- Straightforward access to high-performance organometallic catalysts by fluoride activation: Proof of principle on asymmetric cyanation, asymmetric Michael addition, CO2 addition to epoxide, and reductive alkylation of amines by tetrahydrofuran
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We demonstrate that well-known transition metal catalysts can be transformed into high-performance versions by the simple use of a fluoride anion source. In situ fluoride-activated catalysts are highly active catalytic species. The isolation may lead to degradation of the species or a decrease in catalytic activity. Fluoride activation of known, relatively simple catalysts resulted in the development of one of the most efficient catalytic systems for the asymmetric cyanation of aldehydes, asymmetric Michael addition, and synthesis of cyclic carbonates. Furthermore, the fluoride-assisted reductive opening of tetrahydrofuran (THF) with amines was developed. We believe that the proposed approach can find broad applications in the enhancement of known catalytic processes and in the design of new ones.
- Chusov, Denis,Tsygankov, Alexey A.
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p. 13077 - 13084
(2021/11/01)
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- Homochiral BINAPDA-Zr-MOF for Heterogeneous Asymmetric Cyanosilylation of Aldehydes
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A new homochiral BINAPDA-Zr-MOF was prepared by a new chiral organic linker of (R)-4,4′-(6,6′-dichloro-2,2′-diethoxyl-[1,1′-binaphthalene]-4,4′-diyl)dibenzoic acid (R-L) and ZrCl4 under solvothermal conditions. Its structure was determined by P
- Jin, Fa-Zheng,Zhao, Chen-Chen,Ma, Hui-Chao,Chen, Gong-Jun,Dong, Yu-Bin
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p. 9253 - 9259
(2019/07/08)
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- Chiral Metal-Organic Framework Decorated with TEMPO Radicals for Sequential Oxidation/Asymmetric Cyanation Catalysis
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A chiral porous metal-organic framework (MOF) decorated with radicals has been successfully constructed by cocrystallizing achiral (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO)-substituted tricarboxylate and enantiopure VO(salen)-derived dipyridine ligands. The chiral MOF can function as an efficient heterogeneous catalyst for the sequential alcohol oxidation/asymmetric cyanation of aldehyde reactions with enhanced activity and enantioselectivity compared to the homogeneous counterpart.
- Li, Zijian,Liu, Yan,Kang, Xing,Cui, Yong
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supporting information
p. 9786 - 9789
(2018/08/28)
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- Preparation of chitosan-supported urea materials and their application in some organocatalytic procedures
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An efficient and mild procedure was developed for the preparation of three chitosan-supported ureas containing electron-withdrawing groups. These catalysts were characterized and employed as organocatalysts in different transformations, including the enan
- de Gonzalo, Gonzalo,Franconetti, Antonio,Fernández, Rosario,Lassaletta, José M.,Cabrera-Escribano, Francisca
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p. 365 - 374
(2018/07/25)
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- A homochiral vanadium-salen based cadmium bpdc MOF with permanent porosity as an asymmetric catalyst in solvent-free cyanosilylation
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A homochiral vanadium-salen based MOF with the pcu topology is constructed via in situ synthesis under solvothermal conditions. The synthesized MOF exhibits BET surface areas of 574 m2 g-1, showing the highest H2 adsorptio
- Bhunia, Asamanjoy,Dey, Subarna,Moreno, José María,Diaz, Urbano,Concepcion, Patricia,Van Hecke, Kristof,Janiak, Christoph,Van Der Voort, Pascal
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supporting information
p. 1401 - 1404
(2016/01/25)
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- Enantioselective cyanosilylation of aldehydes catalyzed by a multistereogenic salen-Mn(III) complex with a rotatable benzylic group as a helping hand
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A multistereogenic salen-Mn(iii) complex bearing an aromatic pocket and two benzylic groups as helping hands was found to be efficient in the catalysis of asymmetric cyanosilylation. The salen-Mn catalyst partially mimics the functions of biocatalysts by
- Wei, Yun-Long,Huang, Wei-Sheng,Cui, Yu-Ming,Yang, Ke-Fang,Xu, Zheng,Xu, Li-Wen
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p. 3098 - 3103
(2015/02/02)
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- Enantioselective cyanosilylation of aldehydes catalyzed by novel camphor derived Schiff bases-titanium(IV) complexes
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Five tridentate Schiff bases have been prepared from (1R,2S,3R,4S)-3-amino- 1,7,7-trimethylbicyclo[2.2.1]heptan-2-ol and salicylaldehydes. X-ray structure investigation revealed differences in their molecular conformation, and their titanium(IV) complexes
- B?ocka, Ewelina,Bosiak, Mariusz J.,We?niak, Miros?aw,Ludwiczak, Agnieszka,Wojtczak, Andrzej
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p. 554 - 562
(2014/05/06)
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- Synthesis, characterization and catalytic property of chiral oxo-vanadium (+)-pseudoephedrine complex supported on magnetic nanoparticles Fe3O4 in the cyanosilylation of carbonyl compounds
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Vanadium complex of pseudoephedrine immobilized on magnetic nanoparticle Fe3O4[VO(Pseudoephedrine)@MNPs] was prepared and characterized by UV-vis, SEM, XRD, TGA, EDX, FT-IR, AGFM and elemental analysis techniques. VO(Pseudoephedrine)
- Rostami, Amin,Atashkar, Bahareh
-
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- Dismantling the salen framework: Design of new asymmetric silylcyanation catalysts
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A series of novel chiral phenoxyimine Al(iii) complexes catalyzes asymmetric addition of SiMe3CN to a broad range of aldehydes with high yields and good to excellent enantioselectivities in the presence of a Lewis base.
- Ternel, Jeremy,Roussel, Pascal,Agbossou-Niedercorn, Francine,Gauvin, Regis M.
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p. 580 - 583
(2013/03/28)
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- The synthesis of tetradentate salens derived from (3R,4R)-N-substituted-3, 4-diaminopyrrolidines and their application in the enantioselective trimethylsilylcyanation of aromatic aldehydes
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The in situ formed Ti(IV) complexes of pyrrolidine-based chiral salen ligands derived from natural l-tartaric acid were evaluated as catalysts in the enantioselective trimethylsilylcyanation of aromatic aldehydes. The different activity and selectivity of the catalysts in the formation of the products were found to be dependent on the N-substituent of the pyrrolidine.
- Serra, M. Elisa Silva,Murtinho, Dina,Goth, Albertino
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p. 315 - 319
(2013/04/24)
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- Enantioselective cyanation of aldehydes catalyzed by bifunctional salen-aluminum complex
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Chiral N-oxide salen ligands and their corresponding Al complexes were synthesized. Notably, the catalytic activity and asymmetric induction ability of the bifunctional N-oxide salen-Al for asymmetric cyanosilylation were compared with that of bi-componen
- Lv, Chengwei,Miao, Cheng-Xia,Xu, Daqian,Wang, Shoufeng,Xia, Chungu,Sun, Wei
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p. 138 - 140,3
(2020/07/31)
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- Asymmetric induction by helical poly(amino acid)s in cyanosilylation of aldehydes
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It was first demonstrated that helical poly(amino acid)s have an ability to induce enantioselectivity in the cyanosilylation of aldehydes. The helicity of poly(amino acid)s and the N-terminal amino group were essential for the enantioinduction of the reaction.
- Akagawa, Kengo,Kudo, Kazuaki
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supporting information
p. 5981 - 5983,3
(2020/08/20)
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- Asymmetric cyanohydrin synthesis using an aluminium(salan) complex
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The asymmetric addition of trimethylsilyl cyanide to aldehydes catalysed by chiral metal(salan) complexes has been investigated. Salan complexes of titanium and vanadium displayed only low catalytic activity, but a bimetallic aluminium(salan) complex gave
- North, Michael,Stewart, Emma L.,Young, Carl
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p. 1218 - 1225,8
(2020/09/09)
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- A novel bifunctional Ti(IV) complex catalyzed asymmetric silylcyanation of aldehydes
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A novel Lewis acid and Lewis base bifunctional Ti(IV) complex was formed in situ upon the treatment of ligand (R)-3,3′-bis(diphenylphosphinoyl)-BINOL with Ti(PrO-i)4, which is proven to be an efficient catalyst in the asymmetric trimethylsilylc
- Tang, Hongying,Zhang, Zhongbiao
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experimental part
p. 31 - 35
(2011/10/09)
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- Fine modification of salen ligands - Effects on the salen-Ti-catalyzed asymmetric cyanosilylation of aldehydes
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New bifunctional N-oxide salen-TiIV complexes and a pyrrolidine salen-TiIV complex in combination with achiral N-oxide were developed and applied to the asymmetric addition of trimethylsilyl cyanide to aldehydes. Notably, both enanti
- Lv, Chengwei,Cheng, Qigan,Xu, Daqian,Wang, Shoufeng,Xia, Chungu,Sun, Wei
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supporting information; experimental part
p. 3407 - 3411
(2011/09/12)
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- A practical Ti-salen catalyst based on dimeric salen ligand for asymmetric addition of trimethylsilyl cyanide to aldehydes
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A dimeric salen ligand derived from L-tartaric acid was synthesized through linking two salen units with 1,6-dibromohexane. The corresponding Ti complex was proved to be an efficient catalyst for asymmetric addition of trimethylsilyl cyanide to aldehydes,
- Lv, Chengwei,Xu, Daqian,Wang, Shoufeng,Miao, Cheng-Xia,Xia, Chungu,Sun, Wei
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experimental part
p. 1242 - 1245
(2012/01/06)
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- Investigation of lewis acid versus lewis base catalysis in asymmetric cyanohydrin synthesis
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The asymmetric addition of trimethylsilyl cyanide to aldehydes can be catalysed by Lewis acids and/or Lewis bases, which activate the aldehyde and trimethylsilyl cyanide, respectively. It is not always apparent from the structure of the catalyst whether Lewis acid or Lewis base catalysis predominates. To investigate this in the context of using salen complexes of titanium, vanadium and aluminium as catalysts, a Hammett analysis of asymmetric cyanohydrin synthesis was undertaken. When Lewis acid catalysis is dominant, a significantly positive reaction constant is observed, whereas reactions dominated by Lewis base catalysis give much smaller reaction constants. [{Ti(salen)O}2] was found to show the highest degree of Lewis acid catalysis, whereas two [VO(salen)X] (X = EtOSO3 or NCS) complexes both displayed lower degrees of Lewis acid catalysis. In the case of reactions catalysed by [{Al(salen)}2O] and triphenyl- phosphine oxide, a non-linear Ham- mett plot was observed, which is indicative of a change in mechanism with increasing Lewis base catalysis as the carbonyl compound becomes more electron-deficient. These results suggested that the aluminium complex/tri- phenylphosphine oxide catalyst system should also catalyse the asymmetric addition of trimethylsilyl cyanide to ke- tones and this was found to be the case.
- North, Michael,Omedes-Pujol, Marta,Williamson, Courtney
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experimental part
p. 11367 - 11375
(2010/11/17)
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- The synthesis of novel tetradentate ligands derived from salen and their application in enantioselective silylcyanation of aldehydes
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Two new tetradentate ligands derived from salen have been prepared and their titanium complexes are used as chiral catalysts in the enantioselective silylcyanation of aldehydes, which give the silyl ethers of cyanohydrins in moderate to good enantiomeric
- Lv, Chengwei,Wu, Mei,Wang, Shoufeng,Xia, Chungu,Sun, Wei
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experimental part
p. 1869 - 1873
(2010/11/19)
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- Kinetics and mechanism of vanadium catalysed asymmetric cyanohydrin synthesis in propylene carbonate
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Propylene carbonate can be used as a green solvent for the asymmetric synthesis of cyanohydrin trimethylsilyl ethers from aldehydes and trimethylsilyl cyanide catalysed by VO(salen)NCS, though reactions are slower in this solvent than the corresponding re
- North, Michael,Omedes-Pujol, Marta
-
experimental part
p. 1043 - 1055
(2011/03/22)
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- A bimetallic aluminium(salen) complex for asymmetric cyanohydrin synthesis
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In the presence of a phosphine oxide cocatalyst, a bimetallic aluminium(salen) complex was found to catalyse the asymmetric addition of trimethylsilyl cyanide to aldehydes. Under optimised conditions, enantioselectivities of 53-96% were obtained using 2 m
- North, Michael,Williamson, Courtney
-
experimental part
p. 3249 - 3252
(2009/08/17)
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- The enantioselective cyanosilylation of aldehydes on a chiral VO(Salen) complex encapsulated in SBA-16
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A solid catalyst for enantioselective cyanosilylation of aldehydes was prepared by encapsulating a chiral vanadyl Salen complex [VO(Salen)] in the nanocage of SBA-16. After encapsulation, the pore entrance size of SBA-16 was finely tuned through a silylat
- Yang, Hengquan,Zhang, Lei,Wang, Peng,Yang, Qihua,Li, Can
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experimental part
p. 257 - 264
(2010/04/22)
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- [Ru(phgly)2(binap)]/Li2CO3: A Highly Active, Robust, and Enantioselective Catalyst for the Cyanosilylation of Aldehydes
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The right combination: A series of aromatic, heteroaromatic, aliphatic, and α,β-unsaturated aldehydes can be converted into the desired silylated cyanohydrins by reaction with (CH3)3SiCN and a catalyst system consisting of the combination of a chiral ruthenium complex and Li2CO3 (see scheme). The reaction is highly enantioselective and affords the R products with up to 98% ee within 24 h at a substrate-tocatalyst ratio of 10000:1. (Chemical Equation Presented).
- Kurono, Nobuhito,Arai, Kenta,Uemura, Masato,Ohkuma, Takeshi
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supporting information; experimental part
p. 6643 - 6646
(2009/03/12)
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- Synthesis of chiral pyridyl alcohols using a two-step catalytic approach
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Chira l pyridyl alcohols have been prepared by developing a two-step approach that uses the asymmetric cyanation of aldehydes to give cyanohydrins and subsequent [2+2+2]-cyclotrimerization reaction with acetylene. Georg Thieme Verlag Stuttgart.
- Heller, Barbara,Redkin, Dmitry,Gutnov, Andrey,Fischer, Christine,Bonrath, Werner,Karge, Reinhard,Hapke, Marko
-
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- Enantioselective cyanosilylation of aldehydes catalysed by a diastereomeric mixture of atropisomeric thioureas
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New bifunctional atropisomeric thioureas 1 were synthesised and tested as both a mixture of diastereomers (aR/aS)-(R,R)-1 and as single diastereomers (aR)-(R,R)-1 and (aR)-(S,S)-1, in the organocatalysed, enantioselective, cyanosilylation of a range of al
- Steele, Rebecca M.,Monti, Chiara,Gennari, Cesare,Piarulli, Umberto,Andreoli, Federico,Vanthuyne, Nicolas,Roussel, Christian
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p. 999 - 1006
(2007/10/03)
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- Asymmetric addition of trimethylsilyl cyanide to aldehydes promoted by chiral polymeric vanadium(V) salen complex as an efficient and recyclable catalyst
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The asymmetric addition of trimethylsilyl cyanide to various aldehydes catalyzed by efficient new vanadyl polymeric salen complexes having 12 repeating salen units was investigated at room temperature. An excellent yield of the trimethylsilylether of cyanohydrins (up to 98%) with high chiral induction (96%) in case of 2-methylbenzaldehyde was achieved in 18 h. The catalyst recovered four times with retention of its performance.
- Khan, Noor-ul H.,Agrawal, Santosh,Kureshy, Rukhsana I.,Abdi, Sayed H.R.,Mayani, Vishal J.,Jasra, Raksh V.
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p. 2659 - 2666
(2007/10/03)
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- Asymmetric cyanosilylation of aldehydes catalyzed by novel chiral tetraaza-titanium complexes
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The asymmetric addition of trimethylsilyl cyanide (TMSCN) to a range of aldehydes was efficiently catalyzed by a novel, easily prepared C 2-symmetric chiral tetraaza-Ti(IV) complex in high yields with up to 92% ee under mild conditions. A negative nonlinear effect between the ee of the ligand and the ee of the product was observed. Georg Thieme Verlag Stuttgart.
- Liu, Yanling,Liu, Xiaohua,Xin, Junguo,Feng, Xiaoming
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p. 1085 - 1089
(2007/10/03)
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- Chiral lithium binaphtholate aqua complex as a highly effective asymmetric catalyst for cyanohydrin synthesis
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A highly enantioselective cyanohydrin synthesis with aromatic aldehydes using chiral lithium binaphtholate aqua or alcohol complexes has been developed and is a simple and inexpensive catalyst suitable for process chemistry to give gram-scale cyanohydrins
- Hatano, Manabu,Ikeno, Takumi,Miyamoto, Takashi,Ishihara, Kazuaki
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p. 10776 - 10777
(2007/10/03)
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- Asymmetric cyanohydrin synthesis catalyzed by Al(salen)/triphenylphosphane oxide
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Various aldehydes undergo asymmetric trimethylsilylcyanation with (CH 3)3SiCN (TMSCN) in the presence of a chiral Al(salen) complex and Ph3PO as the catalyst. This is a double activation where Al(salen) plays the role of Lewis acd and POPh3 acts as a Lewis base. Various kind of aldehydes were subjected to the enantioselective addition of (CH3)3SiCN at temperatures between -40 °C and -50 °C. Hydrolysis of the adducts gave cyanohydrins with over 90 % yield and 80 % ee in most cases. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.
- Kim, Sung Soo,Song, Dae Ho
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p. 1777 - 1780
(2007/10/03)
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- Enantioselective addition of trimethylsilyl cyanide to aldehydes catalysed by bifunctional BINOLAM-AlCl versus monofunctional BINOL-AlCl complexes
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A highly enantioselective cyanation of aldehydes takes place by using a bifunctional catalyst derived from 3,3′-bis(diethylaminomethyl) substituted binaphthol (BINOLAM) and dimethylaluminium chloride. The addition is of wide scope and runs best in toluene at temperatures ranging from -20 to -40°C, in the presence of 4 A? MS and triphenylphosphine oxide as additives. The (R)- or (S)-cyanohydrins result when using (S)- or (R)-BINOLAM-AlCl complexes, respectively. The valuable ligand can be recovered by simple extractive work-up and recycled without loss of efficiency (both in terms of chemical and stereochemical yields). This methodology is applied to the Shibasaki synthesis of epothilone A. All the evidence available for the BINOLAM-AlCl enantioselective addition of TMSCN to aldehydes call for the intervention of a hydrocyanation reaction, addition of a catalytic amount of hydrogen cyanide, generated in situ, to an aldehyde, followed by O-silylation. In order to determine the role of the basic amino groups of BINOLAM, comparative studies are carried out with the monofunctional 1,1′-binaphthol-derived complex BINOL-AlCl. Graphical Abstract.
- Casas, Jesús,Nájera, Carmen,Sansano, José M.,Saá, José M.
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p. 10487 - 10496
(2007/10/03)
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- Highly enantioselective cyanosilylation of aldehydes catalyzed by novel β-amino alcohol-titanium complexes
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The β-amino alcohol 1b-Ti(Oi-Pr)4 complex has been shown to catalyze the enantioselective cyanosilylation of aldehydes efficiently. In the presence of 5 mol % of 1b-Ti(Oi-Pr)4 complex catalyst, the aromatic, conjugated, heteroaromatic, and aliphatic aldehydes were converted to their corresponding trimethylsilyl ethers of cyanohydrins in 90-99% yields with up to 94% ee under mild conditions.
- Li, Yan,He, Bin,Qin, Bo,Feng, Xiaoming,Zhang, Guolin
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p. 7910 - 7913
(2007/10/03)
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- The asymmetric addition of trimethylsilylcyanide to aldehydes catalysed by anionic chiral nucleophiles. Part 2
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Studies have been carried out on the addition of trimethylsilylcyanide to aldehydes using highly active chiral lithium phenolate catalysts. The screening of a number of chiral phenolates has resulted in a system which gives the TMS ethers of cyanohydrins
- Holmes,Kagan
-
p. 7457 - 7460
(2007/10/03)
-