- Synthesis of an ionic paramagnetic ruthenium(III) complex and its application as an efficient and recyclable catalyst for the transfer hydrogenation of ketones
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A novel ionic complex, bis[1-butyl-2-(diphenylphosphanyl)-3- methylimidazolium]tetrachloridoruthenium(III) hexafluorophosphate (2), has been synthesized and fully characterized. The single-crystal X-ray diffraction analysis showed that 2 is composed of an Ru complex cation and PF 6- anion. The cation has a highly symmetrical Ru-centered octahedron geometry with four Cl atoms in the equatorial plane and two imidazolium-substituted phosphane ligands in the axial positions. It exhibits paramagnetism due to the presence of one unpaired electron in the phosphane-ligated low-spin RuIII complex. Complex 2 exhibited good catalytic performance in the transfer hydrogenation of a wide range of ketones by using alcohols as hydrogen donors. Owing to its high polarity, good thermal stability, and insensitivity to moisture and oxygen, complex 2 could be used in six catalytic cycles in the transfer hydrogenation of acetophenone without any obvious loss of activity. A novel ionic complex 2 containing an RuIII cation and PF6- anion has been synthesized. The Ru III cation possesses ideal octahedral geometry and exhibits paramagnetism due to the presence of one unpaired electron in the phosphane-ligated low-spin RuIII complex. Complex 2 proves to be an efficient and recyclable catalyst for the transfer hydrogenation of ketones with alcohols as hydrogen donors. Copyright
- Zhou, Chengliang,Zhang, Jing,Dakovic, Marijana,Popovic, Zora,Zhao, Xiaoli,Liu, Ye
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- Dienediolates of unsaturated carboxylic acids in synthesis. Tandem Michael-Dieckmann synthesis of substituted 2-cyclohexenones
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3,5-Disubstituted 2-Cyclohexenones are prepared by tandem Michael-Diekcmann addition of lithium dienediolates of dimethylacrylic and β-methylcinnamic acids to lithium carboxylates of unsaturated carboxylic acids.
- Aurell,Gavina,Gil,Parra,Tortajada,Mestres
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- Metal-Free I2-Catalyzed Highly Selective Dehydrogenative Coupling of Alcohols and Cyclohexenones
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The I2 catalyzed highly selective oxidative condensation of cyclohexenones and alcohols for the synthesis of aryl alkyl ethers has been described. DMSO is employed as the mild terminal oxidant. This novel methodology offers a metal-free reaction condition, operational simplicity and broad substrate scope to afford valuable products from inexpensive reagents. Various meta-substituted aromatic ethers which are hardly synthesized from the reported methods requiring meta-substituted phenols, are efficiently prepared by the present protocol.
- Liang, Yu-Feng,Yuan, Yizhi,Shen, Tao,Song, Song,Jiao, Ning
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supporting information
p. 233 - 240
(2018/02/19)
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- Conversion of Simple Cyclohexanones into Catechols
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A novel I2-catalyzed direct conversion of cyclohexanones to substituted catechols under mild and simple conditions has been described. This novel transformation is remarkable with the multiple oxygenation and dehydrogenative aromatization processes enabled just by using DMSO as the solvent, oxidant, and oxygen source. This metal-free and simple system demonstrates a versatile protocol for the synthesis of highly valuable substituted catechols and therefore streamlines the synthesis and modification of biologically important molecules for drug discovery.
- Liang, Yu-Feng,Li, Xinyao,Wang, Xiaoyang,Zou, Miancheng,Tang, Conghui,Liang, Yujie,Song, Song,Jiao, Ning
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supporting information
p. 12271 - 12277
(2016/09/28)
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- A highly efficient metal-free approach to: Meta - And multiple-substituted phenols via a simple oxidation of cyclohexenones
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A novel and efficient metal-free approach to substituted phenols has been disclosed from simple and readily available cyclohexenones and cyclohexenone equivalents. Dimethyl sulfoxide (DMSO), a simple and common organic reagent, was employed as a mild oxidant in this I2-catalysis, which significantly tolerates various substituents including some easily oxidizable or reducible functionalities. The challenging meta- and multiple-substituted phenols could be well prepared by this method. The metal-free and mild oxidation make this protocol very simple, practical, and easy to handle.
- Liang, Yu-Feng,Song, Song,Ai, Lingsheng,Li, Xinwei,Jiao, Ning
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supporting information
p. 6462 - 6467
(2018/06/08)
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- Organocatalytic kinetic resolution via intramolecular aldol reactions: Enantioselective synthesis of both enantiomers of chiral cyclohexenones
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Kinetic resolution of 6-aryl-2,6-hexanediones was achieved with chiral secondary amine catalyzed intramolecular aldolization. The current kinetic resolution protocol enables the synthesis of both enantiomers of cyclohexenones with moderate to good enantioselectivity. The Royal Society of Chemistry 2010.
- Chen, Liujuan,Luo, Sanzhong,Li, Jiuyuan,Li, Xin,Cheng, Jin-Pei
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scheme or table
p. 2627 - 2632
(2010/07/05)
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- An efficient iron-catalyzed carbon-carbon single-bond cleavage via retro-claisen condensation: A mild and convenient approach to synthesize a variety of esters or ketones
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An efficient iron-salt-catalyzed carbon-carbon bond cleavage occurring through a retro-Claisen condensation reaction has been developed. The reaction is useful for the synthesis of a variety of esters or ketones under mild conditions. This method works under solvent-free conditions without the need of an inert atmosphere. This protocol is also applicable for the one-pot syntheses of ketones through tandem carbon-carbon bond formation (substitution or Michael) followed by a retro-Claisen reaction. However, for Michael adducts, ring annulation takes place subsequently. Notably, this method is very simple, convenient, high yielding, and only a catalytic (5 to 1.0 mol-%) amount of Fe(OTf)3 is needed.
- Biswas, Srijit,Maiti, Sukhendu,Jana, Umasish
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supporting information; experimental part
p. 2861 - 2866
(2010/08/05)
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- A novel synthetic route for the synthesis of 4,6-diaryl-2-methyl-1,3- benzoxazoles
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A new synthetic route was developed for the synthesis of 4,6-diaryl-2-methyl-1,3-benzoxazoles and their hydrogenated derivatives. The target compounds were obtained via the Neber rearrangement from 3,5-diaryl-2-cyclohexen-1-ones. The formation of the isom
- Sridharan,Muthusubramanian,Sivasubramanian
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p. 1321 - 1330
(2007/10/03)
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- Cyclohexenone carboxylates. A versatile source for fused isoxazoles and pyrazoles
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The 6-carbethoxy-3,5-diarylcyclohex-2-enone (1) was subjected to condensation and 1,3-dipolar cycloaddition reactions to get fused isoxazole and pyrazole derivatives.
- Padmavathi,Sharmila,Balaiah,Somasekhar Reddy,Bhaskar Reddy
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p. 2119 - 2126
(2007/10/03)
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- Preparation and utility of novel water-tolerant higher-order lanthanoid alkoxide complexes as a base catalyst
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A series of higher-order lanthanoid-lithium mixed-alkoxide complexes have been prepared as a novel water-tolerant base catalyst which effectively promotes the Robinson-type reaction in the presence of water.
- Kamaura, Masahiro,Daikai, Kazuhiro,Hanamoto, Takeshi,Inanaga, Junji
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p. 697 - 698
(2007/10/03)
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- Aldol Reaction and Robinson-Type Annelation Catalyzed by Lanthanoid Triisopropoxides
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Lanthanoid triisopropoxides are active catalysts for aldol reactions.Aldehydes give the corresponding β-hydroxyaldehydes at low temperatures in good yields, whereas ketones are less reactive, but form condensation products at high temperatures.Exceptionally, γ- or δ-diketones easily undergo condensation to give five- and six-membered unsaturated ketones in high yields.The lanthanoid propoxides, catalyzing the Michael addition of ketones to α,β-unsaturated ketones, which give δ-diketones, are also good catalysts for the Robinson-type annelation.In these reactions, the catalytic activity of the lanthanum propoxide is higher than those of the heavy lanthanoid propoxides, and is almost comparable to that of sodium isopropoxide.Since aluminum triisopropoxide shows poor activity, the lanthanoid propoxides are considerably basic for trivalent metal alkoxides.
- Okano, Tamon,Satou, Yoshikazu,Tamura, Motoshi,Kiji, Jitsuo
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p. 1879 - 1886
(2007/10/03)
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- Dienediolates of Unsaturated Carboxylic Acids in Synthesis. Synthesis of Cyclohexenones and Polycyclic Ketones by Tandem Michael-Dieckmann Decarboxylative Annulation of Unsaturated Carboxylic Acids.
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Substituted 2-cyclohexenones 4 to 7 and hexahydronaphthalenones and hexahydroindenones 13 to 18 are prepared by tandem Michael-Dieckmann addition of lithium dienediolates of acyclic and alicyclic unsaturated carboxylic acids to the lithium salts of the same or other unsaturated carboxylic acids.
- Aurell, Maria J.,Gavina, Pablo,Mestres, Ramon
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p. 2571 - 2582
(2007/10/02)
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- A New Annulation Reagent, 2-Oxo-3-alkenylphosphonates. Reactions with Carbonyl-Stabilized Carboanions or Silyl Enol Ethers Leading to Cyclohexanones
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The reactions of 2-oxo-3-alkenylphosphonates with carbonyl-stabilized carbanions directly lead to 2-cyclohexen-1-ones through a sequence of Michael reaction and intramolecular Horner-Emmons olefination.On the other hand, the Lewis acid-mediated reactions with silyl enol ethers produce 1,5-diketones as Michael adducts, which then undergo cyclization on treatment with sodium hydride or triethylamine/zinc (II) bromide to afford 2-cyclohexen-1-ones or 2-phosphinyl-2-cyclohexen-1-ones, respectively.
- Wada, Eiji,Funakoshi, Junji,Kanemasa, Shuji
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p. 2456 - 2464
(2007/10/02)
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- Synthesis and Structure of Diastereomeric 2,4,6,8-Tetraaryl-3-azabicyclononanes and their Conformation in the Crystal and in Solution. Stereochemistry of the Mannich Reaction of cis-3,5-Diphenylcyclohexanone and -4-heteracyclohexanones
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In the Mannich reaction with ammonium acetate and benzaldehyde, cis-3,5-diphenylcyclohexanone (3a) afforded a mixture of the diastereomeric tetraphenyl-3-azabicyclononanones 4a(A) = 14a and 4a(B) = 2a.In contrast, the use of 4-chlorobenzaldehyde in
- Quast, Helmut,Mueller, Bodo,Peters, Eva-Maria,Peters, Karl,Schnering, Hans Georg von
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p. 424 - 437
(2007/10/02)
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- Acid Catalysed Condensation of β-Diketones with Benzylideneacetophenone
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Anhydrous zinc chloride or BF3 etherate catalysed reaction of benzoylacetone with benzylideneacetophenone gives 6-benzoyl-3,5-diphenylcyclohex-2-enone (II) which on alkaline hydrolysis affords 3,5-diphenylcyclohex-2-enone (III). 7,7-Dimethyl-2,4-diphenyl-5-oxo-5,6,7,8-tetrahydrochromen-2 (V) has been obtained from the reaction of benzylideneacetophenone with 5,5-dimethyl-1,3-cyclohexanedione (dimedone) in the presence of anhydrous zinc chloride.
- Ahmed, M. G.,Ahmed, S. A.,Bahar, M. H.,Khondaker, M. A.,Islam, M. A.,Anam, A. K. M. M.
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p. 470 - 471
(2007/10/02)
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