- Bio-inspired asymmetric aldehyde arylations catalyzed by rhodium-cyclodextrin self-inclusion complexes
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Transition-metal catalysts are powerful tools for carbon-carbon bond-forming reactions that are difficult to achieve using native enzymes. Enzymes that exhibit inherent selectivities and reactivities through host-guest interactions have inspired widesprea
- Asahi, Kaoru,Fujiwara, Shin-Ichi,Iwasaki, Takanori,Kambe, Nobuaki,Takahashi, Ryota,Tsuda, Susumu,Ueda, Ryoji,Yamauchi, Hiroki
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supporting information
p. 801 - 807
(2022/02/03)
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- Binaphthyl-prolinol chiral ligands: Design and their application in enantioselective arylation of aromatic aldehydes
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Binaphthyl-prolinol ligands were designed and applied in enantioselective arylation of aromatic aldehydes and sequential arylation-lactonization of methyl 2-formylbenzoate. Under optimized conditions, the reactions provided the desired diarylmethanols and 3-aryl phthalides in up to 96% yields with up to 99% ee and up to 89% yields with up to 99% ee, respectively. In particular, essentially optically pure 3-aryl phthalides (over 99% ee) were obtained in large quantities through recrystallization. This journal is
- Yao, Chao,Chen, Yaoqi,Sun, Ruize,Wang, Chao,Huang, Yue,Li, Lin,Li, Yue-Ming
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supporting information
p. 3644 - 3655
(2021/05/04)
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- Pd-catalyzed allylative dearomatisation using Grignard reagents
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Pd-catalyzed allylative dearomatisation of naphthyl halides is shown to be feasible by employing Grignard reagents. The high reactivity of the nucleophile allows for fast reactions and low catalyst loading, while a plethora of successfully substituted compounds illustrate the broad scope. Five membered heteroaromatic compounds are also demonstrated to be reactive under similar conditions.
- Boldrini, Cosimo,Harutyunyan, Syuzanna R.
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supporting information
p. 11807 - 11810
(2021/11/30)
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- Synthesis of Triarylmethanes via Palladium-Catalyzed Suzuki-Miyaura Reactions of Diarylmethyl Esters
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The synthesis of triarylmethanes via Pd-catalyzed Suzuki-Miyaura reactions between diarylmethyl 2,3,4,5,6-pentafluorobenzoates and aryl boronic acids is described. The system operates under mild conditions and has a broad substrate scope, including the coupling of diphenylmethanol derivatives that do not contain extended aromatic substituents. This is significant as these substrates, which result in the types of triarylmethane products that are prevalent in pharmaceuticals, have not previously been compatible with systems for diarylmethyl ester coupling. Furthermore, the reaction can be performed stereospecifically to generate stereoinverted products. On the basis of DFT calculations, it is proposed that the oxidative addition of the diarylmethyl 2,3,4,5,6-pentafluorobenzoate substrate occurs via an SN2 pathway, which results in the inverted products. Mechanistic studies indicate that oxidative addition of the diarylmethyl 2,3,4,5,6-pentafluorobenzoate substrates to (IPr)Pd(0) results in the selective cleavage of the O-C(benzyl) bond in part because of a stabilizing η3-interaction between the benzyl ligand and Pd. This is in contrast to previously described Pd-catalyzed Suzuki-Miyaura reactions involving phenyl esters, which involve selective cleavage of the C(acyl)-O bond, because there is no stabilizing η3-interaction. It is anticipated that this fundamental knowledge will aid the development of new catalytic systems, which use esters as electrophiles in cross-coupling reactions.
- Dardir, Amira H.,Casademont-Reig, Irene,Balcells, David,Ellefsen, Jonathan D.,Espinosa, Matthew R.,Hazari, Nilay,Smith, Nicholas E.
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supporting information
p. 2332 - 2344
(2021/06/28)
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- Chiral electron-rich PNP ligand with a phospholane motif: Structural features and application in asymmetric hydrogenation
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Despite the remarkable reactivity that was achieved by a series of transition-metal catalysts with a PNP type ligand, the electron-rich chiral PNP ligands have still been rarely reported because of the difficulties in synthesis and the nature of air-sensitivity. Herein, we report a novel chiral PNP ligand (Heng-PNP) with both a rigid backbone and a bulky tert-butyl group on the phospholane motif. We successfully obtained its divalent iron complex. The chiral environment of its Ir(III) complex was also discussed with quadrant analysis. This tridentate ligand was applied in iridium-catalyzed asymmetric hydrogenation of challenging diaryl ketones: up to 98% ee and 500 TON are achieved. Computational study showed that the twist of conjugate aryl group in the substrate (induced by the special chiral pocket of Ir/Heng-PNP complex) leads to the energy difference in the enantiodetermining step.
- Wang, Heng,Zhang, Yao,Yang, Tilong,Guo, Xiaochong,Gong, Quan,Wen, Jialin,Zhang, Xumu
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supporting information
p. 8796 - 8801
(2020/11/13)
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- Bulky N-Heterocyclic-Carbene-Coordinated Palladium Catalysts for 1,2-Addition of Arylboron Compounds to Carbonyl Compounds
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The synthesis of primary, secondary, and tertiary alcohols by the 1,2-addition of arylboronic acids or boronates to carbonyl compounds, including unactivated ketones, using novel bulky yet flexible N-heterocyclic carbene (NHC)-coordinated 2,6-di(pentan-3-yl)aniline (IPent)-based cyclometallated palladium complexes (CYPs) as catalysts is reported. The PhS-IPent-CYP-catalyzed reactions are efficient at low catalyst loadings (0.02–0.3 mol% Pd), and the exceptional catalytic activity for 1,2-addition is attributed to the steric bulk of the NHC ligand. These reactions can yield a wide range of functionalized benzylic alcohols that are difficult to synthesize by classical protocols using highly active organomagnesium or lithium reagents.
- Okuda, Yuta,Nagaoka, Masahiro,Yamamoto, Tetsuya
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p. 6291 - 6300
(2020/11/30)
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- P-chirogenic Trost ligands mediated asymmetric hydrogenation of simple ketones
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Herein, we report a highly active catalyst system consisting of (Rc,Rc,Rp,Rp)-P-chirogenic Trost ligand and [Ru(C6H6)Cl2]2 for asymmetric hydrogenation of simple ketones, affording the corresponding optically active alcohols in moderate enantioselectivity. A synergetic effect between P- and C-chirogenic centers of the P-chirogenic Trost ligands was observed in this asymmetric hydrogenation process.
- Du, Peng,Liu, Yan-Lan,Lu, Xiao-Bing
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supporting information
(2020/09/22)
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- Chiral Lithium Amido Aryl Zincates: Simple and Efficient Chemo- and Enantio-Selective Aryl Transfer Reagents
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An enantioselective aryl transfer is promoted using chiral tricoordinated lithium amido aryl zincates that are easily accessible reagents and whose chiral appendage is simply recovered for reuse. The arylation reaction is run in good yields (60 % average on twenty substrates) and high enantiomeric excesses (95 % ee average). This occurs whatever the ortho, meta, or para substituent borne by the substrate and a complete chemoselectivity is observed with respect to the aldehyde function. Sensitive groups such as nitriles, esters, ketones, and enolisable substrates resist to the action of the ate reagent, warranting a large scope to this methodology.
- Chaumont-Olive, Pauline,Rouen, Mathieu,Barozzino-Consiglio, Gabriella,Ben Abdeladhim, Amel,Maddaluno, Jacques,Harrison-Marchand, Anne
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supporting information
p. 3193 - 3197
(2019/01/25)
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- Enantiopure Methyl- A nd Phenyllithium: Mixed (Carb-)Anionic Anisyl Fencholate-Aggregates
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Methyl- A nd phenyllithium aggregates with enantiopure anisyl fencholate units form after reaction of organolithium reagent with (+)-anisyl fenchol in hydrocarbon and some ethereal solvents. These carbanionic aggregates are characterized by X-ray crystal analyses and exhibit both 3:1 stoichiometry and distorted cubic Li4O3C1 cores, in which three lithium ions coordinate the carbanion (i.e., methylide or phenylide). These three lithium ions define a Lewis acidic surface (Li3), binding the carbanion and expanding with the steric demand of the carbanion (i.e., from Me: 2.62 ?2, over n-Bu: 2.65 ?2 (previous work) to Ph: 2.79 ?2). Methylation and phenylation reactions of various prochiral aldehydes employing these methyllithium and phenyllithium aggregates yield alcohols with up to 44% ee. To rationalize the formation of the mixed (carb-)anionic aggregates, aggregate formation energies, describing co-condensations of RLi (R = Me, Ph, n-Bu) and lithium fencholates, are computed for the 3:1 and 2:2 stoichiometries. These computed aggregate formation energies point to preferences for 3:1 over 2:2 aggregates, as it is also apparent from experimental aggregate formations, confirmed by X-ray crystal analyses. In close analogy to the X-ray crystal structures, the computed Li3 surfaces increase with increasing steric demand of the carbanions. The chiral, mixed (carb-)anionic RLi-fencholate aggregates hence adapt to different carbanion sized and arise not only with small (Me) or primary carbanions (n-Bu) but even with the larger secondary phenyl anion.
- Grote, Vanessa,Neud?rfl, J?rg-Martin,Goldfuss, Bernd
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supporting information
p. 771 - 779
(2019/02/19)
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- 1,2-Dihydro-1-hydroxy-2,3,1-benzodiazaborine Bearing an Acridine Moiety as a Circular Dichroism Probe for Determination of Absolute Configuration of Mono-Alcohols
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A new chiral probe molecule for mono-alcohols is developed by using 1,2-dihydro-1-hydroxy-2,3,1-benzodiazaborine (DAB) bearing an acridine moiety 1. In the presence of mono-alcohols, DAB 1 forms borate 2 by boronic ester formation, followed by coordination of the acridine moiety to the boron atom. Borate 2 has a chiral center on the boron atom and works as a stereodynamic circular dichroism (CD) probe molecule for chiral mono-alcohols based on the π–π interaction between the acridine moiety and the carbon–carbon unsaturated moiety on mono-alcohols.
- Shimo, Shunsuke,Takahashi, Kohei,Iwasawa, Nobuharu
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supporting information
p. 3790 - 3794
(2019/02/26)
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- Development of Chiral C2-Symmetric N-Heterocyclic Carbene Rh(I) Catalysts through Control of Their Steric Properties
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Chiral square-planar Rh(I) complexes based on new C2-symmetric NHC ligands have been synthesized selectively in a few steps as single diastereoisomers. These chiral precatalysts were applied to the asymmetric transfer hydrogenation of 1-phenylp
- Abadie, Marc-Antoine,Macintyre, Kirsty,Boulho, Cédric,Hoggan, Peter,Capet, Frédéric,Agbossou-Niedercorn, Francine,Michon, Christophe
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supporting information
p. 536 - 543
(2019/01/14)
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- Asymmetric Hydrophosphination of Heterobicyclic Alkenes: Facile Access to Phosphine Ligands for Asymmetric Catalysis
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Asymmetric hydrophosphination is the most atomically economical and straightforward approach to the construction of chiral organophosphorus compounds. Good stereoselectivities have been achieved in asymmetric hydrophosphination of an electron-deficient C=
- Lu, Zhiwu,Zhang, Haoyang,Yang, Zhiping,Ding, Ning,Meng, Ling,Wang, Jun
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p. 1457 - 1463
(2019/02/01)
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- Access to All-Carbon Spirocycles through a Carbene and Thiourea Cocatalytic Desymmetrization Cascade Reaction
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A new catalytic approach for rapid asymmetric access to spirocycles is disclosed. The reaction involves a carbene- and thiourea-cocatalyzed desymmetrization process with the simultaneous installation of a spirocyclic core. The use of a thiourea cocatalyst
- Zhuo, Shitian,Zhu, Tingshun,Zhou, Liejin,Mou, Chengli,Chai, Huifang,Lu, Yunpeng,Pan, Lutai,Jin, Zhichao,Chi, Yonggui Robin
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supporting information
p. 1784 - 1788
(2019/01/14)
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- Nickel Catalyzed Intermolecular Carbonyl Addition of Aryl Halide
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In this study, we develop a nickel-catalyzed carbonyl arylation reaction employing aldehydes with aryl and allyl halides. Various aryl, α,β-unsaturated aldehyde and aliphatic aldehydes can be converted into their corresponding secondary alcohols in moderate-to-high yields. In addition, we extended this approach to develop an asymmetric reductive coupling reaction that combines nickel salts with chiral bisoxazoline ligands to give secondary alcohols with moderate enantioselectivity.
- Ishida, Seima,Suzuki, Hiroyuki,Uchida, Seiichiro,Yamaguchi, Eiji,Itoh, Akichika
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supporting information
p. 7483 - 7487
(2019/12/11)
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- Silica-Supported Catalyst for Enantioselective Arylation of Aldehydes under Batch and Continuous-Flow Conditions
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A silica-supported 3-aryl H8-BINOL-derived titanium catalyst exhibited high performance in the enantioselective arylation of aromatic aldehydes using Grignard and organolithium reagents not only under batch conditions but also under continuous-
- Watanabe, Satoshi,Nakaya, Naoyuki,Akai, Junichiro,Kanaori, Kenji,Harada, Toshiro
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supporting information
p. 2737 - 2740
(2018/05/22)
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- Method for Catalytic Enantioselective Alkylation of Aldehydes Using Grignard Reagents as Alkyl Sources
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Alkyltitanium reagents, generated in situ from Grignard reagents and ClTi(OiPr)3, can be employed without further manipulation in the enantioselective alkylation of aldehyde by the catalysis of a chiral titanium complex derived from DTBP-H8-BINOL. The reaction is performed with good stoichiometry [1.5 equiv each of Grignard reagents and ClTi(OiPr)3] at a low catalyst loading (2 mol %), affording a variety of chiral secondary alcohols in high enantioselectivity and yields and, hence, realizing an asymmetric version of the Grignard reaction in an indirect manner.
- Tanaka, Kento,Tomihama, Munehisa,Yamamoto, Koji,Matsubara, Naoki,Harada, Toshiro
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p. 6127 - 6132
(2018/05/23)
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- The inexpensive additive N-methylmorpholine effectively decreases the equivalents of nucleophiles in the catalytic highly enantioselective arylation of aryl aldehydes
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Highly enantioselective arylation of aryl aldehydes catalyzed by (S)-H8-BINOL-Ti(Oi-Pr)2 complex in the presence of N-methylmorpholine (NMM) as an effective and inexpensive additive is described for the first time. We found high enan
- Wang, Pei,Liu, Yue,Zhang, Ya-Lun,Da, Chao-Shan
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supporting information
p. 443 - 450
(2017/07/25)
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- Application of a Heterogeneous Chiral Titanium Catalyst Derived from Silica-Supported 3-Aryl H8-BINOL to Enantioselective Alkylation and Arylation of Aldehydes
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A 3-aryl H8-BINOL was grafted on the surface of silica gel using a hydrosilane derivative as a precursor, and the resulting silica-supported ligand (6 mol %) was employed in the enantioselective alkylation and arylation of aldehydes in the pres
- Akai, Junichiro,Watanabe, Satoshi,Michikawa, Kumiko,Harada, Toshiro
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supporting information
p. 3632 - 3635
(2017/07/15)
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- Chiral thiophosphoramide catalyzed asymmetric aryl transfer reactions for the synthesis of functional diarylmethanols
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In this investigation, chiral thiophosphoramide 3d was easily prepared from chiral (1R,2R)-1,2-diphenylethylenediamine and then applied as an efficient chiral ligand in the catalytic asymmetric arylation reactions of various aromatic aldehydes. The corresponding diarylmethanol products were produced with good to excellent yields (up to 98%) and enantioselectivities (up to 94%). The recovery of chiral ligand 3d could be as high as 96%.
- Wang, Yabai,Zong, Hua,Huang, Huayin,Song, Ling
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- Planar-chiral phosphine-olefin ligands exploiting a (Cyclopentadienyl)manganese(I) scaffold to achieve high robustness and high enantioselectivity
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A series of 2-methyl-1,3-propenylene-bridged (η5-diarylphosphinocyclopentadienyl)(phosphine)manganese(I) di-carbonyl complexes 2 have been developed as a new class of phosphine-olefin ligands based on a planar-chiral transition-metal scaffold,
- Kamikawa, Ken,Tsen, Ya-Yi,Jian, Jia-Hong,Takahashi, Tamotsu,Ogasawara, Masamichi
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supporting information
p. 1545 - 1553
(2017/02/10)
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- Sodium Bromide-Catalyzed Oxidation of Secondary Benzylic Alcohols Using Aqueous Hydrogen Peroxide as Terminal Oxidant
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A halide salt, hydroperoxide and AcOH catalyst system was applied to the oxidation of secondary benzylic alcohols. This simple system can be applied to a variety of secondary benzylic alcohols and scaled up for gram-scale preparation. High secondary benzylic alcohol selectivity of the present method is demonstrated in hydroxyketone synthesis. Based on several experimental results, a catalytic cycle for our oxidation is proposed.
- Komagawa, Hiromi,Maejima, Yukako,Nagano, Takashi
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supporting information
p. 789 - 793
(2016/03/09)
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- Cobalt-Catalyzed Asymmetric Hydrogenation of 1,1-Diarylethenes
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Highly enantioselective cobalt-catalyzed hydrogenation of 1,1-diarylethenes was developed by using bench-stable chiral oxazoline iminopyridine-cobalt complexes as precatalysts. A unique o-chloride effect was observed to achieve high enantioselectivity. Easy removal as well as further transformations of the chloro group make this protocol a potentially useful alternative to synthesize various chiral 1,1-diarylethanes. This process can be successfully performed under 1 atm of hydrogen at room temperature on gram scale.
- Chen, Jianhui,Chen, Chenhui,Ji, Chonglei,Lu, Zhan
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supporting information
p. 1594 - 1597
(2016/05/02)
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- Photochemically immobilized 4-methylbenzoyl cellulose as a powerful chiral stationary phase for enantioselective chromatography
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A process to immobilize para-methylbenzoyl cellulose (PMBC) on silica gel has been developed and applied to prepare chiral stationary phases (CSPs) for enantioselective chromatography. The immobilization was achieved by simple irradiation of the polysaccharide derivative with ultraviolet light after coating on a silica gel support. The influence of parameters such as irradiation time and solvent on immobilization effectiveness were investigated. The performance of the prepared immobilized phases were evaluated by injection of a series of racemic compounds onto the packed columns and determination of their chiral recognition ability. By contrast to the classical coated phase, the immobilized CSP can be used under various chromatographic conditions without limitation of organic solvent types as the mobile phase. This extended applicability permits to improve selectivity and to resolve chiral compounds which are not or only poorly soluble in the mobile phases which are compatible with the non-immobilized PMBC stationary phase.
- Francotte, Eric,Huynh, Dan,Zhang, Tong
-
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- Synthesis and Catalytic Asymmetric Applications of Quinazolinol Ligands
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A range of chiral quinazolinol ligands were efficiently synthesized and subsequently investigated for catalytic chiral induction in both the asymmetric phenylation of aryl aldehydes and the asymmetric epoxidation of chalcones. Encouragingly, high enantioselectivities (up to 95%) and yields (up to 98%) were achieved under the optimized reaction conditions.
- Karakaya, Idris,Karabuga, Semistan,Mart, Mehmet,Altundas, Ramazan,Ulukanli, Sabri
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p. 1719 - 1726
(2016/05/24)
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- Synthesis of new benzimidazolium salts and their application in the asymmetric arylation of aldehydes
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A series of novel chiral benzimidazolium salts, the precursor of N-heterocyclic carbene ligands, were designed and synthesized from 1,2-dibromobenzene. In situ prepared corresponding carbenes were tested in asymmetric Rh-catalyzed arylation of aromatic aldehydes, affording chiral diarylmethanols with high yields and moderate enantioselectivities.
- He, Wei-Ping,Zhou, Bi-Hui,Zhou, Ya-Li,Li, Xiang-Rong,Fan, Li-Mei,Shou, Hao-Wen,Li, Jie
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supporting information
p. 3152 - 3155
(2016/07/06)
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- Coupling of aromatic aldehydes with aryl halides in the presence of nickel catalysts with diazabutadiene ligands
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Nickel catalysts with diazabutadiene ligands promote cross-coupling of benzaldehydes with aryl halides in the presence of zinc as reducing agent, which leads to the corresponding benzhydrols and benzophenones. The benzophenone percentage considerably increases when lithium chloride additive is used.
- Asachenko,Valaeva,Kudakina,Uborsky,Izmer,Kononovich,Voskoboynikov
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p. 456 - 463
(2017/03/08)
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- Exploring the Reactivity of α-Lithiated Aryl Benzyl Ethers: Inhibition of the [1,2]-Wittig Rearrangement and the Mechanistic Proposal Revisited
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By carefully controlling the reaction temperature, treatment of aryl benzyl ethers with tBuLi selectively leads to α-lithiation, generating stable organolithiums that can be directly trapped with a variety of selected electrophiles, before they can undergo the expected [1,2]-Wittig rearrangement. This rearrangement has been deeply studied, both experimentally and computationally, with aryl α-lithiated benzyl ethers bearing different substituents at the aryl ring. The obtained results support the competence of a concerted anionic intramolecular addition/elimination sequence and a radical dissociation/recombination sequence for explaining the tendency of migration for aryl groups. The more favored rearrangements are found for substrates with electron-poor aryl groups that favor the anionic pathway.
- Velasco, Rocío,Silva López, Carlos,Nieto Faza, Olalla,Sanz, Roberto
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supporting information
p. 15058 - 15068
(2016/10/11)
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- Enantioselective addition of ArTi(OiPr)3 to aldehydes catalyzed by a titanium complex of an N-sulfonylated amino alcohol
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Asymmetric additions of ArTi(OiPr)3 to aldehydes catalyzed by a titanium catalyst of N-sulfonylated amino alcohols were reported, and results showed that the chiral N-sulfonylated amino alcohol with two stereogenic centers could catalyze the asymmetric addition of ArTi(OiPr)3 to aldehydes to afford desired secondary alcohols in good yields with good to excellent enantioselectivities of up to 95% ee.
- Chang, Shih-Ju,Zhou, Shuangliu,Gau, Han-Mou
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p. 9368 - 9373
(2015/02/19)
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- The carbonyl group tuned electron-deficient phosphorus ligands and their application in Rhodium catalyzed arylation to aldehydes
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Acylphosphines, which could be efficiently prepared from acid chlorides and secondary phosphines, were developed as a type of carbonyl group tuned electron-deficient phosphorus ligand. They were found to be a kind of efficient ligand in Rhodium catalyzed arylation to aldehydes through accelerating the transmetalation process. Chiral acylphosphine ligands could be generated from carboxylic acids bearing the chiral framework correspondingly.
- Yang, Jiefang,Chen, Xingyu,Wang, Zhiqian
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supporting information
p. 5673 - 5675
(2015/09/15)
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- Synthesis of Ferrocene Oxazoline N,O ligands and Their Application in Asymmetric Ethyl- and Phenylzinc Additions to Aldehydes
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The synthesis of a range of novel gem-disubstituted ferrocene-oxazoline ligands and their application in both the asymmetric ethyl- and phenylzinc additions to aldehydes is reported. These studies reveal that gem-disubstitution of i-Pr-containing ferrocene oxazoline ligands results in increased enantioselectivity compared to their unsubstituted counterparts. Utilizing zinc catalysis, these ligands provided a wide range of secondary alcohols in yields of up to 93% with ee's of up to >99%. An interesting crystal structure of a ferrocene oxide-lithium tetramer showing lithium-nitrogen coordination in the solid state is also presented.
- Nottingham, Chris,Benson, Robert,Müller-Bunz, Helge,Guiry, Patrick J.
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p. 10163 - 10176
(2015/11/03)
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- Crystal structure studies towards the synthesis and applications of n-heterocyclic carbene-metal complexes derived from [2.2]paracyclophane
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The crystal structures of six planar chiral N-heterocyclic carbene (NHC) precursors and one NHC-Rh complex derived from [2.2]paracyclophane were described. The NHC-metal complexes were prepared to examine their catalytic activities toward the Rh-catalyzed
- Duan, Wenzeng,Ma, Yudao,Huo, Yanmin,Yao, Qingxia
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p. 1472 - 1478
(2015/10/20)
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- C60-catalyzed preparation of aryl and heteroaryl magnesium and zinc reagents using Mg/LiCl
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Addition of a catalytic amount of C60 fullerene (3 mol %) catalyzes the insertion of magnesium to polycyclic aromatic halides, allowing the preparation of the corresponding Grignard reagents in good yields. Furthermore, the use of a cocktail of metallic salts (Mg, ZnCl2, LiCl) in the presence of C60 fullerene (3 mol %) allows preparation of some functionalized polyaromatic zinc reagents. The resulting organomagnesium and organozinc reagents efficiently underwent reactions with electrophiles, such as an aldehyde, an acid chloride, an allylic bromide, or an aryl iodide.
- Shen, Zhi-Liang,Knochel, Paul
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p. 2324 - 2328
(2015/04/14)
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- Chiral Bronsted acid catalyzed enantioselective intermolecular allylic aminations
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This paper describes an enantioselective intermolecular allylic amination catalyzed by a chiral Bronsted acid via a possible chiral contact ion pair intermediate. A variety of symmetrical or unsymmetrical allylic alcohols can be smoothly aminated to affor
- Zhuang, Minyang,Du, Haifeng
-
supporting information
p. 4590 - 4593
(2014/06/24)
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- Palladium-catalyzed arylation of aldehydes with bromo-substituted 1,3-diaryl-imidazoline carbene ligand
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The combination of 0 valent palladium precursor and bromo-substituted 1,3-diaryl-imidazoline carbene ligand precursor such as 1-(2-bromophenyl)-3-(2,6-diisopropylphenyl)-imidazolinium chloride 1a exhibited high catalytic activity for the 1,2-addition of arylboronic acids to aldehydes including aqueous formaldehyde.
- Yamamoto, Tetsuya,Furusawa, Takuma,Zhumagazin, Azamat,Yamakawa, Tetsu,Oe, Yohei,Ohta, Tetsuo
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- Solvent control of product diversity in palladium-catalyzed addition of arylboronic acid to aryl aldehydes
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In Pd-catalyzed arylboronic acid addition to aryl aldehydes, the expected carbinol or asymmetrical ether can be obtained as the major product by altering aqueous solvent composition. Exploiting this methodology with 2-formylbiphenyls as reaction partner, a fluorene scaffold can be readily constructed in two steps.
- Das, Tuluma,Chakraborty, Amarnath,Sarkar, Amitabha
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supporting information
p. 5174 - 5178
(2014/12/10)
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- Lewis base activation of Lewis acids: Group 13. in situ generation and reaction of borenium ions
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A variety of Lewis bases were combined with 9-BBN-NTf2 to establish the requirements for the generation of borenium cations. Five different types of behaviors were found, but the most interesting was the combination of Et3N, DABCO, 2,6-lutidine, or Ph3P=S, which formed borenium ions exclusively even in sub- or superstoichiometric quantities. The 9-BBN borenium ion complex of 2,6-lutidine rapidly catalyzes the hydrosilylation of a variety of ketones in the presence of Et3SiH. Preliminary mechanistic experiments suggest that the reduction involves borenium ion activation of Et3SiH and not the ketone.
- Denmark, Scott E.,Ueki, Yusuke
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supporting information
p. 6631 - 6634
(2014/01/06)
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- Asymmetric transfer hydrogenation of 1-naphthyl ketones by an ansa-Ru(II) complex of a DPEN-SO2N(Me)-(CH2)2(η 6-p-tol) combined ligand
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The first second-generation designer Ru(II) catalyst 1b featuring an enantiopure N,C-(N-ethylene-N-methyl-sulfamoyl)-tethered (DPEN- κ2N,N′)/η6-toluene hybrid ligand is introduced. Using an S/C = 1000 in HCO2H-Et3N 5:2 transfer hydrogenation medium, secondary 1-naphthyl alcohols are obtained in up to >99.9% ee under mild conditions. Mechanistic factors are discussed.
- Kisic, Andrea,Stephan, Michel,Mohar, Barbara
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supporting information
p. 1614 - 1617
(2013/06/26)
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- Synthesis of planar chiral [2.2]Paracyclophanyl imidazo[1,5-a[pyridinium salts for the rhodium-catalyzed asymmetric arylation
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Several novel flexibility-restricted imidazo[1,5-a]pyridinium triflates (abbreviated as imidazolium salts) were synthesized from (4S p,13R p)-()-4-amino-13-bromo[2.2]paracyclophane and pyridylaldehyde. These imidazolium salts can be used as nitrogen-containing heterocyclic carbene precursors in asymmetric catalysis and here they are applied in the Rh-catalyzed asymmetric 1,2-addition of arylboronic acids to aldehydes. After optimizing the catalytic situations and testing a series of substrates, moderate enantioselectivity and good yield were obtained.
- Wang, Dengxia,Ma, Yudao,He, Fuyan,Duan, Wenzeng,Zhao, Lei,Song, Chun
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p. 810 - 825
(2013/02/25)
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- Synthesis of novel planar chiral Ag and Rh N-heterocyclic carbene complexes derived from [2.2]paracyclophane and their application in ultrasound assisted asymmetric addition reactions of organoboronic acids to aldehydes
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Three novel planar chiral N-heterocyclic carbene silver and rhodium complexes based on [2.2]paracyclophane have been prepared. These could be used as catalysts/precatalysts for the asymmetric 1,2-addition of organoboronic acids to aldehydes. We optimized the reaction conditions and have applied ultrasonic irradiation in the asymmetric arylation for the first time. Under ultrasound irradiation, the combination of planar chiral NHC-Ag complex 5 and RhCl 3 can achieve higher catalytic activities in the asymmetric addition of organoboronic acids to aldehydes.
- Duan, Wenzeng,Ma, Yudao,He, Fuyan,Zhao, Lei,Chen, Jianqiang,Song, Chun
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p. 241 - 248
(2013/04/24)
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- Practical enantioselective arylation and heteroarylation of aldehydes with in situ prepared organotitanium reagents catalyzed by 3-aryl-H 8-BINOL-derived titanium complexes
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A highly efficient and practical method for the catalytic enantioselective arylation and heteroarylation of aldehydes with organotitanium reagents, prepared in situ by the reaction of aryl- and heteroaryllithium reagents with ClTi(OiPr)3, is described. Titanium complexes derived from DPP-H 8-BINOL (3 d; DPP=3,5-diphenylphenyl) and DTBP-H8-BINOL (3 e; DTBP=3,5-di-tert-butylphenyl) exhibit excellent catalytic activity in terms of enantioselectivity and turnover efficiency for the transformation, providing diaryl-, aryl heteroaryl-, and diheteroarylmethanol derivatives in high enantioselectivity at low catalyst loading (0.2-2 mol %). The reaction begins with a variety of aryl and heteroaryl bromides through their conversion into organolithium intermediates by Br/Li exchange with nBuLi, thus providing straightforward access to a range of enantioenriched alcohols from commercially available starting materials. Various 2-thienylmethanols can be synthesized enantioselectively by using commercially available 2-thienyllithium in THF. The reaction can be carried out on a 10 mmol scale at 0.5 mol % catalyst loading, demonstrating its preparative utility. Titanium does it! Titanium complexes derived from 3-aryl-H8-BINOLs exhibit excellent catalytic activity in terms of enantioselectivity and turnover efficiency, providing diaryl-, aryl heteroaryl-, and diheteroarylmethanol derivatives in high enantioselectivity at low catalyst loading (0.2-2 mol %; see scheme). Copyright
- Uenishi, Ami,Nakagawa, Yuya,Osumi, Hironobu,Harada, Toshiro
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supporting information
p. 4896 - 4905
(2013/05/09)
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- A chiral ruthenium-monophosphine catalyst for asymmetric addition of arylboronic acids to aryl aldehydes
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A novel ruthenium catalyst on the basis of a chiral monophosphorus ligand is efficient for the asymmetric addition of arylboronic acids to aryl aldehydes, providing a series of chiral diarylmethanols in excellent yields and enantioselectivities (up to 92% ee). Preliminary study has shown that this process is catalyzed by a Ru complex with a single monophosphorus ligand.
- Li, Ke,Hu, Naifu,Luo, Renshi,Yuan, Weicheng,Tang, Wenjun
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p. 6350 - 6355
(2013/07/26)
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- Synthesis of new alkoxy/sulfonate-substituted carbene precursors derived from [2.2]paracyclophane and their application in the asymmetric arylation of aldehydes
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A series of novel planar chiral alkoxy/sulfonate-substituted carbene precursors have been designed and synthesized. They were used as N-heterocyclic carbene ligands in the Rh-catalyzed asymmetric addition of arylboronic acids to aromatic aldehydes, affording chiral diarylmethanols with high yields and moderate enantioselectivities.
- Duan, Wenzeng,Ma, Yudao,Qu, Bo,Zhao, Lei,Chen, Jianqiang,Song, Chun
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p. 1369 - 1375,7
(2012/12/12)
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- Synthesis of new alkoxy/sulfonate-substituted carbene precursors derived from [2.2]paracyclophane and their application in the asymmetric arylation of aldehydes
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A series of novel planar chiral alkoxy/sulfonate-substituted carbene precursors have been designed and synthesized. They were used as N-heterocyclic carbene ligands in the Rh-catalyzed asymmetric addition of arylboronic acids to aromatic aldehydes, affording chiral diarylmethanols with high yields and moderate enantioselectivities.
- Duan, Wenzeng,Ma, Yudao,Qu, Bo,Zhao, Lei,Chen, Jianqiang,Song, Chun
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p. 1369 - 1375
(2013/01/15)
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- Palladium-catalyzed amination of chloromethylnaphthalene and chloromethylanthracene derivatives with various amines
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Palladium-catalyzed amination of chloromethylnaphthalene and chloromethylanthracene derivatives to produce naphthylamines and anthrylamines in satisfactory to good yields has been developed. The unprecedented amination reactions proceeded smoothly under mild conditions in the presence of Pd(PPh3)4 as a catalyst.
- Zhang, Sheng,Wang, Yi,Feng, Xiujuan,Bao, Ming
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supporting information; experimental part
p. 5492 - 5495
(2012/05/20)
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- Dehydrative fragmentation of 5-hydroxyalkyl-1 h -tetrazoles: A mild route to alkylidenecarbenes
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The development of a mild, base-free method for the generation of alkylidenecarbenes is reported. Treatment of 5-hydroxyalkyl-1H-tetrazoles with carbodiimides generates products arising from the 1,2-rearrangement or [1,5]-C-H bond insertion of a putative alkylidenecarbene. Formation of this divalent intermediate is proposed to occur by way of a tetraazafulvene, which undergoes extrusion of 2 mol of dinitrogen. Details of this methodology, its application to the synthesis of combretastatin A-4, and an improved route to 5-hydroxyalkyl-1H-tetrazoles are described.
- Wardrop, Duncan J.,Komenda, John P.
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supporting information; body text
p. 1548 - 1551
(2012/06/05)
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- METHOD FOR SYNTHESIS OF SECONDARY ALCOHOLS
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A method for synthesis of secondary alcohols is provided for pharmaceutical secondary alcohol by addition of organoboronic acids with aldehydes in presence of the cobalt ion and bidentate ligands as the catalyst. In addition, an enantioselective synthesis method for secondary alcohols is also herein provided in the present invention. The present invention has advantages in using less expensive cobalt ion and commercially available chiral ligands as the catalyst, wide scope of organoboronic acids and aldehydes compatible with this catalytic reaction and achieving excellent yields and/or enantiomeric excess.
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Page/Page column 2
(2012/06/16)
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- PROCESS FOR PRODUCING OPTICALLY ACTIVE ALCOHOL
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Disclosed is a method for producing an optically active alcohol including reacting a titanium compound, an aromatic magnesium compound and a carbonyl compound in the presence of an optically active biphenol compound having a predetermined structure and an ether compound having a predetermined structure.
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Page/Page column 21
(2012/02/14)
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- Structural influence of chiral tertiary aminonaphthol ligands on the asymmetric phenyl transfer to aromatic aldehydes
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A series of chiral tertiary aminonaphthol ligands were prepared from 2-naphthol, (S)-1-phenylethylamine, and aldehydes with diverse substituted groups. The results of asymmetric phenyl transfer to aromatic aldehydes catalyzed by these chiral ligands indicated that enantioselectivities were greatly influenced by the electronic and steric effects of the ligands. Copyright
- Wei, Hui,Yin, Lu,Luo, Haibin,Li, Xingshu,Chan, Albert S. C.
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experimental part
p. 222 - 227
(2012/03/27)
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- Instantaneous room-temperature and highly enantioselective ArTi(O-i-Pr)3 additions to aldehydes
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Direct asymmetric additions of ArTi(O-i-Pr)3 to aldehydes catalyzed by a titanium catalyst of (R)-H8-BINOL are reported. The reactions proceed instantaneously at room temperature, affording alcohols in ≥90% ee. Importantly, the ArTi(O-i-Pr)3 reagent differentiates the ligand effectiveness in an order of H8-BINOL > BINOL > TADDOL > diol 3 > disulfonamide 2.
- Wu, Kuo-Hui,Zhou, Shuangliu,Chen, Chien-An,Yang, Mao-Chi,Chiang, Ruei-Tang,Chen, Chi-Ren,Gau, Han-Mou
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supporting information; experimental part
p. 11668 - 11670
(2011/11/29)
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- The synthesis of P-stereogenic MOP analogues and their use in rhodium catalysed asymmetric addition
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The synthesis is reported of novel P-stereogenic binaphthyl substituted monophosphines via a short five-step synthesis using a nickel coupling reaction with separation of the borane-protected diastereomeric products. Extensive coordination studies of these ligands with a number of well-known metal precursors were performed to more effectively understand their behaviour during catalysis. These ligands and some previously reported P-stereogenic ligands were tested in the rhodium catalysed asymmetric addition of phenyl boronic acid to napthaldehyde. These studies in asymmetric catalysis were used to compare the chiral induction of ligands that combine both axial and central chirality with ligands lacking P-stereogenicity.
- Clarke, Eoin F.,Rafter, Eoin,Müller-Bunz, Helge,Higham, Lee J.,Gilheany, Declan G.
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experimental part
p. 3608 - 3615
(2011/12/02)
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