- Catalytic asymmetric cyanoethoxycarbonylation of aldehydes using self-assembled titanium catalysts
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A new self-assembled titanium catalyst system has been developed for the asymmetric cyanoethoxycarbonylation of aldehydes which produced the desired products in moderate to excellent yields (up to 99%) with high enantioselectivities (up to 94% ee) under m
- Wang, Wentao,Gou, Shaohua,Liu, Xiaohua,Feng, Xiaoming
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Read Online
- Asymmetric cyanoethoxycarbonylation of aldehydes catalyzed by heterobimetallic aluminum lithium bis(binaphthoxide) and cinchonine
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Highly efficient catalytic asymmetric cyanoethoxycarbonylation of aldehydes was achieved by 10 mol% cinchonine with 10 mol% heterometallic (S)-aluminum lithium bis(binaphthoxide), which gave the cyanohydrins ethyl carbonates in excellent isolated yields (
- Gou, Shaohua,Wang, Jun,Liu, Xiaohua,Wang, Wentao,Chen, Fu-Xue,Feng, Xiaoming
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Read Online
- Catalytic, Asymmetric Synthesis of Cyanohydrin Ethyl Carbonates
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(Equation presented) The bimetallic titanium complex [(salen)TiO] 2, where salen is the ligand derived from (R,R)-cyclohexanediamine and 3,5-di-tert-butyl-salicylaldehyde, has been shown to catalyze the asymmetric addition of ethyl cyanoformate
- Belokon, Yuri N.,Blacker, A. John,Clutterbuck, Lisa A.,North, Michael
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Read Online
- Tuning the Catalytic Activity of Tertiary-Amine Functionalized Polyacrylonitrile Fibers by Adjusting the Surface Microenvironment
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Polyacrylonitrile fibers were functionalized with different amines to construct special tridimensional catalytic microenvironments at the surface. The polarity of the microenvironments at the surface of the fiber catalyst was tuned by changing the ratio o
- Li, Pengyu,Liu, Yuanyuan,Cao, Jian,Tao, Minli,Zhang, Wenqin
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- Highly enantioselective cyanation of aldehydes catalyzed by a multicomponent titanium complex
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A new multicomponent bifunctional catalytic system based on a titanium complex was used for the efficient enantioselective cyanation of aldehydes. The catalyst was readily prepared from tetraisopropyl titanate (Ti(Oi-Pr) 4), (S)-6,6′-dibromo-1,
- Gou, Shaohua,Chen, Xiaohong,Xiong, Yan,Feng, Xiaoming
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Read Online
- Highly enantioselective cyanoformylation of aldehydes catalyzed by a mononuclear salen-Ti(OiPr)4 complex produced in situ
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An efficient enantioselective cyanoformylation of aldehydes with ethyl cyanoformate, catalyzed by a salen-Ti(OiPr)4 complex generated in situ, has been developed. Studies of non-linear effects indicated that the mononuclear salen-titanium compl
- Chen, Shi-Kui,Peng, Dan,Zhou, Hui,Wang, Li-Wei,Chen, Fu-Xue,Feng, Xiao-Ming
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Read Online
- Kinetics and mechanism of base catalysed ethyl cyanoformate addition to aldehydes Dedicated to the memory of Professor Sandy McKillop
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The mechanism by which tertiary amines catalyse the formation of cyanohydrin carbonates from aldehydes and alkyl cyanoformates is investigated by means of a kinetic study. The reaction rate shows a second order dependence on amine concentration unless the
- North, Michael,Urwin, Stephanie
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Read Online
- Asymmetric cyano-ethoxycarbonylation of aldehydes catalyzed by self-assembled titanium catalyst
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A new self-assembled catalyst based on titanium complex has been developed for the effective enantioselective cyano-ethoxycarbonylation of aldehydes. The self-assembled catalyst was readily prepared from (R)-3,3′-bis((methyl((S)-1-phenylethyl)amino)methyl
- Gou, Shaohua,Liu, Xiaohua,Zhou, Xin,Feng, Xiaoming
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Read Online
- Consecutive reactions to construct tricarbonyl compounds and synthetic applications thereof
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Lithium anions derived from O-carbonate-protected cyanohydrins undergo conjugate addition to cycloalkenones with the concomitant transfer of the alkoxycarbonyl group to produce tricarbonyl compounds. These products offer numerous possibilities for further
- Madro?ero, Diego,Mujica-Martinez, Cesar A.,Vázquez, Alfredo
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p. 33235 - 33244
(2021/12/09)
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- Efficient synthesis in water of mixed carbonates of cyanohydrins from aromatic aldehydes
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An efficient preparation of cyanohydrin ethyl carbonates via cyanocarbonation of aromatic and hetero-aromatic aldehydes with sodium cyanide and ethyl chlorocarbonate using commercial surfactants (5 mol %) in aqueous media at low temperature afforded almos
- Héctor Manuel, Torres Domínguez,Luis ángel, Maldonado,Ronan, Le Lagadec
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supporting information
(2019/12/11)
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- Asymmetric Carboxycyanation of Aldehydes by Cooperative AlF/Onium Salt Catalysts: from Cyanoformate to KCN as Cyanide Source
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Asymmetric 1,2-additions of cyanide yield enantioenriched cyanohydrins as versatile chiral building blocks. Next to HCN, volatile organic cyanide sources are usually used. Among them, cyanoformates are more attractive on technical scale than TMSCN for cos
- Brodbeck, Daniel,álvarez-Barcia, Sonia,Meisner, Jan,Broghammer, Florian,Klepp, Julian,Garnier, Delphine,Frey, Wolfgang,K?stner, Johannes,Peters, René
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supporting information
p. 1515 - 1524
(2019/01/09)
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- Bifunctional Schiff base/Ti(IV) catalysts for enantioselective cyanoformylation of aldehydes with ethyl cyanoformate
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A new bifunctional titanium/Schiff base catalyst was developed for the enantioselective cyanoformylation of aldehydes with ethyl cyanoformate. The reaction proceeded smoothly with a mild reaction condition to afford the cyanohydrin ethyl carbonates in hig
- Ji, Nan,Yao, Lin,He, Wei,Li, Yurong
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p. 209 - 213
(2013/05/08)
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- Enantioselective O-acetylcyanation/cyanoformylation of aldehydes using catalysts with built-in crown ether-like motif in chiral macrocyclic V(V) salen complexes
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Chiral macrocyclic V(V) salen complexes 1a-f derived from macrocyclic ligands obtained by the reaction of 1R,2R-(-) diaminocyclohexane/(1R,2R)-(+)-1, 2-diphenylethylenediamine with bis-aldehydes 2 and 3 were synthesized and used as efficient catalysts in asymmetric cyanation reactions. The V(V) catalysts demonstrated excellent performance (product yields and ees up to 99%) with potassium cyanide (KCN) and sodium cyanide (NaCN). The catalytic system also performed very well with a safer source of cyanide-ethyl cyanoformate to give cyanohydrin carbonates in excellent yield and ee (up to 97%). The V(V) macrocyclic salen complex 1b retained its performance at multi-gram level and was conveniently recycled for a number of times.
- Khan, Noor-Ul H.,Sadhukhan, Arghya,Maity, Nabin C.,Kureshy, Rukhsana I.,Abdi, Sayed H.R.,Saravanan,Bajaj, Hari C.
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scheme or table
p. 7073 - 7080
(2011/10/07)
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- N-heterocyclic carbene catalyzed cyanation reaction of carbonyl compounds with ethyl cyanoformate and acetyl cyanide
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N-heterocyclic carbene (NHC) has been employed as an efficient catalyst for cyanation reaction of carbonyl compounds. Under catalysis of 1 mol % NHCs, various aldehydes and 2,2,2-trifluoroacetophenone coupled with ethyl cyanoformate in THF to provide cyanohydrins ethyl carbonates in excellent yields. While in the presence of 10 mol % catalyst, different types of aldehydes and 2,2,2-trifluoroacetophenone reacted with acetyl cyanide in dichloroethane to give acylated cyanohydrins in moderate to high yields.
- Zhang, Jie,Du, Guangfen,Xu, Yueke,He, Lin,Dai, Bin
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supporting information; experimental part
p. 7153 - 7156
(2012/01/05)
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- METHOD OF PRODUCING AN OPTICALLY ACTIVE CYANOHYDRIN DERIVATIVE
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The present invention relates to a method of producing an optically active cyanohydrin derivative, which comprises reacting an aldehyde or an asymmetrical ketone with a cyanating agent in the presence of a Lewis base and a titanium compound produced from
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Page/Page column 17-18
(2010/08/03)
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- Enantioselective cyanoformylation of aldehydes catalyzed with solid base mediated chiral V(V) salen complexes
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Polymeric and monomeric V(V) chiral salen complexes-catalyzed enantioselective ethyl cyanoformylation of aldehydes using ethyl cyanoformate as a source of cyanide was accomplished in the presence of several basic cocatalysts viz., NaOH, KOH, basic Al
- Khan, Noor-Ul H.,Agrawal, Santosh,Kureshy, Rukhsana I.,Abdi, Sayed H. R.,Pathak, Kavita,Bajaj, Hari C.
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experimental part
p. 153 - 158
(2010/09/04)
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- DMAP-catalyzed cyanation of aldehydes and ketones with ethyl cyanoformate
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The cyanation of carbonyl compounds with ethyl cyanoformate is catalyzed by 4-dimethylaminopyridine (DMAP) to afford the corresponding cyanohydrin carbonates in excellent yields. The system provides a convenient method for cyanation of carbonyl compounds
- Aoki, Shohei,Kotani, Shunsuke,Sugiura, Masaharu,Nakajima, Makoto
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experimental part
p. 3547 - 3549
(2010/08/07)
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- Ionic liquid as catalytic and reusable media for cyanoethoxycarbonylation of aldehydes
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Various ionic liquids (IL 1-9) based on N-methyl N'-alkyl imidazolium salts were explored as catalytic media in cyanoethoxycarbonylation of various aldehydes. The study revealed that the alkyl chain length and counter ion of the ionic liquid are critical
- Khan, Noor-Ul H.,Agrawal, Santosh,Kureshy, Rukhsana I.,Abdi, Sayed H.R.,Sadhukhan, Arghya,Pillai, Renjith S.,Bajaj, Hari C.
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experimental part
p. 907 - 912
(2010/10/03)
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- N,N-Dimethylpyridin-4-Amine mediated protocol for cyanoethoxycarbonylation of aldehydes under solvent-free conditions
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N,N-Dimethylpyridin-4-amine(DAMP)(10 mol%) was successfully employed as catalyst for cyanoethoxycarbonylation of aromatic and aliphatic aldehydes at room temperature under solvent free condition to give corresponding ethylcyanocarbonates in excellent isol
- Khan, Noor-Ul H.,Agrawal, Santosh,Kureshy, Rukhsana I.,Bera, Prasanta K.,Abdi, Sayed H.R.,Bajaj, Hari C.
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experimental part
p. 255 - 260
(2010/11/05)
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- Asymmetric cyanation of aldehydes, ketones, aldimines, and ketimines catalyzed by a versatile catalyst generated from cinchona alkaloid, achiral substituted 2,2′-biphenol and tetraisopropyl titanate
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Full investigation of cyanation of aldehydes, ketones, aldimines and ketimines with trimethylsilyl cyanide (TMSCN) or ethyl cyanoformate (CNCOOEt) as the cyanide source has been accomplished by employing an in situ generated catalyst from cinchona alkaloid, tetraisopropyl titanate [Ti(OiPr)4] and an achiral modified biphenol. With TMSCN as the cyanide source, good to excellent results have been achieved for the Strecker reaction of N-Ts (Ts=p-toluenesulfonyl) aldimines and ketimines (up to >99% yield and >99% ee) as well as for the cyanation of ketones (up to 99% yield and 98% ee). By using CNCOOEt as the alternative cyanide source, cyanation of aldehyde was accomplished and various enantioenriched cyanohydrin carbonates were prepared in up to 99% yield and 96% ee. Noteworthy, CNCOOEt was successfully employed for the first time in the asymmetric Strecker reaction of aldimines and ketimines, affording various a-amino nitriles with excellent yields and ee values (up to >99% yield and >99% ee). The merits of current protocol involved facile availability of ligand components, operational simplicity and mild reaction conditions, which made it convenient to prepare synthetically important chiral cyanohydrins and examino nitriles. Furthermore, control ex-periments and NMR analyses were performed to shed light on the catalyst structure. It is indicated that all the hydroxyl groups in cinchona alkaloid and biphenol complex with TiIV, forming the catalyst with the structure of (biphenoxide) Ti(OR*)(Oi'Pr). The absolute configuration adopted by biphenol 4 m in the catalyst was identified as S configuration according to the evidence from control experiments and NMR analyses. Moreover, the roles of the protonic additive ((iPrOH) and the tertiary amine in the cinchona alkaloid were studied in detail, and the real cyanide reagent in the catalytic cycle was found to be hydrogen cyanide (HCN). Finally, two plausible catalytic cycles were proposed to elucidate the reaction mechanisms.
- Wang, Jun,Wang, Wentao,Li, Wei,Hu, Xiaolei,Shen, Ke,Tan, Cheng,Liu, Xiaohua,Feng, Xiaoming
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scheme or table
p. 11642 - 11659
(2010/04/28)
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- Enantioselective cyanoformylation of aldehydes organocatalyzed by recyclable cinchonidine ammonium salts
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Enantiomerically enriched O-methoxycarbonyl cyanohydrins were obtained using an enantioselective addition of methyl cyanoformate to aldehydes organocatalyzed by a dimeric anthracenyldimethyl-derived cinchonidine ammonium salt (1 mol % catalyst loading) in the presence of substoichiometric amounts of triethylamine (20 mol %). Aromatic and heteroaromatic aldehydes usually afford high enantioselectivities (up to 96%) and quantitative yields of the corresponding O-methoxycarbonyl cyanohydrins, whereas aliphatic and α,β-unsaturated aldehydes give lower enantioselectivities (up to 60%) in high yields. The observed sense of the enantioselection was always the same, and the organocatalyst was almost quantitatively recovered by ether-promoted precipitation without any loss of activity. The use of resin-supported cinchonidine-derived ammonium salts as an organocatalyst in this transformation was also explored.
- Chinchilla, Rafael,Najera, Carmen,Ortega, Francisco J.,Tari, Silvia
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experimental part
p. 2279 - 2286
(2010/03/03)
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- Vanadium(V) salen complex catalyzed highly enantioselective cyanoformylation of aldehydes in the presence of imidazole as a cocatalyst
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Highly enantioselective cyanoformylation of aldehydes catalyzed by V V chiral salen complex by using ethyl cyanoformate as a source of cyanide was accomplished in the presence of several cocatalysts. Excellent yields and ee values for the resul
- Khan, Noor-Ul H.,Agrawal, Santosh,Kureshy, Rukhsana I.,Abdi, Sayed H. R.,Jeya Prathap,Jasra, Raksh V.
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scheme or table
p. 4511 - 4515
(2009/04/19)
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- METHOD OF PRODUCING AN OPTICALLY ACTIVE CYANOHYDRIN DERIVATIVE
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The present invention relates to a method of producing an optically active cyanohydrin derivative, which comprises reacting an aldehyde or an asymmetrical ketone with a cyanating agent in the presence of a Lewis base and a titanium compound produced from
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Page/Page column 44-47
(2008/12/04)
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- Acid-base bifunctional catalysis of silica-alumina-supported organic amines for carbon-carbon bond-forming reactions
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Acid-base bifunctional heterogeneous catalysts were prepared by the reaction of an acidic silica-alumina (SA) surface with silane-coupling reagents possessing amino functional groups. The obtained SA-supported amines (SA-NR 2) were characterized by solid-state 13C and 29Si NMR spectroscopy, FT-IR spectroscopy, and elemental analysis. The solid-state NMR spectra revealed that the amines were immobilized by acid-base interactions at the SA surface. The interactions between the surface acidic sites and the immobilized basic amines were weaker than the interactions between the SA and free amines. The catalytic performances of the SA-NR 2 catalysts for various carbon-carbon bond-forming reactions, such as cyano-ethoxycarbonylation, the Michael reaction, and the nitro-aldol reaction, were investigated and compared with those of homogeneous and other heterogeneous catalysts. The SA-NR2 catalysts showed much higher catalytic activities for the carbon-carbon bond-forming reactions than heterogeneous amine catalysts using other supports, such as SiO2 and Al 2O3. On the other hand, homogeneous amines hardly promoted these reactions under similar reaction conditions, and the catalytic behavior of SA-NR2 was also different from that of MgO, which was employed as a typical heterogeneous base. An acid-base dual-activation mechanism for the carbon-carbon bond-forming reactions is proposed.
- Motokura, Ken,Tomita, Mitsuru,Tada, Mizuki,Iwasawa, Yasuhiro
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experimental part
p. 4017 - 4027
(2009/05/07)
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- PROCESS FOR THE CYANATION OF ALDEHYDES
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The present invention relates to a process for the cyanation of aldehydes, particularly to the asymmetric cyanation of aldehydes, including the synthesis of chiral cyanohydrins and derivatives thereof, such as chiral O-acyl cyanohydrins. The process of th
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Page/Page column 16
(2008/06/13)
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- Asymmetric cyanohydrin synthesis using heterobimetallic catalysts obtained from titanium and vanadium complexes of chiral and achiral salen ligands
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Titanium(IV)(salen) and vanadium(V)(salen) complexes are both known to form catalysts for asymmetric cyanohydrin synthesis. When a mixture of titanium and vanadium complexes derived from the same or different salen ligands is used for the asymmetric addit
- Belokon, Yuri N.,Clegg, William,Harrington, Ross W.,Young, Carl,North, Michael
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p. 5287 - 5299
(2008/02/02)
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- Enantioselective and diastereoselective syntheses of cyanohydrin carbonates
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A new and general synthesis of alkyl cyanoformates is presented starting from the appropriate alcohol and oxalyl chloride. This is used to prepare enantiomerically pure cyanoformates from enantiomerically pure primary and secondary alcohols. Optimal condi
- Belokon', Yuri N.,Clegg, William,Harrington, Ross W.,Ishibashi, Eisuke,Nomura, Hiroshi,North, Michael
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p. 9724 - 9740
(2008/02/12)
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- Enantioselective cyanoformylation of aldehydes catalyzed by a chiral quaternary ammonium salt and triethylamine
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An efficient enantioselective cyanoformylation of aldehydes with ethyl cyanoformate, catalyzed by a chiral quaternary ammonium salt and triethylamine, has been developed. The reaction can be carried out in excellent yields (up to 97%) with moderate enanti
- Peng, Dan,Zhou, Hui,Liu, Xiaohua,Wang, Liwei,Chen, Shikui,Feng, Xiaoming
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p. 2448 - 2450
(2008/03/28)
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- Neutral π-nucleophile-catalyzed cyanation of aldehydes and ketones
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1-Methoxy-2-methyl-1-(trimethylsiloxy)propene, a neutral π-nucleophile, was found to be able to efficiently catalyze the cyanation (cyanosilylation and cyanocarbonation) of various aldehydes and ketones, and this study provided the first illustration of u
- Wang, Xiu,Tian, Shi-Kai
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p. 1416 - 1420
(2008/03/11)
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- Heterogeneous organic base-catalyzed reactions enhanced by acid supports
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Amorphous silica-alumina-supported amines (SA-NR2) were found to be excellent heterogeneous catalysts for a variety of carbon-carbon bond-forming reactions, such as cyano-O-ethoxycarbonylation, Michael reaction, and nitro-aldol reaction. These reactions were hard to proceed either with amines alone or on the SA alone. Solid-state 13C MAS NMR analysis revealed the acid-base interaction of the H+ site and amine group on the SA-NR2 surface, which makes an acid-base dual activation mechanism possible for carbon-carbon bond-forming reactions. Copyright
- Motokura, Ken,Tada, Mizuki,Iwasawa, Yasuhiro
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p. 9540 - 9541
(2008/02/11)
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- Catalytic asymmetric cyano-ethoxycarbonylation reaction of aldehydes using a novel C2-symmetric chiral N,N′-dioxide titanium complex
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The asymmetric addition of ethyl cyanoformate to a range of aldehydes was efficiently catalyzed by a easily prepared C2-symmetric chiral N,N′-dioxide-Ti(IV) complex in high yields with up to 90% ee under mild conditions. A linear effect between
- Li, Qinghan,Chang, Lu,Liu, Xiaohua,Feng, Xiaoming
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p. 1675 - 1678
(2008/02/04)
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- Cyanide ion cocatalysis in Ti(salen) catalysed asymmetric cyanohydrin carbonate synthesis
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In the presence of potassium cyanide or the potassium cyanide/18-crown-6 complex as a cocatalyst, 1-2 mol% of titanium(salen) complex 1 catalyses the asymmetric addition of achiral cyanoformates to aldehydes, giving cyanohydrin carbonates with high enanti
- Belokon, Yuri N.,Ishibashi, Eisuke,Nomura, Hiroshi,North, Michael
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p. 1775 - 1777
(2008/09/16)
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- Dual Lewis acid-Lewis base activation in enantioselective cyanation of aldehydes using acetyl cyanide and cyanoformate as cyanide sources
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Dual activation by a chiral Lewis acid and an achiral or chiral Lewis base enabled cyanation of both aromatic and aliphatic aldehydes with acetyl cyanide and ethyl cyanoformate to provide direct access to O-acetylated and O-alkoxycarbonylated cyanohydrins
- Lundgren, Stina,Wingstrand, Erica,Penhoat, Mael,Moberg, Christina
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p. 11592 - 11593
(2007/10/03)
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- One-pot chemoenzymatic synthesis of protected cyanohydrins
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In a chemoenzymatic one-pot reaction of ethyl cyanoformate with benzaldehyde catalyzed by the hydroxynitrile lyase from Prunus amygdalus ethoxycarbonylated (R)-mandelonitrile is formed in a highly enatioselective manner. The reaction was performed both in
- Purkarthofer, Thomas,Skranc, Wolfgang,Weber, Hansj?rg,Griengl, Herfried,Wubbolts, Marcel,Scholz, Gerald,P?chlauer, Peter
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p. 735 - 739
(2007/10/03)
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- Synthetic and mechanistic studies on asymmetric cyanohydrin synthesis using a titanium(salen) bimetallic catalyst
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A bimetallic titanium(salen) complex 1 was found to catalyse the asymmetric addition of ethyl cyanoformate to aldehydes. Best results were obtained using 5 mol% of the catalyst at -40°C and under these conditions, both aromatic and aliphatic aldehydes were converted into cyanohydrin carbonates with up to 99% enantiomeric excess. The same catalyst could also be used to catalyse the asymmetric addition of potassium cyanide to aldehydes in the presence of propionic anhydride, leading to cyanohydrin esters. Mechanistic studies showed that the enantiomeric excess of the product increased during the early stages of this reaction. However, by adding a 'sacrificial aldehyde' this effect could be eliminated. The structure of the catalyst in solution was investigated using variable concentration, variable temperature and variable solvent NMR studies. These experiments showed that the catalyst exists as a mixture of monometallic 4 and bimetallic 1 species, a result which is consistent with previous mechanistic studies on the asymmetric addition of trimethylsilyl cyanide to aldehydes and ketones catalysed by the same catalyst. A mechanistic rationale for all of these observations is reported. Synthetic and mechanistic studies on the use of titanium(IV) complexes for asymmetric cyanohydrin synthesis are reported. In addition to synthetic studies on the synthesis of both cyanohydrin esters and cyanohydrin carbonates, mechanistic studies concerning the structure of the catalyst in solution are also described.
- Belokon', Yuri N.,Blacker, A. John,Carta, Paola,Clutterbuck, Lisa A.,North, Michael
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p. 10433 - 10447
(2007/10/03)
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- Synthesis of aryl α-keto esters via the rearrangement of aryl cyanohydrin carbonate esters
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A facile synthesis of aryl α-keto esters is reported involving the rearrangement of aryl cyanohydrin carbonate esters induced by the α-carbanion to the nitrile group generated by LDA. However, under similar conditions, an o-benzyloxycyanohydrin carbonate ester rearranged via a domino reaction leading to 2-phenylbenzofuran-3-carboxylic acid.
- Thasana, Nopporn,Prachyawarakorn, Vilailak,Tontoolarug, Sopchok,Ruchirawat, Somsak
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p. 1019 - 1021
(2007/10/03)
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- An asymmetric cyanation reaction and sequential asymmetric cyanation-nitroaldol reaction using a [YLi3{tris(binaphthoxide)}] single catalyst component: Catalyst tuning with achiral additives
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Two catalysts in one! Catalyst tuning with achiral additives effectively constructed and reconstructed a chiral environment around the catalyst [YLi3{tris(binaphthoxide)}], which enabled tandem asymmetric catalysis from achiral substrates using
- Tian, Jun,Yamagiwa, Noriyuki,Matsunaga, Shigeki,Shibasaki, Masakatsu
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p. 3636 - 3638
(2007/10/03)
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- Base-Promoted Rearrangement of Carbonate Esters Derived from Aldehyde Cyanohydrins: Application to the Synthesis of α-Keto Esters
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Acylation of the cyanohydrin derivative (2) of representative aldehydes with ethyl chloroformate, followed by treatment of the corresponding mixed carbonate esters (3) with lithium hexamethyldisilazide, afforded the cyanohydrin derivative (4) of α-keto esters.Cleavage of the latter (4) with 2,6-lutidine in the presence of silver nitrate led to the procurement of α-keto esters in >50percent overall yield.
- Babler, James H.,Marcuccilli, Charles J.,Oblong, John E.
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p. 1831 - 1836
(2007/10/02)
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- Trimethylsilyl Cyanide - A Reagent for Umpolung, XI. On the Ambident Character of Substituted Allylic Anions.
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The dependence of the α/γ-ratio of alkylation products on several factors has been determined with 1-cyano-3-aryl-1-(trimethylsiloxy)allylic anions.Increasing amounts of γ-product are found in more polar solvents, with larger alkali ions, on addition of HMPT, with smaller alkyl groups in the electrophile, and especially with p-cyanophenyl groups.In contrast, temperature and leaving groups have minor effects.On substitution of the O-silyl group by O-methyl and O-ethoxycarbonyl, α-alkylation predominates strongly.The results are compared to known allylic anions.Furthermore, the isomerisation of compounds of type C to type B is described as well as a new addition reaction of cyanoformates to aldehydes.
- Huenig, Siegfried,Reichelt, Helmut
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p. 1772 - 1800
(2007/10/02)
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- CYANO-CARBONATES (I) - EFFICIENT LATENT ACYL CARBANIONS
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Cyano-carbonates, conveniently prepared in excellent yields by in situ trapping of cyanohydrin anions with chloroformates under PTC conditions, have been found to be efficient ketone precursors.
- Au, Andrew T.
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p. 743 - 748
(2007/10/02)
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- CYANO-CARBONATES (II) - EFFICIENT LATENT ACYL CARBANIONS IN 1,4-ADDITIONS
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Alkylations of cyano-carbonate anions with ethyl acrylate or methyl vinyl ketone followed by hydrolysis yield 1,4-addition products in excellent yields.
- Au, Andrew T.
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p. 749 - 754
(2007/10/02)
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