- Conformationally rigid chiral pyridine N-oxides as organocatalyst: Asymmetric allylation of aldehydes
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A pyridine unit with a conformationally rigid chiral backbone has been designed and synthesized in an enantiomerically pure form to utilize in the Lewis base-catalyzed Sakurai-Hosomi-Denmark-type allylation reaction. The chiral pyridine N-oxide in 1:1 mix
- Gnanamani, Elumalai,Someshwar, Nagamalla,Ramanathan, Chinnasamy Ramaraj
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- A detailed NMR- and DFT-based study of the Sakurai-Hosomi-Yamamoto asymmetric allylation reaction
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A Lewis acid complex between benzaldehyde and the silver catalyst was detected by 31P NMR and shown to be the direct precursor to allylation within the Sakurai-Hosomi-Yamamoto reaction. Structural and thermochemical hybrid-DFT calculations indicated that benzaldehyde predominantly formed an η1-σ-complex with the catalyst; however, two other competing conformers involving different coordination modes were found, including an activated μ2-bound complex. The differences in 31P NMR shifts upon complexation were calculated by the gauge-independent atomic orbital (GIAO-DFT) method for each conformer. The minimum energy conformer was found to correlate well with chemical shift trends observed experimentally, and an analysis of Mullikan charge populations revealed that the carbonyl carbon of the highest-energy conformer was the most electron-deficient. Furthermore, one minor and three major silicon intermediates were detected by 29Si NMR and, with the aid of 1H- 29Si HSQC, were assigned by comparison with parent compounds and GIAO-DFT calculations. Finally, a tentative mechanism was proposed based on these findings.
- Hurem, David,Moiseev, Andrey G.,Simionescu, Razvan,Dudding, Travis
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- Chiral bipyridine-annulated bicyclo[3.3.1]nonane N-oxide organocatalysts for stereoselective allylation and hydrosilylation reactions
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The synthesis of chiral C2-symmetric bis(bipyridine N,N′-dioxide) and bis(bipyridine N-monooxide) derivatives featuring bipyridine-annulated bicyclo[3.3.1]nonane framework is reported. The new Lewis basic bipyridine N,N′-dioxides exhibited good
- ?eimyt?, Simona,Ston?ius, Sigitas
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supporting information
(2020/12/21)
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- Emergence of Highly Enantioselective Catalytic Activity in a Helical Polymer Mediated by Deracemization of Racemic Pendants
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Any polymers composed of racemic repeating units are obviously optically inactive and hence chiral functions, such as asymmetric catalysis, will not be expected at all. Contrary to such a preconceived notion, we report an unprecedented helical polymer-based highly enantioselective organocatalyst prepared by polymerization of a racemic monomer with no catalytic activity. Both the right- and left-handed helical poly(biarylylacetylene)s (PBAs) composed of dynamically racemic 2-arylpyridyl-N-oxide monomer units with N-oxide moieties located in the vicinity of the helical polymer backbone can be produced by noncovalent interaction with a chiral alcohol through deracemization of the biaryl pendants. The macromolecular helicity and the axial chirality induced in the PBAs are retained ("memorized") after complete removal of the chiral alcohol. Accordingly, the helical PBAs with dual static memory of the helicity and axial chirality show remarkable enantioselectivity (86% ee) for the asymmetric allylation of benzaldehyde. The enantioselectivity is slightly lower than that (96% ee) of the homochiral PBAs prepared from the corresponding enantiopure (R)- and (S)-monomers, but is comparable to that (88% ee) of the helical PBA composed of nonracemic monomers of ca. 60% ee.
- Ikai, Tomoyuki,Ando, Mitsuka,Ito, Masaki,Ishidate, Ryoma,Suzuki, Nozomu,Maeda, Katsuhiro,Yashima, Eiji
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supporting information
p. 12725 - 12735
(2021/08/24)
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- A chiral oxazoline for catalytic enantioselective Nozaki-Hiyama-Kishi allylation and vinylation of aldehydes
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Asymmetric allylation and vinylation of aldehydes with allyl halides and vinyl halides have been achieved using the chromium(II)-oxazoline catalyst. The catalyst promotes the highly efficient enantioselective Nozaki–Hiyama-Kishi (NHK) allylation of aldehydes using allyl bromide, producing the corresponding homoallylic alcohols in good yields (up to 84%) and a high level of enantioselectivity (up to 98% ee). Meanwhile, the NHK vinylation of aldehydes produce desired allylic alcohols in satisfactory yields (up to 88%) and a high level of enantioselectivity (up to 97% ee). We developed a reliable and milder protocol for preparing chiral homoallylic and allylic alcohols.
- Chen, Chinpiao,Kumbhar, Sharad V.
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- Catalytic Hydroxycyclopropanol Ring-Opening Carbonylative Lactonization to Fused Bicyclic Lactones
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A novel palladium-catalyzed ring opening carbonylative lactonization of readily available hydroxycyclopropanols was developed to efficiently synthesize tetrahydrofuran (THF) or tetrahydropyran (THP)-fused bicyclic γ-lactones, two privileged scaffolds ofte
- Cai, Xinpei,Liang, Weida,Liu, Mingxin,Li, Xiating,Dai, Mingji
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supporting information
p. 13677 - 13682
(2020/09/18)
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- Highly Enantioselective Allylation Reactions of Aldehydes with Allyltrimethylsilane Catalyzed by a Chiral Oxazaborolidinium Ion
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A highly enantioselective allylation reaction of aldehydes with silyl reagents was developed for the synthesis of a variety of chiral homoallylic alcohols. In the presence of a chiral oxazaborolidinium ion (COBI) catalyst, the reaction proceeded in high yield (up to 99percent) with excellent asymmetric induction (up to 99percent ee).
- Kim, Taehyeong,Jeong, Hye-Min,Venkateswarlu, Anipireddy,Ryu, Do Hyun
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supporting information
p. 5198 - 5201
(2020/07/15)
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- Copper(I) Diphosphine Bifluoride Complexes as Efficient Preactivated Catalysts for Nucleophilic Addition on Unsaturated Functional Groups
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Herein we report the synthesis of a family of copper(I) diphosphine bifluoride complexes, their characterization, and their use as efficient preactivated catalysts for nucleophilic copper addition of pronucleophiles on unsaturations. Their use as mechanistic probes is also highlighted by the identification of two copper deuterides.
- Rasson, Corentin,Riant, Olivier
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supporting information
p. 835 - 840
(2020/02/13)
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- 3,3′-Bithiophene-Based Chiral Bisphosphine Oxides as Organocatalysts in Silicon-Derived Lewis Acid Mediated Reactions
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This account summarizes the development of new biheteroaromatic chiral bisphosphine oxides. 3,3′-Bithiophene-based phosphine oxides (BITIOPOs) have been successfully used as organocatalysts to promote Lewis base catalyzed, Lewis acid mediated stereoselective transformations. These highly electron-rich compounds, in combination with trichorosilyl derivatives (allyltrichlorosilane and silicon tetrachloride), generate hypervalent silicon species that act as chiral Lewis acids in highly diastereo- and enantioselective organic reactions. Several relevant examples related to these applications are discussed in detail. 1 Introduction 2 The BITIOPO Family 3 Enantioselective Opening of Epoxides 4 Enantioselective Allylation of Aldehydes 5 Stereoselective Direct (Double) Aldol-Type Reaction with Ketones 6 Stereoselective Direct Aldol-Type Reaction with Ester Derivatives 7 Conclusions.
- Benaglia, Maurizio,Benincori, Tiziana,Raimondi, Laura Maria,Rossi, Sergio
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p. 535 - 546
(2020/03/27)
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- Bi(cyclopentyl)diol-Derived Boronates in Highly Enantioselective Chiral Phosphoric Acid-Catalyzed Allylation, Propargylation, and Crotylation of Aldehydes
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In this study, we disclose the catalytic addition of bi(cyclopentyl)diol-derived boronates to aldehydes promoted by chiral phosphoric acids, allowing for the formation of enantioenriched homoallylic, propargylic, and crotylic alcohols (up to >99% enantiom
- Yuan, Jinping,Jain, Pankaj,Antilla, Jon C.
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p. 12988 - 13003
(2020/11/23)
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- Enantioselective Allylation of Oxocarbenium Ions Catalyzed by Bi(OAc)3/Chiral Phosphoric Acid
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Phthalides as the crucial core skeletons are found extensively in natural products and biological active molecules. Herein we disclose an asymmetric allylation of 3-hydroxyisobenzofuran-1(3H)-ones with boron allylation reagents to construct chiral phthali
- Cheng, Jin-Pei,Li, Xin,Pan, Yu-Liang,Wang, Jie,Yang, Chen,Zheng, Han-Liang
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p. 8069 - 8076
(2020/09/21)
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- Helicity Induction and Its Static Memory of Poly(biphenylylacetylene)s Bearing Pyridine N-Oxide Groups and Their Use as Asymmetric Organocatalysts
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Novel poly(biphenylylacetylene) derivatives carrying different types of pyridine N-oxide units with a bulky or less-bulky substituent at a different position as the functional pendant groups (poly-2a and poly-2b) were synthesized by the rhodium-catalyzed
- Ando, Mitsuka,Ishidate, Ryoma,Ikai, Tomoyuki,Maeda, Katsuhiro,Yashima, Eiji
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p. 2481 - 2490
(2019/11/03)
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- A chemoenzymatic synthesis of ceramide trafficking inhibitor HPA-12
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A chemoenzymatic synthesis of the title compound has been developed using an efficient and highly enantioselective lipase-catalyzed acylation in a hydrophobic ionic liquid, [bmim][PF6], followed by a diastereoselective asymmetric dihydroxylatio
- Kanojia, Seema V.,Chatterjee, Sucheta,Chattopadhyay, Subrata,Goswami, Dibakar
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supporting information
p. 490 - 496
(2019/03/07)
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- Synthesis of new bipyridine N,N′-dioxides and their application in asymmetric allylation of benzaldehyde and aldol addition to acetophenone
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Abstract: Two methods for the synthesis of new axially chiral bipyridine N,N′-dioxides based on catalytic [2+2+2] cyclotrimerization of diynes with nitriles were developed. The N,N′-dioxides were used as catalysts in enantioselective allylation of benzaldehyde with allyltrichlorosilane and aldol reaction of trichlorosilyl ketene acetal of methyl acetate with acetophenone. Graphical abstract: [Figure not available: see fulltext.].
- Bedná?ová, Eva,Ne?as, David,Císa?ová, Ivana,Du?ek, Michal,Lamaty, Frédéric,Kotora, Martin
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- Axially chiral N,N′-dioxides ethers for catalysis in enantioselective allylation of aldehydes
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A series of axially chiral ethers synthesized from biscarboline N,N′-dioxides, (S)-1a to (S)-1n, was investigated in enantioselectivity addition reactions of allyltrichlorosilane with a series of substituted aldehydes, including bulky substituted aldehydes. High enantioselectivities (up to 96%ee) were achieved using the catalyst (S)-1k at 1 mol % loading.
- Wu, Shijie,Xing, Yongfei,Wang, Jie,Guo, Xingchen,Zhu, Huajie,Li, Wan
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supporting information
p. 947 - 957
(2019/08/30)
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- TetraPh-Tol-BITIOPO: A new atropisomeric 3,3′-bithiophene based phosphine oxide as an organocatalyst in Lewis base-catalyzed Lewis acid mediated reactions
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A new chiral phosphine oxide based on a 3,3′-bithiophene scaffold (TetraPh-Tol-BITIOPO) was synthesized, fully characterized and separated into antipodes through chiral HPLC. This new compound was successfully employed as an organocatalyst in Lewis base-catalyzed Lewis acid mediated reactions involving trichlorosilyl compounds. The new atropisomeric catalyst was able to promote the allylation of aldehydes with allyltrichlorosilane in up to 98% yield and up to 96% enantiomeric excess (ee), and the direct aldol reaction to afford β-hydroxy ketones and β-hydroxy thioesters, with good chemical yields and modest stereochemical efficiency. Computational studies helped to elucidate and to rationalize the stereochemical outcome of the reactions catalyzed by TetraPh-Tol-BITIOPO that was found to favour the formation of the isomer with an opposite absolute configuration in comparison with the products obtained with the previously reported 3,3′-bithiophene-based catalyst.
- Mirco, Abbinante Vincenzo,Maurizio, Benaglia,Sergio, Rossi,Tiziana, Benincori,Roberto, Cirilli,Marco, Pierini
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supporting information
p. 7474 - 7481
(2019/08/20)
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- Synthesis of helical π-conjugated polymers bearing pyridine: N -oxide pendants and asymmetric allylation of aldehydes in the helical cavity
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Catalytically active chiral π-conjugated polymers (poly-1(NO)r) bearing pyridine N-oxide pendants were synthesized by ternary copolymerization of a d-glucose-bound diethynyl compound with two types of thieno[3,4-b]thiophene comonomer, one of wh
- Ikai, Tomoyuki,Yoshida, Takumu
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supporting information
p. 8537 - 8540
(2019/10/02)
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- Highly Focused Library-Based Engineering of Candida antarctica Lipase B with (S)-Selectivity Towards sec-Alcohols
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Candida antarctica lipase B (CALB) is one of the most extensively used biocatalysts in both academia and industry and exhibits remarkable (R)-enantioselectivity for various chiral sec-alcohols. Considering the significance of tailor-made stereoselectivity in organic synthesis, a discovery of enantiocomplementary lipase mutants with high (R)- and (S)-selectivity is valuable and highly desired. Herein, we report a highly efficient directed evolution strategy, using only 4 representative amino acids, namely, alanine (A), leucine (L), lysine (K), tryptophan (W) at each mutated site to create an extremely small library of CALB variants requiring notably less screening. The obtained best mutant with three mutations W104V/A281L/A282K displayed highly reversed (S)-selectivity towards a series of sec-alcohol with E values up to 115 (conv. 50%, ee 94%). Compared with the previously reported (S)-selective CALB variant, W104A, a single mutation provided less selectivity, while the synergistic effects of three mutations in the best variant endow better (S)-selectivity and a broader substrate scope than the W104A variant. Structural analysis and molecular dynamics simulation unveiled the source of reversed enantioselectivity. (Figure presented.).
- Cen, Yixin,Li, Danyang,Xu, Jian,Wu, Qiongsi,Wu, Qi,Lin, Xianfu
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p. 126 - 134
(2018/12/05)
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- Hollow organic polymeric nano-bowls-supported BINOL-derived chiral phosphoric acid: enhanced catalytic performances in the enantioselective allylation of aromatic aldehydes
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To improve the catalytic efficiency of expensive and versatile 1, 1′-binaphthol-derived chiral phosphoric acid with 2, 4, 6-tris(isopropyl)phenyl substituents and mass transfer of reactants in heterogeneous catalysis, a hollow organic polymeric nano-bowl
- Yan, Zhengwei,Xie, Guangxin,Zhang, Jianing,Ma, Xuebing
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- Chiral Bisdiphenylphosphine Dioxides Bearing a Bis(triazolyl) Backbone as Promising Lewis Bases for Asymmetric Organocatalysis
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Two chiral C2-symmetric diphenylphosphine dioxides bearing an original bis(triazolyl) backbone were prepared starting from inexpensive and readily available precursors. The key step involves the simultaneous formation of five bonds in one chemi
- Sevrain, Nicolas,Volle, Jean-Noel,Pirat, Jean-Luc,Ayad, Tahar,Virieux, David
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supporting information
p. 2267 - 2272
(2018/06/04)
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- Rhodium(III)-Catalyzed Oxidative Annulation of 2,2′-Bipyridine N-Oxides with Alkynes via Dual C-H Bond Activation
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Rh(III)-catalyzed switchable annulation of 2,2′-bipyridine N-oxides with internal alkynes via dual C-H bond activation has been developed. Tuning the reaction conditions enabled the reaction pathway to be switched between rollover and nonrollover annulation, delivering 5,6-disubstituted-1,10-phenanthrolines and 5,6,7,8-tetrasubstituted-1-(pyridin-2-yl)isoquinoline 2-oxides in high yields, respectively. The procedures feature excellent regioselectivity, broad substrate scope, and high tolerance of functional groups. The synthetic utilities of these obtained products were demonstrated in the catalytic reactions.
- Xu, Xin,Zhao, Haoqiang,Xu, Jianbin,Chen, Changjun,Pan, Yixiao,Luo, Zhenli,Zhang, Zongyao,Li, Huanrong,Xu, Lijin
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supporting information
p. 3843 - 3847
(2018/07/25)
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- Axial-Chiral Biisoquinoline N, N′-Dioxides Bearing Polar Aromatic C-H Bonds as Catalysts in Sakurai-Hosomi-Denmark Allylation
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The design, synthesis, and evaluation of axial-chiral biisoquinolines bearing polar aromatic C-H bonds as Lewis base catalysts are reported. Lewis bases containing the 3,5-bis(trifluoromethyl)phenyl group were found to be significantly more enantioselecti
- Reep, Carlyn,Morgante, Pierpaolo,Peverati, Roberto,Takenaka, Norito
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supporting information
p. 5757 - 5761
(2018/09/29)
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- Chiral Unsymmetrically Substituted Bipyridine N,N′-Dioxides as Catalysts for the Allylation of Aldehydes
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A series of unsymmetrically substituted diastereoisomeric (Ra,R) and (Sa,R) bipyridine N,N′-dioxides was synthesized by using oxidative coupling of the corresponding metallated tetrahydroisoquinoline N-oxides in the presence of iodin
- Ul?, Jan,Ne?as, David,Koukal, Petr,Havlí?ek, Vojtěch,To?ner, Zdeněk,Hybelbauerová, Simona,Kotora, Martin
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supporting information
p. 5109 - 5116
(2018/07/31)
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- Indium-mediated allylation of carbonyl compounds in ionic liquids: Effect of salts in ionic liquids
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The In-mediated allylation of carbonyl compounds can be performed in various types of solvents including ionic liquids. However, we have found that in [bmim][BF4] (where bmim = 1-butyl-3-methylimidazolium), the In-mediated coupling of crotyl bromide with benzaldehyde gives a complex mixture, and some additives, such as halides and amines, are crucial for the successful conversion to the corresponding γ-adduct. Instead, the addition of alcohols or water promotes the formation of the α-adduct. An asymmetric induction with up to 62% enantiomeric excess (ee) was observed employing cinchonidine as an additive in a binary solvent consisting of an ionic liquid and dichloromethane.
- Hirashita, Tsunehisa,Takahashi, Fusako,Noda, Takayuki,Takagi, Yuji,Araki, Shuki
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- Catalytic Nucleophilic Allylation Driven by the Water-Gas Shift Reaction
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The ruthenium-catalyzed allylation of aldehydes with allylic pro-nucleophiles has been demonstrated to be an efficient means to form carbon-carbon bonds under mild conditions. The evolution of this reaction from the initial serendipitous discovery to its general synthetic scope is detailed, highlighting the roles of water, CO, and amine in the generation of a more complete catalytic cycle. The use of unsymmetrical allylic pro-nucleophiles was shown to give preferential product formation through the modulation of reaction conditions. Both (E)-cinnamyl acetate and vinyl oxirane were efficiently used to form the anti-branched products (up to >20:1 anti/syn) and E-linear products (up to >20:1 E/Z) in high selectivity with aromatic, α,β-unsaturated, and aliphatic aldehydes, respectively. Attempts to render the reaction enantioselective are highlighted and include enantioenrichment of up to 75:25 for benzaldehyde.
- Denmark, Scott E.,Matesich, Zachery D.,Nguyen, Son T.,Milicevic Sephton, Selena
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supporting information
p. 23 - 48
(2018/02/19)
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- Rh-Catalyzed Enantioselective Allylation of N-Tosyl- and N-Nosylaldimines: Total Synthesis of (-)-Crispine A
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The unprecedented development of asymmetric Rh-catalyzed 1,2-allylation of N-Ts- and N-Ns-aldimines is achieved. This protocol utilizes potassium allyltrifluoroborates and various aldimines to generate enantioenriched homoallylic amines in the presence of 3.0 mol % of Rh(I)/L1b catalyst with up to 90% yield, 98% ee (R = H), and 10:1 diastereoselectivity (R = Me or Ph), yielding the same major diastereomer when using potassium (E)- and (Z)-crotyltrifluoroborate. Its synthetic utility is also illustrated in the total synthesis of (-)-crispine A.
- Chiang, Pei-Fen,Li, Wei-Sian,Jian, Jia-Hong,Kuo, Ting-Shen,Wu, Ping-Yu,Wu, Hsyueh-Liang
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supporting information
p. 158 - 161
(2018/01/17)
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- Asymmetric Allylation of Carbonyl Compounds Catalyzed by a Chiral Phosphine–Silver Complex
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A catalytic, asymmetric allylation reaction of aldehydes or ketones with allyltrimethoxysilane was achieved by using a BINAP·AgBF4 [BINAP = 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl] complex as the chiral precatalyst and triethylamine as the
- Yanagisawa, Akira,Yang, Nan,Bamba, Kentaro
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supporting information
p. 6614 - 6618
(2017/12/15)
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- C3-Symmetric Boron Lewis Acid with a Cage-Shape for Chiral Molecular Recognition and Asymmetric Catalysis
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Chiral Lewis acids play an important role in the precise construction of various types of chiral molecules. Here, a cage-shaped borate 2 was designed and synthesized as a chiral Lewis acid that possesses a unique C3-symmetric structure composed of three homochiral binaphthyl moieties. The highly symmetrical structure of 2 with homochirality was clearly elucidated by X-ray crystallographic analysis. The peculiar chiral environment of 2?THF exhibited chiral recognition of some simple amines and a sulfoxide. Moreover, the application of 2?THF to hetero-Diels–Alder reactions as a chiral Lewis-acid catalyst afforded the enantioselective products, which were obtained through an entropy-controlled pathway according to the analysis of the relationship between optical yield and reaction temperature. In particular, the robust chiral reaction field of 2?THF allowed the first example of an asymmetric hetero-Diels–Alder reaction with a simple diene despite the requirement of high temperature.
- Konishi, Akihito,Nakaoka, Koichi,Maruyama, Hikaru,Nakajima, Hideto,Eguchi, Tomohiro,Baba, Akio,Yasuda, Makoto
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supporting information
p. 1273 - 1277
(2017/02/05)
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- Novel chiral bis-phosphoramides as organocatalysts for tetrachlorosilane-mediated reactions
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The formation of novel chiral bidentate phosphoroamides structures able to promote Lewis base-catalyzed Lewis acid-mediated reactions was investigated. Two different classes of phosphoroamides were synthetized: the first class presents a phthalic acid/pri
- Rossi, Sergio,Ziliani, Marco,Annunziata, Rita,Benaglia, Maurizio
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supporting information
(2018/01/12)
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- Diastereoselective silylene transfer reactions to chiral enantiopure alkenes: Effects of ligand size and substrate bias
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Silylenes are useful reactive intermediates for the stereoselective construction of compounds containing carbon-silicon bonds. Despite their synthetic utility, the development of either an enantioselective or diastereoselective metal-catalyzed silylene tr
- Rotsides, Christina Z.,Woerpel
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supporting information
p. 8763 - 8768
(2017/07/22)
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- Enantioselective Allyl-, and Allenylboration of Aldehydes Catalyzed by Chiral Hydroxyl Carboxylic Acid
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Asymmetric allylboration of aldehydes with allylboronic acid pinacol ester catalyzed by chiral hydroxyl carboxylic acid is described. This reaction provides synthetically useful homoallyl alcohols in high yield with good to high enantioselectivity. The pr
- Ota, Yuya,Kawato, Yuji,Egami, Hiromichi,Hamashima, Yoshitaka
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supporting information
p. 976 - 980
(2017/05/05)
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- Extremely Active Organocatalysts Enable a Highly Enantioselective Addition of Allyltrimethylsilane to Aldehydes
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The enantioselective allylation of aldehydes to form homoallylic alcohols is one of the most frequently used carbon–carbon bond-forming reaction in chemical synthesis and, for several decades, has been a testing ground for new asymmetric methodology. Howe
- Kaib, Philip S. J.,Schreyer, Lucas,Lee, Sunggi,Properzi, Roberta,List, Benjamin
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supporting information
p. 13200 - 13203
(2016/10/30)
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- NEW DIFLUOROKETAMIDE DERIVATIVES
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The invention provides novel compounds having the general formula (I) wherein R1, R2, R3, R4, R5, R6, R7, R8 and R9 are as described herein, compositions including the compounds and methods of using the compounds.
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Page/Page column 43-44
(2016/12/01)
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- Biocatalytic Dynamic Kinetic Resolution for the Synthesis of Atropisomeric Biaryl N-Oxide Lewis Base Catalysts
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Atropisomeric biaryl pyridine and isoquinoline N-oxides were synthesized enantioselectively by dynamic kinetic resolution (DKR) of rapidly racemizing precursors exhibiting free bond rotation. The DKR was achieved by ketoreductase (KRED) catalyzed reductio
- Staniland, Samantha,Adams, Ralph W.,McDouall, Joseph J. W.,Maffucci, Irene,Contini, Alessandro,Grainger, Damian M.,Turner, Nicholas J.,Clayden, Jonathan
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supporting information
p. 10755 - 10759
(2016/09/03)
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- Polystyrene-Supported TRIP: A highly recyclable catalyst for batch and flow enantioselective allylation of aldehydes
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The widely applicable TRIP phosphoric acid catalyst has been immobilized on polystyrene using a copolymerization-based strategy. The resin (PS-TRIP) has proven to be highly active and enantioselective in the asymmetric allylboration of aldehydes. Moreover
- Clot-Almenara, Lidia,Rodríguez-Escrich, Carles,Osorio-Planes, Laura,Pericas, Miquel A.
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p. 7647 - 7651
(2018/05/23)
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- A Ce(OTf)3/PyBox catalyzed enantioselective Hosomi-Sakurai reaction of aldehydes with allyltrimethylsilane
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An efficient enantioselective Hosomi-Sakurai reaction catalyzed by a chiral Ce(OTf)3/PyBox complex has been explored. In the presence of 20 mol% of a chiral catalytic complex prepared in situ from Ce(OTf)3 and 2,6-bis[(S)-4-isopropyl
- Zhao, Song,Zhang, Xulong,Zhang, Yuwei,Yang, Huanhuan,Huang, Yan,Zhang, Kui,Du, Ting
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supporting information
p. 7734 - 7737
(2015/10/12)
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- Chiral phosphine oxide aziridinyl phosphonate as a Lewis base catalyst for enantioselective allylsilane addition to aldehydes
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A series of chiral Lewis bases, phosphine oxide ferrocenyl aziridinyl methanol 1-4, phosphinyl aziridinyl phosphonates 5 and 6, and phosphine oxide aziridinyl phosphonates 7 and 8 were screened for allylsilane additions to aldehydes. Among the Lewis bases
- Dogan, ?zdemir,Bulut, Adnan,Tecimer, M. Ali
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p. 966 - 969
(2015/09/01)
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- A chiral bipyridyl alcohol for catalytic enantioselective Nozaki-Hiyama-Kishi allylation of aldehydes and ketones
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A class of bipyridyl alcohol ligands has been developed. A catalyst synthesized using a chromium(II)-ligand promotes the enantioselective Nozaki-Hiyama-Kishi (NHK) allylation of aldehydes and ketones with allylic halides. The allylation of various aromati
- Chen, Rui-Yu,Dhondge, Attrimuni P.,Lee, Gene-Hsian,Chen, Chinpiao
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supporting information
p. 961 - 966
(2015/03/30)
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- Application of a high-throughput enantiomeric excess optical assay involving a dynamic covalent assembly: parallel asymmetric allylation and ee sensing of homoallylic alcohols
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Asymmetric Ir-catalyzed C-C coupling of primary alcohols with allyl-acetates, as described by Krische, to form chiral secondary homo-allylic alcohols were performed in parallel as a means to optimize the ee values thereof. Specifically, approximately 400 examples of this reaction were performed by varying the catalyst, added acids and bases, and starting reactants, to form 4-phenyl-1-butene-4-ol (1). The ee values for the transformations were determined in a high-throughput fashion using a 4-component assembly that creates a circular dichroism signal indicative of the extent of asymmetric induction. Further, a parallel and rapid quantitative TLC method measures the yield of each reaction, revealing which reactions give reliable ee values in the CD-based assay. Overall, the nearly 200 reactions whose ee values were determined could be quantitated in under two hours. Using a combination of the TLC method to measure yield with the CD-assay to measure ee values, several trends in reaction conditions were revealed. For example, it was found that the cyclometalated iridium catalyst modified by BINAP and m-nitro-p-cyano-benzoic acid delivered adduct 1 with the highest levels of enantiomeric enrichment (94%), whereas the corresponding SEGPHOS-modified catalyst gave a comparable yield but lower ee (91%). Most importantly, this study shows that supramolecular assemblies can report hundreds of ee values in a rapid and reliable fashion to analyze parallel synthesis routines.
- Jo,Gao,You,Anslyn,Krische
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p. 6747 - 6753
(2015/11/17)
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- Catalytic organic reactions on the surface of silver(I) oxide in water
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We have developed Ag2O-catalyzed allylation reactions of aldehydes with allylsilanes in water, providing homoallylic alcohols in high yields with high anti-selectivities. It was found that the reactions proceeded not in the water solution but o
- Ueno, Masaharu,Tanoue, Arata,Kobayashi, Shu
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p. 1867 - 1869
(2015/01/09)
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- Catalyst-Directed Diastereo- and Site-Selectivity in Successive Nucleophilic and Electrophilic Allylations of Chiral 1,3-Diols: Protecting-Group-Free Synthesis of Substituted Pyrans
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The iridium-catalyzed, protecting group-free synthesis of 4-hydroxy-2,6-cis- or trans-pyrans through successive nucleophilic and electrophilic allylations of chiral 1,3-diols occurs with complete levels of catalyst-directed diastereoselectivity in the absence of protecting groups, premetallated reagents, or discrete alcohol-to-aldehyde redox reactions.
- Shin, Inji,Wang, Gang,Krische, Michael J.
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supporting information
p. 13382 - 13389
(2016/02/19)
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- 2,2,2-Trifluoroacetophenone as an organocatalyst for the oxidation of tertiary amines and azines to N-oxides
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A cheap, mild and environmentally friendly oxidation of tertiary amines and azines to the corresponding Noxides is reported by using polyfluoroalkyl ketones as efficient organocatalysts. 2,2,2-Trifluoroacetophenone was identified as the optimum catalyst for the oxidation of aliphatic tertiary amines and azines. This oxidation is chemoselective and proceeds in high-to-quantitative yields utilizing 10 mol% of the catalyst and H2O2 as the oxidant.
- Limnios, Dimitris,Kokotos, Christoforos G.
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supporting information
p. 559 - 563
(2014/04/03)
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- Rhodium-catalyzed direct coupling of biaryl pyridine derivatives with internal alkynes
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Axially chiral biaryls were synthesized by an isoquinoline or 2-pyridine-directed Rh(iii)-catalyzed dual C-H cleavage and coupling with internal alkynes in good to excellent yields. Oxidation of isoquinoline derivatives with m-CPBA furnished their corresponding N-oxides, which could be utilized as Lewis base catalysts in asymmetric reactions. This journal is the Partner Organisations 2014.
- Zheng, Jun,You, Shu-Li
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supporting information
p. 8204 - 8207
(2014/07/21)
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- Pd(II)-catalyzed intermolecular direct C-H bond iodination: An efficient approach toward the synthesis of axially chiral compounds via kinetic resolution
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An efficient protocol to synthesize axially chiral compounds via kinetic resolution by Pd(II)-catalyzed direct C-H iodination was realized (up to s = 27). The iodide product could be easily transformed to aryl-substituted pyridine N-oxides via the Suzuki-
- Gao, De-Wei,Gu, Qing,You, Shu-Li
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p. 2741 - 2745
(2014/08/18)
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- A synthetic route to chiral C(3)-functionalized phthalides via a Ag(I)-catalyzed allylation/transesterification sequence
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A Ag(I)-catalyzed synthesis of chiral C(3)-substituted phthalides (8a-f) via a Sakurai-Hosomi allylation/transesterification reaction is described (ee ≤86%). A notable feature of this reaction is that it utilizes ortho-substituted aldehydes, which are a class of compounds that generally afford poor levels of stereoinduction when applying most known catalytic asymmetric allylation approaches. It was also found that elongation of the n-alkyl chain length (R1, up to n=6; R2=H) of the starting alkyl 2-formylbenzoates (7g-i) improved the enantiomeric excess (ee) of the product.
- Mirabdolbaghi, Roya,Dudding, Travis
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p. 3287 - 3292
(2013/04/24)
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- Dynamic kinetic resolution of homoallylic alcohols: Application to the synthesis of enantiomerically pure 5,6-dihydropyran-2-ones and δ-lactones
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Dynamic kinetic resolution of various homoallylic alcohols with the use of Candida antarctica lipase B and ruthenium catalyst 2 afforded homoallylic acetates in high yields and with high enantioselectivity. These enantiopure acetates were further transfor
- Warner, Madeleine C.,Shevchenko, Grigory A.,Jouda, Suzan,Bogar, Krisztian,Baeckvall, Jan-E.
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p. 13859 - 13864
(2013/10/22)
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- Synthetically amenable amide derivatives of tosylated-amino acids as organocatalysts for enantioselective allylation of aldehydes: Computational rationale for enantioselectivity
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A phenylalanine derived chiral amide is developed that serves as an effective organocatalyst for the reaction of allyltrichlorosilane with aryl, hetero-aryl and α,β-unsaturated aldehydes to afford the desired homoallylic alcohols in good yield (up to 90%)
- Ghosh, Debashis,Sahu, Debashis,Saravanan,Abdi, Sayed H. R.,Ganguly, Bishwajit,Khan, Noor-Ul H.,Kureshy, Rukhsana I.,Bajaj, Hari C.
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supporting information
p. 3451 - 3460
(2013/06/05)
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- Mechanistic dichotomy in the asymmetric allylation of aldehydes with allyltrichlorosilanes catalyzed by chiral pyridine N-oxides
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Detailed kinetic and computational investigation of the enantio- and diastereoselective allylation of aldehydes 1 with allyltrichlorosilanes 5, employing the pyridine N-oxides METHOX (9) and QUINOX (10) as chiral organocatalysts, indicate that the reaction can proceed through a dissociative (cationic) or associative (neutral) mechanism: METHOX apparently favors a pentacoordinate cationic transition state, while the less sterically demanding QUINOX is likely to operate via a hexacoordinate neutral complex. In both pathways, only one molecule of the catalyst is involved in the rate- and selectivity-determining step, which is supported by both experimental and computational data. Copyright
- Malkov, Andrei V.,Stoncius, Sigitas,Bell, Mark,Castelluzzo, Fabiomassimo,Ramirez-Lopez, Pedro,Biedermannova, Lada,Langer, Vratislav,Rulisek, Lubomir,Kocovsky, Pavel
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p. 9167 - 9185
(2013/07/26)
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- Synthesis of axially chiral C10-BridgePHOS oxides and their use as organocatalysts in enantioselective allylations of aldehydes
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A series of C10-BridgePHOS oxides possessing different substituted groups on the diphenyl phosphine system were synthesized and tested as organocatalysts in the allylation of aldehydes with allyltrichlorosilane, providing chiral homoallylic alc
- Chen, Jianzhong,Liu, Delong,Fan, Dongyang,Liu, Yangang,Zhang, Wanbin
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p. 8161 - 8168
(2013/09/02)
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- Asymmetric synthesis of novel axially chiral 2,2′-bipyridine n,n′-dioxides bearing α-amino acid residues and their applications in enantioselective allylation of aromatic aldehydes with allyltrichlorosilane
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A series of novel axially chiral 2,2′-bipyridine N,N′-dioxides bearing C1 or C2-symmetry have been synthesized by the use of enantiopure α-amino acids as chiral sources. The absolute stereochemistry of the axial chirality of these or
- Zhao, Hongwu,Yue, Yuanyuan,Li, Hailong,Sheng, Zhihui,Yang, Zhao,Meng, Wei
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p. 485 - 493
(2013/08/25)
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- Addition of aldehydes with allyltrichlorosilane catalyzed by chiral bis-N-O secondary amides
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New axially N-oxide amides derived from l-tryptophan were prepared and used as organocatalysts in enantioselective allylation of aromatic aldehydes with allyltrichlorosilanes. The corresponding addition adducts homoallylic chiral alcohols obtained high en
- Deng, Yu,Pan, Wei,Pei, Yu-Ning,Li, Jin-Liang,Bai, Bing,Zhu, Hua-Jie
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p. 10431 - 10437
(2013/11/19)
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