersect with a heterobimetallic, product-releasing C-C coupling step.
- Pye, Dominic R.,Cheng, Li-Jie,Mankad, Neal P.
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p. 4750 - 4755
(2017/07/10)
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- Rhodium-Catalyzed Direct Ortho C-H Arylation Using Ketone as Directing Group with Boron Reagent
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A general method for selective ortho C-H arylation of ketone, with boron reagent enabled by rhodium complexes with excellent yields, is developed. The transformation is characterized by the use of air-stable Rh catalyst, high monoarylation selectivity, and excellent yields of most of the substrates.
- Zhang, Bing,Wang, Huai-Wei,Kang, Yan-Shang,Zhang, Ping,Xu, Hua-Jin,Lu, Yi,Sun, Wei-Yin
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supporting information
p. 5940 - 5943
(2017/11/10)
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- Preparation and use of DMF-stabilized iridium nanoclusters as methylation catalysts using methanol as the C1 source
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We report methylations of alcohols and anilines catalyzed by DMF-stabilized Ir nanoclusters using methanol as the C1 source. The DMF-stabilized Ir nanoclusters were prepared in one step and have diameters of 1-1.5 nm. They react in a borrowing-hydrogen reaction and are efficient methylation catalysts (TON up to 310?000).
- Oikawa, Kei,Itoh, Satoshi,Yano, Hiroki,Kawasaki, Hideya,Obora, Yasushi
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p. 1080 - 1083
(2017/02/05)
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- Utilization of MeOH as a C1 Building Block in Tandem Three-Component Coupling Reaction
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Ru(II) catalyzed tandem synthesis of α-branched methylated ketones via multicomponent reactions following the hydrogen borrowing process is described. This nonphosphine-based air and moisture stable catalyst efficiently produced various methylated ketones using methanol as a methylating agent. This system was found to be highly effective in three-component coupling between methanol, primary alcohols, and methyl ketones. A proposed catalytic cycle for the α-methylation is supported by DFT calculations as well as kinetic experiments.
- Chakrabarti, Kaushik,Maji, Milan,Panja, Dibyajyoti,Paul, Bhaskar,Shee, Sujan,Das, Gourab Kanti,Kundu, Sabuj
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supporting information
p. 4750 - 4753
(2017/09/22)
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- Syndiotactic Poly(aminostyrene)-Supported Palladium Catalyst for Ketone Methylation with Methanol
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Palladium nanoparticles immobilized on an amino-functionalized syndiotactic polystyrene (sPS-N) served as a novel recyclable catalyst for the dimethylation and cross methyl alkylation of a wide range of ketones with methanol as the methylation agent. This heterogeneous catalyst (Pd@sPS-N) was highly robust and showed excellent thermal stability and chemical resistance. It not only showed remarkably high activity, but it could also be easily recovered by filtration without loss of activity.
- Jiang, Lei,Guo, Fang,Shi, Zhenghai,Li, Yang,Hou, Zhaomin
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p. 3827 - 3832
(2017/09/25)
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- Methylation of C(sp3)-H/C(sp2)-H bonds with methanol catalyzed by cobalt system
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A highly efficient Co-based catalytic system, composed of a commercially available Co salt, a tetradentate phosphine ligand P-(CH2CH2PPh2)3(PP3), and a base (denoted as [Co]/PP3/base), is developed for the methylation of C(sp3)-H and C(sp2)-H bonds using methanol as a methylating reagent. The Co(BF4)2.6H2O/PP3/K2CO3 catalytic system showed high catalytic activity for the methylation of C-H bonds in aryl alkyl ketones, aryl acetonitriles, and indoles, with wide substrate scope and good functional group tolerance, and methylsubstituted products were obtained in good to excellent yields at 100 °C. This cheap, readily available, and highly efficient Co-based catalytic system may have promising applications in methylation reaction using methanol.
- Liu, Zhenghui,Yang, Zhenzhen,Yu, Xiaoxiao,Zhang, Hongye,Yu, Bo,Zhao, Yanfei,Liu, Zhimin
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supporting information
p. 5228 - 5231
(2017/11/06)
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- C-C coupling of ketones with methanol catalyzed by a N-heterocyclic carbene-phosphine iridium complex
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An N-heterocyclic carbene-phosphine iridium complex system was found to be a very efficient catalyst for the methylation of ketone via a hydrogen transfer reaction. Mild conditions together with low catalyst loading (1 mol%) were used for a tandem process which involves the dehydrogenation of methanol, C=C bond formation with a ketone, and hydrogenation of the new generated double bond by iridium hydride to give the alkylated product. Using this iridium catalyst system, a number of branched ketones were synthesized with good to excellent conversions and yields.
- Quan, Xu,Kerdphon, Sutthichat,Andersson, Pher G.
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supporting information
p. 3576 - 3579
(2015/03/04)
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- CATALYST
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A catalyst in solid particulate form free from an external carrier material comprising (i) a complex of formula (I) wherein M is zirconium or hafnium; each X is a sigma ligand; L is a divalent bridge selected from -R'2C-, -R'2C-CR'2-, -R'2Si-, -R'2Si-Si R'2-, -R'2 Ge-, wherein each R' is independently a hydrogen atom, C1-20-alkyl, tri(C1-20-alkyl)silyl, C6-20-aryl, C7-20-arylalkyl or C7-20-alkylaryl; R2 is a C1-20-hydrocarbyl radical; R2' is a C1-20-hydrocarbyl radical;R6 is a linear or branched aliphatic C1-20-hydrocarbyl group, SR9or OSR9;R6' is a linear or branched aliphatic C1-20-hydrocarbyl group, SR9'or OR9'; with the proviso that neither R6 or R6' represents a group having a quaternary carbon atom directly attached to the indenyl ring; R9 is a C1-20-hydrocarbyl group;R9' is a C1-20-hydrocarbyl group; Ar is a C6-12-aryl or C5-12-heteroaryl group optionally carrying one or more substituents R8; Ar' is a C6-12-aryl or C5-12-heteroaryl group optionally carrying one or more substituents R8';each R8 is a C1-20-hydrocarbyl group;each R8' is a C1-20 -hydrocarbyl group;wherein at least two of R2 and R2'; R6 and R6'; or Ar and Ar' are the same;and (ii) a cocatalyst comprising a compound of a group 13 metal, e.g. Al or boron.
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Page/Page column 64
(2014/07/08)
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- Iridium-catalyzed selective α-methylation of ketones with methanol
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Iridium-catalyzed selective α-dimethylation and α-methylation of ketones or phenylacetonitriles, using methanol as the methylating agent, were achieved. In addition, three-component cross α-methyl-alkylation was successfully performed using methyl ketones with methanol and primary alcohols with long-chain alkyl groups. This method provides a very convenient direct route to α-methylated ketones, using methanol.
- Ogawa, Shinji,Obora, Yasushi
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supporting information
p. 2491 - 2493
(2014/03/21)
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- Palladium-catalyzed addition of potassium aryltrifluoroborates to aliphatic nitriles: Synthesis of alkyl aryl ketones, diketone compounds, and 2-arylbenzo[b]furans
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A palladium-catalyzed addition of potassium aryltrifluoroborates to aliphatic nitriles has been developed, leading to a wide range of alkyl aryl ketones with moderate to excellent yields. Moreover, several dinitriles (e.g., malononitrile, glutaronitrile, and adiponitrile) were applicable to this process for the construction of 1,3-, 1,5-, or 1,6-dicarbonyl compounds. The scope of the developed approach is successfully explored toward the one-step synthesis of 2-arylbenzo[b]furans via sequential addition and intramolecular annulation reactions. The methodology accepted a wide range of substrates and is applicable to library synthesis.
- Wang, Xingyong,Liu, Miaochang,Xu, Long,Wang, Qingzong,Chen, Jiuxi,Ding, Jinchang,Wu, Huayue
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p. 5273 - 5281
(2013/07/26)
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- Mild ketone formation via Ni-catalyzed reductive coupling of unactivated alkyl halides with acid anhydrides
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Ni-catalyzed ketone formation through mild reductive coupling of a diverse set of unactivated alkyl bromides and iodides with particularly aryl acid anhydrides was successfully developed using zinc as the terminal reductant. These conditions also allow direct coupling of alkyl iodides with aryl acids in the presence of Boc2O and MgCl2. The Royal Society of Chemistry 2012.
- Yin, Hongyu,Zhao, Chenglong,You, Hengzhi,Lin, Kunhua,Gong, Hegui
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supporting information; experimental part
p. 7034 - 7036
(2012/08/14)
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- Enantiopure C1-symmetric bis(imino)pyridine cobalt complexes for asymmetric alkene hydrogenation
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Enantiopure C1-symmetric bis(imino)pyridine cobalt chloride, methyl, hydride, and cyclometalated complexes have been synthesized and characterized. These complexes are active as catalysts for the enantioselective hydrogenation of geminal-disubstituted olefins.
- Monfette, Sebastien,Turner, Zoe R.,Semproni, Scott P.,Chirik, Paul J.
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supporting information; experimental part
p. 4561 - 4564
(2012/04/23)
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- Development of decarboxylative coupling processes for the synthesis of azomethines and ketones
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A bimetallic catalyst system has been developed that allows the synthesis of azomethines by a one-pot three-component decarboxylative coupling, starting from simple, nontoxic precursors, i.e. potassium α-oxo carboxylates, aryl halides and primary amines. In the presence of 15 mol-% copper/phenanthroline and 1 mol-% Pd/dppf, a wide range of valuable imines is conveniently accessible in high yields at 100 °C, an unprecedentedly low temperature for redox-neutral decarboxylative cross-coupling reactions. Hydrogenation of the azomethine products leads to secondary amines. Alternatively, they can be hydrolyzed in situ to aryl ketones. The resulting ketone synthesis via azomethine intermediates is also of interest as it gives higher yields at much lower temperatures than the direct decarboxylative coupling of α-oxo carboxylates with aryl halides. A convenient synthesis of azomethines by a one-pot three-component decarboxylative coupling, starting from potassium α-oxo carboxylates, aryl halides and primary amines is described. Combined with in situ hydrolysis, ketones are obtained. Thisamine-mediated ketone synthesis gives higher yields at lower temperatures than the direct coupling of α-oxo carboxylates. Copyright
- Collet, Florence,Song, Bingrui,Rudolphi, Felix,Goossen, Lukas J.
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experimental part
p. 6486 - 6501
(2011/12/05)
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- Rhodium-catalyzed phenylthiolation reaction of heteroaromatic compounds using α-(phenylthio)isobutyrophenone
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In the presence of catalytic amounts of RhH(PPh3)4 and 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-benzothiazoles, 1,3-benzoxazoles, and benzothiophene reacted with α-(phenylthio) isobutyrophenone giving 2-phenylthio derivatives. Reactive monocyclic heteroaromatics, 1-methyl-1,2,3,4-tetrazole and 2-cyanothiophene were also converted into the 5-phenylthio derivatives. The use of an appropriate phenylthio transfer reagent is crucial for the efficient catalyzed conversion of heteroaromatic C-H bonds into C-S bonds.
- Arisawa, Mieko,Toriyama, Fumihiko,Yamaguchi, Masahiko
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supporting information; experimental part
p. 2344 - 2347
(2011/05/16)
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- Experimental transition state for the B-chlorodiisopinocampheylborane (DIP-Cl) reduction
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Asymmetric reductions of prochiral ketones are important transformations in the syntheses of natural products, pharmaceuticals, and fine chemicals. B-Chlorodiisopinocampheylborane (DIP-Cl), a stoichiometric reagent that is capable of reducing prochiral aralkyl ketones with high selectivity. Here, we utilize a recently developed 13C kinetic isotope effect (KIE) methodology to probe the symmetry breaking process inherent to this asymmetric reduction. Experimental KIEs and computed transition structures indicate significant roles for non-bonding interaction, specific directed orbital interactions, and hydrogen tunneling in this reaction.
- Stafford, Sean E.,Meyer, Matthew P.
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supporting information; experimental part
p. 3027 - 3030
(2009/10/04)
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- NOVEL PROTEIN TYROSINE PHOSPHATASE - IB INHIBITORS
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The present invention relates to the novel compounds of the general formula (I), wherein the symbols are same as described in specification, their pharmaceutically acceptable salts, pharmaceutical compositions containing them, to process and intermediates for the preparation of the above said compounds, having the utility of these compounds in medicine and to methods for their therapeutic use, and their use in the treatment of metabolic disorders.
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Page/Page column 65
(2009/10/22)
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- A mechanistic probe for asymmetric reactions: Deuterium isotope effects at enantiotopic groups
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The development of a mechanistic probe that is especially suitable for the study of asymmetric reactions is presented. Chemically innocuous enantiotopic methyl groups are utilized as probes for the distinct environments that develop at the transition state for the (-)-B-chlorodiisopinocampheylborane reduction of 4′-methylisobutyrophenone. 2H kinetic isotope effects (KIEs) are determined for both enantiotopic methyl groups using two types of competition reactions. One competition is that between the d3-methyl enantiomeric isotopomers. The other competition reaction is that between the d6-dimethyl and perprotiated isotopologues. The rate constant ratios can be converted into kinetic isotope effects upon each of the individual enantiotopic methyl groups by invoking the rule of the geometric mean. The resulting isotope effect measurements yield highly precise values and contribute further understanding to the transition structure for this stereoselective reduction. The results are discussed in the context of steric isotope effects and the origins of these effects, which arise from the impact of steric crowding upon the anharmonicity of C-H bonds in the transition structure relative to the reactant state. Copyright
- West, Jason D.,Stafford, Sean E.,Meyer, Matthew P.
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supporting information; experimental part
p. 7816 - 7817
(2009/02/02)
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- Palladium/copper-catalyzed decarboxylative cross-coupling of aryl chlorides with potassium carboxylates
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(Chemical Equation Presented) Even non-activated aryl chlorides undergo decarboxylative cross-coupling reactions in the presence of a catalyst system generated in situ from CuI, 1,10-phenanthroline, PdI2, and di(tert-butyl)biphenylphosphane. The new catalyst is useful for both the synthesis of biaryl compounds from aromatic carboxylates and the synthesis of aryl ketones from salts of α-ketocarboxylic acids (see scheme; FG=functional group; R=aryl, alkyl).
- Goossen, Lukas J.,Zimmermann, Bettina,Knauber, Thomas
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scheme or table
p. 7103 - 7106
(2009/04/12)
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- The effect of type of acid sites in molecular sieves on activity and selectivity in acylation reactions
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The role of the type of acid site (Broensted vs. Lewis) on the activity and selectivity of molecular sieve catalysts was investigated in ferrocene and toluene acylation. H-, Zn-, Fe-, Aland La-forms of zeolite Beta, USY and mesoporous molecular sieves (A1
- Bejblova, Martina,Vlk, Josef,Prochazkova, Dana,Siklova, Helena,Cejka, Jiri
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p. 728 - 746
(2008/12/22)
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- Friedel-Crafts acylation reaction using carboxylic acids as acylating agents
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Dehydrative Friedel-Crafts acylation reaction of aromatic compounds with carboxylic acids as acylating agents was investigated in the presence of Lewis acid- or Br?nsted acid-catalyst. Various metal triflates and bis(trifluoromethanesulfonyl)amides showed catalytic activity at high temperature, among which Eu(NTf2)3 proved to be the most effective and efficiently catalyzed the acylation reaction of alkyl- and alkoxybenzenes with aliphatic and aromatic carboxylic acids at 250 °C. Bi(NTf2)3 was more effective than Eu(NTf2)3 at lower temperature, but proved to be hydrolyzed in the presence of a small amount of water to give HNTf2 and [Bi6O4(OH)4(H2O)6](NTf2)6. The structure of the latter compound was confirmed by a single crystal X-ray analysis. Among five Br?nsted acids, HOTf, HNTf2, HCTf3, TsOH, and Nafion SAC-13, HNTf2 has proved to be the most efficient catalyst and more effective than Eu(NTf2)3 for the acylation of p-xylene with heptanoic acid at 220 °C or lower temperature. HNTf2 catalyzed the acylation of anisole with carboxylic acids in high yields in refluxing toluene with azeotropic removal of water.
- Kawamura, Masato,Cui, Dong-Mei,Shimada, Shigeru
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p. 9201 - 9209
(2007/10/03)
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- NEW PHOTOINITIATORS
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The invention relates to novel photoinitators of formulae (I), (II), (III), (IV), (V) and (VI) wherein R1 and R2 are each independently of the other C1-C8alkyl; C1-C4alkyl substituted by OH, C1-C4alkoxy, -COO(C1-C8alkyl), (C1-C4alkyl)-COO-, -CN, benzyl, phenyl or by -N(R15)(R16); C3-C6alkerlyl, benzyl, -CH2-C6H4-(C1-C4alkyl) or phenyl; or R1 and R2 together are unbrarched or branched C2-C9alkylene or C3-C6-oxa- or -aza-alkylene; R3, R4, R5 and R6 are each independently of the others hydrogen, C1-C8alkyl, C3-C6alkenyl, benzyl, -CH2-C6H4-(C1-C4alkyl) or phenyl; R3 and R4 together and/or R5 and R6 together are unbranched or branched C2-C9alkylene; A is CI, Br, -O-R9, -N(R11)(R12) or -S-R18, A' is -O-, -NH- or -NR11-; A" is CI, Br, -O-R9, -N(R11)(R12) or -S-R18 or hydrogen, X is -O-R10 or -N(R13)(R14), n is an integer from 1 to 10, preferably an integer from 1 to 4, especially 1, 2 or 3; R7 is a linker; R8 is a bivalent C2-C3alkylele radical.
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Page/Page column 38
(2010/02/14)
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- GaCl3-catalyzed skeletal rearrangement of α,α, α-trisubstituted aldehydes
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(Chemical Equation Presented) GaCl3 is found to be a superior catalyst for the skeletal rearrangement of α,α,α- trisubstituted aldehydes to ketones. The rearrangement can proceed smoothly in the presence of a catalytic amount of GaCl3, and even substrates having no heteroatoms α to the carbonyl group or without steric strains can be used. Double activation of a carbonyl group by two molecules of GaCl 3 was supported on the basis of experimental data and a DFT study.
- Oshita, Masayuki,Okazaki, Takao,Ohe, Kouichi,Chatani, Naoto
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p. 331 - 334
(2007/10/03)
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- Highly efficient Pd-catalyzed carbonylative cross-coupling reactions with tetraorganoindates
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Tetraorganoindates, which were prepared easily from the reaction of 1 equiv of InCl3 with 4 equiv of organometallics, could be employed as effective nucleophilic cross-coupling partners in Pd-catalyzed carbonylative cross-coupling reactions with a variety of organic electrophiles. The present method gave unsymmetrical ketones and 1,4-diacylbenzenes in good yields with highly efficient transfer of almost all the organic groups attached to the indium under a carbon monoxide atmosphere in THF at 60 °C.
- Lee, Sung Wook,Lee, Kooyeon,Seomoon, Dong,Kim, Sundae,Kim, Hyunseok,Kim, Hyun,Shim, Eunkyong,Lee, Miae,Lee, Seokju,Kim, Misook,Lee, Phil Ho
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p. 4852 - 4855
(2007/10/03)
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- Photomediated asymmetric synthesis of (-)-cuparene.
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Generation of a benzylic quaternary stereocentre via the photomediated cyclisation of a chiral alpha-(aminobutyl)styrene followed by a microwave-assisted Cope elimination has led to a total synthesis of the sesquiterpene (-)-cuparene.
- Grainger, Richard S,Patel, Aslam
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p. 1072 - 1073
(2007/10/03)
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- Synthesis of 3H-tolperisone
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Tolperisone has been tritiated to 50 Ci/mmol specific activity in order to use this compound in the study of muscle relaxant binding. Of the two reaction pathways investigated, hydrogenolytic exchange of aromatic bromine is favored over hydrogenation of a double bond.
- Dietrich, Axel,Fels, Gregor
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p. 1125 - 1134
(2007/10/03)
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- Solvolysis of 1-alkyl-1-chloro-1-(4-methyl)phenylmethanes. Nucleophilic solvent intervention and extended YBnCl scale
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The solvolysis of 1-alkyl-1-chloro-1-(4-methyl)phenylmethanes (4a-d) in aqueous acetone, aqueous ethanol, aqueous methanol and ethanol-trifluoroethanol was studied. Grunwald-Winstein-type correlation analysis using the YBnCl scale suggests significant nucleophilic solvent intervention in the case of 1-chloro-1-(4-methyl)phenylethane (4a). Increasing bulkiness of the 1-alkyl substituent from methyl (4a) to ethyl (4b), to isopropyl (4c) and to tert-butyl (4d) resulted in a gradual change to limiting SN1 mechanisms. The observed excellent linear correlations with YBnCl and the good solubility in high-water-containing binary solvents made 4d a suitable reference standard for deriving more YBnCl values. A positive azide salt effect was realized in the solvolysis of 4a but not 4d. A small decrease in the β-deuterium kinetic isotope effect from 4a to 1-chloro-1-(4-methoxyphenyl)propane (5) suggested the presence of additional stabilization of the benzylic cationic transition state. However, no relationship between k(CH3)/k(CD3) and the solvent effect was found. The superiority of employing the YBnCl scale over the combination of YCl and I scales in the mehanistic study was observed.
- Liu, Kwang-Ting,Chang, Lih-Wie,Yu, Der-Gann,Chen, Pang-Shao,Fan, Ju-Ta
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p. 879 - 884
(2007/10/03)
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- Formate ester indane compounds
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The present invention relates to novel formate ester indane compounds having fragrant musk-like aroma.
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- 1,2-Secopyrethroids: Synthesis of (+/-) α-(RS)-cyano-3-phenoxybenzyl-4-methyl-3-phenyl/p-substituted-phenylpentanoates
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A simple, elegant synthesis of (+/-) α-(RS)-cyano-3-phenoxybenzyl-4-methyl-3-phenyl/p-substituted-phenylpentanoates (I,XIV,XXI) has been described.
- Kher, S. M.,Kulkarni, G. H.
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p. 675 - 676
(2007/10/02)
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- The Chemistry of N-Substituted Benzotriazoles. Part 6. A New Synthetic Route to Aromatic Ketones
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Lithiation of p-bis(benzotriazol-1-yl)methyltoluene (4) gives the carbanion (5) which affords substitution products with many electrophiles.Acidic hydrolysis of the lithiation products affords the corresponding aromatic ketones in good yield.The syntheses of simple ketones, of diketones, and of α-hydroxy ketones are described.
- Katritzky, Alan R.,Kuzmierkiewicz, Wojciech
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p. 819 - 824
(2007/10/02)
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- A VERSATILE ACCESS TO UNSYMMETRICAL AND SYMMETRICAL α-DIKETONES VIA ORGANOTIN REAGENTS
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Unsymmetrical α-diketones have been obtained via cross coupling of acyltins with acyl halides under PdCl2(PPh3)2 catalysis while symmetrical α-diketones have been readily obtained via "in situ" formation of acyltins using hexabutylditin and acyl chlorides under similar experimental conditions.
- Verlhac, Jean-Baptiste,Chanson, Evelyne,Jousseaume, Bernard,Quintard, Jean-Paul
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p. 6075 - 6078
(2007/10/02)
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- Novel acyl-polyalkylindan compounds and the use thereof as a base for perfume, as well as perfume compositions
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Novel acyl-polyalkyl indan compounds and the use thereof as a base for perfume, as well as perfume compositions, perfumed materials and perfumed articles.
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