- Supramolecular autoregulation
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Enzyme activity in biological systems is often governed by control mechanisms in which the catalytic properties are made sensitive or insensitive to differences in enzyme or substrate concentration. Here, we report the first supramolecular system where th
- Rodríguez-Llansola, Francisco,Meijer
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- Asymmetric Catalysis, CIII [1]: Enantioselective Michael Addition of 1,3-Dicarbonyl Compounds to Conjugated Nitroalkenes
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Optically active Michael adducts were synthesized by addition of 1,3-dicarbonyl compounds to conjugated nitroalkenes. Good chemical yields were obtained for nitroalkenes stabilized by an aromatic substituent without any further substituents at the double
- Brunner,Kimel
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- Computational Investigations of Enantioselection in Carbon-Carbon Bond Forming Reactions of Ruthenium Guanidinobenzimidazole Second Coordination Sphere Hydrogen Bond Donor Catalysts
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The NH2 group of 2-guanidinobenzimidazole (GBI) can be replaced by (RCRC)-NHCH(CH2)4CHNMe2 and elaborated to the enantiopure chelate salts (SRuRCRC)-[(η5-C5H5)Ru(CO)(GBICH(CH2)4CHNMe2)]+PF6- ((SRuRCRC)-2+PF6-) and (RRuRCRC)-2+PF6-. These catalyze highly e
- Wititsuwannakul, Taveechai,Mukherjee, Tathagata,Hall, Michael B.,Gladysz, John A.
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Read Online
- 1,4-Michael additions of cyclic-β-ketoesters catalyzed by DNA in aqueous media
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In this work, we describe the 1,4-Michael addition of the 1,3-dicarbonyl compounds to activated ethylenes under st-DNA catalysis in water. The reaction of the β-ketoester 4 with nitroolefins and conjugated carbonyls proceeds quite well, whereas other less
- Izquierdo, Cristina,Luis-Barrera, Javier,Fraile, Alberto,Alemán, José
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Read Online
- Synthesis, characterization and catalytic performance in enantioselective reactions by mesoporous silica materials functionalized with chiral thiourea-amine ligand
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Chiral heterogeneous catalysts have been synthesized by grafting of silyl derivatives of (1R, 2R)- or (1S, 2S)-1,2-diphenylethane-1,2-diamine on SBA-15 mesoporous support. The mesoporous material SBA-15 and so-prepared chiral heterogeneous catalysts were characterized by a combination of different techniques such as X-ray diffractometry (XRD), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), and Brunauer–Emmett–Teller (BET) surface area. Results showed that (1R, 2R)- and (1S, 2S)-1,2-diphenylethane-1,2-diamine were successively immobilized on SBA-15 mesoporous support. Chiral heterogeneous catalysts and their homogenous counterparts were tested in enantioselective transfer hydrogenation of aromatic ketones and enantioselective Michael addition of acetylacetone to β-nitroolefin derivatives. The catalysts demonstrated notably high catalytic conversions (up to 99%) with moderate enantiomeric excess (up to 30% ee) for the heterogeneous enantioselective transfer hydrogenation. The catalytic performances for enantioselective Michael reaction showed excellent activities (up to 99%) with poor enantioselectivities. Particularly, the chiral heterogeneous catalysts could be readily recycled for Michael reaction and reused in three consecutive catalytic experiments with no loss of catalytic efficacies.
- G?k, Ya?ar,G?k, Halil Zeki
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p. 853 - 874
(2020/11/10)
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- Novel 1,2,3-triazole epicinchonas: Transitioning from organocatalysis to biological activities
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A small family of novel modular monofunctional epicinchonidine-1,2,3-triazole compounds was prepared in very good overall yield (3 steps from cinchonidine, 49–87% yield) using simple Cu(I) catalyzed click-chemistry. The objective of this study was to acce
- Barrulas, Pedro,Carreiro, Elisabete P.,Veiros, Luis F.,Amorim, Ana C.,Gut, Giri,Rosenthal, Philip J.,López, óscar,Puerta, Adrián,Padrón, José M.,Fernández-Bola?os, José G.,Burke, Anthony J.
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p. 2954 - 2974
(2021/08/24)
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- Molecular Engineering of β-Substituted Oxoporphyrinogens for Hydrogen-Bond Donor Catalysis
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A new class of bifunctional hydrogen-bond donor organocatalyst using oxoporphyrinogens having increased intramolecular hydrogen-bond donor distances is reported. Oxoporphyrinogens are highly non-planar rigid macrocycles containing a multiple hydrogen bond-forming binding site. In this work, we describe the first example of non-planar OxPs as hydrogen-bond donor catalysts prepared using a molecular engineering approach of the binding site for dual activation of substrates. The introduction of β-substituents is key to the catalytic activity and the catalysts are able to catalyze 1,4-conjugate additions and sulfa-Michael additions, as well as, Henry and aza-Henry reactions at low catalyst loadings (≤ 1 mol-%) under mild conditions. Preliminary mechanistic studies have been carried out and a possible reaction mechanism has been proposed based on the bi-functional activation of both substrates through hydrogen-bonding interactions.
- Chahal, Mandeep K.,Payne, Daniel T.,Matsushita, Yoshitaka,Labuta, Jan,Ariga, Katsuhiko,Hill, Jonathan P.
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- Novel carbohydrate-based thioureas as organocatalysts for asymmetric michael addition of 1,3-dicarbonyl compounds to nitroolefins
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A series of novel carbohydrate-derived thioureas were synthesized and examined as catalysts for the asymmetric Michael addition of symmetrical 1,3-dicarbonyl compounds, including dimethyl malonate, to several trans-β-nitrostyrenes. High enantioselectiviti
- Ron?ák, Róbert,Tvrdoňová, Monika,Gonda, Jozef,Ele?ko, Ján
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- Readily accessible mesoporous silica nanoparticles supported chiral urea-amine bifunctional catalysts for enantioselective reactions
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The main objective of this study is to develop readily accessible and recyclable solid catalysts for enantioselective reactions. To achieve this, magnetic MCM-41 and non-magnetic SBA-15 mesoporous supports were prepared, then mesoporous silica supported c
- G?k, Ya?ar,Aykut, ?rem Tutkum,G?k, Halil Zeki
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- A nanoporous metal-organic framework as a renewable size-selective hydrogen-bonding catalyst in water
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A novel squaramide-containing metal-organic framework (MOF) material has been designed and synthesized. A detailed X-ray crystal structure analysis showed that four squaramides of this MOF adopted two orientations in each dependent nanopore, confirming th
- Liu, Yanhong,Ma, Ju,Wu, Pengyan,Zheng, Jia-Jia,Tian, Xueqin,Jiang, Min,He, Yumei,Dong, Han,Wang, Jian
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p. 11855 - 11861
(2019/08/14)
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- Squaramide-decorated covalent organic framework as a new platform for biomimetic hydrogen-bonding organocatalysis
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A squaramide-decorated COF was synthesized and used as a highly efficient heterogeneous catalyst for hydrogen-bonding organocatalysis as exemplified in the context of catalyzing Michael addition reactions under mild conditions. Our work lays a foundation
- Li, Xia,Wang, Zhifang,Sun, Jiaxing,Gao, Jia,Zhao, Yu,Cheng, Peng,Aguila, Briana,Ma, Shengqian,Chen, Yao,Zhang, Zhenjie
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supporting information
p. 5423 - 5426
(2019/05/16)
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- Tetraarylphosphonium inner-salts (TAPIS) as both Lewis base catalyst and phase tag
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Tetraarylphosphonium inner-salts (TAPIS) have been designed, synthesized and verified as recyclable and reusable Lewis base catalysts. The resulted TAPIS catalyst has been successfully applied in Michael addition, cyanation and trifluoromethylation reactions.
- Guo, Shuhui,Mi, Xueling
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p. 2881 - 2884
(2017/07/11)
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- A dramatic synergistic effect of a flexible achiral linker on a rigid chiral cis-1,2-diamine bifunctional organocatalyst
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The combination of a “rigid” chiral bicyclic cis-1,2-diamine skeleton with steric bulkiness and a “flexible” achiral linker was newly designed as a bifunctional organocatalyst framework and it showed excellent catalytic activity of up to 0.05 mol%, accomp
- Matsunaga, Hirofumi,Tajima, Daisuke,Kawauchi, Tetsuro,Yasuyama, Takuro,Ando, Shin,Ishizuka, Tadao
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supporting information
p. 2892 - 2896
(2017/04/10)
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- Supported and Unsupported Chiral Squaramides as Organocatalysts for Stereoselective Michael Additions: Synthesis of Enantiopure Chromenes and Spirochromanes
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Novel supported chiral bifunctional squaramides have been easily prepared starting from diamines derived from natural amino acids and commercially available aminoalkyl polystyrene resins. These squaramides behave as excellent stereoselective recoverable o
- Andrés, José M.,Losada, Jorge,Maestro, Alicia,Rodríguez-Ferrer, Patricia,Pedrosa, Rafael
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p. 8444 - 8454
(2017/08/23)
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- Helical Oligourea Foldamers as Powerful Hydrogen Bonding Catalysts for Enantioselective C-C Bond-Forming Reactions
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Substantial progress has been made toward the development of metal-free catalysts of enantioselective transformations, yet the discovery of organic catalysts effective at low catalyst loadings remains a major challenge. Here we report a novel synergistic
- Bécart, Diane,Diemer, Vincent,Salaün, Arnaud,Oiarbide, Mikel,Nelli, Yella Reddy,Kauffmann, Brice,Fischer, Lucile,Palomo, Claudio,Guichard, Gilles
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supporting information
p. 12524 - 12532
(2017/09/23)
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- A Fluorescent and Switchable Rotaxane Dual Organocatalyst
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Rotaxane organocatalysis presents a new direction toward controlled one-pot catalytic reactions. By combining molecular switches and catalysts, fluorescence and pH-responsive switching along with the exclusive selectivity of dual catalytic reactions are d
- Kwan, Chak-Shing,Chan, Albert S. C.,Leung, Ken Cham-Fai
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supporting information
p. 976 - 979
(2016/03/15)
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- 1,3-Diamine-Derived Bifunctional Organocatalyst Prepared from Camphor
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Chiral 1,2-diamines are privileged structural motifs in organocatalysis, whereas efficient 1,3-diamine-derived organocatalysts are very rare. Herein we report a highly efficient camphor-1,3-diamine-derived squaramide organocatalyst. Its catalytic activity
- Ri?ko, Sebastijan,Svete, Jurij,?tefane, Bogdan,Perdih, Andrej,Golobi?, Amalija,Meden, An?e,Gro?elj, Uro?
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supporting information
p. 3786 - 3796
(2016/12/16)
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- Catalytic Promiscuity of Ancestral Esterases and Hydroxynitrile Lyases
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Catalytic promiscuity is a useful, but accidental, enzyme property, so finding catalytically promiscuous enzymes in nature is inefficient. Some ancestral enzymes were branch points in the evolution of new enzymes and are hypothesized to have been promiscuous. To test the hypothesis that ancestral enzymes were more promiscuous than their modern descendants, we reconstructed ancestral enzymes at four branch points in the divergence hydroxynitrile lyases (HNL's) from esterases ~100 million years ago. Both enzyme types are α/β-hydrolase-fold enzymes and have the same catalytic triad, but differ in reaction type and mechanism. Esterases catalyze hydrolysis via an acyl enzyme intermediate, while lyases catalyze an elimination without an intermediate. Screening ancestral enzymes and their modern descendants with six esterase substrates and six lyase substrates found higher catalytic promiscuity among the ancestral enzymes (P 0.01). Ancestral esterases were more likely to catalyze a lyase reaction than modern esterases, and the ancestral HNL was more likely to catalyze ester hydrolysis than modern HNL's. One ancestral enzyme (HNL1) along the path from esterase to hydroxynitrile lyases was especially promiscuous and catalyzed both hydrolysis and lyase reactions with many substrates. A broader screen tested mechanistically related reactions that were not selected for by evolution: decarboxylation, Michael addition, γ-lactam hydrolysis and 1,5-diketone hydrolysis. The ancestral enzymes were more promiscuous than their modern descendants (P = 0.04). Thus, these reconstructed ancestral enzymes are catalytically promiscuous, but HNL1 is especially so.
- Devamani, Titu,Rauwerdink, Alissa M.,Lunzer, Mark,Jones, Bryan J.,Mooney, Joanna L.,Tan, Maxilmilien Alaric O.,Zhang, Zhi-Jun,Xu, Jian-He,Dean, Antony M.,Kazlauskas, Romas J.
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supporting information
p. 1046 - 1056
(2016/02/05)
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- Scope and limitations of supramolecular autoregulation
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Recently, our group has reported on the ureidopyrimidinone (UPy) induced buffering of 2,7-diamido-1,8-naphthyridine (NaPy) and used this phenomenon to regulate the catalysis of the Michael addition of 2,4-pentanedione to trans-a-nitrostyrene. We now show that the observed catalytic activity of NaPy is the result of a strong synergy between NaPy and trace amounts of K2CO3, resulting in a more than 100-fold increase in reaction rate compared to the two compounds separately. By keeping the concentration of K2CO3, as well as NaPy, constant, an improved regulation of the catalytic activity is achieved. We show that the catalytic activity can be precisely regulated in a noncovalent manner via the addition of the UPy motif. Finally, different salts and Michael substrates are screened to assess the selectivity of this catalytic couple and to provide a platform for future research in molecular buffering, regulation, and chemical networks.
- Teunissen, Abraham J.P.,Van Der Haas, Roy J.C.,Vekemans, Jef A.J.M.,Palmans, Anja R.A.,Meijer
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supporting information
p. 308 - 314
(2016/04/05)
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- Supported bifunctional thioureas as recoverable and reusable catalysts for enantioselective nitro-Michael reactions
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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 l
- Andrés, José M.,Ceballos, Miriam,Maestro, Alicia,Sanz, Isabel,Pedrosa, Rafael
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p. 628 - 635
(2016/07/06)
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- Bifunctional organocatalysis with squaramide-containing Dawson organo-polyoxotungstates
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Two squaramide-containing organo-polyoxometalates (POMs) have been prepared, which efficiently catalyze the addition of dicarbonyl derivatives onto nitroolefins. The POM surface enhances the reactivity of the squaramide, and the hybrid acts as a bifunctio
- Lachkar, David,Lac?te, Emmanuel
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p. 113 - 116
(2016/03/22)
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- Tris-ureas as versatile and highly efficient organocatalysts for Michael addition reactions of nitro-olefins: Mechanistic insight from in-situ diagnostics
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Tris(2-aminoethyl)-amine, TREN based tris-ureas (1a–1d) and tris-thiourea (1e) have been explored towards a wide range of catalytic Michael addition reactions. These tris-ureas, 1a–1d efficiently catalyze the addition reaction of β-nitro styrenes (2a–2d)
- Bera, Milan,Ghosh, Tamal Kanti,Akhuli, Bidyut,Ghosh, Pradyut
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p. 287 - 295
(2017/02/19)
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- One pot domino reaction accessing γ-nitroesters: Synthesis of GABA derivatives
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Michael addition of 1,3-dicarbonyl compounds to nitrostyrenes is efficiently promoted by hydrotalcite [Mg-Al] to afford the respective γ-nitrodicarbonyl adducts. Differently, the addition of Meldrum's acid leads to a direct access of γ-nitroesters through a one pot domino process. GABA derivatives (+/-)-phenibut and (+/-)-baclofen were readily synthesized from the respective nitro adducts.
- Naciuk, Fabricio F.,Vargas, Debora Z.,D'oca, Caroline R. M.,Moro, Celso C.,Russowsky, Dennis
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p. 1643 - 1653
(2015/03/18)
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- Organocatalytic one-pot 1,4-/1,6-/1,2-addition sequence for the stereocontrolled formation of six consecutive stereocenters
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An unprecedented stereoselective organocatalytic one-pot 1,4-/1,6-/1,2-addition sequence between β-dicarbonyl compounds, β-nitroalkenes and 4-nitro-5-styrylisoxazoles sequentially catalyzed by low loading of a squaramide catalyst and an achiral base has b
- Chauhan, Pankaj,Mahajan, Suruchi,Raabe, Gerhard,Enders, Dieter
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supporting information
p. 2270 - 2272
(2015/02/05)
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- Synthesis of novel cinchona-amino acid hybrid organocatalysts for asymmetric catalysis
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Three novel subclasses of cinchonidine derivatives coupled to diverse amino acids were prepared in very good overall yield and tested in a benchmark organocatalytic aldol reaction, between acetone and aromatic aldehydes. These subclasses are a family of a
- Barrulas, Pedro,Benaglia, Maurizio,Burke, Anthony J.
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p. 923 - 935
(2014/07/22)
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- Asymmetric synthesis of tetrahydropyridines via an organocatalytic one-pot multicomponent Michael/aza-Henry/cyclization triple domino reaction
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A low loading of a quinine-derived squaramide efficiently catalyzes the triple-domino Michael/aza-Henry/cyclization reaction between 1,3-dicarbonyl compounds, β-nitroolefins, and aldimines to provide tetrahydropyridines bearing three contiguous stereogeni
- Blümel, Marcus,Chauhan, Pankaj,Hahn, Robert,Raabe, Gerhard,Enders, Dieter
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supporting information
p. 6012 - 6015
(2015/01/08)
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- An expedient and green protocol for the Michael addition of malonates, diketones and p-keto esters to the nitrostyrenes
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A novel methodology has been developed for the rapid synthesis of functionalized nitroalkanes by the addition of less reactive carbon nucleophiles such as malonate esters, acetylacetone and ethyl acetoacetate to various r/ms-p-nitrostyrenes under solvent-
- Agarwal, Jyoti,Naganaboina, Ram Tilak,Peddinli, Rama Krishna
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p. 511 - 518
(2013/06/05)
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- Basic-functionalized recyclable ionic liquid catalyst: A solvent-free approach for Michael addition of 1,3-dicarbonyl compounds to nitroalkenes under ultrasound irradiation
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A task-specific ionic liquid (TSIL) has been introduced as a recyclable catalyst in Michael addition. A series of nitroalkenes and various C-based nucleophiles were reacted in the presence of 30 mol% of recyclable basic-functionalized ionic liquid. Good t
- Narayanaperumal, Senthil,Da Silva, Rodrigo César,Feu, Karla Santos,De La Torre, Alexander Fernández,Corrêa, Arlene G.,Paix?o, Márcio Weber
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p. 793 - 798
(2013/03/13)
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- Lipase/acetamide-catalyzed carbon-carbon bond formations: A mechanistic view
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A lipase B from Candida antarctica (CALB)/acetamide-catalyzed Michael addition of less-activated ketones and aromatic nitroolefins has been developed, which is particularly interesting because neither CALB nor acetamide can independently catalyze the reaction to any appreciable extent. This co-catalyst system was applicable to the Michael additions of cyclic and acyclic ketones to a series of aromatic and heteroaromatic nitroolefins. Hydrogen bonds between acetamide and cyclohexanone were confirmed for the observed activation by experimental facts, and new mechanistic insights into CALB/acetamide co-catalysis are presented. Copyright
- Chen, Xiao-Yang,Chen, Guo-Jun,Wang, Jun-Liang,Wu, Qi,Lin, Xian-Fu
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supporting information
p. 864 - 868
(2013/05/09)
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- Efficient Tertiary Amine/Weak Acid Bifunctional Mesoporous Silica Catalysts for Michael Addition Reactions
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We describe the development and application of efficient bifunctional acid-base mesoporous silica catalysts, denoted hereafter as Ext-SBA-15-NMe2, comprising tertiary amine and silanol (weak acid) groups for the Michael addition reaction. The c
- Das, Sayantani,Goswami, Anandarup,Murali, Nagarajan,Asefa, Tewodros
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p. 910 - 919
(2013/05/09)
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- Organic amine grafting on mesoporous silica as a hybrid catalyst for heterogeneous three-component one-pot reaction
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The organic-inorganic hybrid catalyst was prepared by immobilizing 3-methylaminopropyl moiety onto mesoporous silica, MCM-41, and applied for solid base catalyst of three-component one-pot reaction, i.e. Knoevenagel condensation of aldehyde with the active methylene compound to yield an electron deficient alkene which is subjective to be reacted with nitromethane by Michael addition to form tri-substituted primary nitro compound. The catalyst was characterized by powder-XRD, TG-DTA, FT-IR, nitrogen adsorption-desorption measurement and solid-state cross polarization magic angle spinning (CP/MAS) NMR, and exhibited high catalytic activity in three-component one-pot reaction; however, with poor reusability.
- Komura, Kenichi,Mishima, Yuta,Koketsu, Mamoru
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p. 128 - 132
(2013/02/21)
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- A polystyrene-supported, highly recyclable squaramide organocatalyst for the enantioselective Michael addition of 1,3-dicarbonyl compounds to β-nitrostyrenes
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A chiral squaramide has been supported onto a polystyrene (PS) resin through a copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction and used as a very active, easily recoverable and highly reusable organocatalyst for the asymmetric Michael additio
- Kasaplar, Pinar,Riente, Paola,Hartmann, Caroline,Pericas, Miquel A.
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supporting information
p. 2905 - 2910
(2013/01/15)
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- A novel enzymatic tandem process: Utilization of biocatalytic promiscuity for high stereoselective synthesis of 5-hydroxyimino-4,5-dihydrofurans
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A lipase-catalyzed protocol for the synthesis of 5-hydroxyimino-4,5- dihydrofurans via tandem coupling between β-nitrostyrenes and 1,3-dicarbonyl compounds was developed in a 'one-pot' strategy. A series of β-nitrostyrenes were employed to expand the scope of this new biocatalytic promiscuity with high stereoselectivity (Z/E up to 99:1) and moderate to good yields. The reaction activity of 1,3-cyclohexanedione was found to be better than linear 2,4-pentanedione, while ethyl acetoacetate and diethylmalonate were not suitable for this reaction under the same conditions. Single-crystal X-ray diffraction analysis indicated that the reaction was stereoselective and Z-stereomer was found to be the major product. A reaction mechanism was supposed to elucidate the biocatalytic process.
- Wu, Ming-Yu,Li, Kun,He, Ting,Feng, Xing-Wen,Wang, Na,Wang, Xiao-Yan,Yu, Xiao-Qi
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p. 2681 - 2688
(2011/04/23)
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- Electrophilicities of trans-β-nitrostyrenes
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The kinetics of the reactions of the trans-β-nitrostyrenes 1a-f with the acceptor-substituted carbanions 2a-h have been determined in dimethyl sulfoxide solution at 20 °C. The resulting second-order rate constants were employed to determine the electrophile-specific reactivity parameters E of the trans-β-nitrostyrenes according to the correlation equation log k 2(20 °C) = sN(N + E). The E parameters range from -12 to -15 on our empirical electrophilicity scale (www.cup.lmu.de/oc/mayr/DBintro. html). The second-order rate constants for the reactions of trans-β- nitrostyrenes with some enamines were measured and found to agree with those calculated from the electrophilicity parameters E determined in this work and the previously published N and sN parameters for enamines.
- Zenz, Ivo,Mayr, Herbert
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experimental part
p. 9370 - 9378
(2012/01/06)
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- Organocatalytic enantioselective Michael addition of β-diketones to β-nitrostyrene: The first Michael addition of dipivaloylmethane to an activated olefin
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The addition of a family of β-diketones to β-nitrostyrene was explored using a library of cinchona organocatalysts. A thiourea organocatalyst, under improved reaction conditions, is shown to be much more efficient at catalyzing this reaction than previously reported giving excellent yields and enantioselectivites (up to 95% yield and 97% ee). The same thiourea organocatalyst was employed in the first successful Michael addition of the sterically challenging dipivaloylmethane to β-nitrostyrene (99% ee). ARKAT-USA, Inc.
- Gavin, Declan P.,Stephens, John C.
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experimental part
p. 407 - 421
(2011/08/07)
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- Hydrogen bonding mediated enantioselective organocatalysis in brine: Significant rate acceleration and enhanced stereoselectivity in enantioselective Michael addition reactions of 1,3-dicarbonyls to β-nitroolefins
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Brine provides remarkable rate acceleration and a higher level of stereoselectivity over organic solvents, due to the hydrophobic hydration effect, in the enantioselective Michael addition reactions of 1,3-dicarbonyls to β-nitroolefins using chiral H-dono
- Bae, Han Yong,Some, Surajit,Oh, Joong Suk,Lee, Yong Seop,Song, Choong Eui
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supporting information; experimental part
p. 9621 - 9623
(2011/10/02)
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- A mild and convenient one-pot two-step synthesis of hydroxy- iminodihydrobenzofurans mediated by silica gel under microwave activation conditions
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A convenient one-pot two-step procedure for the synthesis of hydroxyiminodihydrobenzofurans assisted by microwave irradiation in presence of silica gel is described herein. Cyclic 1,3-dicarbonyl compounds reacted smoothly with various nitroolefins to furn
- Barange, Deepak Kumar,Raju, B. Rama,Kavala, Veerababurao,Kuo, Chun-Wei,Tu, Yu-Chen,Yao, Ching-Fa
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experimental part
p. 3754 - 3760
(2010/07/04)
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- Synthetic autocatalysts show organocatalysis of other reactions
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A molecule capable of both autocatalysis and organocatalysis was synthesized. The autocatalytic activity results from the self-complementary recognition sites provided by hydrogen bonding between heterocyclic subunits and the organocatalysis resides in an embedded thiourea function. The behavior of the molecule suggests both replication and metabolism can be engineered into synthetic compounds.
- Kamioka, Seiji,Ajami, Dariush,Rebek Jr., Julius
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supporting information; scheme or table
p. 7324 - 7326
(2010/06/14)
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- Hybrid inorganic-organic materials carrying tertiary amine and thiourea residues tethered on mesoporous silica nanoparticles: Synthesis, characterization, and co-operative catalysis
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Mesoporous silica nanoparticles carrying different loadings of tertiary amine and thiourea residues (residues ratios 53/47, 68/32, and 22/78, respectively) were synthesized by the co-condensation method and fully characterized by CP MAS NMR, powder XRD, S
- Puglisi, Alessandra,Annunziata, Rita,Benaglia, Maurizio,Cozzi, Franco,Gervasini, Antonella,Bertacche, Vittorio,Sala, Maria Chiara
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experimental part
p. 219 - 229
(2009/09/06)
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- Use of immobilized organic base catalysts for continuous-flow fine chemical synthesis
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A continuous-flow two-step process for the production of multifunctional intermediate compounds was performed with a combination of two column reactors packed with different organic immobilized catalysts. The first step of the reaction, nitroaldol condensation between aromatic aldehydes and nitromethane, is promoted by a silica gel-supported primary amine; the second step, Michael addition of β-dicarbonyl compounds to the nitrostyrenes obtained in the first step, is catalyzed by a silica gel-supported guanidine TBD. In both cases, the catalysts can be directly reused for several runs with no significant changes in activity.
- Soldi,Ferstl,Loebbecke,Maggi,Malmassari,Sartori,Yada
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experimental part
p. 289 - 295
(2009/03/11)
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- Acidic alumina as a useful heterogeneous catalyst in the Michael reaction of β-dicarbonyl derivatives with conjugated nitroalkenes
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Addition of a variety of 1,3-dicarbonyl derivatives to conjugated nitroalkenes was efficiently performed under heterogeneous catalysis by acidic alumina in the presence of a minimum amount of solvent (Et2O, 0.5 mL/mmol). The procedure allows sa
- Ballini, Roberto,Maggi, Raimondo,Palmieri, Alessandro,Sartori, Giovanni
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p. 3017 - 3020
(2008/03/13)
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- ACYCLIC IKUR INHIBITORS
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A compound of formula I wherein R1, R2, R3, R4 and R5 are described herein.
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Page/Page column 83
(2010/11/26)
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- Process for preparing optically active nitro compounds and cyano compounds
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[Problem] The problem of the invention is to prepare nitro compounds and cyano compounds in high efficiency and high stereoselectivity by a simple and practical Michael reaction. [Solution] A process for preparing optically active nitro compounds and cyan
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Page/Page column 25
(2008/06/13)
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- Michael additions of aldehydes and ketones to β-nitrostyrenes in an ionic liquid
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Michael additions of different aldehydes and ketones to β-nitrostyrene and 2-(β-nitrovinyl)thiophene in 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF6) were studied. β-Nitrostyrene was a better acceptor than 2-(β-nitrovinyl)thiophen
- Kotrusz, Peter,Toma, Stefan,Schmalz, Hans-Guenther,Adler, Andreas
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p. 1577 - 1583
(2007/10/03)
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- Unusual Michael Reaction of Acyclic 1,3-Dicarbonyl Compounds with Nitro-olefins. A Novel Pyrrole Synthesis
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Acetoacetic esters and pentane-2,4-dione undergo unusual Michael reactions with β-nitrostyrene in methanol-sodium methoxide to form the (2R,3R,2'S,3'S)-bis-(4-acyl-2,3-dihydro-5-methyl-3-phenyl-2)-furylhydroxylamines (5) in high yields.The normal adducts
- Gomez-Sanchez, Antonio,Stiefel, Berta Marco,Fernandez-Fernandez, Rosario,Pascual, Conrado,Bellanato, Juana
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p. 441 - 447
(2007/10/02)
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- Nickel-Catalyzed Michael Additions of β-Dicarbonyls
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Bis(2,4-pentanedionato)nickel(II) is found to be a mild, efficient, and simple to use catalyst for the Michael additions of β-dicarbonyls.Yields are higher than with traditional strongly basic catalysts, unwanted side reactions are reduced, and workup procedures are greatly simplified.The reactions appear to be quite general as β-diketones, β-keto esters, β-keto amides, and β-diesters are all found to react.A rational mechanism which suggests further research is presented.
- Nelson, John H.,Howells, Peter N.,DeLullo, George C.,Landen, George L.,Henry, Ronald A.
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p. 1246 - 1249
(2007/10/02)
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