Bibliografías temáticas / Bifunctional chiral catalysts / Artículos de revistas

Artículos de revistas sobre el tema "Bifunctional chiral catalysts"

Siga este enlace para ver otros tipos de publicaciones sobre el tema: Bifunctional chiral catalysts.
Autor: Grafiati
Publicado: 18 de mayo de 2024

Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros

Elija tipo de fuente:

Consulte los 50 mejores artículos de revistas para su investigación sobre el tema "Bifunctional chiral catalysts".

Junto a cada fuente en la lista de referencias hay un botón "Agregar a la bibliografía". Pulsa este botón, y generaremos automáticamente la referencia bibliográfica para la obra elegida en el estilo de cita que necesites: APA, MLA, Harvard, Vancouver, Chicago, etc.

También puede descargar el texto completo de la publicación académica en formato pdf y leer en línea su resumen siempre que esté disponible en los metadatos.

Explore artículos de revistas sobre una amplia variedad de disciplinas y organice su bibliografía correctamente.

1

Vazquez-Chavez, Josué, Socorro Luna-Morales, Diego A. Cruz-Aguilar, Howard Díaz-Salazar, Wilmer E. Vallejo Narváez, Rodrigo S. Silva-Gutiérrez, Simón Hernández-Ortega, Tomás Rocha-Rinza y Marcos Hernández-Rodríguez. "The effect of chiral N-substituents with methyl or trifluoromethyl groups on the catalytic performance of mono- and bifunctional thioureas". Organic & Biomolecular Chemistry 17, n.º 47 (2019): 10045–51. http://dx.doi.org/10.1039/c9ob01893j.

Texto completo
Resumen
Thiourea organocatalysts with a chiral group containing a trifluoromethyl moiety have better hydrogen bonding properties. However, not all reactions catalysed by bifunctional catalysts are enhanced by stronger NH acidity.
Los estilos APA, Harvard, Vancouver, ISO, etc.
2

Chen, Jianfeng, Xing Gong, Jianyu Li, Yingkun Li, Jiguo Ma, Chengkang Hou, Guoqing Zhao, Weicheng Yuan y Baoguo Zhao. "Carbonyl catalysis enables a biomimetic asymmetric Mannich reaction". Science 360, n.º 6396 (28 de junio de 2018): 1438–42. http://dx.doi.org/10.1126/science.aat4210.

Texto completo
Resumen
Chiral amines are widely used as catalysts in asymmetric synthesis to activate carbonyl groups for α-functionalization. Carbonyl catalysis reverses that strategy by using a carbonyl group to activate a primary amine. Inspired by biological carbonyl catalysis, which is exemplified by reactions of pyridoxal-dependent enzymes, we developed an N-quaternized pyridoxal catalyst for the asymmetric Mannich reaction of glycinate with aryl N-diphenylphosphinyl imines. The catalyst exhibits high activity and stereoselectivity, likely enabled by enzyme-like cooperative bifunctional activation of the substrates. Our work demonstrates the catalytic utility of the pyridoxal moiety in asymmetric catalysis.
Los estilos APA, Harvard, Vancouver, ISO, etc.
3

Wu, Jia-Hong, Jianke Pan y Tianli Wang. "Dipeptide-Based Phosphonium Salt Catalysis: Application to Enantioselective Synthesis of Fused Tri- and Tetrasubstituted Aziridines". Synlett 30, n.º 19 (27 de agosto de 2019): 2101–6. http://dx.doi.org/10.1055/s-0039-1690192.

Texto completo
Resumen
Over the past decades, phase-transfer catalysis (PTC), generally based on numerous chiral quaternary ammonium salts, has been recognized as a powerful and versatile tool for organic synthesis in both industry and academia. In sharp contrast, PTC involving chiral phosphonium salts as the catalysts is insufficiently developed. Recently, our group realized the first enantioselective aza-Darzens reaction for preparing tri- and tetrasubstituted aziridine derivatives under bifunctional phosphonium salt catalysis. This article briefly discusses the recent development in asymmetric reactions (mainly including nucleophilic additions and cyclizations) promoted by chiral quaternary phosphonium salt catalysts. We expect that more catalytic asymmetric reactions will be developed on the basis of such new phase-transfer catalytic systems in the near future.
Los estilos APA, Harvard, Vancouver, ISO, etc.
4

Hu, Xiao-Mu, Rui Zhang, Hai Dong, Yan-Yan Jia, Guo-Qiang Bao y Ping-An Wang. "Chiral bifunctional organocatalysts for enantioselective synthesis of 3-substituted isoindolinones". RSC Advances 13, n.º 35 (2023): 24460–65. http://dx.doi.org/10.1039/d3ra04350a.

Texto completo
Resumen
Chiral tertiary-amine catalysts with a urea group can afford 3-substituted isoindolinones both in higher yields (87% vs. 77%) and enantioselectivities (95% ee vs. 46% ee) than chiral bifunctional phase-transfer catalysts under mild conditions.
Los estilos APA, Harvard, Vancouver, ISO, etc.
5

Yoshida, Yasushi, Tatsuya Ao, Takashi Mino y Masami Sakamoto. "Chiral Bromonium Salt (Hypervalent Bromine(III)) with N-Nitrosamine as a Halogen-Bonding Bifunctional Catalyst". Molecules 28, n.º 1 (2 de enero de 2023): 384. http://dx.doi.org/10.3390/molecules28010384.

Texto completo
Resumen
There has been a great focus on halogen-bonding as a unique interaction between electron-deficient halogen atoms with Lewis basic moieties. Although the application of halogen-bonded atoms in organic chemistry has been eagerly researched in these decades, the development of chiral molecules with halogen-bonding functionalities and their utilization in asymmetric catalysis are still in the\ir infancy. We have previously developed chiral halonium salts with amide functionalities, which behaved as excellent catalysts albeit in only two reactions due to the lack of substrate activation abilities. In this manuscript, we have developed chiral halonium salts with an N-nitrosamine moiety and applied them to the Mannich reaction of isatin-derived ketimines with malonic esters. The study focused on our novel bromonium salt catalyst which provided the corresponding products in high yields with up to 80% ee. DFT calculations of the chiral catalyst structure suggested that the high asymmetric induction abilities of this catalyst are due to the Lewis basic role of the N-nitrosamine part. To the best of our knowledge, this is the first catalytic application of N-nitrosamines.
Los estilos APA, Harvard, Vancouver, ISO, etc.
6

Kamal, Shagufta, Ameer Fawad Zahoor, Sajjad Ahmad, Rabia Akhtar, Iqra Khaliq, Wajiha Qurban y Attia Mehreen. "Recent Trends in the Development of Novel Catalysts for Asymmetric Michael Reaction". Current Organic Chemistry 24, n.º 13 (1 de octubre de 2020): 1397–458. http://dx.doi.org/10.2174/1385272824999200616123744.

Texto completo
Resumen
: Michael reaction is the nucleophilic addition of active methylene compounds to conjugated olefins, resultantly affording a variety of biologically active scaffolds with high enantiopurity. To improve the reaction yield, as well as enantioselectivity of the product, a variety of catalysts (amine-based catalysts, bifunctional L-proline amides, bifunctional squaramides, chiral ionic liquids, cinchona alkaloids, enzymes, indolinols, metal catalysts, peptide derived catalytic system, phase transfer catalysts, pyrrolidine based organocatalysts) have been investigated by a different era of chemists. Besides this, different methodologies have been developed to improve reaction yield and enantioselectivity of the targeted products with low catalyst loading. : This review article provides a concise overview of the catalysts applied recently by different scientists in the Michael addition reaction. Moreover, current strategies and potential applications of this reaction have also been illustrated in this review.
Los estilos APA, Harvard, Vancouver, ISO, etc.
7

Kitamura, Masato, Kengo Miyata, Tomoaki Seki, Namdev Vatmurge y Shinji Tanaka. "CpRu-catalyzed asymmetric dehydrative allylation". Pure and Applied Chemistry 85, n.º 6 (15 de abril de 2013): 1121–32. http://dx.doi.org/10.1351/pac-con-12-10-02.

Texto completo
Resumen
Asymmetric Tsuji–Trost allylation is one of the key chiral technologies for construction of pharmaceutically important compounds because of the high utility of alkenyl-substituted products. Particularly, the dehydrative system using allylic alcohols and protic nucleophiles has started to attract the attention of organic synthetic chemists from the viewpoints of atom and step economy, environmental benignity, and operational simplicity. In this paper, two types of new chiral CpRu catalysts, which have been developed on the basis of redox-mediated donor–acceptor bifunctional catalyst (RDACat) concept, are presented. Complementary use of the chiral catalysts has realized the syntheses of a wide rage of carbocyclic compounds, saturated N- or O-heterocyclic compounds with high reactivity, regioselectivity, enantioselectivity, productivity, and generality.
Los estilos APA, Harvard, Vancouver, ISO, etc.
8

Ikariya, Takao, Shigeki Kuwata y Yoshihito Kayaki. "Aerobic oxidation with bifunctional molecular catalysts". Pure and Applied Chemistry 82, n.º 7 (4 de mayo de 2010): 1471–83. http://dx.doi.org/10.1351/pac-con-09-09-11.

Texto completo
Resumen
A new series of half-sandwich group 8 and 9 metal complexes bearing a metal/NH bifunctional moiety were synthesized from benzylic amines. The isolable Ir amide complexes serve as effective catalysts for aerobic oxidative transformation of secondary and primary alcohols into the corresponding ketones and esters under mild conditions. The aerobic oxidative kinetic resolution of racemic secondary alcohols with chiral bifunctional Ir catalysts was found to proceed smoothly under mild conditions with high selectivity. A novel imido-bridged dirhodium complex, which may be regarded as a dinuclear variant of the bifunctional mononuclear amide complexes, also proved to promote aerobic oxidation of a secondary alcohol and H2.
Los estilos APA, Harvard, Vancouver, ISO, etc.
9

Ruan, Sai, Xiaobin Lin, Lihua Xie, Lili Lin, Xiaoming Feng y Xiaohua Liu. "Asymmetric synthesis of 3-aminodihydrocoumarins via the chiral guanidine catalyzed cascade reaction of azlactones". Organic Chemistry Frontiers 5, n.º 1 (2018): 32–35. http://dx.doi.org/10.1039/c7qo00768j.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
10

Nishiyori, Ryuichi, Ken Okuno, Bun Chan y Seiji Shirakawa. "Chiral Bifunctional Selenide Catalysts for Asymmetric Iodolactonizations". Chemical and Pharmaceutical Bulletin 70, n.º 9 (1 de septiembre de 2022): 599–604. http://dx.doi.org/10.1248/cpb.c22-00049.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
11

Nishiyori, Ryuichi, John R. J. Maynard y Seiji Shirakawa. "Chiral Bifunctional Selenide Catalysts for Asymmetric Bromolactonization". Asian Journal of Organic Chemistry 9, n.º 2 (30 de enero de 2020): 192–96. http://dx.doi.org/10.1002/ajoc.201900688.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
12

Tanaka, Shinji y Masato Kitamura. "Asymmetric Dehydrative Allylation Using Soft Ruthenium and Hard Brønsted Acid Combined Catalyst". Chemical Record 21, n.º 6 (junio de 2021): 1385–97. http://dx.doi.org/10.1002/tcr.202000157.

Texto completo
Resumen
AbstractAsymmetric Pd‐catalyzed Tsuji‐Trost‐type allylation is an important catalytic reaction toward chiral natural and unnatural product syntheses. We successfully modified a desalt‐type reaction using allyl ester or halide to a dehydrative one using allylic alcohol via the establishment of two redox‐mediated donor acceptor bifunctional catalyst systems. These systems were cationic CpRu‐Cl‐Napy‐PyCOOH and cationic CpRu‐Naph‐diPIM‐dioxo‐iPr/p‐TsOH and were designed on the basis of the soft ruthenium and hard Brønsted acid combined catalyst concept. The complementary use of the two chiral catalysts for dehydrative asymmetric allylation expands the application scope facilitating the utilization of both aliphatic and aromatic allylic alcohols with various nucleophiles in the substrate. In this account, the design, synthesis, and application of these catalysts were reported.
Los estilos APA, Harvard, Vancouver, ISO, etc.
13

Maruoka, Keiji. "Designer chiral phase-transfer catalysts for green sustainable chemistry". Pure and Applied Chemistry 84, n.º 7 (13 de marzo de 2012): 1575–85. http://dx.doi.org/10.1351/pac-con-11-09-31.

Texto completo
Resumen
A series of chiral quaternary ammonium salts derived from commercially available (R)- or (S)-binaphthol have been designed as new C2-symmetric chiral phase-transfer catalysts. In order to realize the flexible design of these phase-transfer catalysts, the combinatorial design approach has been developed. Chiral high-performance organocatalysts, thus obtained, have been successfully applied to the highly practical asymmetric synthesis of various amino acid derivatives, including α-alkyl and α,α-dialkyl-α-amino acids in addition to alkaloids. Furthermore, several chiral bifunctional phase-transfer catalysts have been designed and synthesized for effecting base-free phase-transfer reactions under essentially neutral conditions in order to realize green sustainable chemistry.
Los estilos APA, Harvard, Vancouver, ISO, etc.
14

Wang, Yongchao, Angel A. Cobo y Annaliese K. Franz. "Recent advances in organocatalytic asymmetric multicomponent cascade reactions for enantioselective synthesis of spirooxindoles". Organic Chemistry Frontiers 8, n.º 15 (2021): 4315–48. http://dx.doi.org/10.1039/d1qo00220a.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
15

Sawamura, Yasuhiro, Yoshihiro Ogura, Hidefumi Nakatsuji, Akira Sakakura y Kazuaki Ishihara. "Enantioselective bromocyclization of 2-geranylphenols induced by chiral phosphite–urea bifunctional catalysts". Chemical Communications 52, n.º 36 (2016): 6068–71. http://dx.doi.org/10.1039/c6cc00229c.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
16

Okada, Megumi, Kazuma Kaneko, Masahiro Yamanaka y Seiji Shirakawa. "BINOL-derived bifunctional sulfide catalysts for asymmetric synthesis of 3,3-disubstituted phthalides via bromolactonization". Organic & Biomolecular Chemistry 17, n.º 15 (2019): 3747–51. http://dx.doi.org/10.1039/c9ob00417c.

Texto completo
Resumen
An efficient enantioselective synthesis of 3,3-disubstituted phthalides possessing a chiral quaternary carbon center was achieved via catalytic asymmetric bromolactonization using BINOL-derived bifunctional sulfide catalysts.
Los estilos APA, Harvard, Vancouver, ISO, etc.
17

Tsuchihashi, Ayano y Seiji Shirakawa. "Catalyst-Controlled Regio- and Stereoselective Bromolactonization with Chiral Bifunctional Sulfides". Synlett 30, n.º 14 (20 de mayo de 2019): 1662–66. http://dx.doi.org/10.1055/s-0037-1610716.

Texto completo
Resumen
Highly regioselective 5-exo bromolactonizations of stilbene-type carboxylic acids bearing electron-withdrawing substituents are achieved for the first time via the use of chiral bifunctional sulfide catalysts possessing a urea moiety. The chiral phthalide products are obtained in moderate to good enantioselectivities as the result of 5-exo cyclizations.
Los estilos APA, Harvard, Vancouver, ISO, etc.
18

Wan, Wen, Wei Gao, Guobin Ma, Lei Ma, Fan Wang, Jing Wang, Haizhen Jiang, Shizheng Zhu y Jian Hao. "Asymmetric aldol reaction organocatalyzed by bifunctional N-prolyl sulfinamides under solvent-free conditions". RSC Adv. 4, n.º 51 (2014): 26563–68. http://dx.doi.org/10.1039/c4ra03362k.

Texto completo
Resumen
Chiral bifunctional N-prolyl sulfinamide and its TFA salts were synthesized and applied in asymmetric aldol reactions under solvent-free conditions. The aldol adducts were obtained with high to excellent yields, enantioselectivities and diastereoselectivities. A matching effect between chiral proline and sulfinamide moieties was observed for the catalysts.
Los estilos APA, Harvard, Vancouver, ISO, etc.
19

Li, Yun, Qing-chuan Yang, Xiao-Ying Xu, Yong Zhou, Jian-fei Bai, Fei-ying Wang y Li-xin Wang. "A highly asymmetric direct aldol reaction catalyzed by chiral proline amide – thiourea bifunctional catalysts". Canadian Journal of Chemistry 89, n.º 10 (octubre de 2011): 1312–18. http://dx.doi.org/10.1139/v11-029.

Texto completo
Resumen
A series of chiral proline amide – thiourea bifunctional catalysts derived from l-proline and chiral diamine were prepared and successfully applied to highly enantioselective direct aldol reactions of cyclohexanone with various aldehydes in excellent yields (85%–97%), diastereoselectivities (anti/syn > 20:1) and enantioselectivities (up to 91% ee).
Los estilos APA, Harvard, Vancouver, ISO, etc.
20

Šebesta, Radovan, Eva Veverková y Pavlína Molnosiová. "Asymmetric Sequential Michael Addition and Cyclization Reactions of 2-(2-Nitrovinyl)phenols Catalyzed by Bifunctional Amino-Squaramides". SynOpen 05, n.º 04 (octubre de 2021): 278–84. http://dx.doi.org/10.1055/s-0040-1719843.

Texto completo
Resumen
AbstractIn this work, we describe the Michael addition–cyclization reaction of 2-(2-nitrovinyl)phenol with two different reactive Michael donors, which lead to chiral benzopyran derivatives. Specifically, bifunctional amino-squaramides with one or two chiral units in the side chains were evaluated as catalysts in these transformations. Furthermore, the utility of selected green solvents as reaction media for these processes was also tested. The best result was achieved with methyl-cyclopentanone-2-carboxylate as the Michael donor in ethyl (–)-l-lactate with quinine-based amino-squaramide as catalyst (yield 72%, dr >99:1, ee 99%).
Los estilos APA, Harvard, Vancouver, ISO, etc.
21

Kano, Taichi y Keiji Maruoka. "Design of chiral bifunctional secondary amine catalysts for asymmetric enamine catalysis". Chemical Communications, n.º 43 (2008): 5465. http://dx.doi.org/10.1039/b809301f.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
22

Juaristi, Eusebio, Carlos Cruz-Hernández y Perla Hernández-González. "(R)- and (S)-Proline-Derived Chiral Phosphoramides as Organo­catalysts for the Enantiodivergent Aldol Reaction of Isatins with Cyclohexanone in the Presence of Water". Synthesis 50, n.º 09 (5 de febrero de 2018): 1827–40. http://dx.doi.org/10.1055/s-0036-1591916.

Texto completo
Resumen
Novel organocatalysts derived from (R)- and (S)-proline and incorporating a chiral phosphoramide fragment were rationally designed and subsequently synthesized. These chiral compounds catalyze the enantioselective aldol addition reaction of cyclohexanone to prochiral isatins in the presence of water. These observations are particularly relevant since reports of asymmetric aldol reactions between cyclohexanone­ and isatins catalyzed by chiral secondary amines remain scarce, with primary amines being the most studied and successful catalysts. The present report includes a thorough evaluation of the new bifunctional catalysts that actually give rise to either enantiomer of the chiral product by proper selection of the configuration of the proline moiety.
Los estilos APA, Harvard, Vancouver, ISO, etc.
23

Puglisi, Alessandra, Maurizio Benaglia, Elisabetta Massolo y Giuseppe Celentano. "Poly(methylhydrosiloxane)-supported chiral thiourea-based bifunctional catalysts". Recyclable Catalysis 1 (23 de enero de 2012): 1–5. http://dx.doi.org/10.2478/recat-2012-0001.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
24

Savel’yeva, Tat’yana F., Olga V. Khromova, Vladimir A. Larionov, Alexander F. Smol’yakov, Ivan V. Fedyanin, Yuri N. Belokon y Victor I. Maleev. "Expanding the Family of Octahedral Chiral-at-Metal Cobalt(III) Catalysts by Introducing Tertiary Amine Moiety into the Ligand". Catalysts 11, n.º 2 (21 de enero de 2021): 152. http://dx.doi.org/10.3390/catal11020152.

Texto completo
Resumen
Chiral metal-templated complexes are attractive catalysts for organic synthetic transformations. Herein, we introduce a novel chiral cobalt(III)-templated complex based on chiral trans-3,4-diamino-1-benzylpyrrolidine and 3,5-di-tert-butyl-salicylaldehyde which features both hydrogen bond donor and Brønsted base functionalities. The obtained complexes were fully characterized by 1H, 13C NMR, IR-, UV-vis, CD-spectroscopy and by a single X-ray diffraction analysis. It was shown that chlorine anion is connected with amino groups of the complex via a hydrogen bonding. DFT calculations of charges and molecular electrostatic potential of the cobalt(III) complex showed that the basicity of the complex is certainly diminished as compared with the routine tertiary amines but the acidity of the conjugated acid of the complex should be increased. Thus, the catalytic potential of the complex may be much greater as a chiral acid than a chiral base. We believe that this work opens a new way in chiral bifunctional catalyst design.
Los estilos APA, Harvard, Vancouver, ISO, etc.
25

Sobrino, Sonia, Marta Navarro, Juan Fernández-Baeza, Luis F. Sánchez-Barba, Andrés Garcés, Agustín Lara-Sánchez y José A. Castro-Osma. "Efficient CO2 fixation into cyclic carbonates catalyzed by NNO-scorpionate zinc complexes". Dalton Transactions 48, n.º 28 (2019): 10733–42. http://dx.doi.org/10.1039/c9dt01844a.

Texto completo
Resumen
Chiral bifunctional and bicomponent NNO-scorpionate zinc-based catalysts have been developed for the fixation of CO2 into cyclic carbonates with broad substrate scope and functional group tolerance under mild and solvent-free conditions.
Los estilos APA, Harvard, Vancouver, ISO, etc.
26

Tiffner, Maximilian, Johanna Novacek, Alfonso Busillo, Katharina Gratzer, Antonio Massa y Mario Waser. "Design of chiral urea-quaternary ammonium salt hybrid catalysts for asymmetric reactions of glycine Schiff bases". RSC Advances 5, n.º 96 (2015): 78941–49. http://dx.doi.org/10.1039/c5ra14466c.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
27

Phillips, Ana Maria Faisca, Martin H. G. Prechtl y Armando J. L. Pombeiro. "Non-Covalent Interactions in Enantioselective Organocatalysis: Theoretical and Mechanistic Studies of Reactions Mediated by Dual H-Bond Donors, Bifunctional Squaramides, Thioureas and Related Catalysts". Catalysts 11, n.º 5 (29 de abril de 2021): 569. http://dx.doi.org/10.3390/catal11050569.

Texto completo
Resumen
Chiral bifunctional dual H-bond donor catalysts have become one of the pillars of organocatalysis. They include squaramide, thiosquaramide, thiourea, urea, and even selenourea-based catalysts combined with chiral amines, cinchona alkaloids, sulfides, phosphines and more. They can promote several types of reactions affording products in very high yields and excellent stereoselectivities in many cases: conjugate additions, cycloadditions, the aldol and Henry reactions, the Morita–Baylis–Hilman reaction, even cascade reactions, among others. The desire to understand mechanisms and the quest for the origins of stereoselectivity, in attempts to find guidelines for developing more efficient catalysts for new transformations, has promoted many mechanistic and theoretical studies. In this review, we survey the literature published in this area since 2015.
Los estilos APA, Harvard, Vancouver, ISO, etc.
28

Yan, M., X. j. Zhang, S. p. Liu, X. m. Li y A. Chan. "Chiral Sulfamides as Bifunctional Catalysts in Conjugate Addition Reactions". Synfacts 2009, n.º 03 (19 de febrero de 2009): 0326. http://dx.doi.org/10.1055/s-0028-1087722.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
29

Wang, Hongyu, Changwu Zheng y Gang Zhao. "Bifunctional Ion Pair Catalysts from Chiral α‐Amino Acids". Chinese Journal of Chemistry 37, n.º 11 (12 de septiembre de 2019): 1111–19. http://dx.doi.org/10.1002/cjoc.201900276.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
30

Torres, Pol, Marian Guillén, Marc Escribà, Joaquim Crusats y Albert Moyano. "Synthesis of New Amino-Functionalized Porphyrins:Preliminary Study of Their Organophotocatalytic Activity". Molecules 28, n.º 4 (20 de febrero de 2023): 1997. http://dx.doi.org/10.3390/molecules28041997.

Texto completo
Resumen
The design, synthesis, and initial study of amino-functionalized porphyrins as a new class of bifunctional catalysts for asymmetric organophotocatalysis is described. Two new types of amine–porphyrin hybrids derived from 5,10,15,20-tetraphenylporphyrin (TPPH2), in which a cyclic secondary amine moiety is covalently linked either to a β-pyrrolic position (Type A) or to the p-position of one of the meso phenyl groups (Type B), were prepared by condensation, reductive amination, or amidation reactions from the suitable porphyrins (either formyl or methanamine derivatives) with readily available chiral amines. A preliminary study of the possible use of Type A amine–porphyrin hybrids as asymmetric, bifunctional organophotocatalysts was performed using the chiral, imidazolidinone-catalyzed Diels–Alder cycloaddition between cyclopentadiene 28 and trans-cinnamaldehyde 29 as a benchmark reaction. The yield and the stereochemical outcome of this process, obtained under purely organocatalytic conditions, under dual organophocatalysis, and under bifunctional organophotocatalysis, were compared.
Los estilos APA, Harvard, Vancouver, ISO, etc.
31

Han, Zhao y Xufeng Lin. "Synthesis of Chiral Tertiary Amine–Thioureas Based on Spirobi­indane and Application in Catalytic Asymmetric Michael Addition Reaction". Synthesis 52, n.º 07 (4 de febrero de 2020): 1131–39. http://dx.doi.org/10.1055/s-0039-1691643.

Texto completo
Resumen
A series of novel chiral bifunctional tertiary amine–thioureas based on spirobiindane were designed and synthesized as organo­catalysts. One of these catalysts was shown to promote the asymmetric Michael addition reaction of 1,3-diphenylpropane-1,3-dione to nitro­olefins, affording the desired products in good yields (up to 95%) and enantioselectivities (up to 98% ee).
Los estilos APA, Harvard, Vancouver, ISO, etc.
32

Choudary, Boyapati M., Sateesh Madhi, Naidu S. Chowdari y Mannepalli L. Kantam. "Heterogeneous Bifunctional Catalysts for the Synthesis of Chiral Vicinal Diols". Topics in Catalysis 29, n.º 3/4 (junio de 2004): 183–87. http://dx.doi.org/10.1023/b:toca.0000029801.51873.61.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
33

Zhu, Junchao, Dongxiao Cui, Yuedan Li, Jingxu He, Weiping Chen y Pingan Wang. "Enantioselective amination of nitroolefins under base-free and water-rich conditions using chiral bifunctional phase-transfer catalysts". Organic & Biomolecular Chemistry 16, n.º 16 (2018): 3012–17. http://dx.doi.org/10.1039/c8ob00583d.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
34

Andrés, José M., Miriam Ceballos, Alicia Maestro, Isabel Sanz y Rafael Pedrosa. "Supported bifunctional thioureas as recoverable and reusable catalysts for enantioselective nitro-Michael reactions". Beilstein Journal of Organic Chemistry 12 (1 de abril de 2016): 628–35. http://dx.doi.org/10.3762/bjoc.12.61.

Texto completo
Resumen
The catalytic activity of different supported bifunctional thioureas on sulfonylpolystyrene resins has been studied in the nitro-Michael addition of different nucleophiles to trans-β-nitrostyrene derivatives. The activity of the catalysts depends on the length of the tether linking the chiral thiourea to the polymer. The best results were obtained with the thiourea derived from (L)-valine and 1,6-hexanediamine. The catalysts can be used in only 2 mol % loading, and reused for at least four cycles in neat conditions. The ball milling promoted additions also worked very well.
Los estilos APA, Harvard, Vancouver, ISO, etc.
35

Jin, Qiao-Wen, Zhuo Chai, You-Ming Huang, Gang Zou y Gang Zhao. "Asymmetric α-amination of 3-substituted oxindoles using chiral bifunctional phosphine catalysts". Beilstein Journal of Organic Chemistry 12 (15 de abril de 2016): 725–31. http://dx.doi.org/10.3762/bjoc.12.72.

Texto completo
Resumen
A highly enantioselective α-amination of 3-substituted oxindoles with azodicarboxylates catalyzed by amino acids-derived chiral phosphine catalysts is reported. The corresponding products containing a tetrasubstituted carbon center attached to a nitrogen atom at the C-3 position of the oxindole were obtained in high yields and with up to 98% ee.
Los estilos APA, Harvard, Vancouver, ISO, etc.
36

Deng, Yongming, Qing-Qing Cheng y Michael Doyle. "Asymmetric [3+3] Cycloaddition for Heterocycle Synthesis". Synlett 28, n.º 14 (5 de julio de 2017): 1695–706. http://dx.doi.org/10.1055/s-0036-1588453.

Texto completo
Resumen
Asymmetric syntheses of six-membered ring heterocycles are important research targets not only in synthetic organic chemistry but also in pharmaceuticals. The [3+3]-cycloaddition methodology is a complementary strategy to [4+2] cycloaddition for the synthesis of heterocyclic compounds. Recent progress in [3+3]-cycloaddition processes provide powerful asymmetric methodologies for the construction of six-membered ring heterocycles with one to three heteroatoms in the ring. In this account, synthetic efforts during the past five years toward the synthesis of enantioenriched six-membered ring heterocycles through asymmetric [3+3] cycloaddition are reported. Asymmetric organocatalysis uses chiral amines, thioureas, phosphoric acids, or NHC catalysis to achieve high enantiocontrol. Transition-metal catalysts used as chiral Lewis acids to activate a dipolar species is an alternative approach. The most recent advance, chiral transition-metal-catalyzed reactions of enoldiazo compounds, has contributed toward the versatile and highly selective synthesis of six-membered heterocyclic compounds.1 Introduction2 Asymmetric Formal [3+3]-Cycloaddition Reactions by Organo­catalysis2.1 By Amino-Catalysis2.2 By N-Heterocyclic Carbenes2.3 By Bifunctional Tertiary Amine-thioureas2.4 By Chiral Phosphoric Acids3 Asymmetric Formal [3+3]-Cycloaddition Reactions by Transition-Metal Catalysis3.1 Copper Catalysis3.2 Other Transition-Metal Catalysis4 Asymmetric [3+3]-Cycloaddition Reactions of Enoldiazo Compounds4.1 Asymmetric [3+3]-Cycloaddition Reactions of Nitrones with Electrophilic Metallo-enolcarbene Intermediates4.2 Dearomatization in Asymmetric [3+3]-Cycloaddition Reactions of Enoldiazoacetates4.3 Asymmetric Stepwise [3+3]-Cycloaddition Reaction of Enoldiazoacetates with Hydrazones5 Summary and Outlook
Los estilos APA, Harvard, Vancouver, ISO, etc.
37

Novacek, Johanna y Mario Waser. "Bifunctional Chiral Quaternary Ammonium Salt Catalysts: A Rapidly Emerging Class of Powerful Asymmetric Catalysts". European Journal of Organic Chemistry 2013, n.º 4 (19 de diciembre de 2012): 637–48. http://dx.doi.org/10.1002/ejoc.201201425.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
38

Zielińska-Błajet, Mariola, Żaneta A. Mała y Rafał Kowalczyk. "Efficacy of Selenourea Organocatalysts in Asymmetric Michael Reactions under Standard and Solvent-Free Conditions". Molecules 26, n.º 23 (1 de diciembre de 2021): 7303. http://dx.doi.org/10.3390/molecules26237303.

Texto completo
Resumen
By varying the steric and electronic surroundings of the hydrogen-bonding motif, the novel chiral Cinchona-alkaloid based selenoureas were developed. Acting as bifunctional catalysts, they were applied in the Michael reactions of dithiomalonate and nitrostyrene providing chiral adducts with up to 96% ee. The asymmetric Michael–-hemiacetalization reaction of benzylidene pyruvate and dimedone, performed with the assistance of 5 mol% of selenoureas, furnished the product with up to 93% ee and excellent yields. The effectiveness of the new hydrogen-bond donors was also proved in solvent-free reactions under ball mill conditions, supporting the sustainability of the devised catalytic protocol.
Los estilos APA, Harvard, Vancouver, ISO, etc.
39

Zielińska-Błajet, Mariola y Joanna Najdek. "Novel Selenoureas Based on Cinchona Alkaloid Skeleton: Synthesis and Catalytic Investigations". Materials 14, n.º 3 (28 de enero de 2021): 600. http://dx.doi.org/10.3390/ma14030600.

Texto completo
Resumen
An efficient approach to the synthesis of chiral selenoureas consisting of Cinchona alkaloid scaffolds was described. The new selenoureas were assessed as bifunctional organocatalysts in the asymmetric Michael addition reactions under mild conditions. The best results were obtained for selenoureas bearing the 4-fluorophenyl group. These catalysts promoted the reactions with enantioselectivities of up to 96% ee. Additionally, the catalytic performance of the thiourea and selenourea counterpart was compared.
Los estilos APA, Harvard, Vancouver, ISO, etc.
40

Zhang, Ming-Liang, Deng-Feng Yue, Zhen-Hua Wang, Yuan Luo, Xiao-Ying Xu, Xiao-Mei Zhang y Wei-Cheng Yuan. "Organocatalytic asymmetric Henry reaction of 1H-pyrrole-2,3-diones with bifunctional amine-thiourea catalysts bearing multiple hydrogen-bond donors". Beilstein Journal of Organic Chemistry 12 (16 de febrero de 2016): 295–300. http://dx.doi.org/10.3762/bjoc.12.31.

Texto completo
Resumen
For the first time, a catalytic asymmetric Henry reaction of 1H-pyrrole-2,3-diones was achieved with a chiral bifunctional amine-thiourea as a catalyst possessing multiple hydrogen-bond donors. With this developed method, a range of 3-hydroxy-3-nitromethyl-1H-pyrrol-2(3H)-ones bearing quaternary stereocenters were obtained in acceptable yield (up to 75%) and enantioselectivity (up to 73% ee).
Los estilos APA, Harvard, Vancouver, ISO, etc.
41

Wang, Shanshan, Jing He y Zhe An. "Heterogeneous enantioselective synthesis of chromans via the oxa-Michael–Michael cascade reaction synergically catalyzed by grafted chiral bases and inherent hydroxyls on mesoporous silica surface". Chemical Communications 53, n.º 63 (2017): 8882–85. http://dx.doi.org/10.1039/c7cc03556j.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
42

Sato, Yasuhiro, Yuichi Kawata, Shungo Yasui, Yoshihito Kayaki y Takao Ikariya. "New Bifunctional Bis(azairidacycle) with Axial Chirality via Double Cyclometalation of 2,2′-Bis(aminomethyl)-1,1′-binaphthyl". Molecules 26, n.º 4 (22 de febrero de 2021): 1165. http://dx.doi.org/10.3390/molecules26041165.

Texto completo
Resumen
As a candidate for bifunctional asymmetric catalysts containing a half-sandwich C–N chelating Ir(III) framework (azairidacycle), a dinuclear Ir complex with an axially chiral linkage is newly designed. An expedient synthesis of chiral 2,2′-bis(aminomethyl)-1,1′-binaphthyl (1) from 1,1-bi-2-naphthol (BINOL) was accomplished by a three-step process involving nickel-catalyzed cyanation and subsequent reduction with Raney-Ni and KBH4. The reaction of (S)-1 with an equimolar amount of [IrCl2Cp*]2 (Cp* = η5–C5(CH3)5) in the presence of sodium acetate in acetonitrile at 80 °C gave a diastereomeric mixture of new dinuclear dichloridodiiridium complexes (5) through the double C–H bond cleavage, as confirmed by 1H NMR spectroscopy. A loss of the central chirality on the Ir centers of 5 was demonstrated by treatment with KOC(CH3)3 to generate the corresponding 16e amidoiridium complex 6. The following hydrogen transfer from 2-propanol to 6 provided diastereomers of hydrido(amine)iridium retaining the bis(azairidacycle) architecture. The dinuclear chlorido(amine)iridium 5 can serve as a catalyst precursor for the asymmetric transfer hydrogenation of acetophenone with a substrate to a catalyst ratio of 200 in the presence of KOC(CH3)3 in 2-propanol, leading to (S)-1-phenylethanol with up to an enantiomeric excess (ee) of 67%.
Los estilos APA, Harvard, Vancouver, ISO, etc.
43

Moritani, Junki, Yoshihito Kayaki y Takao Ikariya. "Advantageous asymmetric ketone reduction with a competitive hydrogenation/transfer hydrogenation system using chiral bifunctional iridium catalysts". RSC Adv. 4, n.º 105 (2014): 61001–4. http://dx.doi.org/10.1039/c4ra07854c.

Texto completo
Resumen
Asymmetric ketone hydrogenation with bifunctional amidoiridium complexes in methanol or ethanol proceeds competitively with asymmetric transfer hydrogenation, in which the pressurised hydrogen can suppress involuntary racemisation of the product.
Los estilos APA, Harvard, Vancouver, ISO, etc.
44

Maeda, Chihiro, Mayato Mitsuzane y Tadashi Ema. "Chiral Bifunctional Metalloporphyrin Catalysts for Kinetic Resolution of Epoxides with Carbon Dioxide". Organic Letters 21, n.º 6 (27 de febrero de 2019): 1853–56. http://dx.doi.org/10.1021/acs.orglett.9b00447.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
45

Kamezaki, Shoko, Satoshi Akiyama, Yoshihito Kayaki, Shigeki Kuwata y Takao Ikariya. "Asymmetric nitrile-hydration with bifunctional ruthenium catalysts bearing chiral N-sulfonyldiamine ligands". Tetrahedron: Asymmetry 21, n.º 9-10 (mayo de 2010): 1169–72. http://dx.doi.org/10.1016/j.tetasy.2010.03.011.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
46

Wang, Xisheng, Quan Lan, Seiji Shirakawa y Keiji Maruoka. "Chiral bifunctional phase transfer catalysts for asymmetric fluorination of β-keto esters". Chem. Commun. 46, n.º 2 (2010): 321–23. http://dx.doi.org/10.1039/b920099a.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
47

Shirakawa, Seiji, Takashi Tokuda, Atsuyuki Kasai y Keiji Maruoka. "Design of Chiral Bifunctional Quaternary Phosphonium Bromide Catalysts Possessing an Amide Moiety". Organic Letters 15, n.º 13 (13 de junio de 2013): 3350–53. http://dx.doi.org/10.1021/ol4013926.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
48

Novacek, Johanna y Mario Waser. "ChemInform Abstract: Bifunctional Chiral Quaternary Ammonium Salt Catalysts: A Rapidly Emerging Class of Powerful Asymmetric Catalysts". ChemInform 44, n.º 22 (13 de mayo de 2013): no. http://dx.doi.org/10.1002/chin.201322214.

Texto completo
Los estilos APA, Harvard, Vancouver, ISO, etc.
49

Berkessel, Albrecht, Serap Eröksüz y Jörg Neudörfl. "Kinetic Resolution of 5-Substituted Oxazinones with Bifunctional Chiral Base/Squaramide Organocatalysts". Synlett 28, n.º 11 (31 de mayo de 2017): 1278–81. http://dx.doi.org/10.1055/s-0036-1588852.

Texto completo
Resumen
5-Substituted oxazinones provide N-protected β2-amino acid esters upon alcoholytic ring opening. Thus far, this access to enantiopure β2-amino acids has been restricted to the use of enzymes (hydrolases) as catalysts for the kinetic resolution of racemic 5-substituted oxazinones, and branched alkyl or ortho-substituted aryl groups on the substrate oxazinone’s 5-position were typically not tolerated. We herein report that certain bifunctional chiral base/squaramide organocatalysts, in particular those derived from cis-1,2-diaminocyclohexane or 9-amino-9-epi-quinine, allow the first organocatalytic kinetic resolution of this ‘difficult’ class of oxazinone substrates, affording N-protected β2-amino acid esters with selectivity factors up to 43.
Los estilos APA, Harvard, Vancouver, ISO, etc.
50

Berkessel, Albrecht. "Biomimetic and organocatalytic approaches to oxidation catalysis". Pure and Applied Chemistry 77, n.º 7 (1 de enero de 2005): 1277–84. http://dx.doi.org/10.1351/pac200577071277.

Texto completo
Resumen
The lecture summarized our recent work in the fields of (i) catalytic asymmetric epoxidation and cyclopropanation, (ii) C–C coupling reactions, and (iii) dynamic kinetic resolution (DKR). The first section describes the use of chiral Ru-porphyrins as catalysts for the asymmetric epoxidation and cyclopropanation of nonfunctionalized olefins, and of peptides and alkaloid-based phase-transfer catalysts for the asymmetric epoxidation of enones. The second section highlights the application of the DIANANE-salen ligands (DIANANE: endo,endo-2,5-diamino-norbornane) to the asymmetric Nozaki–Hiyama–Kishi coupling of aldehydes with allylic and vinylic electrophiles, and of N-tosyl proline amides for asymmetric aldol additions. In the final section, bifunctional urea-based organocatalysts for the DKR of azlactones to provide enantiomerically enriched amino acid esters are presented.
Los estilos APA, Harvard, Vancouver, ISO, etc.
Ofrecemos descuentos en todos los planes premium para autores cuyas obras están incluidas en selecciones literarias temáticas. ¡Contáctenos para obtener un código promocional único!

Pasar a la bibliografía