- 'Bis-ornithine' (2,2-bis(aminopropyl)glycine): a new tetravalent template for assembling different functional peptides
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Synthesis of bis-ornithine, a new Cα,α-disubstituted α-amino acid bearing orthogonally protected α and δ amine groups is reported. Bis-ornithine (bisOrn) and dipeptides containing bis-ornithine have been synthesized in solution up to multigram
- Aussedat, Baptiste,Chassaing, Gérard,Lavielle, Solange,Burlina, Fabienne
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- Dynamic Catalytic Highly Enantioselective 1,3-Dipolar Cycloadditions
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In dynamic covalent chemistry, reactions follow a thermodynamically controlled pathway through equilibria. Reversible covalent-bond formation and breaking in a dynamic process enables the interconversion of products formed under kinetic control to thermod
- Antonchick, Andrey P.,Brieger, Lukas,Grigalunas, Michael,Strohmann, Carsten,Waldmann, Herbert,Yildirim, Okan
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supporting information
p. 20012 - 20020
(2021/08/06)
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- Copper/GanPhos-Catalyzed 1,3-Dipolar Cycloaddition of Azo?-methine Ylides: An Efficient Access to Chiral Pyrrolidine Spirocycles
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A highly efficient copper/GanPhos-catalyzed 1,3-dipolar cyclo?-addition?-of azomethine ylides is reported. This viable transformation provides a series of optically active spiro[dihydronaphthalene-2,3′-pyrrolidine]s, bearing one spiro quaternary and three tertiary stereogenic centers, in good yields and with high ee values. This protocol features high diastereo- A nd enantioselectivity, broad substrate scope and mild reaction conditions.
- Gan, Zhenjie,Li, Ke,Zhang, Hui,Li, Er-Qing
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supporting information
p. 1331 - 1340
(2020/11/30)
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- Silver-Mediated [3 + 2] Cycloaddition of Azomethine Ylides with Trifluoroacetimidoyl Chlorides for the Synthesis of 5-(Trifluoromethyl)imidazoles
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A silver-mediated [3 + 2] cycloaddition of azomethine ylides with trifluoroacetimidoyl chlorides for the rapid assembly of 5-(trifluoromethyl)imidazoles has been developed. Notable features of the reaction include readily accessible reagents, a broad substrate scope, and high efficiency. The protocol can be successfully applied to construct the analogue of the specific allosteric modulator of GABAA receptors. The silver species could be recycled by a simple operation.
- Yang, Hefei,Lu, Shu-Ning,Chen, Zhengkai,Wu, Xiao-Feng
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supporting information
p. 4361 - 4370
(2021/03/09)
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- Copper(i)/Ganphos catalysis: enantioselective synthesis of diverse spirooxindoles using iminoesters and alkyl substituted methyleneindolinones
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A copper-catalyzed asymmetric 1,3-dipolar cycloaddition of glycine iminoesters with alkyl substituted 3-methylene-2-oxindoles is described. By usingde novodesign of P-stereogenic phosphines as ligands, spiro[pyrrolidin-3,3'-oxindole]s are generated in good to excellent yields with high asymmetric induction. A further reduced catalyst loading of 0.1 mol% is sufficient to achieve a satisfactory enantioselectivity of 90% ee. The DFT calculations suggest the second Michael addition of the 1,3-dipole to be the rate- andenantio-determining step. A key feature of this 1,3-dipolar cycloaddition is the wide substrate applicability, even with alkyl aldehyde-derived azomethine ylide; thus it has streamlined a highly enantioselective access to a new class of antiproliferative agents, MDM2-p53.
- Cui, Hao,Duan, Zheng,Li, Er-Qing,Li, Ke,Mathey, Fran?ois,Song, Manman,Wang, Congcong,Wang, Yue,Wei, Donghui
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supporting information
p. 3740 - 3746
(2020/06/03)
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- Silver/palladium relay catalyzed 1,3-dipole annulation/allylation reactions to access fully substituted allyl imidazolidines
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A silver/palladium relay catalyzed 1,3-dipole annulation/allylation reaction of iminoesters and Baylis-Hillman acetates for the construction of fully substituted allyl imidazolidines is reported. The reaction of both iminoesters and Baylis-Hillman acetate
- Han, Ruiping,Ding, Yue,Jin, Xueke,Li, Er-Qing
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supporting information
p. 646 - 649
(2020/02/11)
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- Facile synthesis of chiral [2,3]-fused hydrobenzofuran: Via asymmetric Cu(i)-catalyzed dearomative 1,3-dipolar cycloaddition
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Intermolecular asymmetric dearomative 1,3-dipolar cycloaddition of 2-nitrobenzofurans with azomethine ylides was enabled by using a chiral Cu(i)/(S,Sp)-iPr-Phosferrox catalyst. As a result, a series of highly stereoselective chiral [2,3]-fused hydrobenzofurans possessing four contiguous stereogenic centers were obtained with good to high yields, diastereoselectivities and enantioselectivities. The reaction has broad substrate scope tolerating various functional groups.
- Liang, Lei,Niu, Hong-Ying,Wang, Dong-Chao,Yang, Xin-He,Qu, Gui-Rong,Guo, Hai-Ming
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supporting information
p. 553 - 556
(2019/01/10)
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- Well-Designed Phosphine-Urea Ligand for Highly Diastereo- and Enantioselective 1,3-Dipolar Cycloaddition of Methacrylonitrile: A Combined Experimental and Theoretical Study
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A novel chiral phosphine-urea bifunctional ligand has been developed for Cu-catalyzed asymmetric 1,3-dipolar cycloaddition of iminoesters with methacrylonitrile, a long-standing challenging substrate in asymmetric catalysis. Distortion-interaction energy analysis based on density functional theory (DFT) calculations reveals that the distortion energy plays an important role in the observed enantioselectivity, which can be attributed to the steric effect between the phosphine ligand and the dipole reactant. DFT calculations also indicate that nucleophilic addition is the enantioselectivity-determining step and hydrogen bonding between the urea moiety and methacrylonitrile assists in control of the diastereo- and enantioselectivity. By a combination of metal catalysis and organocatalysis, excellent diastereo- and enantioselectivities (up to 99:1 diastereomeric ratio, 99% enantiomeric excess) as well as good yields are achieved. A wide range of substitution patterns of both iminoester and acrylonitrile is tolerated by this catalyst system, providing access to a series of highly substituted chiral cyanopyrrolidines with up to two quaternary stereogenic centers. The synthetic utility is demonstrated by enantioselective synthesis of antitumor agent ETP69 with a pivotal nitrile pharmacophore and an all-carbon quaternary stereogenic center.
- Xiong, Yang,Du, Zhuanzhuan,Chen, Haohua,Yang, Zhao,Tan, Qiuyuan,Zhang, Changhui,Zhu, Lei,Lan, Yu,Zhang, Min
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supporting information
p. 961 - 971
(2019/01/14)
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- Ag/P-Stereogenic Phosphine-Catalyzed Enantioselective 1,3-Dipolar Cycloadditions: A Method to Optically Active Pyrrolidines
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A Ag/P-stereogenic phosphine-complex-catalyzed 1,3-dipolar cycloaddition of azomethine ylides with electron-deficient olefins is reported. In this reaction, highly functionalized pyrrolines with a spiro-quaternary stereogenic center were obtained in good yields (up to 99%) with excellent levels of diastereo-(up to >20:1 dr) and enantioselectivities (up to >99% ee). The chirality of adducts was controlled predominantly by the P-stereogenic phosphines.
- Zhi, Mengna,Gan, Zhenjie,Ma, Rong,Cui, Hao,Li, Er-Qing,Duan, Zheng,Mathey, Fran?ois
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supporting information
(2019/05/07)
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- Ligand-Controlled Inversion of Diastereo- and Enantioselectivity in Silver-Catalyzed Azomethine Ylide-Imine Cycloaddition of Glycine Aldimino Esters with Imines
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A highly diastereo- and enantioselective silver-catalyzed azomethine ylide-imine (AYI) cycloaddition reaction of glycine aldimino esters with imines was developed in which the Xing-Phos-controlled syn-selective or DTBM-Segphos-induced anti-selective AYI cycloaddition reaction could be applied to the synthesis of a variety of stereodivergent 1-alkyl-2,5-substituted imidazolidines with high yields and excellent enantioselectivities (up to 99% ee) as well as good diastereoselectivities (up to 99:1 dr) under mild reaction conditions.
- Yu, Bo,Yang, Ke-Fang,Bai, Xing-Feng,Cao, Jian,Zheng, Zhan-Jiang,Cui, Yu-Ming,Xu, Zheng,Li, Li,Xu, Li-Wen
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supporting information
p. 2551 - 2554
(2018/05/17)
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- Tandem nucleophilic addition-cycloaddition of arynes with α-iminoesters: Two concurrent pathways to imidazolidines
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The tandem nucleophilic addition-cycloaddition reaction has been developed for the synthesis of functionalized imidazolidine derivatives. A variety of α-iminoesters and aryne precursors were well tolerated under the mild reaction conditions. This asymmetric cycloaddition afforded imidazolidine derivatives with high yields, complete regioselectivities, and excellent diastereo- and enantioselectivities. Aryne-induced ylides working as 1,3-dipoles for asymmetric cycloaddition are the notable feature of the present reaction. In the tandem reaction, the [3+2] cycloaddition of aryne-induced ylides with metallized α-iminoesters and metal-catalyzed [3+2] cycloaddition of azomethine ylide with α-iminoesters are two concurrent pathways to imidazolidines.
- Jia, Hao,Guo, Zhenyan,Liu, Honglei,Mao, Biming,Shi, Xueyan,Guo, Hongchao
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supporting information
p. 7050 - 7053
(2018/07/05)
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- Silicon-based Bulky Group?Tuned Parallel Kinetic Resolution in Copper-Catalyzed 1,3-Dipolar Additions
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The development of new strategies or reaction processes that tease new reactivity of functional groups continues to spur synthetic chemists toward innovative solutions that access new compounds. Herein, we find that the silicon-based bulky group enables a 1,3-dipolar addition?initiated parallel kinetic resolution (PKR) to occur unexpectedly, leading to the highly enantioselective synthesis of two structurally different types of amino acid derivatives via chemodivergent [3+2] cycloaddition reactions and tandem conjugate addition-elimination reaction respectively. The resulting and structurally divergent enantioenriched amino acid derivatives that contain four contiguous stereogenic centers and an all-carbon quaternary center were obtained with up to 99% ee with >95:1 dr and good yields. (Figure presented.).
- Yuan, Yang,Zheng, Zhan-Jiang,Li, Li,Bai, Xing-Feng,Xu, Zheng,Cui, Yu-Ming,Cao, Jian,Yang, Ke-Fang,Xu, Li-Wen
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supporting information
p. 3002 - 3008
(2018/04/30)
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- Total synthesis and biological evaluation of spirotryprostatin A analogs
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Based on the spirotryprostatin A structure, a series of compounds belonging to spiro-indolyl diketopiperazine structural class were designed and synthesized, which embody an oxindole with an all-carbon quaternary stereocenter. The total synthesis can efficiently be accessed in a seven-step reaction sequence with 18–28% overall yield from commercially available materials, and a highly enantioselective 1,3-dipolar cycloaddition, N-acylation of the resulting stereochemically complex spiro[pyrrolidin-3,3′-oxindole]s core with Fmoc-L-pro-Cl and spontaneous ring closure upon N-deprotection were obtained. The synthesized compounds 13a–e and 15a–e were evaluated for their antibacterial activities. The result showed that compounds 13b and 15b were active only against Gram-positive bacteria, and selective antibacterial activity was exhibited by compounds 13d and 13e against Streptococcus lactis. Further, all the remaining compounds showed a certain degree of antibacterial activity. In addition, the structure–activity relationship is also discussed.
- Ma, Yangmin,Fan, Chao,Jia, Bin,Cheng, Pei,Liu, Jia,Ma, Yuqiang,Qiao, Ke
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p. 737 - 746
(2017/10/17)
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- Synthesis of Pyrrole via a Silver-Catalyzed 1,3-Dipolar Cycloaddition/Oxidative Dehydrogenative Aromatization Tandem Reaction
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Pyrroles are an important group of heterocyclic compounds with a wide range of interesting properties, which have resulted in numerous applications in a variety of fields. Despite the importance of these compounds, there have been few reports in the literature pertaining to the synthesis of pyrroles from simple alkenes using a one-pot sequential 1,3-dipolar cycloaddition/aromatization reaction sequence. Herein, we report the development of a benzoyl peroxide-mediated oxidative dehydrogenative aromatization reaction for the construction of pyrroles. We subsequently developed a one-pot tandem reaction that combined this new method with a well-defined silver-catalyzed 1,3-dipolar cycloaddition reaction, thereby providing a practical method for the synthesis of multisubstituted pyrroles from easy available alkenes. The mechanism of this oxidative dehydrogenative aromatization reaction was also examined in detail.
- Liu, Yan,Hu, Huayou,Wang, Xiang,Zhi, Sanjun,Kan, Yuhe,Wang, Chao
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p. 4194 - 4202
(2017/04/28)
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- Aromatic substitution spiro indolyl diketopiperazine compound and synthesis method thereof
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The invention discloses an aromatic substitution spiro indolyl diketopiperazine compound and a synthesis method thereof. Glycine is used as a raw material and subjected to esterification reaction with methyl alcohol and thionyl chloride to obtain methyl glycinate hydrochloride, methyl glycinate hydrochloride and aromatic aldehyde are subjected to condensation reaction to obtain Schiff base, isatin is used as a raw material and subjected to reduction reaction under the action of hydrazine hydrate to obtain indoline-2-ketone, indoline-2-ketone and benzaldehyde are subjected to Knoevenagel reaction under piperidine catalysis to obtain 3-phenylidene-1,3-dihydro-2H-indol-2 ketone, 3-phenylidene-1,3-dihydro-2H-indol-2 ketone and Schiff base are subjected to 1,3-dipole cycloaddition reaction under catalysis of chiral ligand (S)-TF-BiphamPhos/AgoAc to obtain spiro pyrrolidine, and protecting group removal and ring closure are carried out on spiro pyrrolidine and N-(9-fluorene methoxycarbonyl)-L-prolyl chloride through base catalysis to obtain the target product. The method has the advantages of being simple in path, high in yield, high in diastereoselectivity and single in product spatial configuration, and the raw materials are low in price and easy to obtain.
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Paragraph 0040; 0044
(2017/08/28)
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- Ag2CO3/CA-AA-amidphos multifunctional catalysis in the enantioselective 1,3-dipolar cycloaddition of azomethine ylides
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The new Ag2CO3/CA-AA-amidphos complexes have been demonstrated as highly efficient multifunctional catalysts in the asymmetric 1,3-dipolar cycloaddition of azomethine ylides. Under optimal conditions, highly functionalized endo-4 pyrrolidines were obtained with excellent yields (up to 99% yield) and enantioselectivities (up to 96% ee).
- Wang, Haifei,Deng, Qifu,Zhou, Zhipeng,Hu, Shunqin,Liu, Zhiguo,Zhou, Li-Yi
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supporting information
p. 404 - 407
(2016/02/18)
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- Synthesis of Azacyclic Nucleoside Analogues via Asymmetric [3 + 2] Cycloaddition of 9-(2-Tosylvinyl)-9H -purines
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With 9-(2-tosylvinyl)-9H-purines as the dipolarophiles, a series of chiral azacyclic nucleosides with four continuous stereocenters were obtained in 86-99% yields, >20:1 dr, and 94 → 99% ee via the Cu(I)-catalyzed asymmetric [3 + 2] cycloaddition. Both (E)- and (Z)-9-(2-tosylvinyl)-9H-purines were suitable dipolarophiles, enriching the structure diversity of azacyclic nucleosides. Furthermore, when α-methyl imino ester was explored, the corresponding azacyclic nucleoside with a chiral quaternary stereocenter could also be afforded with excellent results. (Chemical Equation Presented).
- Zhang, Dan-Jie,Xie, Ming-Sheng,Qu, Gui-Rong,Gao, Yao-Wei,Guo, Hai-Ming
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supporting information
p. 820 - 823
(2016/03/01)
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- Enantiodivergent Combination of Natural Product Scaffolds Enabled by Catalytic Enantioselective Cycloaddition
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An efficient strategy has been established for the enantiodivergent synthesis of natural product inspired compounds embodying both tropane and pyrrolidine natural product fragments. This strategy includes the enantioselective kinetic resolution of racemic tropanes by means of a copper(I)-catalyzed [3+2] cycloaddition and allows the preparation of two enantiopure products in a one-pot reaction in high yield and with high diastereo- and enantioselectivity by using one chiral catalyst.
- Xu, Hao,Golz, Christopher,Strohmann, Carsten,Antonchick, Andrey P.,Waldmann, Herbert
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supporting information
p. 7761 - 7765
(2016/07/07)
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- Cycloaddition reactions of glycine imine anions to phenylazocarboxylic esters - A new access to 1,3,5-trisubstituted 1,2,4-triazoles
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Phenylazocarboxylic tert-butyl esters have recently been shown to be highly versatile building blocks due to their ability to undergo nucleophilic aromatic substitutions under mild conditions, particularly well with [18F]fluoride, and to act as precursors for aryl radicals. In this article, we now report first examples for cycloaddition reactions to phenylazocarboxylates. In a one-pot reaction with readily accessible glycine imines, a variety of highly substituted 1,2,4-triazoles could be obtained.
- Lasch, Roman,Heinrich, Markus R.
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p. 4282 - 4295
(2015/06/08)
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- A rapid and divergent access to chiral azacyclic nucleoside analogues via highly enantioselective 1,3-dipolar cycloaddition of β-nucleobase substituted acrylates
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A rapid and divergent access to chiral azacyclic nucleoside analogues has been established via highly exo-selective and enantioselective 1,3-dipolar cycloaddition of azomethine ylides with β-nucleobase substituted acrylates. Using 1 mol% of a chiral copper complex, various chiral azacyclic nucleoside analogues were obtained in high yields, excellent exo-selectivities and enantioselectivities (98 to >99% ee). This journal is
- Yang, Qi-Liang,Xie, Ming-Sheng,Xia, Chao,Sun, Huan-Li,Zhang, Dan-Jie,Huang, Ke-Xin,Guo, Zhen,Qu, Gui-Rong,Guo, Hai-Ming
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supporting information
p. 14809 - 14812
(2014/12/11)
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- Asymmetric [3+2] cycloaddition of azomethine ylides catalyzed by silver(I) triflate with a chiral bipyrrolidine-derived phosphine ligand
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Two novel chiral bipyrrolidine-derived phosphine ligands L1 and L2 were synthesized. The AgOTf + L1 protocol catalyzes the asymmetric [3+2] cycloaddition of azomethine ylides with alkenes to give highly substituted pyrrolidines in good yields (up to 90%) with moderate to high diastereoselectivities (up to >19:1 dr) and enantioselectivities (up to 76%).
- Gu, Xin,Xu, Zhen-Jiang,Che, Chi-Ming,Lo, Vanessa Kar-Yan
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p. 3307 - 3314,8
(2012/12/12)
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- Asymmetric [3+2] cycloaddition of azomethine ylides catalyzed by silver(I) triflate with a chiral bipyrrolidine-derived phosphine ligand
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Two novel chiral bipyrrolidine-derived phosphine ligands L1 and L2 were synthesized. The AgOTf + L1 protocol catalyzes the asymmetric [3+2] cycloaddition of azomethine ylides with alkenes to give highly substituted pyrrolidines in good yields (up to 90%) with moderate to high diastereoselectivities (up to >19:1 dr) and enantioselectivities (up to 76%). Georg Thieme Verlag Stuttgart.New York.
- Gu, Xin,Xu, Zhen-Jiang,Lo, Vanessa Kar-Yan,Che, Chi-Ming
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p. 3307 - 3314
(2013/01/15)
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- Silver-catalyzed 1,3-dipolar cycloaddition of azomethine ylides with β-boryl acrylates
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The Ag-catalyzed 1,3-dipolar cycloaddition of (?)-β-borylacrylates with azomethine ylides is described. The resulting 3-borylpyrrolidine derivatives were obtained in high yields and complete endo selectivities using AgOAc/ dppe as catalyst system and B(dam) as boryl group. Transformation of the B(dam) group into pinacol borane and oxidation afforded 3-hydroxyproline derivatives in high yields.
- Lopez-Perez, Ana,Segler, Marwin,Adrio, Javier,Carretero, Juan C.
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supporting information; experimental part
p. 1945 - 1948
(2011/06/20)
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- Asymmetric construction of 3-vinylidene-pyrrolidine derivatives containing allene moiety via Ag(i)/TF-BiphamPhos-catalyzed 1,3-dipolar cycloaddition of azomethine ylides with diethyl 2-(3,3-diphenylpropa-1,2-dienylidene) malonate
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Catalytic asymmetric 1,3-dipolar cycloaddition of various azomethine ylides with diethyl 2-(3,3-diphenylpropa-1,2-dienylidene)malonate has been developed successfully with good to excellent enantioselectivity for the effcient construction of 3-vinylidene-pyrrolidine derivatives containing a unique allene moiety.
- Xue, Zhi-Yong,Fang, Xin,Wang, Chun-Jiang
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supporting information; experimental part
p. 3622 - 3624
(2011/06/17)
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- Metal-free asymmetric 1,3-dipolar cycloaddition of N-arylmaleimides to azomethine ylides catalyzed by chiral tertiary amine thiourea
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The first metal-free asymmetric 1,3-dipolar cycloaddition of N-arylmaleimides to azomethine ylides catalyzed by chiral tertiary amine thiourea to form multiply substituted pyrrolidines in excellent yields (up to 89%) and enantioselectivities (up to 96% ee) is presented. This procedure allows a rapid diversity-oriented synthesis of chiral pyrrolidine derivatives with high optical purity. A series of bifunctional thiourea catalysts were applied for the first time to the highly asymmetric 1,3-dipolar cycloaddition of N-arylmaleimides to azomethine ylides togive the products in excellent yields (up to 89%) and enantioselectivities (up to 96% ee).
- Bai, Jian-Fei,Wang, Liang-Liang,Peng, Lin,Guo, Yun-Long,Ming, Jun-Nan,Wang, Fei-Ying,Xu, Xiao-Ying,Wang, Li-Xin
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experimental part
p. 4472 - 4478
(2011/10/01)
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- Sc(OTf)3-catalyzed tandem [3+2] cycloaddition/nucleophilic ring-opening reaction of cyclopropane 1,1-diesters with azomethine ylides
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A new Sc(OTf)3-catalyzed tandem reaction combined with a dimerized self-[3+2] cycloaddition of azomethine ylide and a nucleophilic ring-opening of cyclopropane 1,1-diester has been developed. A series of polyfunctionalized imidazolidine derivatives were synthesized by this reaction (Yield 44-77 %). In some cases, this tandem reaction was also accompanied by a cross-[3+2] cycloaddition of cyclopropane 1,1-diester with imine.
- Fang,Hu,Ren,Wang
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experimental part
p. 1479 - 1487
(2011/12/22)
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- Cu-catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylides with β-phenylsulfonyl enones. Ligand controlled diastereoselectivity reversal
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(Chemical Equation Presented) A catalytic asymmetric procedure for the 1,3-dipolar cycloaddition of (E)-β-phenylsulfonyl enones with azomethine ylides to provide highly functionalized pyrrolidine derivatives is described. In the presence of chiral CuI-Segphos catalysts the aducts were obtained with high regio-, diastereo-, and enantioselectivity. Interestingly, a switch from endo to exo selectivity was observed when Segphos or DTBM-Segphos ligand was used.
- Robles-Machin, Rocio,Gonzalez-Esguevillas, Maria,Adrio, Javier,Carretero, Juan C.
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supporting information; experimental part
p. 233 - 236
(2010/04/06)
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- Pyrrole and oligopyrrole synthesis by 1,3-dipolar cycloaddition of azomethine ylides with sulfonyl dipolarophiles
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A procedure for the synthesis of functionalized, substituted pyrroles by 1,3-dipolar cycloaddition of azomethine ylides has been developed. This protocol is based on the metal-catalyzed cycloaddition of α-iminoesters with sulfonyl dipolarophiles, followed by the base-promoted elimination of the sulfonyl groups. A wide variety of 2,5-disubstituted and 2,3,5- and 2,4,5trisubstituted pyrroles have been prepared in satisfactory yields from 1,2bis(sulfonyl ethylene), ss-sulfonylenones, and ss- sulfonylacrylates. This method can be applied in an iterative and straightforward manner to the construction of oligopyrroles, from bipyrroles to pentapyrroles. Iterative [n+1] and [n+2] approaches have been devised, the latter involves double 1,3-dipolar cycloaddition from pyrrolylbased bis(iminoesters).
- Robles-Machin, Rocio,Lopez-Perez, Ana,Gonzalez-Esguevillas, Maria,Adrio, Javier,Carretero, Juan Carlos
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supporting information; experimental part
p. 9864 - 9873
(2010/11/16)
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- Cyclopalladation of schiff bases from methyl esters of α-Amino acids. Unexpected activation of the O-Me bond with formation of a bianionic tridentate metallacycle
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The action of palladium acetate on imines from methyl esters of the a-amino acids glycine, alanine, valine, and tyrosine is herein described. The reactivity of the new metallacycles obtained with phosphines and amines is also described, as well as the synthesis of isoquinolinium salts by insertion of diphenylacetylene into the Pd-C bond. Besides this, the unexpected activation of the Me-O bond of the ester group of the amino acid fragment is also reported, in a process that affords new cyclopalladated derivatives having the metalated molecule as a dianionic (C,N,O) ligand.
- Albert, Joan,Crespo, Margarita,Granell, Jaume,Rodriguez, Judit,Zafrilla, Javier,Calvet, Teresa,Merce, Font-Bardia,Solans, Xavier
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experimental part
p. 214 - 225
(2010/03/26)
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- Cyclometallated platinum(II) compounds with imine ligands derived from amino acids: Synthesis and oxidative addition reactions
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The reactions of [PtMe2(μ-SMe2)]2 with imines 4-ClC6H4CH{double bond, long}NCHRCO2Me (R = H (1a), Me (1b), iPr (1c), CH2C6H4(4'-OH) (1d), C6H5 (1e), CH2C6H5(1f)) derived from natural amino acids produced under mild conditions cyclometallated platinum(II) compounds [PtMe{κ2-(C,N)-4-ClC6H3CH{double bond, long}NCHRCO2Me}(SMe2)] (2a-2f). These compounds gave the corresponding phosphine derivatives [PtMe{κ2-(C,N)-4-ClC6H3CH{double bond, long}NCHRCO2Me}(PPh3)] (3a-3f). The corresponding cyclometallated platinum(IV) compounds [PtMe2I{κ2-(C,N)-4-ClC6H3CH{double bond, long}NCHRCO2Me}(PPh3)] (4) arising from intermolecular oxidative addition of methyl iodide were obtained with a high degree of stereo selectivity. Analogous results were obtained for imine 2,6-Cl2C6H3CH{double bond, long}NCH(CH2C6H5)CO2Me (1g) in a process involving intramolecular oxidative addition of a C-Cl bond. The obtained compounds were fully characterized including structure determinations for compounds 3f, 4d and 4f.
- Rodríguez, Judit,Zafrilla, Javier,Albert, Joan,Crespo, Margarita,Granell, Jaume,Calvet, Teresa,Font-Bardia, Mercè
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supporting information; experimental part
p. 2467 - 2475
(2009/12/01)
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- Highly enantioselective 1,3-dipolar cycloaddition of azomethine ylides catalyzed by AgOAc/TF-BiphamPhos
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A novel and highly efficient AgOAc/TF-BiphamPhos catalytic system shows excellent reactivity, diastereo-/enantioselectivity and structural scope in asymmetric 1,3-dipolar cycloaddition of azomethine ylides, especially derived from various α-substituted α-amino acids, with N-substituted maleimides and other electron-deficient alkenes.
- Wang, Chun-Jiang,Xue, Zhi-Yong,Liang, Gang,Lu, Zhou
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supporting information; experimental part
p. 2905 - 2907
(2009/12/01)
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- Silver acetate/TF-biphamphos-catalyzed endo-selective enantioselective 1,3-dipolar cycloaddition of azomethine ylides with vinyl phenyl sulfone
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The first catalytic endo-selective 1,3-dipolar cycloaddition of azomethine ylides and vinyl phenyl sulfone has been developed successfully. The highly efficient silver acetate (AgOAc)/TF-BiphamPhos catalytic system exhibited high reactivity, excellent diastereoselectivity (>98:2), good enantioselectivity (67-92% ee) and broad substrate scope under mild conditions.
- Liang, Gang,Tong, Min-Chao,Wang, Chun-Jiang
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supporting information; experimental part
p. 3101 - 3106
(2010/04/06)
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- Axially chiral BINIM and Ni(II)-catalyzed highly enantioselective 1,3-dipolar cycloaddition reactions of azomethine ylides and N-arylmaleimides
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(Chemical Equation Presented) Axially chiral BINIM-Ni(II) complexes are effective catalysts in the asymmetric 1,3-dipolar cycloaddition reactions of azomethine ylides and N-arylmaleimides to give the corresponding adducts in good yields and up to 95% enan
- Shi, Jing-Wen,Zhao, Mei-Xin,Lei, Zhi-Yu,Shi, Min
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p. 305 - 308
(2008/09/17)
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- Chiral thiophosphoramide and selenophosphoramide ligands in the Cu(I)-promoted catalytic enantioselective 1,3-dipolar cycloaddition reactions of azomethine ylides and pyrrole-2,5-dione derivatives
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Chiral C2-symmetric diphenylthiophosphoramide ligand L1 prepared from C2-symmetric (1S,2S)-(-)-1,2-diphenylethylenediamine was found to be a fairly effective chiral ligand for Cu(I)-promoted 1,3-dipolar cycloaddition of imines and py
- Shi, Min,Shi, Jing-Wen
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p. 645 - 650
(2007/10/03)
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- Hydrogen-bonding directed reversal of enantioselectivity
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A successful stereochemical reversal was achieved in AgOAc catalyzed [3+2] cycloaddition by the formation of hydrogen bonding between ligand and reactant. This strategy provides an efficient and convenient route to prepare both enantiomers of a chiral compound. DFT studies proposed a reasonable mechanism of the reversal of the enantioselectivity; hydrogen bonding changed the transition state. The strategy may provide some useful hints for ligand design. Copyright
- Zeng, Wei,Chen, Guo-Ying,Zhou, Yong-Gui,Li, Yu-Xue
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p. 750 - 751
(2007/10/03)
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- Cu(I)-catalyzed highly exo-selective and enantioselective [3 + 2] cycloaddition of azomethine ylides with acrylates
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(Chemical Equation Presented) A novel Cu(I)-catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylides with acrylates has been developed. Up to 98/2 exo/endo selectivity and up to 98% enantiomeric excess have been achieved.
- Gao, Wenzhong,Zhang, Xumu,Raghunath, Malati
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p. 4241 - 4244
(2007/10/03)
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- Bifunctional AgOAc-catalyzed asymmetric [3 + 2] cycloaddition of azomethine ylides
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(Chemical Equation Presented) A bifunctional AgOAc-catalyzed asymmetric cycloaddition of azomethine ylides with electronic-deficient alkenes was developed using ferrocenyloxazoline-derived N,P ligands. The reactive metal-bound azomethine ylide dipole is formed by the deprotonation with acetate, and extra base is not necessary. The reactions proceed with high enantioselectivity. This method provides an efficient and convenient route to optically active pyrrolidine derivatives.
- Zeng, Wei,Zhou, Yong-Gui
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p. 5055 - 5058
(2007/10/03)
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- exo- and Enantioselective Cycloaddition of Azomethine Ylides Generated from N-Alkylidene Glycine Esters Using Chiral Phosphine - Copper Complexes
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(Equation presented) High diastereo- and enantioselectivities were obtained for the asymmetric 1,3-dipolar cycloaddition of azomethine ylides generated from N-alkylideneglycine esters with dipolarophiles using chiral phosphine-copper complexes as catalysts. Whereas the cycloaddition of azomethine ylides catalyzed by metal salts generally afforded endo-adducts as the predominant product, the present method is the first example of an exo-selective cycloaddition.
- Oderaotoshi, Yoji,Cheng, Wenji,Fujitomi, Shintaro,Kasano, Yukihiro,Minakata, Satoshi,Komatsu, Mitsuo
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p. 5043 - 5046
(2007/10/03)
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- A novel preparation of 2-aryl-5-methoxyoxazoles
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2-Aryl-5-methoxyoxazoles can be synthesized by oxidation of Schiff's bases with (diacetoxyiodo) benzene in good yields under mild conditions.
- Xia
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p. 382 - 383
(2007/10/03)
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