共查询到20条相似文献,搜索用时 62 毫秒
1.
Alexander V. Artem'ev Svetlana F. Malysheva Nataliya A. Belogorlova Nadezhda I. Protzuk Alexander I. Albanov Irina Yu. Bagryanskaya Elena Yu. Schmidt Nina K. Gusarova Boris A. Trofimov 《Heteroatom Chemistry》2015,26(6):455-462
γ‐Ketophosphine chalcogenides, precursors for plethora of novel functionalized phosphine chalcogenides and phosphines, are synthesized by chemo‐ and regioselective addition of secondary phosphine chalcogenides to β,γ‐ethylenic ketones under catalyst‐ and solvent‐free conditions (80–100°C, 8–70 h) in excellent yields. The straightforward superbase‐catalyzed synthesis of starting β,γ‐ethylenic ketones from ketones and acetylenes insures the expedient access to the target γ‐ketophosphine chalcogenides. 相似文献
2.
Junxian Yang Zheng Wang Zeyuan He Guofeng Li Liang Hong Wangsheng Sun Rui Wang 《Angewandte Chemie (International ed. in English)》2020,59(2):642-647
The first asymmetric synthesis of tetrasubstituted α‐amino allenoates by a chiral phosphoric acid catalyzed dearomative γ‐addition reaction of 2,3‐disubstituted indoles to β,γ‐alkynyl‐α‐imino esters is reported. This method provides access to a series of highly functionalized tetrasubstituted allenes featuring quaternary stereocenters in high yields, and with excellent regio‐, diastereo‐, and enantioselectivities under mild conditions without by‐product formation. Representative large‐scale reactions and diverse transformations of the products into various scaffolds with potential biological activities render are also disclosed. The mechanism of the reaction was elucidated by control reactions and DFT calculations. 相似文献
3.
Kiron Kumar Ghosh Alexander Uttry Arup Mondal Francesca Ghiringhelli Philipp Wedi Manuel van Gemmeren 《Angewandte Chemie (International ed. in English)》2020,59(31):12848-12852
We report the ligand‐enabled C?H activation/olefination of free carboxylic acids in the γ‐position. Through an intramolecular Michael addition, δ‐lactones are obtained as products. Two distinct ligand classes are identified that enable the challenging palladium‐catalyzed activation of free carboxylic acids in the γ‐position. The developed protocol features a wide range of acid substrates and olefin reaction partners and is shown to be applicable on a preparatively useful scale. Insights into the underlying reaction mechanism obtained through kinetic studies are reported. 相似文献
4.
Yu‐Hua Liao Xiong‐Li Liu Dr. Zhi‐Jun Wu Prof. Xi‐Lin Du Prof. Dr. Xiao‐Mei Zhang Prof. Dr. Wei‐Cheng Yuan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(21):6679-6687
An asymmetric conjugate addition of 3‐monosubstituted oxindoles to a range of (E)‐1,4‐diaryl‐2‐buten‐1,4‐diones, catalyzed by commercially available cinchonine, is described. This organocatalytic asymmetric reaction affords a broad range of 3,3′‐disubstituted oxindoles that contain a 1,4‐dicarbonyl moiety and vicinal quaternary and tertiary stereogenic centers in high‐to‐excellent yields (up to 98 %), with excellent diastereomeric and moderate‐to‐high enantiomeric ratios (up to 99:1 and 95:5, respectively). Subsequently, cyclization of the 1,4‐dicarbonyl moiety in the resultant Michael adducts under different Paal–Knorr conditions results in two new kinds of 3,3′‐disubstituted oxindoles—3‐furanyl‐ and 3‐pyrrolyl‐3‐alkyl‐oxindoles—in high yields and good enantioselectivities. Notably, the studies presented here sufficiently confirm that this two‐step strategy of sequential conjugate addition/Paal–Knorr cyclization is not only an attractive method for the indirect enantioselective heteroarylation of 3‐alkyloxindoles, but also opens up new avenues toward asymmetric synthesis of structurally diverse 3,3′‐disubstituted oxindole derivatives. 相似文献
5.
Palladium‐Catalyzed Carbonylative α‐Arylation of 2‐Oxindoles with (Hetero)aryl Bromides: Efficient and Complementary Approach to 3‐Acyl‐2‐oxindoles
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Zhong Lian Stig D. Friis Prof. Dr. Troels Skrydstrup 《Angewandte Chemie (International ed. in English)》2014,53(36):9582-9586
An efficient Pd‐catalyzed carbonylative α‐arylation of 2‐oxindoles with aryl and heteroaryl bromides for the one‐step synthesis of 3‐acyl‐2‐oxindoles has been developed. This reaction proceeds efficiently under mild conditions and is complementary to the more common oxindole forming reactions. The transformation only requires a mild base and provides good to excellent yields even with heteroaromatic substrates. Employing a near stoichiometric amount of 13COgen, the methodology was easily extended to [13C] acyl labeling. The general applicability of the reaction conditions was demonstrated in the synthesis of a structure related to the pharmaceutically active 3‐acyl‐2‐oxindoles, tenidap. 相似文献
6.
A Metal‐free Approach to 3‐Aryl‐3‐hydroxy‐2‐oxindoles by Treatment of 3‐Acyloxy‐2‐oxindoles with Diaryliodonium Salts
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A mild, metal‐free approach has been realized for the facile construction of highly valuable 3‐(hetero)aryl‐3‐hydroxy‐2‐oxindoles. Direct arylations of 3‐acyloxy‐2‐oxindoles with diaryliodonium salts as arylation reagents are implemented in the presence of K2CO3 at room temperature without using an organometallic promoter to deliver an array of 3‐(hetero)aryl‐3‐hydroxy‐2‐oxindoles in good yields. 相似文献
7.
《中国化学》2017,35(9):1469-1473
A phosphine‐catalyzed [4 + 2] annulation of α ‐substituted allenoate with exocyclic alkene moiety of oxindoles or indan‐1,3‐diones has been developed. Thus, under the catalysis of PPh3 (20 mol%), a series of spirooxindole‐ or spiroindan‐1,3‐dione‐cyclohexenes have been obtained in moderate to excellent yields and regioselectivity from the annulations of α ‐methyl allenoates with 3‐methyleneoxindoles or 2‐methyleneindan‐1,3‐diones. This method offers an easy access to structurally novel spirocyclohexenes. 相似文献
8.
Timothy B. Wright Ben W. H. Turnbull P. Andrew Evans 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(29):9991-9995
An enantioselective rhodium‐catalyzed allylic alkylation of β,γ‐unsaturated α‐amino nitriles is described. This protocol provides a novel approach for the construction of β‐stereogenic carbonyl derivatives via the catalytic asymmetric alkylation of a homoenolate equivalent. The particularly challenging nature of this transformation is highlighted by the fact that three modes of selectivity must be manipulated, namely regio‐ and enantioselectivity, in addition to geometrical control. The γ‐stereogenic cyanoenamine products can be readily hydrolyzed in situ to afford the β‐substituted carboxylic acids, which in turn provide expedient access to a number of related carbonyl derivatives. Additionally, control experiments indicate that the chiral rhodium‐allyl intermediate facilitates the selective formation of the E‐cyanoenamine products, which is critical since the Z‐isomer affords significantly lower enantiocontrol. 相似文献
9.
Dr. Suhua Li Ru‐Yi Zhu Dr. Kai‐Jiong Xiao Prof. Dr. Jin‐Quan Yu 《Angewandte Chemie (International ed. in English)》2016,55(13):4317-4321
PdII‐catalyzed arylation of γ‐C(sp3)?H bonds of aliphatic acid‐derived amides was developed by using quinoline‐based ligands. Various γ‐aryl‐α‐amino acids were prepared from natural amino acids using this method. The influence of ligand structure on reactivity was also systematically investigated. 相似文献
10.
Prof. Dr. Yasunori Yamamoto Masaaki Yohda Tomohiko Shirai Prof. Dr. Hajime Ito Prof. Dr. Norio Miyaura 《化学:亚洲杂志》2012,7(10):2446-2449
A chiral O‐linked C2‐symmetric bidentate phosphoramidite (Me‐BIPAM) was found to be efficient for the ruthenium‐catalyzed addition of arylboronic acids to isatins. Asymmetric synthesis of 3‐aryl‐3‐hydroxy‐2‐oxindoles by 1,2‐addition of arylboronic acids to isatins was carried out in the presence of [RuCl2(PPh3)3]/(R,R)‐Me‐BIPAM and KF, resulting in an enantioselectivity as high as 90 % ee. It was found that the reaction with N‐protected isatins proceeds with high yields and good enantioselectivities. The best protective groups on the nitrogen atom were different depending on the substituents on the aromatic ring. The use of a N‐benzyl group resulted in excellent enantioselectivities in many substrates compared with other groups. 相似文献
11.
Dr. Michael Wilsdorf Prof. Dr. Hans‐Ulrich Reissig 《Angewandte Chemie (International ed. in English)》2014,53(17):4332-4336
The total synthesis of the human telomerase inhibitor γ‐rubromycin in its racemic form was accomplished in 3.8 % overall yield. The key feature of this synthesis is an efficient acid‐catalyzed spiroketalization for the construction of the spiroketal core. The required electronically well‐balanced spiroketal precursor was obtained by the convergent assembly of a naphthyl‐substituted aldehyde, an α‐methoxyallyl‐γ‐silyl‐substituted phosphonate as the central C3 building block, and a highly functionalized aryl Grignard reagent. Another key feature is the late‐stage construction of the isocoumarin moiety and a simultaneous protodesilylation furnishing the known methyl aryl ether protected precursor of γ‐rubromycin. 相似文献
12.
Single‐Flask Multicomponent Palladium‐Catalyzed α,γ‐Coupling of Ketone Enolates: Facile Preparation of Complex Carbon Scaffolds
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Michael Grigalunas Prof. Dr. Per‐Ola Norrby Prof. Dr. Olaf Wiest Prof. Dr. Paul Helquist 《Angewandte Chemie (International ed. in English)》2015,54(40):11822-11825
A three‐component palladium‐catalyzed reaction sequence has been developed in which γ‐substituted α,β‐unsaturated products are obtained in a single flask by an α‐alkenylation with either a subsequent γ‐alkenylation or γ‐arylation of a ketone enolate. Coupling of a variety of electronically and structurally different components was achieved in the presence of a Pd/Q‐Phos catalyst (2 mol %), usually at 22 °C with yields of up to 85 %. Most importantly, access to these products is obtained in one simple operation in place of employing multiple reactions. 相似文献
13.
Amino Acid Derived Phosphine‐Catalyzed Enantioselective 1,4‐Dipolar Spiroannulation of Cyclobutenones and Isatylidenemalononitrile
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Yangyan Li Xiao Su Wei Zhou Dr. Wenbo Li Prof. Dr. Junliang Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(11):4224-4228
Cyclobutenones have been explored as a new type of chiral 1,4‐dipole four‐carbon synthon, which readily undergoes organophosphine‐mediated C?C bond cleavage and asymmetric intermolecular 1,4‐dipolar spiroannulation with isatylidenemalononitrile in the presence of amino acid‐derived chiral phosphine catalyst to furnish enantioenriched 3‐spirocyclohexenone 2‐oxindoles in good yield with up to 87 % ee. To our knowledge, this is the first example of asymmetric transformation of cyclobutenones and the phosphine‐catalyzed asymmetric 1,4‐dipolar cycloaddition consisting of C?C bond activation is unprecedented. 相似文献
14.
Synthesis of Highly Substituted γ‐Butyrolactones by a Gold‐Catalyzed Cascade Reaction of Benzyl Esters
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Maria Camila Blanco Jaimes Alexander Ahrens Daniel Pflästerer Dr. Matthias Rudolph Prof. Dr. A. Stephen K. Hashmi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(1):427-433
Easily accessible benzylic esters of 3‐butynoic acids in a gold‐catalyzed cyclization/rearrangement cascade reaction provided 3‐propargyl γ‐butyrolactones with the alkene and the carbonyl group not being conjugated. Crossover experiments showed that the formation of the new C?C bond is an intermolecular process. Initially propargylic–benzylic esters were used, but alkyl‐substituted benzylic esters worked equally well. In the case of the propargylic–benzylic products, a simple treatment of the products with aluminum oxide initiated a twofold tautomerization to the allenyl‐substituted γ‐butyrolactones with conjugation of the carbonyl group, the olefin, and the allene. The synthetic sequence can be conducted stepwise or as a one‐pot cascade reaction with similar yields. Even in the presence of the gold catalyst the new allene remains intact. 相似文献
15.
Organocatalytic Asymmetric Friedel–Crafts Reaction of Sesamol with Isatins: Access to Biologically Relevant 3‐Aryl‐3‐hydroxy‐2‐oxindoles
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Dr. Akshay Kumar Jasneet Kaur Dr. Pankaj Chauhan Prof. Dr. Swapandeep Singh Chimni 《化学:亚洲杂志》2014,9(5):1305-1310
The Friedel–Crafts reaction of electron‐rich phenols with isatins was developed by employing bifunctional thiourea–tertiary amine organocatalysts. Cinchona alkaloid derived thiourea epiCDT‐ 3 a efficiently catalyzed the Friedel–Crafts‐type addition of phenols to isatin derivatives to provide 3‐aryl‐3‐hydroxy‐2‐oxindoles 7 and 9 in good yield (80–95 %) with good enantiomeric excess (83–94 %). Friedel–Crafts adduct 7 t was subjected to a copper(I)‐catalyzed azide–alkyne cycloaddition to obtain biologically important 3‐aryl‐3‐hydroxy‐2‐oxindole 11 in good enantiomeric excess and having a 1,2,3‐triazole moiety. 相似文献
16.
Phosphine‐Catalyzed Annulations of 4,4‐Dicyano‐2‐Methylenebut‐3‐enoates with Maleimides and Maleic Anhydride
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Xiao‐Nan Zhang Gen‐Qiang Chen Dr. Xiang‐Ying Tang Dr. Yin Wei Dr. Min Shi 《Angewandte Chemie (International ed. in English)》2014,53(40):10768-10773
A novel phosphine‐catalyzed [4+1] annulation of maleimides with 4,4‐dicyano‐2‐methylenebut‐3‐enoates has been developed to afford spirocyclic products, and the maleimides serves as C1 synthons. Moreover, a phosphine‐catalyzed formal [3+2] annulation between 4,4‐dicyano‐2‐methylenebut‐3‐enoates and maleic anhydride has been also achieved, and maleic anhydride behaved as a C3 synthon in the reaction, thus efficiently affording the functionalized cyclopentenones. A stable phosphinium‐containing zwitterionic compound is the key reactive intermediate in both annulations and was successfully isolated. Plausible mechanisms have been proposed on the basis of control experiments and deuterium‐labeling experiments. 相似文献
17.
《Angewandte Chemie (International ed. in English)》2017,56(20):5551-5555
Despite the burgeoning demand for fluorine‐containing chemical entities, the construction of CF3‐containing stereogenic centers has remained elusive. Herein, we report the strategic merger of CuI/base‐catalyzed enolization of an α‐CF3 amide and Pd0‐catalyzed allylic alkylation in an enantioselective manner to deliver chiral building blocks bearing a stereogenic carbon center connected to a CF3, an amide carbonyl, and a manipulable allylic group. The phosphine complexes of CuI and Pd0 engage in distinct catalytic roles without ligand scrambling to render the dual catalysis operative to achieve asymmetric α‐allylation of the amide. The stereoselective cyclization of the obtained α‐CF3‐γ,δ‐unsaturated amides to give tetrahydropyran and γ‐lactone‐fused cyclopropane skeletons highlights the synthetic utility of the present catalytic method as a new entry to non‐racemic CF3‐containing compounds. 相似文献
18.
An Exclusively trans‐Selective Chlorocarbamoylation of Alkynes Enabled by a Palladium/Phosphaadamantane Catalyst
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Christine M. Le Xiao Hou Theresa Sperger Prof. Dr. Franziska Schoenebeck Prof. Dr. Mark Lautens 《Angewandte Chemie (International ed. in English)》2015,54(52):15897-15900
Pharmaceutically relevant methylene oxindoles are synthesized by a palladium(0)‐catalyzed intramolecular chlorocarbamoylation reaction of alkynes. A relatively underexplored class of caged phosphine ligands is uniquely suited for this transformation, enabling high levels of reactivity and exquisite trans selectivity. This report entails the first transition‐metal‐catalyzed atom‐economic addition of a carbamoyl chloride across an alkyne. 相似文献
19.
Carina I. Jette Z. Jaron Tong Ryan G. Hadt Brian M. Stoltz 《Angewandte Chemie (International ed. in English)》2020,59(5):2033-2038
Herein, we report a Cu‐catalyzed enantioselective allylic alkylation using a γ‐butyrolactone‐derived silyl ketene acetal. Critical to the development of this work was the identification of a novel mono‐picolinamide ligand with the appropriate steric and electronic properties to afford the desired products in high yield (up to 96 %) and high ee (up to 95 %). Aryl, aliphatic, and unsubstituted allylic chlorides bearing a broad range of functionality are well‐tolerated. Spectroscopic studies reveal that a CuI species is likely the active catalyst, and DFT calculations suggest ligand sterics play an important role in determining Cu coordination and thus catalyst geometry. 相似文献
20.
Han Seul Park Zhoulong Fan Ru‐Yi Zhu Jin‐Quan Yu 《Angewandte Chemie (International ed. in English)》2020,59(31):12853-12859
Reported herein is the distal γ‐C(sp3)?H olefination of ketone derivatives and free carboxylic acids. Fine tuning of a previously reported imino‐acid directing group and using the ligand combination of a mono‐N‐protected amino acid (MPAA) and an electron‐deficient 2‐pyridone were critical for the γ‐C(sp3)?H olefination of ketone substrates. In addition, MPAAs enabled the γ‐C(sp3)?H olefination of free carboxylic acids to form diverse six‐membered lactones. Besides alkyl carboxylic acids, benzylic C(sp3)?H bonds also could be functionalized to form 3,4‐dihydroisocoumarin structures in a single step from 2‐methyl benzoic acid derivatives. The utility of these protocols was demonstrated in large scale reactions and diversification of the γ‐C(sp3)?H olefinated products. 相似文献