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1.
Zhengbo Zhu Dr. Minami Odagi Dr. Chenfei Zhao Dr. Khalil A. Abboud Helmi Ulrika Kirm Jaan Saame Dr. Märt Lõkov Prof. Dr. Ivo Leito Prof. Dr. Daniel Seidel 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(5):2044-2048
Acyclic ketone-derived oxocarbenium ions are involved as intermediates in numerous reactions that provide valuable products, however, they have thus far eluded efforts aimed at asymmetric catalysis. We report that a readily accessible chiral carboxylic acid catalyst exerts control over asymmetric cyclizations of acyclic ketone-derived trisubstituted oxocarbenium ions, thereby providing access to highly enantioenriched dihydropyran products containing a tetrasubstituted stereogenic center. The high acidity of the carboxylic acid catalyst, which exceeds that of the well-known chiral phosphoric acid catalyst TRIP, is largely derived from stabilization of the carboxylate conjugate base through intramolecular anion-binding to a thiourea site. 相似文献
2.
Chiral Metal–Organic Frameworks Bearing Free Carboxylic Acids for Organocatalyst Encapsulation
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Prof. Yan Liu Dr. Xiaobing Xi Chengcheng Ye Tengfei Gong Zhiwei Yang Prof. Yong Cui 《Angewandte Chemie (International ed. in English)》2014,53(50):13821-13825
Two chiral carboxylic acid functionalized micro‐ and mesoporous metal–organic frameworks (MOFs) are constructed by the stepwise assembly of triple‐stranded heptametallic helicates with six carboxylic acid groups. The mesoporous MOF with permanent porosity functions as a host for encapsulation of an enantiopure organic amine catalyst by combining carboxylic acids and chiral amines in situ through acid–base interactions. The organocatalyst‐loaded framework is shown to be an efficient and recyclable heterogeneous catalyst for the asymmetric direct aldol reactions with significantly enhanced stereoselectivity in relative to the homogeneous organocatalyst. 相似文献
3.
Regioselective and Enantioselective Synthesis of β‐Indolyl Cyclopentenamides by Chiral Anion Catalysis
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Dr. Subramani Rajkumar Jiawen Wang Sujuan Zheng Donglei Wang Xueqian Ye Xuejiao Li Prof. Dr. Qian Peng Prof. Dr. Xiaoyu Yang 《Angewandte Chemie (International ed. in English)》2018,57(41):13489-13494
The regioselective and enantioselective synthesis of β‐indolyl cyclopentenamides, a versatile chiral building block, by asymmetric addition of indoles to α,β‐unsaturated iminium intermediates has been achieved through chiral anion catalysis. Key to the success of this methodology is the generation of a chiral anion‐paired ketone‐type α,β‐unsaturated iminium intermediate from α‐hydroxy enamides. Preliminary mechanistic studies and DFT calculations are consistent with a mechanism involving multiple, concurrent pathways for isomerization of the initially formed azaallylcation into the key α,β‐unsaturated iminium intermediate, all mediated by the phosphoric acid catalyst. 相似文献
4.
《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(1):174-184
Palladium‐catalyzed asymmetric allylic alkylation of nonstabilized ketone enolates to generate quaternary centers has been achieved in excellent yield and enantioselectivity. Optimized conditions consist of performing the reaction in the presence of two equivalents of LDA as base, one equivalent of trimethytin chloride as a Lewis acid, 1,2‐dimethoxyethane as the solvent, and a catalytic amount of a chiral palladium complex formed from π‐allyl palladium chloride dimer 3 and cyclohexyldiamine derived chiral ligand 4 . Linearly substituted, acyclic 1,3‐dialkyl substituted, and unsubstituted allylic carbonates function well as electrophiles. A variety of α‐tetralones, cyclohexanones, and cyclopentanones can be employed as nucleophiles. The absolute configuration generated is consistent with the current model in which steric factors control stereofacial differentiation. The quaternary substituted products available by this method are versatile substrates for further elaboration. 相似文献
5.
Iridium‐Catalyzed Enantioselective Hydrogenation of Oxocarbenium Ions: A Case of Ionic Hydrogenation
Tilong Yang Yongjie Sun Heng Wang Zhenyang Lin Jialin Wen Xumu Zhang 《Angewandte Chemie (International ed. in English)》2020,59(15):6108-6114
Ionic hydrogenation has not been extensively explored, but is advantageous for challenging substrates such as unsaturated intermediates. Reported here is an iridium‐catalyzed hydrogenation of oxocarbenium ions to afford chiral isochromans with high enantioselectivities. A variety of functionalities are compatible with this catalytic system. In the presence of a catalytic amount of the Brønsted acid HCl, an α‐chloroether is generated in situ and subsequentially reduced. Kinetic studies suggest first‐order kinetics in the substrate and half‐order kinetics in the catalyst. A positive nonlinear effect, together with the half kinetic order, revealed a dimerization of the catalyst. Possible reaction pathways based on the monomeric iridium catalyst were proposed and DFT computational studies revealed an ionic hydrogenation pathway. Chloride abstraction and the cleavage of dihydrogen occur in the same step. 相似文献
6.
Yawen Hu Jianzhong Chen Bowen Li Zhenfeng Zhang Ilya D. Gridnev Wanbin Zhang 《Angewandte Chemie (International ed. in English)》2020,59(13):5371-5375
Earth‐abundant nickel, coordinated with a suitable chiral bisphosphine ligand, was found to be an efficient catalyst for the asymmetric hydrogenation of 2‐amidoacrylates, affording the chiral α‐amino acid esters in quantitative yields and excellent enantioselectivity (up to 96 % ee). The active catalyst component was studied by NMR and HRMS, which helped us to realize high catalytic efficiency on a gram scale with a low catalyst loading (S/C=2000). The hydrogenated products could be simply converted into chiral α‐amino acids, β‐amino alcohols, and their bioactive derivatives. Furthermore, the catalytic mechanism was investigated using deuterium‐labeling experiments and computational calculations. 相似文献
7.
Catalytic Enantioselective Synthesis of α‐Chiral Azaheteroaryl Ethylamines by Asymmetric Protonation
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Dr. Chao Xu Calum W. Muir Dr. Andrew G. Leach Dr. Alan R. Kennedy Dr. Allan J. B. Watson 《Angewandte Chemie (International ed. in English)》2018,57(35):11374-11377
The direct enantioselective synthesis of chiral azaheteroaryl ethylamines from vinyl‐substituted N‐heterocycles and anilines is reported. A chiral phosphoric acid (CPA) catalyst promotes dearomatizing aza‐Michael addition to give a prochiral exocyclic aryl enamine, which undergoes asymmetric protonation upon rearomatization. The reaction accommodates a broad range of N‐heterocycles, nucleophiles, and substituents on the prochiral centre, generating the products in high enantioselectivity. DFT studies support a facile nucleophilic addition based on catalyst‐induced LUMO lowering, with site‐selective, rate‐limiting, intramolecular asymmetric proton transfer from the ion‐paired prochiral intermediate. 相似文献
8.
A Cinchona Alkaloid‐Functionalized Mesostructured Silica for Construction of Enriched Chiral β‐Trifluoromethyl‐β‐Hydroxy Ketones over An Epoxidation‐Relay Reduction Process
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Cuibao Li Xiaomin Shu Liang Li Genwei Zhang Ronghua Jin Tanyu Cheng Prof. Guohua Liu 《化学:亚洲杂志》2016,11(14):2072-2077
A cinchona alkaloid‐functionalized heterogeneous catalyst is prepared through a thiol‐ene click reaction of chiral N‐(3,5‐ditrifluoromethylbenzyl)quininium bromide and a mesostructured silica, which is obtained by co‐condensation of 1,2‐bis(triethoxysilyl)ethane and 3‐(triethoxysilyl)propane‐1‐thiol. Structural analyses and characterizations disclose its well‐defined chiral single‐site active center, and electron microscopy images reveal its monodisperse property. As a heterogenous catalyst, it enables an efficient asymmetric epoxidation of achiral β‐trifluoromethyl‐β,β‐disubstituted enones, the obtained chiral products can then be converted easily into enriched chiral β‐trifluoromethyl‐β‐hydroxy ketones through a sequential epoxidation‐relay reduction process. Furthermore, such a heterogeneous catalyst can be recovered conveniently and reused in asymmetric epoxidation of 4,4,4‐trifluoro‐1,3‐diphenylbut‐2‐enone, showing an attractive feature in a practical construction of enriched chiral β‐CF3‐substituted molecules. 相似文献
9.
Yafei Guo Johanan Kootstra Prof. Dr. Syuzanna R. Harutyunyan 《Angewandte Chemie (International ed. in English)》2018,57(41):13547-13550
A method for catalytic asymmetric alkylation of conjugated dienyl amides has been developed and it allows efficient and high‐yielding transformations of a wide range of polyconjugated amides into the corresponding chiral products. Smooth addition of organomagnesium reagents to relatively unreactive dienyl amides with excellent 1,6‐ and 1,4‐selectivities, as well as enantioselectivites above 90 %, is achieved owing to the complementary action of the Lewis acid and a chiral copper‐based catalyst. 相似文献
10.
Trio Catalysis Merging Enamine,Brønsted Acid,and Metal Lewis Acid Catalysis: Asymmetric Three‐Component Aza‐Diels–Alder Reaction of Substituted Cinnamaldehydes,Cyclic Ketones,and Arylamines
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Dr. Yongming Deng Siddhartha Kumar Prof. Kraig Wheeler Prof. Hong Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(21):7874-7880
A trio catalyst system, composed of arylamine, BINOL‐derived phosphoric acid, and Y(OTf)3, enables the combination of enamine catalysis with both hard metal Lewis acid catalysis and Brønsted acid catalysis for the first time. Using this catalyst system, a three‐component aza‐Diels–Alder reaction of substituted cinnamaldehyde, cyclic ketone, and arylamine is carried out with high chemo‐ and enantioselectivity, affording a series of optically active 1,4‐dihydropyridine (DHP) derivatives are obtained in 91–99 % ee and 59–84 % yield. DHPs bearing a chiral quaternary carbon center are also obtained with good enantioselectivity and moderate yield (three examples). Preliminary mechanistic investigations have also been conducted. 相似文献
11.
Using chiral phosphoramide ligand 2d‐ Zn (II) complex derived from (1R,2R)‐1,2‐diphenylethylenediamine as the catalyst, we have developed efficient catalytic asymmetric 1,2‐addition/lactonization tandem reactions of diverse organozinc reagents with varied methyl 2‐formylbenzoates for the construction of optically enriched 3‐aryl or alkyl substituted phthalides, which are significant building blocks of many important chiral pharmaceuticals and natural products. The corresponding products could be afforded with good to excellent yields (up to 95%) and moderate to good enantioselectivities (up to 89%). 相似文献
12.
Yao Ge Dr. Zhaobin Han Dr. Zheng Wang Chen‐Guo Feng Qian Zhao Guo‐Qiang Lin Prof. Dr. Kuiling Ding 《Angewandte Chemie (International ed. in English)》2018,57(40):13140-13144
The first asymmetric hydrogenation of 3‐ylidenephthalides has been developed using the IrI complex of a spiro[4,4]‐1,6‐nonadiene‐based phosphine‐oxazoline ligand (SpinPHOX) as the catalyst, affording a wide variety of chiral 3‐substituted phthalides in excellent enantiomeric excesses (up to 98 % ee). The utility of the protocol has been demonstrated in the asymmetric synthesis of chiral drugs NBP and BZP precursor, as well as the natural products chuangxinol and typhaphthalide. 相似文献
13.
Shang Gao Meng Duan Kendall N. Houk Ming Chen 《Angewandte Chemie (International ed. in English)》2020,59(26):10540-10548
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
14.
Catalytic Asymmetric Iodocyclization of N‐Tosyl Alkenamides using Aminoiminophenoxy Copper Carboxylate: A Concise Synthesis of Chiral 8‐Oxa‐6‐Azabicyclo[3.2.1]octanes
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Prof. Dr. Takayoshi Arai Ohji Watanabe Shinnosuke Yabe Prof. Dr. Masahiro Yamanaka 《Angewandte Chemie (International ed. in English)》2015,54(43):12767-12771
A newly developed aminoiminophenoxy copper carboxylate ( L7 ‐Cu‐OAc)‐catalyzed asymmetric iodocyclization of N‐Tosyl alkenamides gave O‐cyclized products in good yields with high enantioselectivity. From the O‐cyclized products, a skeletal transformation was succeeded in the synthesis of biologically important chiral 8‐oxa‐6‐azabicyclo[3.2.1]octanes. DFT calculations suggested that the acetoxy anion of the [ L7 ‐Cu‐OAc] acts as a base to generate the anion of N‐Tosyl alkenamide substrates. The exchanged acetic acid reconstructs a new hydrogen‐bonding network between the catalyst and the substrates to accomplish the highly efficient asymmetric O‐iodocyclization of N‐Tosyl alkenamides. 相似文献
15.
Asymmetric Radical–Radical Cross‐Coupling through Visible‐Light‐Activated Iridium Catalysis
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Chuanyong Wang Jie Qin Xiaodong Shen Radostan Riedel Dr. Klaus Harms Prof. Dr. Eric Meggers 《Angewandte Chemie (International ed. in English)》2016,55(2):685-688
Combining single electron transfer between a donor substrate and a catalyst‐activated acceptor substrate with a stereocontrolled radical–radical recombination enables the visible‐light‐driven catalytic enantio‐ and diastereoselective synthesis of 1,2‐amino alcohols from trifluoromethyl ketones and tertiary amines. With a chiral iridium complex acting as both a Lewis acid and a photoredox catalyst, enantioselectivities of up to 99 % ee were achieved. A quantum yield of <1 supports the proposed catalytic cycle in which at least one photon is needed for each asymmetric C? C bond formation mediated by single electron transfer. 相似文献
16.
Enantioselective Rhodium‐Catalyzed Dimerization of ω‐Allenyl Carboxylic Acids: Straightforward Synthesis of C2‐Symmetric Macrodiolides
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Philip Steib Prof. Dr. Bernhard Breit 《Angewandte Chemie (International ed. in English)》2018,57(22):6572-6576
Herein, we report on the first enantioselective and atom‐efficient catalytic one‐step dimerization method to selectively transform ω‐allenyl carboxylic acids into C2‐symmetric 14‐ to 28‐membered bismacrolactones (macrodiolides). This convenient asymmetric access serves as an attractive route towards multiple naturally occuring homodimeric macrocyclic scaffolds and demonstrates excellent efficiency to construct the complex, symmetric core structures. By utilizing a rhodium catalyst with a modified chiral cyclopentylidene‐diop ligand, the desired diolides were obtained in good to high yields, high diastereoselectivity, and excellent enantioselectivity. 相似文献
17.
Catalytic Asymmetric Synthesis of 3,3′‐Diaryloxindoles as Triarylmethanes with a Chiral All‐Carbon Quaternary Center: Phase‐Transfer‐Catalyzed SNAr Reaction
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Dr. Seiji Shirakawa Kenta Koga Takashi Tokuda Kenichiro Yamamoto Prof. Dr. Keiji Maruoka 《Angewandte Chemie (International ed. in English)》2014,53(24):6220-6223
Catalytic asymmetric synthesis of unsymmetrical triarylmethanes with a chiral all‐carbon quaternary center was achieved by using a chiral bifunctional quaternary phosphonium bromide catalyst in the SNAr reaction of 3‐aryloxindoles under phase‐transfer conditions. The presence of a urea moiety in the chiral phase‐transfer catalyst was important for obtaining high enantioselectivity in this reaction. 相似文献
18.
Asymmetric Michael Addition/Intramolecular Cyclization Catalyzed by Bifunctional Tertiary Amine–Squaramides: Construction of Chiral 2‐Amino‐4H‐chromene‐3‐Carbonitrile Derivatives
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The efficient asymmetric Michael addition/intramolecular cyclization of malononitrile with dienones catalyzed by a chiral bifunctional tertiary amine–squaramide catalyst for the synthesis of chiral 2‐amino‐4H‐chromene‐3‐carbonitrile derivatives was developed. The corresponding products were obtained in good to excellent yields (up to 99 %) with excellent enantioselectivities (up to 98 % ee) for most of the bisarylidenecyclopentanones. 相似文献
19.
Gold‐Catalyzed Cascade Reactions for Synthesis of Carbo‐ and Heterocycles: Selectivity and Diversity
This account describes our recent efforts devoted to gold chemistry since 2009. Based on furyl–Au 1,3‐dipole analogues and related gold carbene intermediates, a rich variety of gold‐catalyzed cascade reactions have been developed, which provide facile access to a diverse range of novel carbo‐ and heterocycles. In these reactions, the selectivity can be well controlled by the catalyst (ligand and metal), substrate or reagent. In addition, we have also developed the corresponding enantioselective variants, which are guided by bis(phosphinegold) complexes derived from axially chiral scaffolds and asymmetric gold/chiral Brønsted acid relay catalysis. 相似文献
20.
A Three‐Component Enantioselective Cyclization Reaction Catalyzed by an Unnatural Amino Acid Derivative
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Dr. María de Gracia Retamosa Dr. Andrea Ruiz‐Olalla Dr. Tamara Bello Dr. Abel de Cózar Prof. Dr. Fernando P. Cossío 《Angewandte Chemie (International ed. in English)》2018,57(3):668-672
A new diastereo‐ and enantioselective three‐component cyclization reaction is described. The reaction takes place between a ketone, a carboxylic acid, and a nitroalkene to yield a bicyclic octahydro‐2H‐indol‐2‐one scaffold possessing three chiral centers. This reaction involves a rearrangement of the nitro group under simple thermal conditions. A plausible mechanism is proposed for this new reaction based on DFT calculations and isotope‐labeling experiments. A new concise enantioselective synthesis of the alkaloid (+)‐pancracine is presented as an example of the potential of this novel organocatalytic cyclization reaction in the synthesis of natural products. 相似文献