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High Enantioselectivity (high + enantioselectivity)
Selected AbstractsThe Origin of the High Enantioselectivity in Asymmetric Cyclopropanation of Unfunctionalized OlefinsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2010Yiying Zheng Abstract The mechanism of the asymmetric Simmons,Smith cyclopropanation for unfunctionalized olefins was investigated using density functional theory (DFT) methods. The calculated results of model reactions showed that the coordinated Lewis acidic zinc halide ZnX2 (X=Cl, I) and/or halomethylzinc halide XZnCH2X in the catalyst play an important role in the enantioselectivity. The catalyst not only forms the ring with the substance in the reaction centre, but also establishes two steric repulsions that can lead to an explanation for the high enantioselectivity. Hence, these results highlight some important insights for the prerequisites of an effective catalyst and a proper substrate towards high enantioselectivity for this kind of reaction. [source] Titanium(IV)/Tridentate BINOL Derivative as Catalyst for meso -Aziridine Ring-Opening Reactions: High Enantioselectivity, Strong Positive Non-Linear Effect and Structural CharacterizationADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 1-2 2009Rongmin Yu Abstract A titanium-based chiral Lewis acid was found to be effective for the ring-opening reactions of meso -aziridines with aniline nucleophiles. The products were generally isolated in high yields and with high to excellent enantioselectivity. The catalytic system was studied by X-ray single crystal analysis. In experiments on non-linear effects a strong non-linear effect of the catalyst system was observed. [source] A Ruthenium Catalyst that Does not Require an N,H Ligand to Achieve High Enantioselectivity for Hydrogenation of an Alkyl Aryl Ketone.CHEMINFORM, Issue 27 2003Carolyn G. Leong Abstract For Abstract see ChemInform Abstract in Full Text. [source] Asymmetric Reduction of Ketones Under Mild Conditions Using NaBH4 and TarB-NO2: An Efficient and Unusual Chiral Acyloxyborohydride Reducing System,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 24 2005David B. Cordes Abstract High enantioselectivities are obtained for the reduction of a series of ketones using the inexpensive and mild reducing agent NaBH4 with TarB-NO2 (1). This easily prepared tartaric acid-based reagent combines a Lewis acid with carboxylic acids in a single bifunctional reagent. When combined with NaBH4, the resulting chiral acyloxyborohydride mediates the reduction of aromatic ketones to provide the product alcohols in enantiomeric excesses of 93,98,%. Several aliphatic ketones were also reduced with moderate to excellent enantioselectivity. A unique mechanism is provided with supporting calculations for the proposed active species and transition state. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Copper-Catalyzed Asymmetric Allylic Alkylation of Racemic Cyclic Substrates: Application of Dynamic Kinetic Asymmetric Transformation (DYKAT)ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 2-3 2010Jean-Baptiste Langlois Abstract The copper-catalyzed asymmetric allylic alkylation (AAA) is of great interest in organic synthesis. This reaction was extensively studied using a broad range of substrates, ligands and organometallic reagents. However, the use of racemic substrates was still limited. Although some processes of kinetic resolution are reported in the literature, no examples of quantitative deracemization are described as is the case for the Pd-catalyzed allylic alkylation. We present here a full account of our investigations through the development of the first example of such a process in copper-catalyzed AAA. High enantioselectivities (up to 99% ee), scope of the reaction and mechanistic considerations are reported herein. [source] Rhodium-Catalyzed Asymmetric [5+2] Cycloaddition of Alkyne,VinylcyclopropanesCHEMISTRY - A EUROPEAN JOURNAL, Issue 35 2009Ryo Shintani Dr. Easy to scale: A rhodium-catalyzed asymmetric intramolecular [5+2] cycloaddition of alkyne,vinylcyclopropanes has been developed. High enantioselectivities of up to >99.5,% ee have been achieved by the use of a chiral phosphoramidite ligand. The reaction can be easily scaled up and the stereochemical model of the present catalysis has also been proposed. [source] Dynamic Enzymatic Kinetic Resolution of Methyl 2,3-Dihydro-1H -indene-1-carboxylateEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 35 2009Jörg Pietruszka Abstract A new reaction setup for kinetic enzymatic resolution was established and is demonstrated for the case of the hydrolase-catalysed conversion of methyl 2,3-dihydro-1H -indene-1-carboxylate (1) in conjunction with a base-catalysed racemisation. The system allows controlled racemisation, resulting in efficient dynamic kinetic resolution (DKR) of the title compound. Short reaction times and high enantioselectivities were obtained with CAL-B and TBD (1,5,7-triazabicyclo[4.4.0]dec-5-ene). Compound (R)- 1 (ee 95,%) served as a starting material in a domino reaction that led to the biaryl indanyl ketone (R)- 8, a lead compound for novel inhibitors of peptidyl-prolyl- cis/trans -isomerases, in 94,% ee. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Organocatalytic Enantioselective Michael Addition of 4-Hydroxycoumarin to ,,,-Unsaturated Ketones: A Simple Synthesis of WarfarinEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 30 2009Zhenhua Dong Abstract A type of C2 -symmetric secondary amine amide catalysts were developed for the asymmetric Michael addition of 4-hydroxycoumarin to ,,,-unsaturated ketones. A series of important biologically and pharmaceutically active compounds were obtained in excellent yields (up to 99,%) with high enantioselectivities (up to 89,%,ee) under mild conditions. In addition, enantiopure product could be obtained by a single recrystallization. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Rhodium-Catalyzed Asymmetric Nitroallylation of Arylmetallics with Cyclic Nitroallyl Acetates and Applications in Organic SynthesisEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 18 2006Lin Dong Abstract Highly enantioselective rhodium-catalyzed nitroallylations of arylboronic acids and arylzinc chlorides with cyclic nitroallyl acetates are described. Catalyst screening indicated that the rhodium complex of [Rh(OH)(COD)]2 and optically pure binap is the optimal catalyst for the nitroallylation of arylboronic acids with 2-nitrocyclohex-2-enyl esters, providing good yields and high enantioselectivities of up to 99,% ee. The rhodium complex prepared from Rh(acac)(C2H4)2 and (R)-binap efficiently catalyzed the nitroallylation of arylzinc chlorides with 2-nitrocyclohex-2-enyl acetate at 0 °C in high yields of up to 93,% and with high enantioselectivities of up to 96,% ee. A number of synthetically useful intermediates with high optical purity were prepared with this reaction as starting point: concise total syntheses of optically pure (+)-,-lycorane in 53,% overall yield and of (+)-,-lycorane in 52,% overall yield were achieved by commencing with the asymmetric nitroallylation of 3,4-methylenedioxyphenylzinc chloride with 2-nitrocyclohex-2-enyl acetate. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] A Bifunctional Cinchona Alkaloid-Squaramide Catalyst for the Highly Enantioselective Conjugate Addition of Thiols to trans -ChalconesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2010Le Dai Abstract A chiral squaramide catalysts-promoted asymmetric sulfa-Michael conjugated addition of thiols to trans -chalcones is presented. Moderate to excellent yields and high enantioselectivities (up to 99% ee) were achieved under mild conditions. [source] Palladium(II) Complexes of C2 -Bridged Chiral Diphosphines: Application to Enantioselective Carbonyl-Ene ReactionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 8 2010He-Kuan Luo Abstract (11bR,11,bR)-4,4,-(1,2-Phenylene)bis[4,5-dihydro-3H -dinaphtho[2,1- c:1,,2,- e]phosphepin] [abbreviated as (R)-BINAPHANE], (3R,3,R,4S,4,S,11bS,11,bS)-4,4,-bis(1,1-dimethylethyl)-4,4,,5,5,-tetrahydro-3,3,-bi-3H -dinaphtho[2,1- c:1,,2,- e]phosphepin [(S)-BINAPINE], (1S,1,S,2R,2,R)-1,1,-bis(1,1-dimethylethyl)-2,2,-biphospholane [(S,S,R,R)-TANGPHOS] and (2R,2,R,5R,5,R)-1,1,-(1,2-phenylene)bis[2,5-bis(1-methylethyl)phospholane] [(R,R) -i- Pr-DUPHOS] are C2 -bridged chiral diphosphines that form stable complexes with palladium(II) and platinum(II) containing a five-membered chelate ring. The Pd(II)-BINAPHANE catalyst displayed good to excellent enantioselectivities with ee values as high as 99.0% albeit in low yields for the carbonyl-ene reaction between phenylglyoxal and alkenes. Its Pt(II) counterpart afforded improved yields while retaining satisfactory enantioselectivity. For the carbonyl-ene reaction between ethyl trifluoropyruvate and alkenes, the Pd(II)-BINAPHANE catalyst afforded both good yields and extremely high enantioselectivities with ees as high as 99.6%. A comparative study on the Pd(II) catalysts of the four C2 -bridged chiral diphosphines revealed that Pd(II)-BINAPHANE afforded the best enantioselectivity. The ee values derived from Pd(II)-BINAPHANE are much higher than those derived from the other three Pd(II) catalysts. A comparison of the catalyst structures shows that the Pd(II)-BINAPHANE catalyst is the only one that has two bulky (R)-binaphthyl groups close to the reaction site. Hence it creates a deep chiral space that can efficiently control the reaction behavior in the carbonyl-ene reactions resulting in excellent enantioselectivity. [source] Hexahydropyrrolo[2,3- b]indoles: A New Class of Structurally Rigid Tricyclic Skeleton for Oxazaborolidine-Catalyzed Asymmetric Borane ReductionADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7 2010Jian Xiao Abstract A new class of structurally rigid tricyclic chiral ligands based on the hexahydropyrrolo[2,3- b]indole skeleton has been rationally designed and the catalytic abilities in asymmetric catalysis have been shown in the enantioselective borane reduction of prochiral ketones to afford the chiral alcohols in excellent yields and high enantioselectivities (up to 97% ee). [source] Facile Creation of 3-Indolyl-3-hydroxy-2-oxindoles by an Organocatalytic Enantioselective Friedel,Crafts Reaction of Indoles with IsatinsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 5 2010Jing Deng Abstract The first direct enantioselective Friedel,Crafts reaction of indoles with isatins has been developed. The process is catalyzed by simple cupreine under mild reaction conditions and affords synthetically and biologically interesting, chiral 3-indolyl-3-hydroxy-2-oxindoles in good yields (68,97%) and with high enantioselectivities (76,91%). [source] Efficient Method for the Synthesis of Optically Active 2-Amino-2-chromene Derivatives via One-Pot Tandem ReactionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2009Jian-Wu Xie Abstract The asymmetric synthesis of functionalized 2-amino-2-chromene derivatives with high enantioselectivities via one-pot tandem reactions of functionalized ,,,-unsaturated ketones with malononitrile catalyzed by 9-amino-9-deoxyepiquinine (1a) in combination with (R)-1,1,-binaphth-2,2,-diyl hydrogen phosphate (1c) is reported for the first time. [source] Room Temperature Highly Enantioselective Nickel-Catalyzed HydrovinylationADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2009Nicolas Lassauque Abstract At room temperature, nickel catalysts based on the new phosphoramidite (11bR)- N -[(S)-1-(naphthalen-1-yl)ethyl]- N -[(S)-1-(naphthalen-2-yl)ethyl]dinaphtho[2,1- d:1,,2,- f][1,3,2]dioxaphosphepin-4-amine provide excellent selectivities for 3-arylbut-1-enes (93,99%) with high enantioselectivities (90,95% ee) and TOFs (up to 8300,h,1) in the hydrovinylation of electron-rich and electron-poor vinylarenes. Within a few minutes, useful chiral building blocks and intermediates can be synthesized using this practical catalytic system. [source] Catalytic Asymmetric Ring-Opening Reaction of meso -Epoxides with Aryl Selenols and Thiols Catalyzed by a Heterobimetallic Gallium-Titanium-Salen ComplexADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6 2009Jiangtao Sun Abstract A chiral heterobimetallic Lewis acid complex has been developed as an efficient catalyst. The enantioselective desymmetrization of meso -epoxides with aryl selenols and thiols catalyzed by the heterobimetallic complex has been optimized. The optically active , -arylseleno alcohols and ,- hydroxy sulfides were obtained in good yields and high enantioselectivities (up to 97% ee and 92% ee, respectively). A strong synergistic effect between different Lewis acids was exhibited in the catalytic process. [source] A Catalytic Asymmetric Electrocyclization-Protonation ReactionADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 1-2 2009Magnus Rueping Abstract The first enantioselective Brønsted acid-catalyzed electrocyclization-protonation reaction has been developed which provides a number of different cyclopentenones in good yields and with high enantioselectivities. The stereodetermining step of this asymmetric Nazarov cyclization reaction is an asymmetric Brønsted acid-catalyzed kinetic protonation. [source] An N -Linked Bidentate Phosphoramidite Ligand (N- Me-BIPAM) for Rhodium-Catalyzed Asymmetric Addition of Arylboronic Acids to N- SulfonylarylaldiminesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 1-2 2009Kazunori Kurihara Abstract A chiral N -linked C2 -symmetric bidentate phosphoramidite (N- Me-BIPAM) was newly developed for the rhodium-catalyzed enantioselective addition of arylboronic acids to N- sulfonylimines. This ligand achieved high enantioselectivities in a range of 84,99% ee in additions of arylboronic acids to N- tosyl- and N- nosylarylaldimines. [source] Convenient General Asymmetric Synthesis of Roche Ester Derivatives through Catalytic Asymmetric Hydrogenation: Steric and Electronic Effects of LigandsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 16 2008Cyrielle Pautigny Abstract An efficient and concise asymmetric hydrogenation of acrylate esters promoted by the cationic ruthenium monohydride complex [Ru(H)(,6 -cot)SYNPHOS]+BF4, is reported. A full investigation of the effects of catalyst precursors, solvents, temperature, hydrogen pressure, substrates as well as steric and electronic properties of ligands was carried out. The corresponding valuable Roche ester derivatives were obtained in good to excellent isolated yields and high enantioselectivities under mild conditions. The robustness and practicability of this highly enantioselective hydrogenation was demonstrated by the synthesis of the 3-hydroxy-2-methylpropanoic acid tert -butyl ester on a multigram scale, resulting in excellent yield and ee up to 94%. [source] A Novel Bis-Thiourea Organocatalyst for the Asymmetric Aza-Henry ReactionADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2008Constantinos Rampalakos Abstract A novel bis-thiourea/2,2,-diaminobinaphthalene (BINAM)-based catalyst for the asymmetric aza-Henry reaction has been developed. This catalyst promotes the reaction of N -Boc imines with nitroalkanes to afford ,-nitroamines with good yields and high enantioselectivities. This catalyst has the advantage that it can be prepared in a single step from commercially available materials. A model is proposed for the catalyst action where both components of the reaction are activated simultaneously by hydrogen bonding. Regardless of the mechanism, the success of the present catalyst demonstrates the potential of bis-thioureas as an interesting class of relatively unexplored catalysts. [source] Organocatalytic Asymmetric Formal [3+3],Cycloaddition Reactions of ,,,-Unsaturated Aldehydes with Nazarov ReagentsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2008Ming-Kui Zhu Abstract An organocatalytic asymmetric formal [3+3],cycloaddition reaction of ,,,-unsaturated aldehydes with Nazarov reagents promoted by prolinol derivatives afforded, after oxidation, 3,4-dihydropyranones in good yields with high enantioselectivities of up to 97% ee. [source] Highly Enantioselective Allylation of Aromatic ,-Keto Phosphonates Catalyzed by Chiral N,N,- Dioxide-Indium(III) ComplexesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 2 2008Jinglun Huang Abstract The ramipril derivative N,N, -dioxide 3g -indium(III) complex was found to be an efficient catalyst for the allylation of the aromatic ,-keto phosphonates. The corresponding ,-hydroxy phosphonates were obtained with high yields (up to 98,%) and high enantioselectivities (up to 91,% ee). A bifunctional catalyst system was described with an N -oxide as Lewis base activating tetraallyltin and indium as Lewis acid activating aromatic ,-keto phosphonates. A possible catalytic cycle has been proposed to explain the mechanism of the reaction. [source] Asymmetric Cyanoethoxycarbonylation of Aldehydes Catalyzed by Heterobimetallic Aluminum Lithium Bis(binaphthoxide) and CinchonineADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 3 2007Shaohua Gou Abstract Highly efficient catalytic asymmetric cyanoethoxycarbonylation of aldehydes was achieved by 10 mol,% cinchonine with 10 mol,% heterometallic (S)-aluminum lithium bis(binaphthoxide), which gave the cyanohydrins ethyl carbonates in excellent isolated yields (up to 99,%) with moderate to high enantioselectivities (up to 95,% ee) under mild conditions (at ,20,°C). Especially, the solid aluminum lithium bis(binaphthoxide) free of tetrahydrofuran was obtained by a new procedure using (S)-bi(2-naphthol), aluminum isopropoxide and n -butyllithium in dichloromethane, which was insensitive to air and moisture and was very convenient to store and use. A catalytic cycle based on experimental phenomena was proposed to explain the nature of the asymmetric induction. [source] New Carbohydrate-Based Phosphite-Oxazoline Ligands as Highly Versatile Ligands for Palladium-Catalyzed Allylic Substitution ReactionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 15 2005Yvette Mata Abstract We have designed and synthesized a new family of readily available phosphite-oxazoline ligands for Pd-catalyzed asymmetric allylic substitution reactions. These ligands can be tuned in two regions to explore their effect on catalytic performance. By carefully selecting the ligand components, we obtained high enantioselectivities in the Pd-catalyzed allylic substitution in substrates with different steric properties [source] Partially Hydrogenated 1,1,-Binaphthyl as Ligand Scaffold in Metal-Catalyzed Asymmetric SynthesisADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 5 2003T.-L., Terry Abstract Although chiral binaphthyl-type ligands are already known to be effective over a broad spectrum of reactions, they sometimes fail in providing high enantioselectivities in some catalytic asymmetric reactions. This article summarizes recent attempts to elevate their performance by partly hydrogenating the naphthyl components of the binaphthyl. The synthetic routes to some of these ligands are briefly outlined. Positive results are observed in asymmetric hydrogenation, alkylation, borane reduction, epoxidation and hetero-Diels,Alder reactions. The function of the partially reduced binaphthyl skeleton, however, can sometimes be disadvantageous or ambiguous as illustrated in reactions such as asymmetric ring-closing metathesis, 1,4-conjugate addition, epoxidation, allylic alkylation, trimethylsilylcyanation, epoxide ring-opening and hydroformylation. [source] ChemInform Abstract: Iridium/Chiral Diene-Catalyzed Asymmetric 1,6-Addition of Arylboroxines to ,,,,,,,-Unsaturated Carbonyl Compounds.CHEMINFORM, Issue 42 2010Takahiro Nishimura Abstract The title reaction of dienones, dienamides, or a dienoate affords ,-arylated carbonyl compounds with high enantioselectivities by use of the C2 -symmetric tetrafluorobenzobarrelene-derived iridium complex IRB as catalyst. [source] ChemInform Abstract: anti-Diastereo- and Enantioselective Carbonyl (Hydroxymethyl)allylation from the Alcohol or Aldehyde Oxidation Level: Allyl Carbonates as Allylmetal Surrogates.CHEMINFORM, Issue 32 2010Yong Jian Zhang Abstract The first enantioselective carbonyl (hydroxymethyl)allylation in the presence of aromatic, allylic, or aliphatic alcohols (II) is reported employing an (S)-SEGPHOS-modified iridium C,O-benzoate complex to provide products (III) in good isolated yields, good anti-diastereoselectivities and high enantioselectivities. [source] Highly Enantioselective Synthesis of ,-Heteroaryl-Substituted Dihydrochalcones Through Friedel,Crafts Alkylation of Indoles and PyrroleCHEMISTRY - A EUROPEAN JOURNAL, Issue 5 2010Wentao Wang Abstract A highly enantioselective Friedel,Crafts (F,C) alkylation of indoles and pyrrole with chalcone derivatives catalyzed by a chiral N,N, -dioxide,Sc(OTf)3 complex has been developed that tolerates a wide range of substrates. The reaction proceeds in moderate to excellent yields and high enantioselectivities (85,92,% enantiomeric excess) using 2,mol,% (for indole) or 0.5,mol,% (for pyrrole) catalyst loading, which showed the potential value of the catalyst system. Meanwhile, a strong positive nonlinear effect was observed. On the basis of the experimental results and previous reports, a possible working model is proposed to explain the origin of the activation and asymmetric induction. [source] Asymmetric Synthesis of Fluorinated Flavanone Derivatives by an Organocatalytic Tandem Intramolecular Oxa-Michael Addition/Electrophilic Fluorination Reaction by Using Bifunctional Cinchona AlkaloidsCHEMISTRY - A EUROPEAN JOURNAL, Issue 48 2009Hai-Feng Wang A bifunctional quinidine derivative, containing a trifluoromethyl group, was found to catalyze a tandem intramolecular oxa-Michael addition/electrophilic fluorination reaction of activated ,,,-unsaturated ketones (see scheme). A series of chiral fluorinated flavanone derivatives were obtained in excellent yields and with high enantioselectivities. [source] Catalytic and Highly Enantioselective Reactions of ,-Sulfonyl Carbanions with Chiral Bis(oxazoline)sCHEMISTRY - A EUROPEAN JOURNAL, Issue 18 2008Shuichi Nakamura Prof. Abstract The enantioselective reactions of lithiated benzyl trifluoromethyl sulfones with a substoichiometric amount of a bis(oxazoline) and various aldehydes is disclosed. The products were formed with excellent diastereo- and enantioselectivities. Fluorination of the sulfone with N -fluorobenzenesulfonimide and a stoichiometric amount of a bis(oxazoline) gave products with extremely high enantioselectivities (up to 99,%,ee; ee=enantiomeric excess). The enantioselective reaction was confirmed to proceed through a dynamic thermodynamic resolution pathway. [source] | |||||||||||||||||||||||||