The Experts below are selected from a list of 570 Experts worldwide ranked by ideXlab platform
Tsunetake Seki - One of the best experts on this subject based on the ideXlab platform.
-
the Tishchenko Reaction a classic and practical tool for ester synthesis
Chemistry Letters, 2006Co-Authors: Tsunetake Seki, Tetsuo Nakajo, Makoto OnakaAbstract:This article reviews the Tishchenko Reaction: 2 RCHO → RCOOCH2R (R = hydrogen, alkyl, and aryl), describing the Reaction mechanisms, homogeneous and heterogeneous catalysts developed for the reacti...
-
Sulfated Mesoporous Alumina: A Highly Effective Solid Strong Base Catalyst for the Tishchenko Reaction in Supercritical Carbon Dioxide
The journal of physical chemistry. B, 2006Co-Authors: Tsunetake Seki, Makoto OnakaAbstract:Heterogeneous strong base catalysis for the intramolecular Tishchenko Reaction of aromatic 1,2-dicarbaldehydes to the corresponding phthalides in supercritical CO2CscCO2 has been realized with meso...
-
strong base catalysis of sulfated mesoporous alumina for the Tishchenko Reaction in supercritical carbon dioxide
Chemistry Letters, 2005Co-Authors: Tsunetake Seki, Makoto OnakaAbstract:Heterogeneous strong base catalysis for the Tishchenko Reaction in acidic scCO 2 solvent has been realized with mesoporous alumina modified with SO 4 2 - , while a conventional solid base like CaO showed almost no catalytic performance in scCO 2 .
-
Tishchenko Reaction over solid base catalysts
Catalysis Surveys From Asia, 2003Co-Authors: Tsunetake Seki, Hideshi HattoriAbstract:Catalytic behavior of solid bases for mixed Tishchenko Reaction in which an equimolar mixture of two different aldehydes is allowed to react was investigated employing the combinations of benzaldehyde and pivalaldehyde, pivalaldehyde and cyclopropanecarbaldehyde, and cyclopropanecarbaldehyde and benzaldehyde. The Reactions were performed at 353 K for 4 h in vacuo without solvent using 5 mmol of each aldehyde and 100 mg of solid base catalyst. For all the combinations, the catalytic activity of alkaline earth oxides increased in the order of BaO≪MgO
-
Tishchenko Reaction Over Solid Base Catalysts
Catalysis Surveys from Asia, 2003Co-Authors: Tsunetake Seki, Hideshi HattoriAbstract:Catalytic behavior of solid bases for mixed Tishchenko Reaction in which an equimolar mixture of two different aldehydes is allowed to react was investigated employing the combinations of benzaldehyde and pivalaldehyde, pivalaldehyde and cyclopropanecarbaldehyde, and cyclopropanecarbaldehyde and benzaldehyde. The Reactions were performed at 353 K for 4 h in vacuo without solvent using 5 mmol of each aldehyde and 100 mg of solid base catalyst. For all the combinations, the catalytic activity of alkaline earth oxides increased in the order of BaO≪MgO
Hideshi Hattori - One of the best experts on this subject based on the ideXlab platform.
-
Dynamic behavior of basic sites of MgO in Tishchenko Reaction
Catalysis Today, 2006Co-Authors: Hideto Tsuji, Hideshi HattoriAbstract:Abstract Tishchenko Reaction of benzaldehyde was carried out over the MgO whose surface O atoms were enriched with 18 O to examine whether the surface O atoms of MgO are incorporated into the product and reactant. The surface lattice 18 O atoms were incorporated in both the product and reactant. The 18 O concentration was significantly higher for the product than for the reactant. In addition, the 18 O in the product ester was located not only in the carbonyl group (C O) but also in the bridging position (C O C); 18 O exchange between benzaldehyde and MgO surface occurred not only in the adsorption–desorption of benzaldehyde, but also in the dimerization process. The oxygen exchange results in the migration of active sites of coordinative unsaturated site (CUS) over the surface of MgO catalyst during the Reaction.
-
Tishchenko Reaction over solid base catalysts
Catalysis Surveys From Asia, 2003Co-Authors: Tsunetake Seki, Hideshi HattoriAbstract:Catalytic behavior of solid bases for mixed Tishchenko Reaction in which an equimolar mixture of two different aldehydes is allowed to react was investigated employing the combinations of benzaldehyde and pivalaldehyde, pivalaldehyde and cyclopropanecarbaldehyde, and cyclopropanecarbaldehyde and benzaldehyde. The Reactions were performed at 353 K for 4 h in vacuo without solvent using 5 mmol of each aldehyde and 100 mg of solid base catalyst. For all the combinations, the catalytic activity of alkaline earth oxides increased in the order of BaO≪MgO
-
Tishchenko Reaction Over Solid Base Catalysts
Catalysis Surveys from Asia, 2003Co-Authors: Tsunetake Seki, Hideshi HattoriAbstract:Catalytic behavior of solid bases for mixed Tishchenko Reaction in which an equimolar mixture of two different aldehydes is allowed to react was investigated employing the combinations of benzaldehyde and pivalaldehyde, pivalaldehyde and cyclopropanecarbaldehyde, and cyclopropanecarbaldehyde and benzaldehyde. The Reactions were performed at 353 K for 4 h in vacuo without solvent using 5 mmol of each aldehyde and 100 mg of solid base catalyst. For all the combinations, the catalytic activity of alkaline earth oxides increased in the order of BaO≪MgO
-
synthesis of phthalide skeleton using selective intramolecular Tishchenko Reaction over solid base catalysts
Journal of Catalysis, 2003Co-Authors: Tsunetake Seki, Hiroto Tachikawa, Takashi Yamada, Hideshi HattoriAbstract:Abstract An efficient, economical, and environmentally benign method for the synthesis of phthalide–skeleton using heterogeneous catalytic intramolecular Tishchenko Reaction with solid bases is described. Among the solid base catalysts examined, MgO, CaO, and SrO exhibited high catalytic performances for the intramolecular Tishchenko Reaction of o-phthalaldehyde to yield phthalide exclusively in excellent yields at 313 K in the short time span of 0.25 h. Application of γ-alumina to the intramolecular Tishchenko Reaction of o-phthalaldehyde was also successful; phthalide was obtained selectively in excellent yields at 313 K in 4 h. The employment of KF/alumina and KOH/alumina at 313 K for 4 h resulted in the selective formation of phthalide in moderate yields. The heterogeneous catalytic systems realized by the use of CaO and γ-alumina were also successfully applicable to the selective intramolecular Tishchenko Reaction of 2,3-naphthalenedicarbaldehyde to give the corresponding five-membered lactone in excellent yields at 333 K for 2 and 20 h, respectively. Based on the Reaction results, the infrared spectra of adsorbed o-phthalaldehyde, and the quantum chemical calculations conducted at the PM3-MO level of theory for elucidation of the molecular and electronic structures of o-phthalaldehyde and the potential intermediates, a plausible Reaction mechanism for the intramolecular Tishchenko Reaction of o-phthalaldehyde to phthalide over MgO and γ-alumina was proposed. The catalytically active species should be o-MOCH2C6H4CHO (M=Mg or Al).
-
Synthesis of phthalide–skeleton using selective intramolecular Tishchenko Reaction over solid base catalysts
Journal of Catalysis, 2003Co-Authors: Tsunetake Seki, Hiroto Tachikawa, Takashi Yamada, Hideshi HattoriAbstract:Abstract An efficient, economical, and environmentally benign method for the synthesis of phthalide–skeleton using heterogeneous catalytic intramolecular Tishchenko Reaction with solid bases is described. Among the solid base catalysts examined, MgO, CaO, and SrO exhibited high catalytic performances for the intramolecular Tishchenko Reaction of o-phthalaldehyde to yield phthalide exclusively in excellent yields at 313 K in the short time span of 0.25 h. Application of γ-alumina to the intramolecular Tishchenko Reaction of o-phthalaldehyde was also successful; phthalide was obtained selectively in excellent yields at 313 K in 4 h. The employment of KF/alumina and KOH/alumina at 313 K for 4 h resulted in the selective formation of phthalide in moderate yields. The heterogeneous catalytic systems realized by the use of CaO and γ-alumina were also successfully applicable to the selective intramolecular Tishchenko Reaction of 2,3-naphthalenedicarbaldehyde to give the corresponding five-membered lactone in excellent yields at 333 K for 2 and 20 h, respectively. Based on the Reaction results, the infrared spectra of adsorbed o-phthalaldehyde, and the quantum chemical calculations conducted at the PM3-MO level of theory for elucidation of the molecular and electronic structures of o-phthalaldehyde and the potential intermediates, a plausible Reaction mechanism for the intramolecular Tishchenko Reaction of o-phthalaldehyde to phthalide over MgO and γ-alumina was proposed. The catalytically active species should be o-MOCH2C6H4CHO (M=Mg or Al).
Stephen J. Connon - One of the best experts on this subject based on the ideXlab platform.
-
Selenide ions as catalysts for homo- and crossed-Tishchenko Reactions of expanded scope.
Organic letters, 2012Co-Authors: Simon P. Curran, Stephen J. ConnonAbstract:Selenide ions have been shown to catalyze the Tishchenko Reaction for the first time. These catalysts are superior to previously reported thiolate analogues and promote the disproportionation of aldehydes with increased Reaction rates and broader scope at lower catalyst loadings and temperatures. Significantly improved catalyst performance was also observed in the aryl selenide mediated crossed intermolecular Tishchenko Reaction.
-
Microwave-Assisted Efficient Thiolate-Catalyzed Homo- and Crossed Intermolecular Tishchenko Reactions.
ChemInform, 2011Co-Authors: Cornelius J. O’connor, Francesco Manoni, Simon P. Curran, Stephen J. ConnonAbstract:Fast and efficient homo and cross Tishchenko Reaction is achieved under microwave irradiation to give esters (II), (V) and (VII) in moderate to high yields within 10 to 180 minutes.
-
tunable bromomagnesium thiolate Tishchenko Reaction catalysts intermolecular aldehyde trifluoromethylketone coupling
ChemInform, 2010Co-Authors: Linda Cronin, Francesco Manoni, Cornelius J Oconnor, Stephen J. ConnonAbstract:The thiolate generated from PhMgBr and BnSH is found to be an efficient catalyst for the Tishchenko Reaction.
-
Tunable Bromomagnesium Thiolate Tishchenko Reaction Catalysts: Intermolecular Aldehyde—Trifluoromethylketone Coupling.
ChemInform, 2010Co-Authors: Linda Cronin, Francesco Manoni, Cornelius J. O’connor, Stephen J. ConnonAbstract:The thiolate generated from PhMgBr and BnSH is found to be an efficient catalyst for the Tishchenko Reaction.
-
Tunable bromomagnesium thiolate Tishchenko Reaction catalysts: intermolecular aldehyde-trifluoromethylketone coupling.
Angewandte Chemie (International ed. in English), 2010Co-Authors: Linda Cronin, Francesco Manoni, Cornelius J. O' Connor, Stephen J. ConnonAbstract:The ‘Tishchenko Reaction’ (discovered by Claisen in 1887) is the disproportionation of two aldehyde molecules to furnish an ester product (Scheme 1). Aluminium alkoxides and boric acid, were the first classes of synthetically relevant homogeneous catalysts for this Reaction, these were then followed by a range of transition metal complexes of low-high catalytic activity but often limited practical utility. More recently, lanthanide, actinide and calcium 11 ] complexes capable of promoting aldehyde dimerization with excellent activity have been reported. A generalized mechanistic outline of the process is given in Scheme 1 – Reaction of the transition metal complex 1 with the aldehyde generates the metal-alkoxide 2, which acts as the hydride transfer agent in a metal-mediated redox process (i.e. 3) leading to ester 4.
Makoto Onaka - One of the best experts on this subject based on the ideXlab platform.
-
the Tishchenko Reaction a classic and practical tool for ester synthesis
Chemistry Letters, 2006Co-Authors: Tsunetake Seki, Tetsuo Nakajo, Makoto OnakaAbstract:This article reviews the Tishchenko Reaction: 2 RCHO → RCOOCH2R (R = hydrogen, alkyl, and aryl), describing the Reaction mechanisms, homogeneous and heterogeneous catalysts developed for the reacti...
-
Sulfated Mesoporous Alumina: A Highly Effective Solid Strong Base Catalyst for the Tishchenko Reaction in Supercritical Carbon Dioxide
The journal of physical chemistry. B, 2006Co-Authors: Tsunetake Seki, Makoto OnakaAbstract:Heterogeneous strong base catalysis for the intramolecular Tishchenko Reaction of aromatic 1,2-dicarbaldehydes to the corresponding phthalides in supercritical CO2CscCO2 has been realized with meso...
-
strong base catalysis of sulfated mesoporous alumina for the Tishchenko Reaction in supercritical carbon dioxide
Chemistry Letters, 2005Co-Authors: Tsunetake Seki, Makoto OnakaAbstract:Heterogeneous strong base catalysis for the Tishchenko Reaction in acidic scCO 2 solvent has been realized with mesoporous alumina modified with SO 4 2 - , while a conventional solid base like CaO showed almost no catalytic performance in scCO 2 .
Christoph Schneider - One of the best experts on this subject based on the ideXlab platform.
-
zirconium binolate catalyzed enantioselective aldol Tishchenko Reactions of aromatic ketone aldols
Tetrahedron-asymmetry, 2006Co-Authors: Christoph Schneider, Markus Hansch, Pankajakshan SreekumarAbstract:Abstract 3,3′-Substituted BINOL’s have been identified as suitable chiral ligands for the zirconium-catalyzed aldol-Tishchenko Reaction of aromatic ketone aldols with aliphatic aldehydes. 1,3- anti -Diol monoesters were obtained in excellent yields, complete anti -diastereocontrol, and enantioselectivities of up to 60% ee.
-
Zirconium–BINOLate-catalyzed, enantioselective aldol-Tishchenko Reactions of aromatic ketone aldols
Tetrahedron: Asymmetry, 2006Co-Authors: Christoph Schneider, Markus Hansch, Pankajakshan SreekumarAbstract:Abstract 3,3′-Substituted BINOL’s have been identified as suitable chiral ligands for the zirconium-catalyzed aldol-Tishchenko Reaction of aromatic ketone aldols with aliphatic aldehydes. 1,3- anti -Diol monoesters were obtained in excellent yields, complete anti -diastereocontrol, and enantioselectivities of up to 60% ee.
-
The zirconium alkoxide-catalyzed aldol-Tishchenko Reaction of ketone aldols.
Chemistry (Weinheim an der Bergstrasse Germany), 2005Co-Authors: Christoph Schneider, Markus Hansch, Timo WeideAbstract:The aldol-Tishchenko Reaction of ketone aldols as enol equivalents has been developed as an efficient strategy to furnish differentiated 1,3-anti-diol monoesters in one step. The thermodynamically unstable ketone aldols undergo a facile retro-aldolization to yield a presumed zirconium enolate in situ, which then undergoes the aldol-Tishchenko Reaction in typically high yields and with complete 1,3-anti diastereocontrol. Evaluation of a broad range of metal alkoxides as catalysts and optimization of the Reaction protocol led to a modified zirconium alkoxide catalyst with attenuated Lewis acidity and dichloromethane as solvent, which resulted in suppression of the undesired acyl migration to a large extent. Various ketone aldols have been prepared and subjected to the general process, giving rise to a broad range of differently substituted 1,3-anti-diol monoesters, which may be hydrolyzed to the corresponding 1,3-anti-diols.
-
First Catalytic, Enantioselective Aldol-Tishchenko Reactions with Ketone Aldols as Enol Equivalents
Synlett, 2003Co-Authors: Christoph Schneider, Markus HanschAbstract:Chiral zirconiumTADDOLates were found to catalyze the aldol-Tishchenko Reaction of diacetone alcohol (la) and two other ketone aldol adducts 1b and 1c with a range of aldehydes giving rise to differentiated 1,3-anti-diol monoesters in good yields, complete diastereocontrol and moderate enantioselectivities.
-
Zr(OtBu)4-catalysed synthesis ofacetone aldol adducts and domino aldol-Tishchenko Reactions with diacetonealcohol as enol equivalent
Chemical Communications, 2001Co-Authors: Christoph Schneider, Markus HanschAbstract:Zr(OtBu)4 was found to be a potent catalyst for the synthesis of acetone aldol adducts with diacetone alcohol as enol equivalent and for domino aldol-Tishchenko Reaction giving rise to 1,3-anti-diol monoesters with excellent diastereoselectivity.