- Iridium-catalyzed chemoselective transfer hydrogenation of α, β-unsaturated ketones to saturated ketones in water
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A chemoselective iridium-catalyzed transfer hydrogenation of α, β-unsaturated ketones was realized in water. The C[dbnd]C double bonds of 2-benzylidene indanones and analogues were hydrogenated exclusively catalyzed by an iridium complex (0.1 mol%) bearin
- Chen, Jinxun,Chen, Yongsheng,Cui, Xiaofeng,Jiang, Xiaolan,Liu, Qixing,Zhou, Haifeng
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- Intramolecular One-Carbon Homologation of Unstrained Ketones via C-C Activation-Enabled 1,1-Insertion of Alkenes
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Here, we describe the development of a Rh-catalyzed intramolecular one-carbon homologation of unstrained aryl ketones through a formal 1,1-insertion process of olefins, enabled by temporary directing group (TDG)-aided C-C activation. The reaction provides a distinct approach to access various substituted 1-indanones. Computational mechanistic studies reveal that the formal 1,1-insertion is realized by a selective C(sp2)-C(sp3) activation and turnover limiting 2,1-insertion into the alkene, followed by a facile β-H elimination and reinsertion process.
- Huang, Jiangkun,Zhang, Rui,Wu, Xiuli,Dong, Guangbin,Xia, Ying
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p. 2436 - 2440
(2022/04/07)
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- Boronic Acid-Mediated Photocatalysis Enables the Intramolecular Hydroacylation of Olefins Using Carboxylic Acids
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An intramolecular hydroacylation of olefins using carboxylic acids (CAs) has been developed. With the aid of a boronic acid, CAs can be used as acyl-radical precursors in catalytic photoredox reactions driven by visible light. The CAs are easily converted into their corresponding cyclic ketones without the need to use any stoichiometric activating reagents. Mechanistic studies implied that the formation of an “ate” complex from the CA and boronic acid is crucial for the generation of the acyl radical equivalent from the unreactive carboxy group.
- Nanjo, Takeshi,Takemoto, Yoshiji,Yumura, Taichi
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- Enantioselective Nickel-Catalyzed Reductive Aryl/Alkenyl-Cyano Cyclization Coupling to All-Carbon Quaternary Stereocenters
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An enantioselective nickel-catalyzed intramolecular reductive cross-coupling of C(sp2) electrophiles and cyano groups is reported. Enantioenriched CN-containing all-carbon quaternary stereocenters are assembled by desymmetrizing cyclization of aryl/alkeny
- Chen, Zi-Hao,Sun, Rui-Ze,Yao, Fei,Hu, Xu-Dong,Xiang, Long-Xue,Cong, Hengjiang,Liu, Wen-Bo
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supporting information
p. 4776 - 4782
(2022/03/27)
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- Concise syntheses of GB22, GB13, and himgaline by cross-coupling and complete reduction
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Neuroactive metabolites from the bark of Galbulimima belgraveana occur in variable distributions among trees and are not easily accessible through chemical synthesis because of elaborate bond networks and dense stereochemistry. Previous syntheses of compl
- Landwehr, Eleanor M.,Baker, Meghan A.,Oguma, Takuya,Burdge, Hannah E.,Kawajiri, Takahiro,Shenvi, Ryan A.
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p. 1270 - 1274
(2022/03/31)
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- Iron-catalyzed chemoselective hydride transfer reactions
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A Diaminocyclopentadienone iron tricarbonyl complex has been applied in chemoselective hydrogen transfer reductions. This bifunctional iron complex demonstrated a broad applicability in mild conditions in various reactions, such as reduction of aldehydes over ketones, reductive alkylation of various functionalized amines with functionalized aldehydes and reduction of α,β-unsaturated ketones into the corresponding saturated ketones. A broad range of functionalized substrates has been isolated in excellent yields with this practical procedure.
- Coufourier, Sébastien,Ndiaye, Daouda,Gaillard, Quentin Gaignard,Bettoni, Léo,Joly, Nicolas,Mbaye, Mbaye Diagne,Poater, Albert,Gaillard, Sylvain,Renaud, Jean-Luc
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- Tuning the Product Selectivity of the α-Alkylation of Ketones with Primary Alcohols using Oxidized Titanium Nitride Photocatalysts and Visible Light
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The direct α-alkylation of ketones with alcohol to synthesize important α-alkylated ketones and enones is an attractive procedure for C-C bond formation. High reaction temperatures are always needed for heterogeneous catalysis using non-noble metals, and switching product selectivity in one catalysis system remains a great challenge. In the present study, a visible-light-driven procedure for this reaction is proposed, using oxidized TiN photocatalysts under mild conditions, whereby the product selectivity can be well-tuned. Oxidized TiN photocatalysts with tunable surface N/O ratios were successfully synthesized through the facile and flexible thermal oxidation treatment of low-cost TiN nanopowder. The α-alkylation of acetophenone with benzyl alcohol to form the two important compounds chalcone and dihydrochalcone occurred even at room temperature and almost complete conversion was achieved at 100 °C under visible light. The proportion of the two products can be well-tuned by switching the surface N/O ratio of the synthesized photocatalysts. Visible light is demonstrated to affect the surface N/O ratio of the photocatalysts and contribute to tuning the product selectivity. Light intensity and action spectrum study proves that the generation of energetic charge carriers results in the observed activities under visible light, based on interband transitions of TiN or the ligand-to-metal charge transfer (LMCT) effect of the surface complex formed on TiO2. Thermal energy can be coupled with light energy within this photocatalytic system, which will facilitate the full use of solar energy. Different sequential reaction mechanisms on TiN and TiO2 are proposed to be responsible for the tunable product selectivity. The wide reaction scope, the fine conversion at a low light intensity, and the favorable reusability of photocatalysts prove the great application potential of this visible-light-driven procedure for the α-alkylation of ketones with primary alcohols.
- Li, Peifeng,Su, Haijia,Xiao, Gang,Zhao, Yilin
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p. 3640 - 3649
(2020/04/09)
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- Method for synthesizing alpha-alkylated ketone in water
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The invention discloses a method for synthesizing alpha-alkylated ketone in water. The method comprises the following steps: adding ketone, compound alcohol, a transition metal iridium catalyst, an alkali and a solvent, namely water into a reaction container, carrying out a reflux reaction on a reaction mixture in the air for several hours, carrying out cooling to room temperature, carrying out rotary evaporation to remove the solvent, and carrying out column separation (ethyl acetate/petroleum ether) to obtain a target compound, namely alpha-alkylated ketone. A reaction equivalent substrate is used in the reaction process, so raw material waste is avoided; equivalent alkali is used, so better environmental protection performance is obtained; water reflux reaction conditions are milder; and non-toxic and harmless pure water is used as the solvent in the reaction, only water is generated as a by-product, so atom reaction economy is high, and the requirements of green chemistry are met.
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Paragraph 0137-0141
(2020/08/22)
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- Bidentate NHC-Cobalt Catalysts for the Hydrogenation of Hindered Alkenes
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Herein, we report a series of easily accessible bidentate N-heterocyclic carbene (NHC) cobalt catalysts, which enable the hydrogenation of hindered alkenes under mild conditions. The four-coordinated bidentate NHC-Co(II) complexes were characterized by X-ray diffraction, elemental analysis, ESI-HRMS, and magnetic moment measurements, revealing a distorted-tetrahedral geometry and a high-spin configuration of the metal center. The activity of the in situ formed catalytic system, which was obtained from easily available NHC precursors, CoCl2, and NaHBEt3, was identical with those of well-defined NHC-cobalt catalysts. This highlights the potential utility of this reaction system.
- Wei, Zeyuan,Wang, Yujie,Li, Yibiao,Ferraccioli, Raffaella,Liu, Qiang
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p. 3082 - 3087
(2020/10/02)
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- Nickel-catalyzed: Exo -selective hydroacylation/Suzuki cross-coupling reaction
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The first nickel-catalyzed intramolecular hydroacylation/Suzuki cross coupling cascade of o-allylbenzaldehydes with a broad range of phenylboronic acid neopentyl glycol esters has been developed. This strategy shows high regioselectivity and step economy in the construction of two C-C bonds via aldehyde C-H bond activation, affording valuable indanones with high efficiency.
- Lee, Shao-Chi,Guo, Lin,Rueping, Magnus
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supporting information
p. 14984 - 14987
(2019/12/24)
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- B(C6F5)3-Catalyzed Highly Stereoselective Hydrogenation of Unfunctionalized Tetrasubstituted Olefins
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A metal-free hydrogenation of unfunctionalized tetrasubstituted olefins were successfully realized using a combination of B(C6F5)3 and Ph2NMe catalyst. The corresponding products were afforded in 58-98% yields with up to >99:1 cis/trans selectivity.
- Dai, Yun,Feng, Xiangqing,Du, Haifeng
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supporting information
p. 6884 - 6887
(2019/10/02)
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- Synthesis and Structures of Arene Ruthenium (II)–NHC Complexes: Efficient Catalytic α-alkylation of ketones via Hydrogen Auto Transfer Reaction
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A panel of six new arene Ru (II)-NHC complexes 2a-f, (NHC?=?1,3-diethyl-(5,6-dimethyl)benzimidazolin-2-ylidene 1a, 1,3-dicyclohexylmethyl-(5,6-dimethyl)benzimidazolin-2-ylidene 1b and 1,3-dibenzyl-(5,6-dimethyl)benzimidazolin-2-ylidene 1c) were synthesized from the transmetallation reaction of Ag-NHC with [(η6-arene)RuCl2]2 and characterized. The ruthenium (II)-NHC complexes 2a-f were developed as effective catalysts for α-alkylation of ketones and synthesis of bioactive quinoline using primary/amino alcohols as coupling partners respectively. The reactions were performed with 0.5?mol% catalyst load in 8?h under aerobic condition and the maximum yield was up to 96%. Besides, the different alkyl wingtips on NHC and arene moieties were studied to differentiate the catalytic robustness of the complexes in the transformations.
- Balamurugan, Gunasekaran,Balaji, Sundarraman,Ramesh, Rengan,Bhuvanesh, Nattamai S.P.
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- The α-alkylation of ketones with alcohols in pure water catalyzed by a water-soluble Cp?Ir complex bearing a functional ligand
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A water-soluble dinuclear Cp?Ir complex bearing 4,4′,6,6′-tetrahydroxy-2,2′-bipyrimidine as a bridging ligand was found to be a highly effective catalyst for the α-alkylation of ketones with alcohols in pure water. In the presence of catalyst (0.5 mol%), a series of desirable products were obtained with high reaction economy under environmentally benign conditions. The importance of the hydroxy group in the ligand for catalytic hydrogen transfer was confirmed by mechanism experiments. Furthermore, the application of this catalytic system for the synthesis of a biologically active molecule donepezil in pure water has been accomplished. Notably, this research would facilitate the progress of C-C bond-forming reactions in water catalyzed by water-soluble metal-ligand bifunctional catalysts.
- Meng, Chong,Xu, Jing,Tang, Yawen,Ai, Yao,Li, Feng
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p. 14057 - 14065
(2019/09/18)
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- β-Amino Phosphine Mn Catalysts for 1,4-Transfer Hydrogenation of Chalcones and Allylic Alcohol Isomerization
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Mn complexes with amino acid derived PN ligands were used in the catalytic transfer hydrogenation (TH) of ketone and chalcone substrates in 2-propanol with mild heating. Moreover, chalcones are reduced selectively to the saturated ketone at short times and can be fully converted to the alcohol when reactions are prolonged. The mechanism of chalcone reduction was briefly considered. Allylic alcohols are not reactive in 2-propanol, but quantitative isomerization occurs in toluene. Thus, we suspect that the allylic alcohols are dehydrogenated and the resulting ketone is formed through a direct 1,4-hydrogenation of the chalcone. Finally, several other related ligands that have been used in Mn-based TH reactions were explored to test the viability of ligand design in favoring chemoselectivity. The β-amino phosphine ligands proved most effective in this regard.
- Vigneswaran, Vipulan,MacMillan, Samantha N.,Lacy, David C.
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supporting information
p. 4387 - 4391
(2019/11/14)
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- Photocatalytic acylarylation of unactivated alkenes with diaryliodonium salts toward indanones and related compounds
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A novel photocatalytic acylarylation of unactivated alkenes using diaryliodonium salts as the arylation reagent is described. The reaction produces a variety of 2-benzyl indanones, 3,4-dihydronaphthalen-1(2H)-ones, and 2,3-dihydroquinolin-4(1H)-ones in pr
- Chen, Yongtao,Shu, Chenyun,Luo, Fang,Xiao, Xiaohui,Zhu, Gangguo
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p. 5373 - 5376
(2018/06/01)
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- NNN pincer Ru(II)-complex-catalyzed α-alkylation of ketones with alcohols
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A series of novel ruthenium(II) complexes supported by a symmetrical NNN ligand were prepared and fully characterized. These complexes exhibited good performance in transfer hydrogenation to form new C-C bonds using alcohols as the alkylating agents, generating water as the only byproduct. A broad range of substrates, including (hetero)aryl- or alkyl-ketones and alcohols, were well tolerated under the optimized conditions. Notably, α-substituted methylene ketones were also investigated, which afforded α-branched steric hindrance products. A potential application of α-alkylation of methylene acetone to synthesize donepezil was demonstrated, which provided the desired product in 83% yield. Finally, this catalytic system could be applied to a one-pot double alkylation procedure with sequential addition of two different alcohols. The current protocol is featured with several characteristics, including a broad substrate scope, low catalyst (0.50 mol %) loadings, and environmental benignity.
- Cao, Xiao-Niu,Wan, Xiao-Min,Yang, Fa-Liu,Li, Ke,Hao, Xin-Qi,Shao, Tian,Zhu, Xinju,Song, Mao-Ping
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p. 3657 - 3668
(2018/04/14)
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- Ni-Catalyzed Alkene Carboacylation via Amide C-N Bond Activation
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We report Ni-catalyzed formal carboacylation of o-allylbenzamides with arylboronic acid pinacol esters. The reaction is triggered by oxidative addition of an activated amide C-N bond to a Ni(0) catalyst and proceeds via alkene insertion into a Ni(II)-acyl bond. The exo-selective carboacylation reaction generates 2-benzyl-2,3-dihydro-1H-inden-1-ones in moderate to high yields (46-99%) from a variety of arylboronic acid pinacol esters and substituted o-allylbenzamides. These results show that amides are practical substrates for alkene carboacylation via amide C-N bond activation, and this approach bypasses challenges associated with alkene carboacylation triggered by C-C bond activation.
- Walker, James A.,Vickerman, Kevin L.,Humke, Jenna N.,Stanley, Levi M.
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p. 10228 - 10231
(2017/08/10)
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- Enantiodivergent Synthesis of Tertiary α-Aryl 1-Indanones: Evidence Toward Disparate Mechanisms in the Palladium-Catalyzed Decarboxylative Asymmetric Protonation
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Herein, we describe a study into the scope and origin of an enantiodivergent effect in the palladium-catalyzed decarboxylative asymmetric protonation. By switching the achiral proton source, both enantiomers of a series of tertiary α-aryl-1-indanones are readily accessed from the corresponding α-aryl-β-keto allyl esters. In this example of dual stereocontrol, enantioselectivities up to 94% (S) and 92% (R) were achieved using Meldrum's acid and formic acid, respectively. In an attempt to rationalize this switch in absolute configuration an investigation of the ambiguous mechanism of the decarboxylative asymmetric protonation was conducted. A novel catalytic cycle for the reaction with formic acid is proposed and subjected to a variety of experimental studies.
- Kingston, Cian,Guiry, Patrick J.
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p. 3806 - 3819
(2017/04/13)
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- Method for synthesizing alpha-alkyl ketone
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The invention discloses a method for synthesizing alpha-alkyl ketone, and especially includes the following steps of: in a reaction vessel, adding secondary alcohol, a transition metal catalyst, and a solvent tertiary amyl alcohol; and heating and refluxing a reaction mixture in an oil bath for several hours, cooling the mixture to a room temperature; then adding primary alcohol and alkali, heating and refluxing the reaction mixture for several hours, and then obtaining a target compound through column separation. The method for synthesizing the alpha-alkyl ketone starts from the primary alcohol and the secondary alcohol. With the participation of the transition metal catalyst, the alpha-alkyl ketone is generated through a serial secondary alcohol non-acceptor dehydrogenation oxidation reaction/alpha-alkylation reaction of ketone. The reaction shows three obvious advantages that 1) non-toxic alcohols are used as the starting materials; 2) only hydrogen and water are generated in the reaction without environmental hazards; 3) atomic economy is high in the reaction; and 4) only 0.1 equivalents of carbonate is needed for the reaction, and the reaction only takes 3-6 hours. Therefore, the reaction meets the requirements of green chemistry and has broad development prospects.
- -
-
Paragraph 0158; 0159; 0160; 0161; 0162
(2017/04/12)
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- Use of a Cyclometalated Iridium(III) Complex Containing a N∧C∧N-Coordinating Terdentate Ligand as a Catalyst for the α-Alkylation of Ketones and N-Alkylation of Amines with Alcohols
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A cyclometalated iridium(III) complex containing a N∧C∧N-coordinating terdentate ligand [Ir(dpyx-N,C,N)Cl(μ-Cl)]2 was found to be a general and highly effective catalyst for the α-alkylation of ketones and N-alkylation of amines with alcohols. In the presence of catalyst (1 mol % Ir) and base (0.2-0.5 equiv), a variety of desirable products were obtained in good yields under an air atmosphere. Notably, this research exhibited the new potential of Ir(III) complexes bearing non-Cp? ligand and will facilitate the progress of the hydrogen autotransfer process.
- Liu, Pengcheng,Liang, Ran,Lu, Lei,Yu, Zhentao,Li, Feng
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p. 1943 - 1950
(2017/02/26)
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- Efficient alkylation of ketones with primary alcohols catalyzed by ruthenium(II)/P,N ligand complexes
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An efficient catalytic system containing [RuCl2(η6-p-cymene)]2 and one P,N ligand, N-diphenylphosphino-2-aminopyridine (L1) was loaded in catalyzing the alkylation of ketones with primary alcohols for a diverse array of substrates. Other five P,N ligands based on pyridin-2-amine and pyrimidin-2-amine were also examined in this reaction to explore the influence of steric hindrance and electronic effects. Monitoring by 1H NMR and ESI-MS reveals a stable cationic L1-coordinated ruthenium hydride intermediate, identified as [Ru(η6-p-cymene)(κ2-L1)H]+. Organic intermediates consistent with a three-step dehydrogenation, alkylation and hydrogenation pathway were also observed. The final step in this reaction, the ruthenium-catalysed transfer hydrogenation reduction of α,β-unsaturated ketone with benzyl alcohol was performed separately.
- Liu, Shi-Yuan,Xu, Lin-Yan,Liu, Chun-Yu,Ren, Zhi-Gang,Young, David James,Lang, Jian-Ping
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p. 2374 - 2381
(2017/04/03)
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- Method for synthesizing alpha-alkyl ketone
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The invention discloses a method for synthesizing alpha-alkyl ketone. The method comprises the following steps: adding ketone, a compound alcohol, an iridium complex catalyst, an alkali and a solvent tert-amyl alcohol in a reaction container, carrying out a refluxing reaction on the above obtained reaction mixture in air for several hours, cooling the obtained reaction product to room temperature, carrying out rotary evaporation to remove the solvent, and carrying out column separation to obtain the target compound. The meta-organic bifunctional iridium complex is used, only 0.1 equivalent carbonate is added in the reaction process, and the reaction is carried in air for 6h, so obvious advantages are displayed; and the reaction accords with green chemistry requirements, and has wide development prospect.
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-
Paragraph 0165; 0166; 0167; 0168; 0169
(2016/10/07)
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- Synthesis of a-Alkylated Ketones via Tandem Acceptorless Dehydrogenation/a-Alkylation from Secondary and Primary Alcohols Catalyzed by Metal-Ligand Bifunctional Iridium Complex [CpIr(2,2′-bpyO)(H2O)]
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A new strategy for the synthesis of α-alkylated ketones via tandem acceptorless dehydrogenation/α-alkylation from secondary and primary alcohols was proposed and accomplished. In the presence of metal-ligand bifunctional iridium complex [CpIr(2,2′-bpyO)(H2O)], various desirable products were obtained in high yields. Compared with previous methods for the direct dehydrogenative coupling of secondary alcohols with primary alcohols to α-alkylated ketones, this protocol has obvious advantages including complete selectivity for α-alkylated ketones and more environmentally benign conditions. Notably, the study also exhibited the potential to develop tandem reactions catalyzed using a metal-ligand bifunctional iridium complex.
- Wang, Rongzhou,Ma, Juan,Li, Feng
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p. 10769 - 10776
(2015/11/18)
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- Enantioselective Intramolecular Hydroacylation of Unactivated Alkenes: An NHC-Catalyzed Robust and Versatile Formation of Cyclic Chiral Ketones
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A highly enantioselective intramolecular N-heterocyclic carbene (NHC)-catalyzed hydroacylation reaction gives access to a range of cyclic ketones from unactivated olefin-substituted aldehydes (up to 99% ee). Remarkably, aliphatic aldehydes were also transformed efficiently in an NHC-catalyzed hydroacylation reaction for the first time. 100% Organic: A highly enantioselective N-heterocyclic carbene (NHC)-catalyzed intramolecular hydroacylation of aromatic and, more interestingly, aliphatic aldehydes with unactivated olefins offers access to a range of cyclic α-chiral ketones bearing quaternary centers. The reaction was found to be highly robust and proceeds with excellent yield in the presence of a diverse range of functional groups.
- Janssen-Müller, Daniel,Schedler, Michael,Fleige, Mirco,Daniliuc, Constantin G.,Glorius, Frank
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p. 12492 - 12496
(2015/10/12)
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- Free radical-mediated chemoselective reduction of enones
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A novel methodology has been devised for the chemoselective reduction of enones involving the use of nBu3SnH and azobisisobutyronitrile. The 1,4-reduction of variously substituted ,β-unsaturated cyclic and acyclic enones has been successfully c
- Sultan, Aeysha,Raza, Abdul Rauf,Tahir, Muhammad Nawaz
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p. 267 - 274
(2013/12/04)
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- Dehydrogenation and oxidative coupling of alcohol and amines catalyzed by organosilicon-supported TiO2@PMHSIPN
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The catalytic dehydrogenation and tandem transformation of aromatic alcohols, including oxidative coupling of alcohols and amines, were achieved successfully using a catalytic amount of organosilicon-supported titania (TiO2@PMHSIPN), which enables the efficient synthesis of aromatic aldehydes, imines, and benzimidazoles in good to excellent yields. This journal is the Partner Organisations 2014.
- Wang, Hu,Zhang, Jin,Cui, Yu-Ming,Yang, Ke-Fang,Zheng, Zhan-Jiang,Xu, Li-Wen
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p. 34681 - 34686
(2014/11/08)
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- α-alkylation of ketones by trialkylamines under heterogeneous Pd/C catalysis
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Ketones are regioselectively α-alkylated with trialkylamines in toluene at 120 °C in the presence of Pd/C.
- Yoon, Il Chul,Kim, Tae Gyun,Cho, Chan Sik
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p. 1890 - 1892
(2014/05/06)
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- Lithium tert-butoxide mediated α-alkylation of ketones with primary alcohols under transition-metal-free conditions
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LiOtBu was found to efficiently promote the α-alkylation reaction of ketones with primary alcohols, without the addition of any transition metal catalyst.
- Liang, Yu-Feng,Zhou, Xin-Feng,Tang, Shi-Ya,Huang, Yao-Bing,Feng, Yi-Si,Xu, Hua-Jian
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p. 7739 - 7742
(2013/06/27)
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- Deaminative and decarboxylative catalytic alkylation of amino acids with ketones
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It cuts two ways: The cationic [Ru-H] complex catalyzes selective coupling of α- and β-amino acids with ketones to form α-alkylated ketone products. The reaction involves C-C and C-N bond cleavage which result in regio- and stereoselective alkylation using amino acids. A broad substrate scope and high functional-group tolerance is demonstrated. Copyright
- Kalutharage, Nishantha,Yi, Chae S.
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supporting information
p. 13651 - 13655
(2014/01/06)
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- Synthesis of five- and six-membered benzocyclic ketones through intramolecular alkene hydroacylation catalyzed by Nickel(0)/N-Heterocyclic Carbenes
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Getting some closure: Mechanistic studies supported the participation of an oxanickelacycle complex in the hydroacylation step of the title reaction, which proceeds without decarbonylation even in the absence of well-known chelation assistance by heteroatoms. Copyright
- Hoshimoto, Yoichi,Hayashi, Yukari,Suzuki, Haruka,Ohashi, Masato,Ogoshi, Sensuke
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supporting information
p. 10812 - 10815
(2013/01/15)
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- Asymmetric microbial conversion of (E)-2-benzylideneindan-1-one by the filamentous fungi Botrytis cinerea, Trichoderma viride, and Eutypa lata
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The transformation of (E)-2-benzylideneindan-1-one 1 by the filamentous fungi Botrytis cinerea, Trichoderma viride, and Eutypa lata as biocatalysts was studied. The results showed the catalytic potential of these fungi in affording several hydroxylation a
- Pinedo-Rivilla, Cristina,Aleu, Josefina,Collado, Isidro G.
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experimental part
p. 1653 - 1657
(2012/01/30)
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- Domino Friedel-crafts-type cyclizations of difluoroalkenes promoted by the α-cation-stabilizing effect of fluorine: An efficient method for synthesizing angular PAHs
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In order to synthesize polycyclic aromatic hydrocarbons with nonlinear arrangements (angular PAHs), acid-promoted domino cyclizations of 1,1-difluoroalk-1-enes and 1,1-difluoroalka-1,3-dienes were studied. 1,1-Difluoroalkenes, each bearing two aryl substituents, were regioselectively protonated with FSO3H·SbF5 to generate fluorine-stabilized carbocations, which readily underwent domino Friedel-Crafts-type cyclizations to give carbocycles based on 6/n/m/6 ring systems (n,m=5-7) in good to high yields. Protonation of 1,1-difluoroalka-1,3- dienes took place at their electron-rich methylene (CH2) carbon atoms in the presence of milder acids such as camphorsulfonic acid and trifluoromethanesulfonic acid. Domino cyclizations of the resulting fluorine-stabilized allylic carbocations afford carbocycles based on 6/6/6/6 or 6/6/5/6 ring systems in high yields.
- Fuchibe, Kohei,Jyono, Hideharu,Fujiwara, Masaki,Kudo, Takao,Yokota, Misaki,Ichikawa, Junji
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p. 12175 - 12185
(2011/12/01)
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- Organocatalyzed enantioselective protonation of silyl enol ethers: Scope, limitations, and application to the preparation of enantioenriched homoisoflavones
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In the present work, enantioselective protonation of silyl enol ethers is reported by means of a variety of chiral nitrogen bases as catalysts, mainly derived from cinchona alkaloids, in the presence of various protic nucleophiles as proton source. A detailed study of the most relevant reaction parameters is disclosed allowing high enantioselectivities of up to 92% ee with excellent yields to be achieved under mild and eco-friendly conditions. The synthetic utility of this organocatalytic protonation was demonstrated during the preparation of two homoisoflavones 4a and 4b, isolated from Chlorophytum Inornatum and Scilla Nervosa, which were obtained with 81% and 78% ee, respectively.
- Poisson, Thomas,Gembus, Vincent,Dalla, Vincent,Oudeyer, Sylvain,Levacher, Vincent
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experimental part
p. 7704 - 7716
(2010/12/29)
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- Rapid and regioselective hydrogenation of α,β-unsaturated ketones and alkylidene malonic diesters using Hantzsch ester catalyzed by titanium tetrachloride
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A regioselective hydrogenation of α,β-unsaturated ketones and alkylidene malonic diesters using Hantzsch ester as the reducing agent and titanium tetrachloride as a catalyst is described. The short reaction times and mild reaction conditions are the advantages of this method. Georg Thieme Verlag Stuttgart New York.
- Che, Jun,Lam, Yulin
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experimental part
p. 2415 - 2420
(2010/11/19)
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- Biocatalytic preparation and absolute configuration of enantiomerically pure fungistatic anti-2-benzylindane derivatives. Study of the detoxification mechanism by Botrytis cinerea
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Enantiomerically pure 2-benzylindane derivatives were prepared using biocatalytic methods and their absolute configuration determined. (1R,2S)-2-Benzylindan-1-ol ((1R,2S)-2) and (S)-2-benzylindan-1-one ((S)-3) were produced by fermenting baker's yeast. Li
- Pinedo-Rivilla, Cristina,Aleu, Josefina,Grande Benito, Manuel,Collado, Isidro G.
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experimental part
p. 3784 - 3789
(2010/09/06)
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- Scandium triflate-catalyzed intramolecular Friedel-Crafts acylation with Meldrum's acids: insight into the mechanism
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The intramolecular Friedel-Crafts acylation of arenes with Meldrum's acid derivatives catalyzed by Sc(OTf)3 was reported as a mild and general entry into functionalized 1-indanones. Mechanistic investigations were undertaken to determine the rate-determining step in the acylation sequence using Meldrum's acid, as well as to examine the role of the Lewis acid catalyst. Enolizable Meldrum's acid derivatives react via an acyl ketene intermediate under thermal conditions, while quaternized Meldrum's acid derivatives are thermally stable and only act as effective Friedel-Crafts acylating agents in the presence of a Lewis acid catalyst. The acylation was postulated to proceed through direct acylation of a Lewis acid-activated carbonyl. In the catalytic Friedel-Crafts acylation of Meldrum's acids, triflic acid appeared to be the active catalytic species, with Sc(OTf)3 serving as a very mild and convenient reagent for its delivery.
- Fillion, Eric,Fishlock, Dan
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scheme or table
p. 6682 - 6695
(2011/02/26)
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- Cinchona alkaloid catalyzed enantioselective fluorination of allyl silanes, silyl enol ethers, and oxindoles
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(Chemical Equation Presented) Catalytic variant: Allyl silanes and silyl enol ethers 1 are good substrates for the catalytic highly enantioselective fluorodesilylation using a combination of a biscinchona alkaloid, N-fluorobenzenesulfonimide (NFSI), and base (see scheme). Pharmaceutically attractive 3-aryl-3-fluorooxindoles such as 3 can also be synthesized with high enantioselectivity.
- Ishimaru, Takehisa,Shibata, Norio,Horikawa, Takao,Yasuda, Naomi,Nakamura, Shuichi,Toru, Takeshi,Shiro, Motoo
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supporting information; experimental part
p. 4157 - 4161
(2009/03/11)
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- Straightforward organocatalytic enantioselective protonation of silyl enolates by means of cinchona alkaloids and carboxylic acids
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The combination of cinchona alkaloids and carboxylic acids provides a very simple chiral proton source. By using this system, enantioselective protonation of silyl enolates was achieved affording the corresponding ketones in high yields and in up to 75% e
- Poisson, Thomas,Oudeyer, Sylvain,Dalla, Vincent,Marsais, Francis,Levacher, Vincent
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experimental part
p. 2447 - 2450
(2009/04/10)
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- Organocatalytic enantioselective protonation of silyl enolates mediated by cinchona alkaloids and a latent source of HF
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Hidden benefits: The enantioselective organocatalytic protonation of silyl enolates has been achieved by using readily available cinchona alkaloid catalysts (1) and a latent source of HF that delivers "at will" the active catalytic hydrogen fluoride salt
- Poisson, Thomas,Dalla, Vincent,Marsais, Francis,Dupas, Georges,Oudeyer, Sylvain,Levacher, Vincent
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p. 7090 - 7093
(2008/09/17)
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- A ruthenium-catalyzed one-pot method for α-alkylation of ketones with aldehydes
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Ketones react with an array of aldehydes in dioxane at 80 °C in the presence of a catalytic amount of RuCl2(PPh3)3 along with KOH to give the corresponding α-alkylated ketones in moderate to good yields. A reaction pathway involving base-catalyzed cross-aldol reaction between ketones and aldehydes to form α,β-unsaturated ketones and regioselective reduction of carbon-carbon double bond of α,β-unsaturated ketones is proposed for this catalytic process.
- Cho, Chan Sik,Shim, Sang Chul
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p. 4329 - 4332
(2007/10/03)
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- Some unusual reactions of Meldrum's acid. Synthesis of cinnamic acids, coumarins and 2-benzyl-1-indanone
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The use of Meldrum's acid (1) in the synthesis of the substituted cinnamic acid 3 and malonic acid 4, the coumarins 8 and 9, and of 2-benzyl-1-indanone (13), is reported. The structure of benzylidene benzalmalonate is corrected to 14.
- Mahulikar,Mane
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- Studies on the chemistry of 2-(2-oxo-3-phenylpropyl)-benzaldehydes: Novel total synthesis of 3-phenylnaphthalen-2-ols and 2-hydroxy-3-phenyl-1,4- naphthoquinones
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We describe the first studies on the chemistry of 2-(2-oxo-3-phenylpropyl) benzaldehydes, which were converted into 3-benzylisochromen-1-ones via the corresponding 2-(2-oxo-3-phenylpropyl)benzoic acid. The 2-(2-oxo-3-phenylpropyl) benzaldehydes proved to be convenient starting materials for the synthesis of 3-phenyl-2-naphthols. Oxidation of the latter compounds resulted in a novel, efficient synthesis of 3-phenyl-1,2-naphthoquinones, which were efficiently transformed into 2-hydroxy-3-phenyl-1,4-naphthoquinones.
- Martínez, Ana,Fernández, Marcos,Estévez, Juan C.,Estévez, Ramón J.,Castedo, Luis
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p. 485 - 492
(2007/10/03)
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- Meldrum's acids as acylating agents in the catalytic intramolecular Friedel-Crafts reaction
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(Chemical Equation Presented) The intramolecular Friedel-Crafts acylation of aromatics with Meldrum's acid derivatives catalyzed by metal trifluoromethanesulfonates is reported. Meldrum's acids are easily prepared, functionalized, handled, and purified. The synthesis of polysubstituted 1-indanones from benzyl Meldrum's acids was investigated thoroughly, and it was shown that a variety of catalysts were effective, while accommodating a diversity of functional groups under mild conditions. The scope, limitations, and functional group tolerance (terminal alkene and alkyne, ketal, dialkyl ether, dialkyl thioether, aryl methyl ether, aryl TIPS and TBDPS ethers, nitrile- and nitro-substituted aryls, alkyl and aryl halides) for a variety of 5-benzyl (enolizable Meldrum's acids) and 5-benzyl-5-substituted Meldrum's acids (quaternized Meldrum's acids), forming 1-indanones and 2-substituted-1- indanones, respectively, are delineated. This method was further applied to the synthesis of 1-tetralones, 1-benzosuberones, and the potent acetylcholinesterase inhibitor donepezil. Rate of cyclization as a function of ring size was established for various benzocyclic ketones via competition experiments: 1-tetralones form faster than both 1-indanones and 1-benzosuberones, and 1-benzosuberones cyclize faster than 1-indanones.
- Fillion, Eric,Fishlock, Dan,Wilsily, Ashraf,Goll, Julie M.
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p. 1316 - 1327
(2007/10/03)
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- Recyclable palladium catalyst for highly selective α alkylation of ketones with alcohols
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(Chemical Equation Presented) An air-stable, heterogeneous, and recyclable catalyst composed of palladium nanoparticles entrapped in aluminum hydroxide was applied to a highly selective α alkylation. A wide range of aliphatic and aromatic ketones and primary alcohols were coupled to prepare enones in an O2 atmosphere and ketones in an argon atmosphere (see scheme).
- Kwon, Min Serk,Kim, Namdu,Seo, Seong Hyeok,Park, In Soo,Cheedrala, Ravi Kumar,Park, Jaiwook
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p. 6913 - 6915
(2007/10/03)
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- IMIDAZOLE COMPOUNDS AS Alpha2-ADRENOCEPTORS ANTAGONISTS
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An imidazole derivative of formula (I) or a pharmaceutically acceptable salt or derivative thereof. The compounds of formula (I) exhibit affinity for alpha2 adrenoceptors.
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- Ruthenium-catalyzed regioselective α-alkylation of ketones with primary alcohols
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Ketones are regioselectively alkylated with an array of primary alcohols in dioxane at 80°C in the presence of a catalytic amount of a ruthenium catalyst together with KOH and a hydrogen acceptor.
- Cho, Chan Sik,Kim, Bok Tae,Kim, Tae-Jeong,Chul Shim, Sang
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p. 7987 - 7989
(2007/10/03)
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- Imidazole derivatives
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An imidazole derivative of formula (I) or a pharmaceutically acceptable salt or derivative thereof. The compounds of formula I exhibit affinity for alpha2 adrenoceptors.
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- One-pot inter- and intramolecular Friedel-Crafts reactions in Baylis-Hillman chemistry: A novel facile synthesis of (E)-2-arylideneindan-1-ones
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A simple one-pot stereoselective transformation of tert-butyl 3-aryl-3-hydroxy-2-methylenepropanoates, the Baylis-Hillman adducts obtained from t-butyl acrylate, into (E)-2-arylideneindan-1-ones involving one inter- and one intramolecular Friedel-Crafts r
- Basavaiah, Deevi,Reddy, Ravi Mallikarjuna
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p. 3025 - 3027
(2007/10/03)
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- Regioselective reduction of the homoisoflavone system with dialkylboranes in the presence of palladium catalysts
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(E)-3-Benzylidene-4-chromanones were regioselectively reduced to 3- benzyl-4-chromanones through the 1,4-addition of dialkylboranes, especially 9-borabicyclo[3.3.1]nonane, in excellent yields. The reaction was efficiently promoted by some palladium cataly
- Hoshino, Yukio,Tanaka, Hiroto,Takeno, Noboru
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p. 2923 - 2928
(2007/10/03)
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- On the baker's yeast mediated transformation of α-bromoenones. Synthesis of (1S,2R)-2-bromoindan-1-ol and (2s,3s)-3-bromo-4-phenylbutan-2- ol
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Fermenting baker's yeast converts α-bromo substituted enones 7 and 10 into enantiomerically pure (1S,2R)2-bromoindan-1-ol 3 and (2S,3S)-3-bromo-4- phenylbutan-2-ol 11, respectively, through the intermediacy of the corresponding saturated ketones. Structurally related 16 provides the (2R)- allylic alcohol 17 prevalently.
- Aleu, Josephina,Fronza, Giovanni,Fuganti, Claudio,Perozzo, Valentina,Serra, Stefano
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p. 1589 - 1596
(2007/10/03)
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