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1.
Marta Meazza Victor Ceban Dr. Mateusz B. Pitak Prof. Dr. Simon J. Coles Prof. Dr. Ramon Rios 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(51):16853-16857
A novel catalytic enantioselective methodology based on synergistic catalysis is reported. The strategy involves: 1) the metal‐Lewis‐acid activation of alkylazaarenes, and 2) the secondary‐amine activation of enals. Consequently, highly functionalized chiral alkylazaarenes were obtained in good yields and with reasonable stereoselectivity. 相似文献
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Abhisek Midya Laxman Devidas Khalse Prof. Prasanta Ghorai 《European journal of organic chemistry》2023,26(14):e202201409
Disclosed here an amine-catalyzed reductive aldol-condensation followed by an intramolecular reductive Michael-addition cascade employing Hantzsch ester as hydride source to a keto-bis-enone to provide enantio- and diastereoselective benzannulated diquinanes having three consecutive stereocenters, one of which is an all-carbon quaternary formyl stereocenter. Interestingly, on changing a tether connecting the ketone and an enone moiety from an aliphatic to an aromatic, a change in reactivity is observed. In this case, instead of the above-mentioned reductive aldol condensation, an asymmetric aldol reaction occurs, followed by an iminium/enamine isomerization and, finally diastereoselective Michael addition reaction occurs. As a result, a bis-benzannulated diquinane is obtained with vicinal congested quaternary chiral centers. 相似文献
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Regio‐ and Stereoselective Conjugate Addition of Aldehydes to β‐Tosyl Enones under the Catalysis of a Binaphthyl‐Modified Chiral Amine 下载免费PDF全文
Dr. Taichi Kano Hisashi Sugimoto Hiroki Maruyama Prof. Keiji Maruoka 《Angewandte Chemie (International ed. in English)》2015,54(29):8462-8465
A simple axially chiral amine catalyst promoted the regio‐, diastereo‐, and enantioselective conjugate addition of aldehydes to β‐tosyl enones, which serve as ynone surrogates. The adducts were readily converted by treatment with L‐selectride into less accessible enones with a γ stereogenic center. Such compounds cannot be prepared through the amine‐catalyzed conjugate addition of aldehydes to ynones. The obtained enones underwent further conjugate addition of diorganozinc compounds in the presence of a copper catalyst. 相似文献
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《Angewandte Chemie (International ed. in English)》2017,56(32):9487-9491
A chiral‐amine‐catalyzed enantioselective and diastereodivergent method for aldehyde addition to electron‐deficient olefins is presented. Hydrogen bonding was used as a control element to achieve unusual anti selectivity, which was further elucidated through mechanistic and computational studies. 相似文献
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Connor J. Thomson David M. Barber Darren J. Dixon 《Angewandte Chemie (International ed. in English)》2020,59(13):5359-5364
The catalytic enantioselective synthesis of α‐fluorinated chiral tertiary alcohols from (hetero)aryl methyl ketones is described. The use of a bifunctional iminophosphorane (BIMP) superbase was found to facilitate direct aldol addition by providing the strong Brønsted basicity required for rapid aryl enolate formation. The new synthetic protocol is easy to perform and tolerates a broad range of functionalities and heterocycles with high enantioselectivity (up to >99:1 e.r.). Multi‐gram scalability has been demonstrated along with catalyst recovery and recycling. 1H NMR studies identified a 1400‐fold rate enhancement under BIMP catalysis, compared to the prior state‐of‐the‐art catalytic system. The utility of the aldol products has been highlighted with the synthesis of various enantioenriched building blocks and heterocycles, including 1,3‐aminoalcohol, 1,3‐diol, oxetane, and isoxazoline derivatives. 相似文献
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Wei Yang Dr. Ke‐Zhi Jiang Xing Lu Hua‐Meng Yang Dr. Li Li Prof. Dr. Yixin Lu Prof. Dr. Li‐Wen Xu 《化学:亚洲杂志》2013,8(6):1182-1190
A combined catalyst system of a cinchonidine‐derived primary amine and triphenylphosphine (CD‐NH2/PPh3) exhibited high catalytic performance in the Michael reaction of aldehydes with maleimides, thereby affording the corresponding functionalized aldehydes in excellent yields (up to 99 %) and enantioselectivities (>99 % ee). More interestingly, the significance of the phosphine in enhancing the enantioselectivities in the chiral‐primary‐amine‐catalyzed Michael reaction was revealed. Furthermore, we explored the origin of the reaction mechanism in the Michael addition promoted by the dual organocatalytic system. On the basis of experimental results and spectroscopic analysis, such as UV/Vis, fluorescence emission (FL), NMR, and circular dichroism (CD) spectroscopy, as well as ESI‐MS, we found that the molecular assembly of phosphine and primary amine played a crucial role in this enantioselective reaction, in which a possible supramolecular complex was formed as an effective chiral catalyst through noncovalent molecular interactions of a cinchona alkaloid‐derived primary amine with triphenylphosphine. 相似文献
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Organocatalyzed Asymmetric Conjugate Addition of Heteroaryl and Aryl Trifluoroborates: a Synthetic Strategy for Discoipyrrole D 下载免费PDF全文
Jiun‐Le Shih Thien S. Nguyen Prof. Jeremy A. May 《Angewandte Chemie (International ed. in English)》2015,54(34):9931-9935
Bis‐heteroaryl or bis‐aryl stereocenters were formed by an organocatalytic enantioselective conjugate addition using the respective trifluoroborate salts as nucleophiles. Control studies suggested that fluoride dissociation is necessary in the anhydrous conditions. This strategy is applicable to the synthesis of discoipyrrole D, an inhibitor of BR5 fibroblast migration. 相似文献
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Jian Lv Dr. Jiaming Zhang Dr. Zhu Lin Dr. Yongmei Wang Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(4):972-979
A general enantioselective synthesis of functionalized nitrocyclopropanes by organocatalytic conjugate addition of a variety of bromonitroalkanes to α,β‐unsaturated enone systems is presented. The process, efficiently catalyzed by the salts of 9‐amino‐9‐deoxyepiquinine 1 d serves as a powerful approach to the preparation of synthetically and biologically important cyclopropanes with high levels of enantio‐ and diastereoselectivities. Since only 0.6 equivalents of bromonitromethane are used as a reagent, (S)‐ 2 e is obtained enantiomerically pure by employing chiral 1 d as a highly efficient catalyst for its kinetic resolution (97 % ee at 51 % conversion, selectivity s=120). 相似文献
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Highly E‐Selective and Enantioselective Michael Addition to Electron‐Deficient Internal Alkynes Under Chiral Iminophosphorane Catalysis 下载免费PDF全文
Dr. Daisuke Uraguchi Kohei Yamada Prof. Dr. Takashi Ooi 《Angewandte Chemie (International ed. in English)》2015,54(34):9954-9957
A highly E‐selective and enantioselective conjugate addition of 2‐benzyloxythiazol‐5(4H)‐ones to β‐substituted alkynyl N‐acyl pyrazoles is achieved under the catalysis of a P‐spiro chiral iminophosphorane. Simultaneous control of the newly generated central chirality and olefin geometry is possible with a wide array of the alkynyl Michael acceptors possessing different aromatic and aliphatic β‐substituents, as well as the various α‐amino acid‐derived thiazolone nucleophiles. This protocol provides access to structurally diverse, optically active α‐amino acids bearing a geometrically defined trisubstituted olefinic component at the α‐position. 相似文献
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Sarah Sulzer‐Mossé Alexandre Alexakis Prof. Jiri Mareda Dr. Guillaume Bollot Gerald Bernardinelli Dr. Yaroslav Filinchuk Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(13):3204-3220
Chiral framework : Chiral amines with pyrrolidine frameworks catalyze the enantioselective conjugate addition of a wide range of aldehydes to various vinyl sulfones and vinyl phosphonates in high yields and with enantioselectivities up to >99 % ee (see scheme). The high versatility of the Michael adducts is exemplified by various functionalizations with conservation of the optical purity.
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Depeng Zhao Ye Yuan Dr. Albert S. C. Chan Prof. Rui Wang Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(12):2738-2741
Zinc benefits : The first catalytic asymmetric phospha‐Michael addition of enones has been developed. Under mild reaction conditions, the γ‐oxo phosphonates could be obtained in high yields (up to 99 %) with excellent enantioselectivities (93–99 % ee; see scheme). The strategy makes the asymmetric synthesis of biologically important phosphonate compounds more accessible.
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Organocatalytic 1,4‐Addition Reaction of 2‐Formyl(thio)esters to Vinylketones: An Efficient Access to Acyclic Chiral Building Blocks with a Quaternary Carbon Stereocenter 下载免费PDF全文
Toshifumi Tatsumi Dr. Tomonori Misaki Prof. Dr. Takashi Sugimura 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(52):18971-18974
2‐Formyl(thio)esters were utilized as pronucleophiles to obtain less‐accessible acyclic chiral building blocks bearing versatile functional groups on a quaternary carbon atom for enantioselective 1,4‐addition to vinylketones. To achieve high enantioselectivity in the present 1,4‐addition reaction, thiourea‐tertiary amines containing a bulky chiral backbone were developed as catalysts, and several derivatizations of the products were performed to demonstrate the synthetic utility of the products. 相似文献
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A Cu(I) generated in situ from CuSO4·5H2O/sodium ascorbate catalyzed cross‐coupling reaction of aryl halides with aqueous ammonia for the synthesis of primary aromatic amines has been developed. Key to the success included the application of aqueous ammonia under a homogeneous condition. 相似文献