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1.
Hyung-Joon Kang Changseok Lee Prof. Dr. Sungwoo Hong 《Angewandte Chemie (International ed. in English)》2023,62(24):e202305042
Kinetic resolution is a powerful strategy for the isolation of enantioenriched compounds from racemic mixtures, and the development of selective catalytic processes is an active area of research. Here, we present a nickel-catalyzed kinetic resolution of racemic α-substituted unconjugated carbonyl alkenes via the enantio-, diastereo-, and regioselective hydroamination. This protocol affords both chiral α-substituted butenamides and syn-β2,3-amino acid derivatives with high enantiomeric purity (up to 99 % ee) and selectivity factor up to >684. The key to the excellent kinetic resolution efficiency is the distinctive architecture of the chiral nickel complex, which enables successful resolution and enantioselective C−N bond construction. Mechanistic investigations reveal that the unique structure of the chiral ligand facilitates a rapid migratory insertion step with one enantiomer. This strategy provides a practical and versatile approach to prepare a wide range of chiral compounds. 相似文献
2.
Alix A Lalli C Retailleau P Masson G 《Journal of the American Chemical Society》2012,134(25):10389-10392
Metal-free chiral phosphoric acids and chiral calcium phosphates both catalyze highly enantio- and diastereoselective electrophilic α-bromination of enecarbamates to provide an atom-economical synthesis of enantioenriched vicinal haloamines. Either enantiomer can be formed in good yield with excellent diastereo- and enantioselectivity simply by switching the catalyst from a phosphoric acid to its calcium salt. 相似文献
3.
Shang Gao Meng Duan Prof. Dr. Kendall N. Houk Prof. Dr. Ming Chen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(26):10627-10635
We report a dual function asymmetric catalysis by a chiral phosphoric acid catalyst that controls both enantioselective addition of an achiral α-vinyl allylboronate to aldehydes and pseudo-axial orientation of the α-vinyl group in the transition state. The reaction produces dienyl homoallylic alcohols with high Z-selectivities and enantioselectivities. Computational studies revealed that minimization of steric interactions between the alkyl groups of the diol on boron and the chiral phosphoric acid catalyst influence the orientation of α-vinyl substituent of the allylboronate reagent to occupy a pseudo-axial position in the transition state. 相似文献
4.
Enantioselective Construction of Spiroindolines with Three Contiguous Stereogenic Centers and Chiral Tryptamine Derivatives via Reactive Spiroindolenine Intermediates 下载免费PDF全文
Dr. Chun‐Xiang Zhuo Yong Zhou Qiang Cheng Lin Huang Prof. Dr. Shu‐Li You 《Angewandte Chemie (International ed. in English)》2015,54(47):14146-14149
The highly efficient synthesis of the enantioenriched spiroindolines by iridium‐catalyzed asymmetric allylic dearomatization and reduction is presented. Spiroindolines containing three contiguous stereogenic centers were obtained with excellent diastereo‐ and enantioselectivity. In addition, a chiral tryptamine derivative could be easily accessed in good yield with excellent ee value through an unprecedented dearomatization/retro‐Mannich/hydrolysis cascade reaction of an indole derivative. 相似文献
5.
《Tetrahedron》2019,75(23):3063-3079
The -CHF2 moiety has shown a growing interest in pharmaceutical and agrochemical applications over the last few years. Its introduction is therefore a current research topic for organic chemists. Several groups have reported the synthesis of difluoromethylated compounds. However, the more challenging enantioselective introduction of the difluoromethyl group has been scarcely described yet. We recently developed a new strategy, based on the use of an enantiopure difluoromethyl sulfoxide used as chiral and traceless auxiliary, for the synthesis of highly enantioenriched α-difluoromethyl alcohols. The first method developed in our laboratory aims to access highly stereoenriched α,α-difluoro-β-hydroxysulfoxides through the condensation of the enantiopure difluoromethyl sulfoxide on carbonyl derivatives. It is noteworthy that highly diastereo- and enantioenriched α,α-difluoro-β-hydroxysulfoxides can also be accessed after the diastereoselective reduction of highly enantioenriched α,α-difluoro-β-ketosulfoxides. Finally, the expected difluoromethyl-substituted alcohols can be obtained after removal of the chiral auxiliary with complete retention of stereoenrichment at carbon. 相似文献
6.
Stable allylboronates with a stereogenic centre α to the boronic ester moiety represent versatile reagents for stereoselective synthesis of homoallylic alcohols. Use of microwave irradiation in desilylation and sigmatropic rearrangement reactions allows rapid synthesis of α-chiral allylboronates utilized in the highly diastereo- and enantioselective synthesis of (Z)-configured homoallylic α-hydroxy esters by allyl additions to ethyl glyoxylate. 相似文献
7.
Jinxiu Xu Yanji Song Jia Yang Bingqian Yang Prof. Dr. Zhishan Su Prof. Dr. Lili Lin Prof. Dr. Xiaoming Feng 《Angewandte Chemie (International ed. in English)》2023,62(13):e202217887
Compared to γ-addition, the α-addition of α-branched β,γ-unsaturated aldehydes faces larger steric hindrance and disrupts the π–π conjugation, which might be why very few examples are reported. In this article, a highly diastereo- and enantioselective α-regioselective Mannich reaction of isatin-derived ketimines with α-, β- or γ-branched β,γ-unsaturated aldehydes, generated in situ from Meinwald rearrangement of vinyl epoxides, is realized by using chiral N,N′-dioxide/ScIII catalysts. A series of chiral α-quaternary allyl aldehydes and homoallylic alcohols with vicinal multisubstituted stereocenters are constructed in excellent yields, good d.r. and excellent ee values. Experimental studies and DFT (density functional theory) calculations reveal that the large steric hindrance of the ligand and the Boc (tButyloxy carbonyl) protecting group of imines are critical factors for the α-regioselectivity. 相似文献
8.
A novel catalytic asymmetric Michael addition of azomethine ylide with β-substituted alkylidene bisphosphates was realized in the presence of a chiral copper(I)/TF-BiphamPhos complex. The present system provides a unique and facile access to enantioenriched unnatural α-amino acid derivatives containing gem-bisphosphonates (gem-BPs) in high yields with excellent diastereoselectivities and enantioselectivities. Subsequent transformations lead to the expedient preparation of biologically active unnatural α-amino acid derivatives containing BPs and bisphosphonic acids without loss of diastereo- and enantiomeric excess. 相似文献
9.
Timothy A. Boebel 《Tetrahedron》2008,64(29):6824-6830
A two-step conversion of 1,3-disubstituted arenes to chiral α,α-diaryl methylammonium chlorides is described. In this procedure, arenes are converted to aryl boronic esters by iridium-catalyzed borylation, and the aryl boronic esters are converted to enantioenriched amines by subsequent rhodium-catalyzed addition to chiral tert-butanesulfinimes. 相似文献
10.
Ignacio Viera Eduardo Manta Lucía González Graciela Mahler 《Tetrahedron: Asymmetry》2010,21(5):631-635
Novel α,α-disubstituted epoxy esters were prepared in enantiopure form by hydrolytic kinetic resolution (HKR) of the corresponding racemic mixtures using chiral salenCo(III) as catalyst. The methodology provides a convenient route to enantioenriched β,γ-epoxy esters 2a, 2c and 2d. 相似文献
11.
Guoyu Zhang Song Zhou Dr. Liang Fu Dr. Pinhong Chen Prof. Yibiao Li Prof. Dr. Jianping Zou Prof. Dr. Guosheng Liu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(46):20619-20624
The first copper-catalyzed asymmetric cyanation and etherification reactions of enamides have been established, where a carbon-centered radical adjacent to a nitrogen atom (CRAN) is enantioselectively trapped by a chiral copper(II) species. Moreover, the asymmetric cyanation of vinyl esters was disclosed as well. These reactions feature very mild reaction conditions and high functional group tolerance, and give a series of chiral α-cyano amides, α-cyano esters and α-hemiaminals in good yields with excellent enantioselectivity. The chiral α-cyano amides can be easily converted into enantioenriched 1,2-diamines and amino acids. 相似文献
12.
Catalytic α-allylation of unprotected amino acid esters to produce α-quaternary α-allyl amino acid esters is reported. Catalytic loadings of picolinaldehyde and Ni(II) salts induce preferential reactivity at the enolizable α-carbon of amino acid esters over the free nitrogen with electrophilic palladium π-allyl complexes. Fourteen examples are given. Additionally, the use of chiral ligands to access enantioenriched α-quaternary amino acid esters from racemic precursors is demonstrated by the enantioselective synthesis of α-allyl phenylalanine methyl ester from racemic phenylalanine methyl ester. 相似文献
13.
The asymmetric domino Michael-S(N)2 reaction of various 1,3-dicarbonyl compounds to α-bromonitroalkenes is described for the first time, employing readily available cinchona-derived bifunctional thioureas as organocatalysts. The novel transformations were highly regio-, chemo-, diastereo-, and enantioselective, which simultaneously gave the chiral tricyclic 2,3-dihydrofurans, bicyclic 2,3-dihydrofurans, and tetrasubstituted 2,3-dihydrofurans with two vicinal chiral carbon centers. 相似文献
14.
Peng Chen Yue Li Dr. Zhi-Chao Chen Prof. Dr. Wei Du Prof. Dr. Ying-Chun Chen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(18):7149-7154
The catalytic diastereodivergent construction of stereoisomers having two or more stereogenic centers has been extensively studied. In contrast, the switchable introduction of another stereogenic element, that is, Z/E configuration involving a polysubstituted alkene group, into the optically active stereoisomers, has not been recognized yet. Disclosed here is the pseudo-stereodivergent synthesis of highly enantioenriched tetrasubstituted alkene architectures from isatin-based Morita–Baylis–Hillman carbonates and allylic derivatives, under the cooperative catalysis of a tertiary amine and a chiral iridium complex. The success of the switchable construction of the tetrasubstituted alkene motif relies on the diastereodivergent 1,3-oxo-allylation reaction between N-allylic ylides and chiral π-allyliridium complex intermediates by ligand and substrate control, followed by the stereoselective concerted 3,3-Cope rearrangement process. 相似文献
15.
Peng Chen Yue Li Zhi‐Chao Chen Wei Du Ying‐Chun Chen 《Angewandte Chemie (International ed. in English)》2020,59(18):7083-7088
The catalytic diastereodivergent construction of stereoisomers having two or more stereogenic centers has been extensively studied. In contrast, the switchable introduction of another stereogenic element, that is, Z/E configuration involving a polysubstituted alkene group, into the optically active stereoisomers, has not been recognized yet. Disclosed here is the pseudo‐stereodivergent synthesis of highly enantioenriched tetrasubstituted alkene architectures from isatin‐based Morita–Baylis–Hillman carbonates and allylic derivatives, under the cooperative catalysis of a tertiary amine and a chiral iridium complex. The success of the switchable construction of the tetrasubstituted alkene motif relies on the diastereodivergent 1,3‐oxo‐allylation reaction between N‐allylic ylides and chiral π‐allyliridium complex intermediates by ligand and substrate control, followed by the stereoselective concerted 3,3‐Cope rearrangement process. 相似文献
16.
Ling Chen Dr. Thi Minh Thi Le Prof. Dr. Jean-Philippe Bouillon Prof. Dr. Thomas Poisson Prof. Dr. Philippe Jubault 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(42):e202201254
The catalytic asymmetric synthesis of highly functionalized cyclopropanes from α-substituted allyl sulfones and silanes is reported. The reaction, using α-aryl diazoacetates or diacceptor diazo reagents, catalyzed by a chiral rhodium complex (Rh2((S)-BTPCP)4), furnished the corresponding cyclopropanes in moderate to high yields (27–97 %), high diastereoselectivities (68 : 32 to 20 : 1 d.r.) and moderate to excellent ee (40–99 %). This methodology offers a privileged access to an underexplored class of enantioenriched cyclopropanes with a high level of functionality, an asset for further post-functionalization and their incorporation into more complex structure. 相似文献
17.
Ling Zhao Yicong Luo Dr. Junzhe Xiao Dr. Xiaohong Huo Prof. Dr. Shengming Ma Prof. Dr. Wanbin Zhang 《Angewandte Chemie (International ed. in English)》2023,62(9):e202218146
The stereodivergent synthesis of allene compounds bearing α,β-adjacent central chiralities has been realized via the Pd/Cu-catalyzed dynamic kinetic asymmetric alkylation of racemic allenylic esters. The matched reactivity of bimetallic catalytic system enables the challenging reaction of racemic aryl-substituted allenylic acetates with sterically crowded aldimine esters smoothly under mild reaction conditions. Various chiral non-natural amino acids bearing a terminal allenyl group are easily synthesized in high yields and with excellent diastereo- and enantioselectivities (up to >20 : 1 dr, >99 % ee). Importantly, all four stereoisomers of the product can be readily accessed by switching the configurations of the two chiral metal catalysts. Furthermore, the easy interconversion between the uncommon η3-butadienyl palladium intermediate featuring a weak C=C/Pd coordination bond and a stable Csp2−Pd bond is beneficial for the dynamic kinetic asymmetric transformation process (DyKAT). 相似文献
18.
Iridium‐Catalyzed Diastereoselective and Enantioselective Allylic Substitutions with Acyclic α‐Alkoxy Ketones 下载免费PDF全文
Xingyu Jiang Wenyong Chen Prof. John F. Hartwig 《Angewandte Chemie (International ed. in English)》2016,55(19):5819-5823
The asymmetric alkylation of acyclic ketones is a longstanding challenge in organic synthesis. Reported herein are diastereoselective and enantioselective allylic substitutions with acyclic α‐alkoxy ketones catalyzed by a metallacyclic iridium complex to form products with contiguous stereogenic centers derived from the nucleophile and electrophile. These reactions occur between allyl methyl carbonates and unstabilized copper(I) enolates generated in situ from acyclic α‐alkoxy ketones. The resulting products can be readily converted into enantioenriched tertiary alcohols and tetrahydrofuran derivatives without erosion of enantiomeric purity. 相似文献
19.
Tingting Xia Yinhui Wu Jiangtao Hu Dr. Xianqing Wu Prof. Dr. Jingping Qu Prof. Dr. Yifeng Chen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2024,136(7):e202316012
Chromium-catalyzed enantioselective Nozaki–Hiyama–Kishi (NHK) reaction represents one of the most powerful approaches for the formation of chiral carbon-heteroatom bond. However, the construction of sterically encumbered tetrasubstituted stereocenter through NHK reaction still posts a significant challenge. Herein, we disclose a cobalt-catalyzed aza-NHK reaction of ketimine with alkenyl halide to provide a convenient synthetic approach for the manufacture of enantioenriched tetrasubstituted α-vinylic amino acid. This protocol exhibits excellent functional group tolerance with excellent 99 % ee in most cases. Additionally, this asymmetric reductive method is also applicable to the aldimine to access the trisubstituted stereogenic centers. 相似文献
20.
Asymmetric Conjugate Addition of Grignard Reagents to 3‐Silyl Unsaturated Esters for the Facile Preparation of Enantioenriched β‐Silylcarbonyl Compounds and Allylic Silanes 下载免费PDF全文
Kai Zhao Prof. Dr. Teck‐Peng Loh 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(50):16764-16772
A highly enantioselective conjugate addition of Grignard reagents to 3‐silyl unsaturated esters to deliver synthetically useful chiral β‐silylcarbonyl compounds was developed. The synthetic value of this methodology was further illustrated by the synthesis of enantioenriched β‐hydroxyl esters and the facile access granted to various α‐chiral allylic silanes. A plethora of diastereoselective transformations of β‐silylenolates were also investigated and afforded manifold organosilanes that contained contiguous stereogenic centers with excellent enantioselectivity. 相似文献