- N-Aroylbenzotriazoles as Efficient Reagents for o-Aroylation in Absence of Organic Solvent
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N-Aroylbenzotriazoles have been shown to be efficient reagents for esterification in the absence of organic solvent. Grinding of N-aroylbenzoytiazoles with twofold excess of alcohols for a couple of hours at room temperature gave corresponding esters in high percentage of yields.
- Hahnvajanawong, Viwat,Phungpis, Baramee
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p. 2671 - 2674
(2021/10/25)
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- N-Heterocyclic Carbene Catalyzed Ester Synthesis from Organic Halides through Incorporation of Oxygen Atoms from Air
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Oxygenation reactions with molecular oxygen (O2) as the oxygen source provides a green and straightforward strategy for the construction of O-containing compounds. Demonstrated here is a novel N-heterocyclic carbene (NHC) catalyzed oxidative transformation of simple and readily available organic halides into valuable esters through the incorporation of O-atoms from O2. Mechanistic studies prove that the deoxy Breslow intermediate generated in situ is oxidized to a Breslow intermediate for further transformation by this oxidative protocol. This method broadens the field of NHC catalysis and promotes oxygenation reactions with O2.
- Tan, Hui,Wang, Shen-An,Yan, Zixi,Liu, Jianzhong,Wei, Jialiang,Song, Song,Jiao, Ning
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supporting information
p. 2140 - 2144
(2020/12/01)
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- Sodium organoaluminate containing bidentate pyrrolyl ligand: Synthesis, structure, and catalytic activity for the Tishchenko reaction
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An novel sodium organoaluminate containing bidentate pyrrolyl ligand [C4H3NH(2-CH2NHtBu)] was efficiently synthesized and characterized by X-ray crystallography. The molecular structure shows it is a monodimensional infinite chain structures with linear arrangements. Its basic repeat unit comprises the Al atom bonded to two deprotonated pyrrole rings and Na atom coordinated to of nitrogen atoms of –NtBu fragment, which undergoes further to coordinates a pyrrolyl ring of an adjacent molecule in a ?2-fasion. Furthermore, this sodium organoaluminate exhibited high catalytic activities for Tishchenko reaction.
- Liu, Yu,Guo, Zhiqiang,Wang, Yakong
-
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- Disproportionation of aliphatic and aromatic aldehydes through Cannizzaro, Tishchenko, and Meerwein–Ponndorf–Verley reactions
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Disproportionation of aldehydes through Cannizzaro, Tishchenko, and Meerwein–Ponndorf–Verley reactions often requires the application of high temperatures, equimolar or excess quantities of strong bases, and is mostly limited to the aldehydes with no CH2 or CH3 adjacent to the carbonyl group. Herein, we developed an efficient, mild, and multifunctional catalytic system consisting AlCl3/Et3N in CH2Cl2, that can selectively convert a wide range of not only aliphatic, but also aromatic aldehydes to the corresponding alcohols, acids, and dimerized esters at room temperature, and in high yields, without formation of the side products that are generally observed. We have also shown that higher AlCl3 content favors the reaction towards Cannizzaro reaction, yet lower content favors Tishchenko reaction. Moreover, the presence of hydride donor alcohols in the reaction mixture completely directs the reaction towards the Meerwein–Ponndorf–Verley reaction. Graphic abstract: [Figure not available: see fulltext.].
- Sharifi, Sina,Sharifi, Hannah,Koza, Darrell,Aminkhani, Ali
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p. 803 - 808
(2021/07/20)
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- Synthesis of Unsymmetrical N-Heterocyclic Carbene-Nitrogen-Phosphine Chelated Ruthenium(II) Complexes and Their Reactivity in Acceptorless Dehydrogenative Coupling of Alcohols to Esters
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Two novel ruthenium complexes RuH(CO)Cl(PPh3)(κ2-CP) (1) and [fac-RuH(CO)(PPh3)(κ3-CNP)]Cl (2) bearing unsymmetrical N-heterocyclic carbene-nitrogen-phosphine (CNP) were synthesized and characterized with 1H NMR, 31P NMR, and HRMS. The structure of complex 2 was further confirmed by single-crystal X-ray diffraction. An anion exchange experiment proved that complex 2 could transform into complex 1 in solution. The two complexes exhibited a highly catalytic performance in acceptorless dehydrogenative coupling of alcohols to esters, and the excellent isolated yields of esters were given in a catalyst loading of 1% for para- and meta-substituted benzyl alcohols and long-chain primary alcohols. Although some ortho-substituted benzyl alcohols displayed a relatively low reactivity due to the steric hindrance and the coordination of electron donor with the ruthenium center, the good product yields were still obtained by prolonging the reaction time. Especially, this system successfully realized the dehydrogenative cross-coupling to esters between two different primary alcohols.
- He, Xiaochun,Li, Yaqiu,Fu, Haiyan,Zheng, Xueli,Chen, Hua,Li, Ruixiang,Yu, Xiaojun
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p. 1750 - 1760
(2019/04/17)
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- Aldehyde effect and ligand discovery in Ru-catalyzed dehydrogenative cross-coupling of alcohols to esters
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The presence of different aldehydes is found to have a significant influence on the catalytic performance when using PN(H)P type ligands for dehydrogenation of alcohols. Accordingly, hybrid multi-dentate ligands were discovered based on an oxygen-transfer alkylation of PNP ligands by aldehydes. The relevant Ru-PNN(PO) system provided the desired unsymmetrical esters in good yields via acceptorless dehydrogenation of alcohols. Hydrogen bonding interactions between the phosphine oxide moieties and alcohol substrates likely assisted the observed high chemoselectivity.
- Jiang, Xiaolin,Zhang, Jiahui,Zhao, Dongmei,Li, Yuehui
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p. 2797 - 2800
(2019/03/27)
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- Direct oxidative esterification of primary alcohols and oxidation of secondary alcohols over mesoporous spherical silica encapsulated MnO2 nanoparticles
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In this work, a simple and efficient strategy for the fabrication of novel encapsulated MnO2 nanoparticles inside spherical mesoporous silica hollow-nanoparticles was described. They were synthesized by consecutively anchoring MnO2 nanoparticles on poly(styrene-co-methacrylic acid) particles, coating with a mesoporous silica shell, and subsequently removing the polymeric core by dissolving in acetone. The catalytic activity of the nanoparticles was examined in the aerobic oxidation of various primary and secondary alcohols, which showed good activity and selectivity for the transformation of primary alcohols to the corresponding esters through the oxidative esterification process and secondary alcohols to ketones in short reaction times under mild reaction conditions. In addition, the catalyst system was utilized for the oxidation of primary alcohols to aldehydes using tert-butyl hydroperoxide (TBHP) as an oxidant under mild conditions and produced an excellent product yield.
- Hosseinzadeh, Shahram Zare,Babazadeh, Mirzaagha,Shahverdizadeh, Gholam Hossein,Hosseinzadeh-Khanmiri, Rahim
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p. 9491 - 9499
(2019/06/21)
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- A animal pen halogen oxidation autoconnected joint into aromatic benzyl ester method (by machine translation)
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The invention discloses an animal pen halogen oxidation autoconnected joint into aromatic benzyl ester method, organic solvent, animal pen halogen in the 1, 3 - double (2, 4, 6 - trimethyl-phenyl) imidazole and chloride under the action of alkali, one-step synthesis of benzoic acid benzyl ester; wherein the reaction form is: X chlorine, bromine or iodine, R is hydrogen, C1 - C4 alkyl, alkoxy, nitro, chlorine, bromine or fluorine. The invention mild reaction conditions, easy operation processing, the atom economy is high, the production cost is low. (by machine translation)
- -
-
Paragraph 0066; 0067; 0071
(2019/01/05)
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- Cobalt-Catalyzed Acceptorless Dehydrogenative Coupling of Primary Alcohols to Esters
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A novel catalytic system with a tripodal cobalt complex is developed for efficiently converting primary alcohols to esters. KOtBu is found essential to the transformation. A preliminary mechanistic study suggests a plausible reaction route that involves an initial Co-catalyzed dehydrogenation of alcohol to aldehyde, followed by a Tishchenko-type pathway to ester mediated by KOtBu.
- Paudel, Keshav,Pandey, Bedraj,Xu, Shi,Taylor, Daniela K.,Tyer, David L.,Torres, Claudia Lopez,Gallagher, Sky,Kong, Lin,Ding, Keying
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supporting information
p. 4478 - 4481
(2018/08/09)
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- Rhodium-catalyzed synthesis of imines and esters from benzyl alcohols and nitroarenes: Change in catalyst reactivity depending on the presence or absence of the phosphine ligand
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The [Rh(COD)Cl]2/xantphos/Cs2CO3 system efficiently catalyzes the reductive N-alkylation of aryl nitro compounds with alcohols by a borrowing-hydrogen strategy to afford the corresponding imine products in good to excellent yields. In the absence of xantphos, the [Rh(COD)Cl]2/Cs2CO3 catalytic system behaves as an effective catalyst for the dehydrogenative coupling of alcohols to esters, with nitrobenzene as a hydrogen acceptor. The reactivity of the rhodium catalytic system can be easily manipulated to selectively afford the imine or ester.
- Song, Taemoon,Park, Ji Eun,Chung, Young Keun
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p. 4197 - 4203
(2018/04/14)
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- Ruthenium complexes featuring cooperative phosphine-pyridine-iminophosphorane (PNN) ligands: Synthesis, reactivity and catalytic activity
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The coordination to ruthenium(ii) centres of two phosphine-pyridine-iminophosphorane ligands LR (PPh2CH2(C6H3N)CH2NPR3, R = Ph or Cy) differing by the nature of the substituent of the PN phosphorus was explored. Coordination to [RuCl2(PPh3)3] afforded the complexes [RuLRCl2(PPh3)] that were successfully deprotonated at the acidic phosphinomethyl position. With LCy, coordination led to a mixture of two isomers. The complexes [RuLRHCl(PPh3)] were similarly obtained from [RuHCl(PPh3)3]. The stability of these complexes depends on the ligand substitution pattern; with LPh a CH activation process took place, while [RuLCyHCl(PPh3)] was thermally stable. Deprotonation of this latter complex was achieved and gave a catalytically competent species for the acceptorless dehydrogenative coupling of alcohols.
- Cheisson, Thibault,Mazaud, Louis,Auffrant, Audrey
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p. 14521 - 14530
(2018/10/31)
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- Osmium Catalysts for Acceptorless and Base-Free Dehydrogenation of Alcohols and Amines: Unusual Coordination Modes of a BPI Anion
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A novel type of catalyst precursors for the dehydrogenation of hydrogen carriers based on organic liquids has been discovered. Complexes OsH6(PiPr3)2 (1) and OsH(OH)(CO)(PiPr3)2 (2) react with 1,3-bis(6′-methyl-2′-pyridylimino)isoindoline (HBMePI) to give OsH3{κ2-Npy,Nimine-(BMePI)}(PiPr3)2 (3) and OsH{κ2-Npy,Nimine-(BMePI)}(CO)(PiPr3)2 (4). The unprecedented κ2-Npy,Nimine coordination mode of BMePI is thermodynamically preferred with Os(IV) and Os(II) metal fragments and allows for preparation of BMePI-based dinuclear metal cations. Treatment of OsH2Cl2(PiPr3)2 (5) with 0.5 equiv of HBMePI in the presence of KOtBu affords the chloride salt of the bis(osmium(IV)) dinuclear cation [{OsH3(PiPr3)2}2{μ-(κ2-Npy,Nimine)2-BMePI}]+ (6). Related homoleptic bis(osmium(II)) complexes have been also synthesized. Complex 4 reacts with the bis(solvento) [OsH(CO){κ1-O-[OCMe2]2}(PiPr3)2]BF4 to give [{OsH(CO)(PiPr3)2}2{μ-(κ2-Npy,Nimine)2-BMePI}]BF4 (7), whereas the addition of 0.5 equiv of HBMePI to {OsCl(η6-C6H6)}2(μ-Cl)2 (8) affords [{OsCl(η6-C6H6)}2{μ-(κ2-Npy,Nimine)2-BMePI}]Cl (9). The reactions of 4 with 8 and {OsCl(η6-p-cymene)}2(μ-Cl)2 (10) lead to the heteroleptic cations [(PiPr3)2(CO)HOs{μ-(κ2-Npy,Nimine)2-BMePI}OsCl(η6-arene)]+ (arene = C6H6 (11), p-cymene (12)). The electronic structrure and electrochemical properties of the dinuclear complexes were also studied. Complexes 3 and 4 are efficient catalyst precursors for the acceptorless and base-free dehydrogenation of secondary and primary alcohols and cyclic and lineal amines. The primary alcohols afford aldehydes. The amount of H2 released per gram of heterocycle depends upon the presence of a methyl group adjacent to the nitrogen atom, the position of the nitrogen atom in the heterocycle, and the size of the heterocycle.
- Buil, María L.,Esteruelas, Miguel A.,Gay, M. Pilar,Gómez-Gallego, Mar,Nicasio, Antonio I.,O?ate, Enrique,Santiago, Alicia,Sierra, Miguel A.
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p. 603 - 617
(2018/03/08)
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- Base-Free and Acceptorless Dehydrogenation of Alcohols Catalyzed by an Iridium Complex Stabilized by a N, N, N-Osmaligand
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The preparation of a N,N,N-osmaligand, its coordination to iridium to afford an efficient catalyst precursor, and the catalytic activity of the latter in dehydrogenation reactions of hydrogen carriers based on alcohols are reported. Complex OsH2Cl2(PiPr3)2 (1) reacts with 3-(2-pyridyl)pyrazol to give the osmium(II) complex 2H, which contains an acidic hydrogen atom. Deprotonation of the latter by the bridging methoxy groups of the dimer [Ir(μ-OMe)(n4-COD)]2 (COD = 1,5-cyclooctadiene) leads to Ir(2)( n 4-COD) (3), where osmaligand 2 has a free-nitrogen atom. Iridium complex 3 catalyzes the dehydrogenation of secondary and primary alcohols to ketones and aldehydes or esters, respectively, and the dehydrogenation of diols to lactones. Cyclooctatriene is detected during the catalysis by GC-MS, suggesting that the true catalyst of the reactions is a dihydride IrH2(2)-species with osmaligand 2 acting as N,N,N-pincer. The presence of a phenyl group in the substrates favors the catalytic processes. The dehydrogenative homocoupling of primary alcohols to esters appears to take place via the transitory formation of hemiacetals.
- Alabau, Roberto G.,Esteruelas, Miguel A.,Martínez, Antonio,Oliván, Montserrat,O?ate, Enrique
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p. 2732 - 2740
(2018/09/10)
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- Thorium complexes possessing expanded ring N-heterocyclic iminato ligands: Synthesis and applications
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Six and seven membered N-heterocyclic iminato ligands (L) are introduced allowing access a new class of Th(iv) complexes of the type Cp?2Th(L)(CH3). These complexes were studied in the Tishchenko reaction. Stoichiometric reactions together with kinetic and thermodynamic studies permit us to propose a plausible mechanism.
- Ghatak, Tapas,Drucker, Shani,Fridman, Natalia,Eisen, Moris S.
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supporting information
p. 12005 - 12009
(2017/09/25)
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- Formamides as Lewis Base Catalysts in SNReactions—Efficient Transformation of Alcohols into Chlorides, Amines, and Ethers
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A simple formamide catalyst facilitates the efficient transformation of alcohols into alkyl chlorides with benzoyl chloride as the sole reagent. These nucleophilic substitutions proceed through iminium-activated alcohols as intermediates. The novel method, which can be even performed under solvent-free conditions, is distinguished by an excellent functional group tolerance, scalability (>100 g) and waste-balance (E-factor down to 2). Chiral substrates are converted with excellent levels of stereochemical inversion (99 %→≥95 % ee). In a practical one-pot procedure, the primary formed chlorides can be further transformed into amines, azides, ethers, sulfides, and nitriles. The value of the method was demonstrated in straightforward syntheses of the drugs rac-Clopidogrel and S-Fendiline.
- Huy, Peter H.,Motsch, Sebastian,Kappler, Sarah M.
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supporting information
p. 10145 - 10149
(2016/08/16)
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- Dicopper Complexes with Anthyridine-Based Ligands: Coordination and Catalytic Activity
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Two new anthyridine-based ligands, 5-phenyl-2,8-bis(2-pyridinyl)-1,9,10-anthyridine (L3) and 5-phenyl-2,8-bis(6′-bipyridinyl)-1,9,10-anthyridine (L4), were designed for accommodation of dimetallic systems with the metal ions separated by 5 ?. Complexation of Cu(ClO4)2 with L3 and L4 provided the corresponding dicopper complexes [{Cu2(L3)(H2O)4(CH3CN)2}(ClO4)4] (3) and [{Cu2(L4)(μ-ClO4)2}(PF6)2] (4), respectively. Both complexes were characterized by spectroscopic methods, and the detail structural features were further confirmed by X-ray crystallography. Structural analyses of 3 and 4 reveal the Cu···Cu distances in the complexes being 4.9612(7) and 5.013 (2) ?, respectively. Both complexes are active in the catalytic oxidation of benzyl alcohols into the corresponding aldehydes. Furthermore, complex 4 appears to be a good catalyst for the oxidative coupling of primary alcohols into the corresponding esters with the use of hydrogen peroxide as the oxidant in an aqueous medium. The possible cooperative interactions between the metal ions during the catalysis are discussed.
- Huang, Da-Wei,Liu, Yi-Hung,Peng, Shie-Ming,Liu, Shiuh-Tzung
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p. 151 - 158
(2016/02/05)
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- Aluminum complexes of β-hydroxy-imino ligands: Synthesis, structures and application in the Tishchenko reaction
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Four aluminum alkoxide complexes containing β-hydroxy-imino ligands, [(2,6-Me2C6H3)NCPhCH2CPh2O]2AlMe (3a), [(2,6-iPr2C6H3)NCPhCH2CPh2O]2AlMe (3b), [(2,6-Me2C6H3)NCPhCH2C(C12H8)OAlMe2]2 (3c) and [(2,6-iPr2C6H3)NCPhCH2C(C12H8)OAlMe2]2 (3d) were synthesized in high yields, and their structural features were provided. The catalytic behavior of those four complexes about the Tishchenko reaction with a range of aromatic aldehydes as substrates were assessed, and it present a synthetically useful protocol to the solvent-free Tishchenko reaction under mild conditions.
- Guo, Zhiqiang,Wang, Song,Wei, Xuehong
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p. 115 - 122
(2016/07/06)
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- The promoted Tishchenko reaction and catalytic intermediate by 2-aminopyrrolyl dilithium compounds
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The dimerization of aldehydes to the analogous carboxylic esters (Tischenko reaction) has been achieved in impressive yields using the dilithium compounds containing bidentate di-anionic pyrrolyl ligands as initiators. The initiated intermediate {[2-(tBuNCH)C4H3NLi][PhCH2OLi(TMEDA)]}2 was isolated and characterized by satisfactory C, H and N microanalysis, 1H, 13C{1H} and 7Li NMR spectra in pyridine-d5 at ambient temperature, and single crystal X-ray structural data. The processes involve a redox reaction of 2-aminopyrrolyl dilithium compound with aldehyde.
- Guo, Zhiqiang,Wei, Xuehong,Tong, Hongbo,Chao, Jianbin,Liu, Diansheng
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supporting information
p. 73 - 76
(2015/03/14)
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- Bulky guanidinate stabilized homoleptic magnesium, calcium and zinc complexes and their catalytic activity in the Tishchenko reaction
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Bulky guanidinate stabilized homoleptic complexes of [LM(thf)nL] [L = {ArNC (NiPr2)NAr} (Ar = 2,6- Me2-C6H3)]; M = Mg, Ca, and Zn; n = 0-1) have been synthesized with three different synthetic routes. First, treatment of bis{bis(trimethylsilyl)amide}s of Mg, Ca, and Zn i.e. [M{(N(SiMe3)2}2] (M = Mg, Ca(thf)2, and Zn) with free guanidine ligand (LH) at 80 °C, elimination of NH(SiMe3)2 and formation of [LM(thf)nL] (M = Mg, Ca and Zn; n = 0-1) (3-5) complexes were occurred. Second, the reaction of two equivalents of potassium salt of LH with metal dihalides via salt metathesis led to the formation of homoleptic complexes. Third, the reaction between MR2 (M = Mg, Ca, Zn; R = alkyl or OTf) and LH at reflux temperature, formation of bis(guanidinate) magnesium, calcium, and zinc complexes have been observed. The solid state structures of LH(1), LK(2) and all three bis(guanidinate) magnesium, calcium and zinc complexes (3-5) were confirmed by X-ray structural analysis. Furthermore, dimerization of a range of aromatic, heteroaromatic and aliphatic aldehydes (Tishchenko reaction) has been demonstrated by using catalysts 3-5.
- Barman, Milan Kr,Baishya, Ashim,Nembenna, Sharanappa
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- Efficient and simple approaches towards direct oxidative esterification of alcohols
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The present article describes novel oxidative protocols for direct esterification of alcohols. The protocols involve successful demonstrations of both "cross" and "self" esterification of a wide variety of alcohols. The cross-esterification proceeds under a simple transition-metal-free condition, containing catalytic amounts of TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy)/TBAB (tetra-n-butylammonium bromide) in combination with oxone (potassium peroxo monosulfate) as the oxidant, whereas the self-esterification is achieved through simple induction of Fe(OAc)2/dipic (dipic=2,6-pyridinedicarboxylic acid) as the active catalyst under an identical oxidizing environment. One-pot oxidative esterification: A wide variety of alcohols undergo transition-metal-free (in the presence of oxone/2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO)/tetra-n-butylammonium bromide (TBAB)) selective "cross" esterification in moderate to excellent yields (see Figure). The "self" esterification process has however been achieved in the presence of Fe(OAc)2/2,6-pyridinedicarboxylic acid (dipic) as the active catalytic species under a similar oxidizing environment.
- Ray, Ritwika,Jana, Rahul Dev,Bhadra, Mayukh,Maiti, Debabrata,Lahiri, Goutam Kumar
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supporting information
p. 15618 - 15624
(2016/02/18)
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- Easy access to benzylic esters directly from alkyl benzenes under metal-free conditions
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An efficient metal free protocol has been developed for the synthesis of benzylic esters via a cross dehydrogenative coupling (CDC) involving alkylbenzene(s) as a self- or as a cross-coupling partner(s) via the intermediacy of Ar-COOH and the benzylic carbocation obtained from the other half of the alkylbenzene; both symmetrical as well as unsymmetrical esters can be prepared using Bu4NI and TBHP. The Royal Society of Chemistry.
- Majji, Ganesh,Guin, Srimanta,Gogoi, Anupal,Rout, Saroj Kumar,Patel, Bhisma K.
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supporting information
p. 3031 - 3033
(2013/05/09)
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- Solvent-controlled copper-catalyzed oxidation of benzylic alcohols to aldehydes and esters
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A procedure for the copper-catalyzed selective oxidation of primary alcohols to esters and aldehydes was developed. Under solvent-free conditions, self-oxidative esterification and cross-esterification of benzyl alcohols with various aliphatic alcohols proceed smoothly to give the corresponding esters in good yields. If DMF was used as a solvent, the benzyl alcohols were selectively converted into the corresponding aldehydes in excellent yields. Depend on solvent! Under solvent-free conditions, Cu-catalyzed oxidative self-esterification and cross-esterification of benzylic alcohols with various aliphatic alcohols proceed smoothly to give the corresponding esters in good yields. If DMF is used as a solvent, the benzylic alcohols are selectively converted into the corresponding aldehydes in excellent yields. DTBP = di-tert-butyl peroxide. Copyright
- Zhu, Yefeng,Wei, Yunyang
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supporting information
p. 4503 - 4508
(2013/07/26)
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- Oxidant controlled Pd-catalysed selective oxidation of primary alcohols
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The oxidant controlled palladium catalysed selective oxidation of primary alcohols to aldehydes or esters was investigated. The electronic properties of the benzylic alcohols and the structure of the oxidant are both important factors in controlling the selectivity between aldehydes and esters. A covalent benzyl ligand derived from BnCl provides η3 coordination to the Pd centre. This covalent ligand is the key to the selective oxidative esterification of primary alcohols.
- Liu, Chao,Tang, Shan,Lei, Aiwen
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supporting information
p. 1324 - 1326
(2013/03/13)
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- Pt, Pd and Au nanoparticles supported on a DNA-MMT hybrid: Efficient catalysts for highly selective oxidation of primary alcohols to aldehydes, acids and esters
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Novel DNA-MMT hybrid supported metal nanoparticle catalysts, such as Pt/DNA-MMT, Pd/DNA-MMT, Au/DNA-MMT, were prepared for application in highly selective aerobic oxidation of primary alcohols to aldehydes, acids and esters, respectively. Taking advantage of the water-soluble reversibility of these catalysts, all the transformations could be performed smoothly in water and reuse of the catalysts has also been accomplished by a very simple phase separation process.
- Tang, Lin,Guo, Xuefeng,Li, Yunfeng,Zhang, Shuai,Zha, Zhenggen,Wang, Zhiyong
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supporting information
p. 5213 - 5215
(2013/06/27)
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- Synthesis, structures, and reactivities of guanidinatozinc complexes and their catalytic behavior in the Tishchenko reaction
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Treatment of a secondary amine (pipH, Bz2NH, Et2NH) with sequentially diethylzinc and N,N′-dicyclohexylcarbodiimide in hexane has afforded in good yield the new crystalline guanidinatozinc complexes. Each has been X-ray and solution NMR spectrally characterized. Three are dimeric (mono)guandinatozinc alkyls, two are dinuclear (tris)guanidinatozinc amides, and one is a homoleptic zinc bis(guanidinate). The reactions of dinuclear (tris)guanidinatozinc amides with diethylzinc and N,N′- dicyclohexylcarbodiimide in the molar ratios of 1:2:1 led to the dimeric (mono)guandinatozinc alkyls; homoleptic zinc bis(guanidinate) with an equimolar portion of diethylzinc also yielded dimeric (mono)guandinatozinc alkyls. Each of the complexes exhibited good to excellent catalytic activity for the solvent-free Tishchenko reaction under mild conditions.
- Li, Jie,Shi, Jingchao,Han, Hongfei,Guo, Zhiqiang,Tong, Hongbo,Wei, Xuehong,Liu, Diansheng,Lappert, Michael F.
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p. 3721 - 3727
(2013/07/26)
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- Alkali metal tert-butoxides, hydrides and bis(trimethylsilyl)amides as efficient homogeneous catalysts for Claisen-Tishchenko reaction
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Shelf-available alkali metal tert-butoxides, hydrides and bis(trimethylsilyl)amides were shown to be highly efficient homogeneous precatalysts for the disproportionation of aldehydes to the corresponding carboxylic esters. Potassium compounds in combination with 18-crown-6 ether could drastically increase the rate of reaction in a few cases. Alternatively, efficient aldol condensations were found for aldehydes possessing an enolizable methylene group at the α-position to the aldehyde functionality. The active species involved in this esterification using any of these alkali metal catalysts is expected to be the metal alkoxide. Potassium compounds were found to be much more efficient when compared to analogous sodium compounds and kinetic studies revealed the rate-determining step to be a second order concerted hydride transfer from a potassium hemiacetal species to another molecule of aldehyde. Copyright
- Rajesh, Kunjanpillai,Berke, Heinz
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supporting information
p. 901 - 906
(2013/05/08)
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- Transition-metal-free aerobic oxidative cleavage of C-C bonds in α-hydroxy ketones and mechanistic insight to the reaction pathway
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Clear cut: For the title reaction, O2, the ideal oxidant, was used as the only oxidizing reagent. The dimer intermediate (see scheme) and isotopic labeling control experiments with 18O2 partially disclosed the reaction mec
- Liu, Hui,Dong, Chao,Zhang, Zeguang,Wu, Peiyu,Jiang, Xuefeng
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supporting information
p. 12570 - 12574
(2013/02/22)
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- The thiolate-catalyzed intermolecular crossed tishchenko reaction: Highly chemoselective coupling of two different aromatic aldehydes
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Crossed products: Ortho-substituted benzaldehydes react with other aromatic aldehydes in a highly selective, atom-economical Tishchenko disproportionation (see scheme) in the presence of a readily prepared, inexpensive thiolate-based catalyst. The methodo
- Curran, Simon P.,Connon, Stephen J.
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supporting information
p. 10866 - 10870
(2013/01/15)
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- Photolytic decomposition of dibenzylic sulfites
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The photolytic decay of a library of para-substituted dibenzylic sulfites has been evaluated by UV radiation in a Srinivasan-Griffin-Rayonet photochemical reactor in various deuterated solvents. The decay for each dibenzylic sulfite was examined with respect to Swain and Lupton's field constant, F. The rate of photolytic decay varies depending on the identity of the benzyl substituents. Furthermore, it has been observed that the solvent affects both the rate of sulfite photolytic decay as well as final product distribution.
- Grenga, Paolo N.,Stoutenburg, Eric G.,Priefer, Ronny
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p. 4933 - 4937
(2012/11/13)
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- 4-N,N-dimethylaminopyridine promoted selective oxidation of methyl aromatics with molecular oxygen
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4-N,N-Dimethylaminopyridine (DMAP) as catalyst in combination with benzyl bromide was developed for the selective oxidation of methyl aromatics. DMAP exhibited higher catalytic activity than other pyridine analogues, such as 4-carboxypyridine, 4-cyanopyridine and pyridine. The sp3 hybrid carbon-hydrogen (C-H) bonds of different methyl aromatics were successfully oxygenated with molecular oxygen. The real catalyst is due to the formation of a pyridine onium salt from the bromide and DMAP. The onium salt was well characterized by NMR and the reaction mechanism was discussed.
- Zhang, Zhan,Gao, Jin,Wang, Feng,Xu, Jie
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experimental part
p. 3957 - 3968
(2012/07/27)
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- Dehydrogenation of alcohols under ambient atmosphere by a recyclable sol-gel encaged iridium pincer catalyst
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We demonstrate that a sol-gel entrapped iridium-pincer catalyst 1 is capable of promoting acceptorless dehydrogenation of primary and secondary alcohols. Although the dehydrogenations by the non-heterogenized catalyst are faster than by the sol-gel encaged complex, recyclability and significant stabilization of the organometallic species toward non-inert conditions represent a clear advantage from the environmental and practical points of view.
- Oded, Kobi,Musa, Sanaa,Gelman, Dmitri,Blum, Jochanan
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experimental part
p. 68 - 70
(2012/06/16)
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- Ligand-metal cooperation in pcppincer complexes: Rational design and catalytic activity in acceptorless dehydrogenation of alcohols
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A helping hand: The dibenzobarrelene-based PCsp3Ppincer complex 1 was designed as a bifunctional catalyst for the acceptorless dehydrogenation of alcohols. The mechanism of the H2 release involves interaction between the hydride ligand and the acidic sidearm in the intermediate 2 (red O, yellow Cl, green P, blue Ir). The feasibility of the complete catalytic cycle was studied using a stoichiometric model and the reaction was subsequently realized in a catalytic fashion. Copyright
- Musa, Sanaa,Shaposhnikov, Irina,Cohen, Shmuel,Gelman, Dmitri
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supporting information; experimental part
p. 3533 - 3537
(2011/04/27)
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- Organoactinides promote the dimerization of aldehydes: Scope, kinetics, thermodynamics, and calculation studies
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Surprising catalytic activities have been found for the actinide complexes Cp*2ThMe2 (1), Th(NEtMe)4 (2), and Me2SiCp″2Th(C4H9) 2(3) toward oxygenated substrates. During the catalytic dimerization of benzaldehydes to their corresponding esters, complexes 1 and 2 gave 65 and 85% yield in 48 h, respectively, while the geometry-constrained complex 3 gave 96% yield in 24 h. Exploring the effect of substituents on benzaldehyde, it has been found that, in general, electron-withdrawing groups facilitate the reaction. Kinetic study with complexes 1 and 3 reveals that the rate of the reaction is first order in catalyst and substrate, which suggests the rate equation "rate = k[catalyst]1[aldehyde]1". The activation energy of the reaction was found to be 7.16 ± 0.40 and 3.47 ± 0.40 kcal/mol for complexes 1 and 3 respectively, which clearly indicates the advantage of the geometry-constrained complex. Astonishing are the reactivity of the organoactinide complexes with oxygen-containing substrates, and especially the reactivity of complex 3, toward the dimerization of substrates like p-methoxybenzaldehyde, m/p-nitrobenzaldehyde, and furanaldehyde and the reactivity toward the polymerization of terephthalaldehyde. Density functional theory mechanistic study reveals that the catalytic cycle proceeds via an initially four-centered transition state (+6 kcal/mol), followed by the rate-determining six-centered transition state (+13.5 kcal/mol), to yield thermodynamically stable products.
- Sharma, Manab,Andrea, Tamer,Brookes, Nigel J.,Yates, Brian F.,Eisen, Moris S.
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experimental part
p. 1341 - 1356
(2011/04/16)
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- Tunable bromomagnesium thiolate tishchenko reaction catalysts: Intermolecular aldehyde-trifluoromethylketone coupling
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(Figure Presented) Applied knowledge: A new thiolate-catalyzed Tishchenko reaction inspired by biochemical processes features exceptionally good control over the catalyst's steric/electronic properties. The isolation of reaction intermediates provided valua-ble insights into the reaction mechanism, which in turn has allowed the development of the first cross-Tishchenko coupling reactions between aldehydes and activated ketones (see example).
- Cronin, Linda,Manoni, Francesco,O'Connor, Cornelius J.,Connon, Stephen J.
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supporting information; experimental part
p. 3045 - 3048
(2010/07/05)
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- Sodium hydride catalyzed Tishchenko reaction
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A convenient and practical method for the dimerization of aldehydes is described. The conversion of aromatic and even heteroaromatic aldehydes in the presence of catalytic amounts of sodium hydride leads to the corresponding Tishchenko esters in high yields (up to 95 %). The reaction can be performed under standard laboratory conditions and on a multigram scale (up to 10 g). The use of catalytic amounts of sodiumhydride as an efficient promoter for the dimerization of aromatic and even heteroaromatic aldehydes under standard laboratory conditions is reported. A range of substituted aromatic and heteroaromatic aldehydes was converted, and the corresponding esters were obtained in good to excellent yields even on a multigram scale. Copyright
- Werner, Thomas,Koch, Juliane
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supporting information; experimental part
p. 6904 - 6907
(2011/02/23)
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- An environmentally benign solvent-free Tishchenko reaction
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Herein, we describe the solvent-free ball milling Tishchenko reaction. Using high speed ball milling and a sodium hydride catalyst, the Tishchenko reaction was performed for aryl aldehydes in high yields in 0.5 hours. The reaction is not affected by the type of ball bearing used and can be successful when conducted in a liquid nitrogen environment.
- Waddell, Daniel C.,Mack, James
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experimental part
p. 79 - 82
(2010/04/22)
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- Mild amidation of aldehydes with amines mediated by lanthanide catalysts
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(Chemical Equation Presented) Catalytic amidation of aldehydes with amines is efficiently mediated by homoleptic lanthanide amido complexes, Ln[N(SiMe 3)2]3 (Ln = La, Sm, and Y). Amidation reactivity follows the trend: La > Sm ≈ Y. These reactions proceed in high yield without added oxidants, bases, and/or heat or light, which are usually required in other catalytic amidation processes. The reaction is demonstrated with a variety of amines, with yields as high as 98% based on amine.
- Seo, SungYong,Marks, Tobin J.
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p. 317 - 319
(2008/09/19)
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- Organoactinides promote the Tishchenko reaction: The myth of inactive actinide-alkoxo complexes
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For many decades, compounds containing oxygen atoms were excluded from the actinide-catalysis field because of the high oxophilic nature of these complexes. Pursuing the conceptual question about the potential activity of actinide-oxo bonds we were surprised to find that the coupling of aromatic aldehydes catalyzed by Cp*2ThMe2 and Th(NEtMe)4 via thorium-alkoxide intermediates takes place in high yields to produce the corresponding esters. In this paper we present our breakthrough results including comprehensive mechanistic, deuterium labeling, kinetic, and thermodynamic studies. A plausible mechanism is presented taking into account as well the thermochemistry of the process. Copyright
- Andrea, Tamer,Barnea, Eyal,Eisen, Moris S.
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p. 2454 - 2455
(2008/09/18)
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- Lithium bromide as a flexible, mild, and recyclable reagent for solvent-free cannizzaro, tishchenko, and meerwein-ponndorf-verley reactions
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A room temperature convenient disproportionation or reduction of aldehydes prompted by lithium bromide and triethylamine is described in a solvent-free environment. Distribution of the products to selectively direct the process toward Cannizzaro or Tishchenko reactions is controlled by the type of workup selection. The presence of hydrogen donor alcohols in the mixture completely diverts the process toward the MeerweinPonndorf-Verley reaction.
- Mojtahedi, Mohammad M.,Akbarzadeh, Elahe,Sharifi, Roholah,Abaee, M. Saeed
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p. 2791 - 2793
(2008/02/05)
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- Iridium-catalyzed oxidative dimerization of primary alcohols to esters using 2-butanone as an oxidant
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Oxidative dimerization of primary alcohols with 2-butanone in the presence of an amino alcohol-based Ir bifunctional catalyst was accomplished for the first time. The reaction proceeds with 1-2 mol% of the catalyst and 0.3 mol equivalents of K2CO3 in 2-butanone at room temperature to give the corresponding dimeric esters in 30-93% yield. Georg Thieme Verlag Stuttgart.
- Suzuki, Takeyuki,Matsuo, Tomohito,Watanabe, Kazuhiro,Katoh, Tadashi
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p. 1453 - 1455
(2007/10/03)
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- Tishchenko reaction using an iridium-ligand bifunctional catalyst
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Tishchenko reaction of aldehydes in the presence of an amino alcohol-based Ir bifunctional catalyst was developed. The reaction proceeds with 1 mol% of the catalyst and 20-30 mol% of K2CO3 in acetonitrile at room temperature to give the corresponding dimeric esters in good yield. Georg Thieme Verlag Stuttgart.
- Suzuki, Takeyuki,Yamada, Taichiro,Matsuo, Tomohito,Watanabe, Kazuhiro,Katoh, Tadashi
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p. 1450 - 1452
(2007/10/03)
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- Modification of mesoporous silicate SBA-15 with tris[bis(trimethylsilyl) amido]samarium and its utility in Tishchenko reaction
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Treatment of mesoporous silicate SBA-15 with Sm[N(SiMe3) 2]3 led to the formation of a novel organolanthanide/ inorganic hybrid material [SBA-15]Sm[N(SiMe3)2] x via abstraction of N(SiMe3)2 by terminal silanol groups and subsequent surface silylation. The hybrid material was characterized by elemental analyses, IR spectroscopy, X-ray diffraction, and nitrogen sorption, indicating a successful tailoring inside the silicate SBA-15 and the maintenance of the well-ordered mesostructure. This hybrid material is a promising heterogeneous catalyst for the Tishchenko reaction, where it is superior to the homogeneous correspondent in deactivation behavior, reusability and relative tolerance to oxygen, particularly in the control of selectivity of mixed Tishchenko reaction due to the steric hindrance and the diffusion control derived from the surface confinement.
- Chen, Yinghua,Zhu, Zhenyu,Zhang, Jie,Shen, Jianzhong,Zhou, Xigeng
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p. 3783 - 3789
(2007/10/03)
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- Catalytic oxidation of alcohols with allyl diethyl phosphate and palladium acetate
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Allyl diethyl phosphate (ADP) was found to function as a stoichiometric hydrogen acceptor in a catalytic oxidation reaction of alcohols with Pd(OAc)2. A variety of acyclic primary and secondary alcohols were oxidized in good yields and under mild conditions to the corresponding aldehydes and ketones, in the presence of Na2CO3 or K2CO3. Simple aliphatic primary alcohols yielded esters, exclusively. Polar ligand solvents (DMF, DMSO) were found to accelerate the reaction. Slow, but high yield reactions were encountered in THF and acetonitrile as solvents. The reactivity of several other allyl systems serving as H-acceptors, and several Pd compounds serving as catalysts, in the above oxidation reaction, was evaluated. It has been experimentally demonstrated (H-NMR) that ADP is capable of generating a π-allyl-Pd complex using a Pd(0) complex. Consequently, a catalytic cycle was proposed for the above oxidation reaction.
- Shvo, Youval,Goldman-Lev, Vered
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p. 151 - 156
(2007/10/03)
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- Homoleptic lanthanide amides as homogeneous catalysts for alkyne hydroamination and the Tishchenko reaction
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The homoleptic bis(trimethylsilyl)amides of Group 3 metals and lanthanides of the general type [Ln{N(SiMe3)2}3] (1) (Ln = Y, lanthanide) represent a new class of Tishchenko precatalysts and, to a limited extent, precatalysts for the hydroamination/cyclization of aminoalkynes. It is shown that 1 is the most active catalyst for the Tishchenko reaction. This contribution presents investigations on the scope of the reaction, substrate selectivity, lanthanide-ion size-effect, and kinetic/ mechanistic aspects of the Tishchenko reaction catalyzed by 1. The turnover frequency is increased by the use of large-center metals and electron-with-drawing substrates. The reaction rate is second order with respect to the substrate. While donor atoms, such as nitrogen, oxygen, or sulfur, on the substrate decrease the turnover frequency, 1 shows a tolerance for a large number of functional groups. For the hydroamination/cyclization of aminoalkynes, 1 is less active than the well-known metallocene catalysts. On the other hand, 1 is much more readily accessible (one-step synthesis or commercially available), than the metallocenes and might therefore be an attractive alternative catalyst.
- Buergstein, Markus R.,Berberich, Helga,Roesky, Peter W.
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p. 3078 - 3085
(2007/10/03)
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- Simple Syntheses, Structural Diversity, and Tishchenko Reaction Catalysis of Neutral Homoleptic Rare Earth(II or III) 3,5-Di-tert-butylpyrazolates - The Structures of [Sc(tBu2pz)3], [Ln2(tBu2pz)6] (Ln = La, Nd, Yb, Lu), and [Eu4(tB2pz)8]
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The homoleptic rare-earth pyrazolate complexes [Sc(tBu2pz)3], [Ln2(tBu2pz)6] (Ln = La, Nd, Sm, Lu), [Eu4(tBu2pz)8] and the mixed oxidation state species [Yb2(tBu2pz)5] (tBu2pz = 3,5-di-tert-butylpyrazolate) have been prepared by a simple reaction between the corresponding rare-earth metal and 3,5-di-tert-butylpyrazole, in the presence of mercury, at elevated temperatures. In addition, [Yb2(tBu2pz)6] was prepared by redox transmetallation/ligand exchange between ytterbium, diphenylmercury(II) and tBu2pzH in toluene, whilst the same reactants in toluene under different conditions or in diethyl ether gave [Yb2(tBu2pz)5]. The complexes of the trivalent lanthanoids display dimeric structures [Ln2(tBu2pz)6] (Ln = La, Nd, Yb, Lu) with chelating η-terminal and η2:η2-bridging pyrazolate coordination. The considerably smaller Sc(3+) ion forms monomeric [Sc(tBu2pz)3] of putative D3h molecular symmetry, with pyrazolate ligands solely η2-bonded. [Eu4(tBu2pz)8] is a structurally remarkable tetranuclear Eu(II) complex with two types of europium centres in a linear array. The outer two are bonded to one terminal and two bridging pyrazolates, and the inner two are coordinated by four bridging ligands. Unprecedented μ-η5:η2 pyrazolate ligation is observed, with each outer Eu(2+) sandwiched between two η5-bonded pyrazolate groups, which are also η2-linked to an inner Eu(2+). The two inner Eu(2+) ions are linked together by two equally occupied components of each of two symmetry related, disordered pyrazolate groups with one component η4:η2 bridging and one η3:η2 bridging. [La2(tBu2pz)6] has also been shown to be a Tishchenko reaction catalyst with several organic substrates.
- Deacon, Glen B.,Gitlits, Alex,Roesky, Peter W.,Buergstein, Markus R.,Lim, Kevin C.,Skelton, Brian W.,White, Allan H.
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p. 127 - 138
(2007/10/03)
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- Lanthanoid-catalysed Tishchenko reaction of mono- or di-aldehydes
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Lanthanoid complexes are found to be very active catalysts for the Tishchenko reaction of aldehydes. In the presence of Cp*2LnCH(SiMe3)2 (Ln = Nd, La), esters are obtained from corresponding monoaldehydes in high yields. This method is applicable to dialdehydes. The reaction of o-phthalaldehyde proceeds intramolecularly to give phthalide quantitatively. Terephthalaldehyde and di(4-formylphenyl) ether are cleanly converted into the poly[p-(carboxymethylene)phenylene] (II) and poly[p-(carboxymethylene)(p-phenylenoxy)phenylene] (III), respectively. On the other hand, isophthalaldehyde polymerizes first and then the polymer is transformed into a macrocyclic lactone 1,5,11-trioxo-2,4;8,10;14,16-tribenzo-6,12,18-trioxacyclooctadecane (1-a) in high yields. The 18-membered macrocyclic structure of 1-a was determined by the X-ray analysis. Stoichiometric reactions of the La complex with benzaldehyde indicated the intermediacy of alkoxo complexes in the catalysis.
- Onozawa, Shun-Ya,Sakakura, Toshiyasu,Tanaka, Masato,Shiro, Motoo
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p. 4291 - 4302
(2007/10/03)
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- Homogeneous Metal-Catalyzed Sequential Rosenmund-Tishchenko Reactions
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Esters can be isolated in good yields by the reaction of acid chlorides with hydrogen in the presence of 2,4,6-collidine and catalytic quantities of either (Ph3P)3Ru(H)Cl or (Ph3P)RuCl2 in toluene.Acrylruthenium hydrides are possible reaction intermediates.
- Grushin, Vladimir V.,Alper, Howard
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p. 5159 - 5161
(2007/10/02)
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- Trimethylamine-Borane a Useful Reagent in the One-Pot Preparation of Carboxylic Esters from Carboxylic Acids
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The carboxylic esters 2a-h (R1CO2CH2R1) and 4a-d (R1CO2CH2R2) are synthesized from alkyl or aryl carboxylic acids, a one-pot reaction involving in situ reduction followed by esterification, both steps are mediated by trimethylamine-borane.
- Trapani, Giuseppe,Reho, Antonia,Latrofa, Andrea,Liso, Gaetano
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p. 853 - 854
(2007/10/02)
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- CHEMISTRY OF ORGANOLANTHANOIDS: LANTHANOID-CATALYZED TISHCHENKO CONDENSATION OF ALDEHYDES TO ESTERS
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Ethyllanthanoid iodide complex, 'EtLnI', prepared from Ln (Ln=Pr, Nd, Sm) and EtI, have been found to serve as catalyst precursor for the Tischenko condensation of aldehydes such as benzaldehyde, p-chlorobenzaldehyde, p-tolualdehyde, p-anisaldehyde, and pivalaldehyde, to corresponding esters.
- Yokoo, Kazuhiro,Mine, Norioko,Taniguchi, Hiroshi,Fujiwara, Yuzo
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p. C19 - C21
(2007/10/02)
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- Carbon-Carbon Bond-Forming Reactions Using Cerium Metal or Organocerium(III) Reagents
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Carbon-carbon bond-forming reactions using cerium metal or organocerium(III) reagents have been investigated.Cerium amalgam is an effective reagent for the chemoselective preparation of homoallylic alcohols from allyl halides and carbonyl compounds.These same reagent can also be satisfactorily employed for the Reformatsky-type reaction of α-halo esters with carbonyl compounds.It has been shown that organocerium(III) reagents are conveniently generated by the reaction of organolithiums with cerium(III)iodide or cerium(III)chloride.The reagents are less basic thanorganolithiums or Grignard reagents, and they react cleanly at -78 to -65 deg C with various carbonyl compounds to afford the addition products in high yields, even though the substrates are susceptible to enolization or metal-halogen exchange with simple organolithiums.The same reagents react also with α,β-unsaturated compounds to yield 1,2-addition products in high selectivity.
- Imamoto, Tsuneo,Kusumoto, Tetsuo,Tawarayama, Yoshinori,Sugiura, Yasushi,Mita, Takeshi,et al.
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p. 3904 - 3912
(2007/10/02)
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