- Enantioenrichment by Iterative Retro-Aldol/Aldol reaction catalyzed by an achiral or racemic base
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Chemical Equation Presented Did nature use the same strategy? The combination of crystal growth and iterative retro-aldol/aldol reactions catalyzed by a simple achiral (or racemic) base allows improvement of the enantiomer ratio of a product obtained from a stereochemically imperfect aldol reaction (see scheme).
- Flock, Angelika M.,Reucher, Christine M. M.,Bolm, Carsten
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- An investigation of chiral diamides as organocatalysts in asymmetric aldol reaction
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Seven novel proline and 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (THIQA) based diamides were synthesized successfully by simple amidation reactions and characterized by their spectral data. Their catalytic activities in asymmetric aldol reaction w
- Aydogan, Feray,Yilmaz, Dilek Gul,Yolacan, Cigdem
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- Biomass waste-derived recyclable heterogeneous catalyst for aqueous aldol reaction and depolymerization of PET waste
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In this work, we discuss the valorization of biomass waste-derived orange peel ash (OPA) by exploring its applicability as a heterogeneous catalyst in aqueous aldol reactions and demonstrating its versatility by promoting the methanolysis of poly(ethylene terephthalate) (PET) waste. The catalyst was characterized using Fourier-transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET) analysis, X-ray powder diffraction (XRD), X-ray fluorescence (XRF), energy dispersive X-ray (EDX) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and thermal gravimetric analysis (TGA) to decode its chemical composition. The aldol reactions were carried out at ambient temperature in the presence of water as a solvent. PET depolymerization was performed in an autoclave for 1 h using only 6% w/w OPA. The catalyst was recovered and reused in both the reactions for up to four successive cycles with minimal loss in the catalytic activity. The use of OPA as a cost-free, eco-friendly and effective recyclable catalyst enables a greener route for C-C bond formation and PET waste recycling.
- Khiangte, Vanlalngaihawma,Laldinpuii, Z. T.,Lalhmangaihzuala, Samson,Lalmuanpuia, Chhakchhuak,Pachuau, Zodinpuia,Vanlaldinpuia, Khiangte
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p. 19542 - 19552
(2021/11/09)
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- Application of polyamines and amino acid derivatives based on 2-azabicycloalkane backbone in enantioselective aldol reaction
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Carbon–carbon bond forming reactions, such as aldol reaction and condensation, belong to extremely desired transformations as manifested by >25,000 entries in SciFinder. Their stereoselective variant requires the use of an appropriate catalyst with a stri
- Iwan, Dominika,Kamińska, Karolina,Wojaczyńska, El?bieta
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- A chemo-enzymatic oxidation/aldol sequential process directly converts arylbenzyl alcohols and cyclohexanol into chiral β-hydroxy carbonyls
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The development of a combination enzyme and organocatalyst for aqueous sequential organic transformation has great significance, in that it is not only environmentally friendly but also overcomes only a single methodological drawback, either in the chemical or biological process. Herein, through the utilization of the bulky steric hindrance of chiral proline derivatives, an integrated laccase and proline as a chemo-enzymatic co-catalyst system is developed. It enables an efficient oxidation/aldol enantioselective sequential reaction to be accomplished, overcoming the mutual deactivation issue. As we present in this study, this one-pot organic transformation, an initial laccase-mediated oxidation of arylbenzyl alcohols and cyclohexanol to form aldehydes and cyclohexanone, followed by a subsequent proline derivative-catalyzed aldol condensation of the in situ generated intermediates, provides various 1,2-diastereoisomeric chiral β-hydroxy ketones with acceptable yields and high enantio-/diastereoselectivities.
- Cheng, Qipeng,Li, Hongyu,Liu, Guohua,Su, Yu,Tan, Chunxia,Wang, Chengyi,Wang, Yu,Xiao, Rui
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supporting information
p. 7773 - 7779
(2021/10/12)
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- Isothiouronium salt based chiral proline amide as efficient bifunctional organocatalyst for direct asymmetric aldol reactions in aqueous medium
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We developed the first chiral proline amide-isothiouronium based bifunctional organocatalyst, it was prepared by methylation of the corresponding thiourea. This asymmetric catalyst provides aldol products in high to quantitative yields while achieving exc
- Kang, Sungmin,Kim, Taek Hyeon,Yeo, Hyoung Min
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supporting information
(2021/08/25)
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- A Zn(II)-Coordination Polymer for the Instantaneous Cleavage of Csp3-Csp3 Bond and Simultaneous Reduction of Ketone to Alcohol
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Two coordination polymers of Zn(II) and Cu(II) with n-butylmalonic acid have been achieved in this work. The crystallographic structural descriptions along with the sedimentary rock-type microstructural morphology of these two coordination polymers (CPs) have been explored. The reactivity of β-hydroxy ketones with these two CPs has also been investigated. The Zn(II)-CP shows a specific reactivity with β-hydroxy ketone at room temperature and in open air conditions. Through a microcolumn-based filtration technique, the Zn(II)-CP shows the capability to break the Csp3-Csp3 σ bonds of β-hydroxy ketone and simultaneously reduce the associated ketone to alcohol. Such conversion has been progressed without the use of any additional external reducing agent and any chemical workup or column chromatographic purification protocol. Other similar type CPs of Cu(II) and Mn(II) with n-butylmalonic acid completely failed to show similar reactivity with β-hydroxy ketone. On the basis of much experimental evidence, the most possible mechanistic pathway of the reactivity between β-hydroxy ketone and Zn(II)-CP has also been proposed through this work.
- Das, Gourab Kanti,Dey, Biswajit,Dhibar, Subhendu,Ghosh, Debasish,Gupta, Vivek K.
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supporting information
(2020/04/10)
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- Self-assembled Polydiacetylene Nanoribbons for Semi-heterogeneous and Enantioselective Organocatalysis of Aldol Reactions in Water
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We report the synthesis, characterization, and supra-molecular assembly of novel diacetylene amphiphilic units bearing a chiral proline-derived head group. In water, these amphiphiles self-assemble into twisted ribbons that are photo-polymerized to afford
- Hoang, Minh-Duc,Kumar, Ramar Arun,Buisson, David A.,Ling, Wai Li,Gravel, Edmond,Doris, Eric
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p. 1156 - 1160
(2020/01/02)
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- Thermal and magnetic dual-responsive L-proline nanohybrids for aqueous asymmetric aldol reaction
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Thermal and magnetic dual-responsive L-proline nanohybrids (L-Pro-based-TMNHs) were prepared by grafting thermal-responsive thiol-terminated P(NIPAM-co-L-ProlA)-b-POEGA-SH (PNLPO-SH) to vinyl-functionalized Fe3O4?SiO2-MPS
- Wang, Qinya,Tang, Yu,Wu, Lexuan,Xu, Weiwei,Shen, Yinghua,Shi, Lijuan,Dai, Sheng
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- A pH-Switchable Aqueous Organocatalysis with Amphiphilic Secondary Amine–Porphyrin Hybrids
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A series of amphiphilic 5-(cyclic-secondary-amine)-10,15,20-tris(4-sulfonatophenyl)porphyrins, designed with the aim of using the amphiphilic porphyrin moiety for the modulation of the aggregation state of the compound by the pH of the medium, have been synthesised, and the relationship between their supramolecular behaviour in acidic aqueous media and their organocatalytic activity in Michael and aldol reactions has been investigated. In particular, we have found that the catalytic activity of the pyrrolidine moiety in an amphiphilic isoindoline–porphyrin hybrid for the aldol reaction of cyclohexanone with 4-nitrobenzaldehyde can be selectively and reversibly switched on and off by adjusting the homogeneity of its solutions through pH variations. The catalysis of the aldol reaction by the secondary amine moiety would otherwise take place regardless of the pH of the medium. We have demonstrated that the aggregation behaviour of these amine–porphyrin hybrids can be also used for the recovery and reutilization of the catalysts.
- Arlegui, Aitor,Crusats, Joaquim,Cuesta, Victor,Moyano, Albert,Torres, Pol
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- Pepsin-Catalyzed Asymmetric Cross Aldol Reaction Promoted by Ionic Liquids and Deep Eutectic Solvents
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Abstract: Pepsin was found to catalyze asymmetric cross aldol reactions of aromatic and polycyclicaromatic aldehydes with cyclic ketones in ionic liquids and deep eutectic solvents for the first time. Pepsin exhibited high catalytic activity and excellent
- Wang, Yun,Chen, Xin-Yi,Liang, Xin-Yi,Liang, Zhi-Hui,Cheng, Hong,Li, Xiang,Li, Li-Ling
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p. 2549 - 2557
(2020/03/24)
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- New Mesoporous silica-supported organocatalysts based on (2S)-(1,2,4-Triazol-3-yl)-Proline: Efficient, reusable, and heterogeneous catalysts for the asymmetric aldol reaction
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Novel organocatalytic systems based on the recently developed (S)-proline derivative (2S)-[5-(benzylthio)-4-phenyl-(1,2,4-triazol)-3-yl]-pyrrolidine supported on mesoporous silica were prepared and their efficiency was assessed in the asymmetric aldol rea
- Juaristi, Eusebio,Romero-Sedglach, Kevin A.,Sánchez-Antonio, Omar,Vázquez-Orta, Erika C.
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- Chiral amphiphilic secondary amine-porphyrin hybrids for aqueous organocatalysis
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Two chiral proline-derived amphiphilic 5-substituted-10,15,20-tris(4-sulfonatophenyl)porphyrins were prepared, and their pH-dependent supramolecular behavior was studied. In neutral aqueous solutions, the free-base form of the hybrids is highly soluble, a
- Arlegui, Aitor,Torres, Pol,Cuesta, Victor,Crusats, Joaquim,Moyano, Albert
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- Multifunctional phosphoramide-(S)-prolinamide derivatives as efficient organocatalysts in asymmetric aldol and Michael reactions
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The synthesis and evaluation of three novel chiral organocatalysts derived from (S)-proline and containing a bis-amidophosphoryl amine fragment are reported. The structure and conformation of the new compounds were determined by NMR spectroscopy and X-ray crystallographic analysis. The present study represents an effort directed to enhance the performance of (S)-proline-derived organocatalysts in asymmetric aldol and Michael reactions by means of increased steric interactions arising from the incorporation of naphthyl moieties in the catalysts. In the event, the stereoselectivity achieved with naphthyl substituents turned out to be rather similar to that obtained with phenyl analogs. Nevertheless, the new organocatalysts exhibited rather good enantio- and diastereoselectivities in aldol reactions with various isatins and aryl carbaldehydes, affording products with up to 94?:?6 diastereomeric ratios and enantiomeric ratios as high as 95?:?5. Furthermore, products obtained from Michael addition reactions exhibited up to 96?:?4 diastereomeric ratios and enantiomeric ratios as high as 98?:?2.
- Cruz-Hernández, Carlos,Landeros, José M.,Juaristi, Eusebio
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supporting information
p. 5455 - 5465
(2019/04/05)
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- Synthesis of a new chiral organocatalyst derived from (S)-proline containing a 1,2,4-triazolyl moiety and its application in the asymmetric aldol reaction. Importance of one molecule of water generated in situ
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A simple and efficient preparation of a novel chiral derivative of (S)-proline containing a 1,2,4-triazolyl moiety is described. The high-yielding synthetic protocol includes the use of microwave irradiation to afford new chiral pyrrolidine derivatives in
- Sánchez-Antonio, Omar,Juaristi, Eusebio
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supporting information
(2019/09/16)
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- Histidine-based copper tetrapeptides as enantioselective catalysts for aldol reactions
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Copper(ii)-peptides are widely used as industrial catalysts such as in the aerobic oxidation of organic molecules, formation of new C-H bonds and in the azide-alkyne cycloaddition reaction. The length of peptides and the effect of adding copper metal into
- Sharifa Zaithun, Begum,Emilia, AbdulMalek,Mohamed Ibrahim Mohamed, Tahir,Karen Anne, Crouse,Mohd Basyaruddin, Abdul Rahman
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p. 34004 - 34011
(2018/10/20)
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- Proline-Glycine Dipeptidic Derivatives of Chiral Phosphoramides as Organocatalysts for the Enantiodivergent Aldol Reaction of Aryl Aldehydes and Isatins with Cyclohexanone in the Presence of Water
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The synthesis of several novel organocatalysts derived from (R)- and (S)-proline-glycine dipeptides and incorporating a chiral phosphoramide fragment was accomplished. These chiral compounds catalyze the enantioselective aldol addition reaction of cyclohe
- Cruz-Hernández, Carlos,Hernández-González, Perla E.,Juaristi, Eusebio
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p. 3445 - 3459
(2018/06/08)
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- (R)- and (S)-Proline-Derived Chiral Phosphoramides as Organo catalysts for the Enantiodivergent Aldol Reaction of Isatins with Cyclohexanone in the Presence of Water
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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
- Cruz-Hernández, Carlos,Hernández-González, Perla E.,Juaristi, Eusebio
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p. 1827 - 1840
(2018/02/14)
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- Engineering a Zirconium MOF through Tandem "click" Reactions: A General Strategy for Quantitative Loading of Bifunctional Groups on the Pore Surface
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Metal-organic frameworks (MOFs) assembled from linkers of identical length but with different functional groups have gained increasing interests recently. However, it is very challenging for precise control of the ratios of different functionalities. Here
- Zhang, Yingfan,Gui, Bo,Chen, Rufan,Hu, Guiping,Meng, Yi,Yuan, Daqiang,Zeller, Matthias,Wang, Cheng
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p. 2288 - 2295
(2018/02/23)
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- Heterogenization of homogeneous chiral polymers in metal-organic frameworks with enhanced catalytic performance for asymmetric catalysis
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Metal-organic framework (MOF)-based asymmetric heterogeneous catalysts have attracted increasing attention; however, some challenges need to be addressed, such as the rigidity of chiral auxiliary groups within MOFs and the lack of a versatile methodology
- Dong, Xiao-Wu,Yang, Yong,Che, Jin-Xin,Zuo, Jun,Li, Xiao-Hua,Gao, Liang,Hu, Yong-Zhou,Liu, Xin-Yuan
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supporting information
p. 4085 - 4093
(2018/09/11)
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- A copper-templated, bifunctional organocatalyst: A strongly cooperative dynamic system for the aldol reaction
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The study of novel metal-templated dynamic organocatalytic systems has led to the identification of CuSO4 as the most efficient template to assemble monofunctional prolinamide- and thiourea-modified pyridine ligands. The structural and electron
- Serra-Pont, Anna,Alfonso, Ignacio,Solà, Jordi,Jimeno, Ciril
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supporting information
p. 6584 - 6591
(2017/08/16)
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- Aldol Reactions by Lipase From Rhizopus niveus, an Example of Unspecific Protein Catalysis
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The lipase from Rhizopus niveus (RNL) catalyzed by unspecific protein catalysis the aldol reactions between cyclohexanone and aromatic aldehydes in organic solvents with water or aqueous buffer solution. The reactional conditions strongly influenced the y
- Birolli, Willian G.,Fonseca, Luis P.,Porto, André L. M.
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p. 1977 - 1987
(2017/07/25)
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- Towards a Series of Chiral Primary Amines Bearing α-Amino Acid and Benzo[d]imidazole Pendants, and Their Application in Asymmetric Aldol Reactions
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A straightforward reaction path towards chiral primary amines bearing α-amino acid and benzo[d]imidazole pendants has been developed. Six starting essential α-amino acids were converted into the target chiral amines in a four-step synthesis. The prepared
- Mohite, Pravinkumar Hansraj,Drabina, Pavel,Bure?, Filip
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p. 1613 - 1622
(2017/03/21)
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- Optically active microspheres from helical substituted polyacetylene with pendent ferrocenyl amino-acid derivative. Preparation and recycling use for direct asymmetric aldol reaction in water
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The contribution reports a novel type of chiral microspheres in which ferrocenyl amino-acid derived catalytic moieties were integrated with optically active helical substituted polyacetylene. The microspheres were prepared by suspension copolymerization o
- Deng, Jinrui,Deng, Jianping
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p. 200 - 207
(2017/08/30)
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- With Fmoc - L - hydroxy proline optically active phenylacetylene derivative and its preparation and application method
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The present invention provides an optically active phenylacetylene derivative with Fmoc-L-hydroxyproline and preparation and application methods. According to the present invention, a novel optically active phenylacetylene derivative with Fmoc-L-hydroxypr
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Paragraph 0071; 0072-0074
(2018/02/04)
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- Catalyst-free aldol reaction in a water medium
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Background: With growing interest in developing environmentally friendly reactions and atom-economic processes in recent years, the utilization of water as a solvent has attracted a great deal of attention. This is not only for its low-cost, safe and envi
- Yao, Weirong,Cui, Yanli,Wang, Peipei,Mao, Yangyi
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p. 293 - 296
(2016/05/24)
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- Ion-Tagged Prolinamide Organocatalysts for the Direct Aldol Reaction On-Water
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A concise synthesis of two imidazolium ion-tagged prolinamide organocatalysts 3 and 4, varying in anionic component (CF3COO- and PF6 -, respectively) is presented. The latter could be classified as an ionic liqu
- Eyckens, Daniel J.,Brozinski, Hannah L.,Delaney, Joshua P.,Servinis, Linden,Naghashian, Sahar,Henderson, Luke C.
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p. 212 - 219
(2016/02/23)
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- L-hydroxyproline immobilized on MCM-41 by ionic liquid as a heterogeneous organocatalyst for direct asymmetric aldol addition
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A new heterogenized silica-based organocatalyst was prepared via anion exchange of imidazolium ionic liquid with L- hydroxyproline material. This was evaluated as a heterogenous organocatalyst for the asymmetric aldol reaction of nitrobenzaldehydes, cyclo
- Alimohammadzadeh, Rana,Galehassadi, Mohammad
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p. 496 - 503
(2016/11/19)
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- Cooperative Effects Between Arginine and Glutamic Acid in the Amino Acid-Catalyzed Aldol Reaction
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Catalysis of the aldol reaction between cyclohexanone and 4-nitrobenzaldehyde by mixtures of L-Arg and of L-Glu in wet dimethyl sulfoxide (DMSO) takes place with higher enantioselectivity (up to a 7-fold enhancement in the anti-aldol for the 1:1 mixture)
- Valero, Guillem,Moyano, Albert
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supporting information
p. 599 - 605
(2016/08/27)
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- Proline Functionalized UiO-67 and UiO-68 Type Metal-Organic Frameworks Showing Reversed Diastereoselectivity in Aldol Addition Reactions
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Functionalization of dicarboxylate linkers with proline was used to generate catalytically active metal-organic frameworks (MOFs) for diastereoselective aldol addition. Due to high robustness and chemical stability, zirconium based MOFs, namely UiO-67 and
- Kutzscher, Christel,Nickerl, Georg,Senkovska, Irena,Bon, Volodymyr,Kaskel, Stefan
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p. 2573 - 2580
(2016/06/01)
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- Binaphthyl-based chiral bifunctional organocatalysts for water mediated asymmetric List-Lerner-Barbas aldol reactions
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Novel binaphthyl-based chiral bifunctional organocatalysts were designed, synthesized and successfully applied to the asymmetric List-Lerner-Barbas aldol reaction in the presence of water. These organocatalysts were found to be effective catalysts for the
- Ashokkumar, Veeramanoharan,Chithiraikumar, Chinnadurai,Siva, Ayyanar
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p. 9021 - 9032
(2016/10/07)
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- An Acid/Base-Regulated Recyclable Strategy for Homogeneous Cinchona Alkaloid-Derived Primary Amine Organocatalysts in Aldol, Vinylogous Michael and Double-Michael Cascade Reactions
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A practical, recyclable strategy for homogeneous cinchona alkaloid-derived primary amine organocatalysts was developed by controlling the solubilities in an aqueous/organic biphasic system through regulating the pH of the aqueous phase, effecting the prot
- Wan, Jingwei,Zhao, Zhiwei,Wang, Falu,Ma, Xuebing
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supporting information
p. 5755 - 5763
(2015/09/15)
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- A photoswitchable organocatalyst based on a catalyst-imprinted polymer containing azobenzene
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An l-proline-catalyzed aldol reaction was photo-controlled using an l-proline-imprinted polymer containing azobenzene. Upon UV irradiation, azobenzene chromophores underwent trans → cis isomerization, thereby releasing l-proline to catalyze the aldol reac
- Liu, Hua-Dong,Zheng, An-Xun,Gong, Cheng-Bin,Ma, Xue-Bing,Hon-Wah Lam, Michael,Chow, Cheuk-Fai,Tang, Qian
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p. 62539 - 62542
(2015/08/06)
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- Synthesis of sulphur-modified bifunctional hydrotalcites and study of their surface characteristics by inverse gas chromatography
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In this study, various sulphur-modified hydrotalcite catalysts were prepared, and the influence of calcination temperature on their acid-base properties was investigated. Structural characterization of the catalysts was studied using X-ray powder diffraction, scanning electron microscopy, N2 physisorption, elemental analysis and Fourier transform infrared spectroscopy. The structural characterization indicated that the layer structure of all catalysts was retained but the specific surface areas were enlarged. Inverse gas chromatography was carried out to quantitatively determine the catalysts' acid-base properties by calculating the thermodynamic parameters, including dispersive surface free energy, adsorption free energy, adsorption enthalpy, and acid-base interaction constants. The results showed that the strength and content of acidic and alkaline sites were enhanced with increasing calcination temperature. Moreover, several typical aldol condensation reactions were selected to study the catalytic activity of the developed catalysts. The results showed that the sulphur-modified hydrotalcite catalysts possess high activity and good regenerability for typical aldol condensation reactions.
- Ren, Xiaoqian,Hu, Xi,Zhang, Feng,Wang, Junge,Liang, Jinhua,Wu, Wenliang,Jiang, Min,Wang, Jun
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p. 4813 - 4820
(2015/10/05)
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- Dynamic assembly of a zinc-templated bifunctional organocatalyst in the presence of water for the asymmetric aldol reaction
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A bifunctional organocatalytic system consisting of simple pyridine ligands containing separate catalytic functionalities was assembled using ZnCl2. This novel metal-templated catalyst furnished high yields and stereoselectivities towards the a
- Serra-Pont, Anna,Alfonso, Ignacio,Jimeno, Ciril,Solà, Jordi
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supporting information
p. 17386 - 17389
(2015/12/08)
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- Magnetic nano-organocatalysts: Impact of surface functionalization on catalytic activity
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Iron oxide nanoparticles (γ-Fe2O3) have been synthesized using soft chemistry in aqueous media. The particles were then stabilized on a surface using bifunctional coating agents bearing terminal functional groups which enable post functionalization with the desired catalyst (proline derivatives, peptides). The hybrid nanomaterials were characterized with various techniques in order to determine their properties. The catalysts' activities were evaluated using aldolization and 1,4-Michael addition as model reactions. For both reactions the crucial impact of the nanocatalyst surface functionalisation on the catalytic properties is demonstrated. For the Michael addition, good selectivity was achieved using a small amount of nano-catalyst.
- Nehlig,Motte,Guénin
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p. 104688 - 104694
(2015/12/30)
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- METHOD FOR PRODUCING OPTICALLY ACTIVE COMPOUND
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PROBLEM TO BE SOLVED: To provide a method of producing an optically active compound by using asymmetric catalyst particles, which can easily correspond to micro organic synthesis irrespective of a scale and enables separation of a reaction product from th
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Paragraph 0069-0073
(2016/10/08)
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- PRODUCTION METHOD OF OPTICALLY ACTIVE COMPOUND
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PROBLEM TO BE SOLVED: To provide a method of producing an optically active compound capable of separating a reaction product from a catalyst using asymmetric catalyst particles without complex separation operation. SOLUTION: In a production method of an o
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Paragraph 0055-0059; 0062
(2017/01/02)
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- Aqueous asymmetric aldol reaction catalyzed by nanomagnetic solid acid SO42-/Zr(OH)4-Fe3O4
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Magnetic solid acid catalysts SO42-/Zr(OH)4-Fe3O4 were prepared using magnetic Fe3O4 nanoparticles, ZrOCl2·8H2O, and sulfuric acid as starting materials in
- Wu, Tao,Wan, Jingwei,Ma, Xuebing
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p. 425 - 431
(2015/09/28)
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- Proline functionalization of the mesoporous metal-organic framework DUT-32
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The linker functionalization strategy was applied to incorporate proline moieties into a metal-organic framework (MOF). When 4,4′-biphenyldicarboxylic acid was replaced with a Boc-protected proline-functionalized linker (H2L) in the synthesis o
- Kutzscher, Christel,Hoffmann, Herbert C.,Krause, Simon,Stoeck, Ulrich,Senkovska, Irena,Brunner, Eike,Kaskel, Stefan
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supporting information
p. 1003 - 1009
(2015/02/19)
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- Pyrrolidine-diaminomethylenemalononitrile organocatalyst for solvent-free asymmetric direct aldol reactions
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Pyrrolidine-diaminomethylenemalononitrile (pyrrolidine-DMM) organocatalyst has been an efficient reaction medium to promote asymmetric direct aldol reactions to afford the corresponding addition products in high yields with up to 99% ee under solvent-free
- Nakashima, Kosuke,Hirashima, Shin-Ichi,Akutsu, Hiroshi,Koseki, Yuji,Tada, Norihiro,Itoh, Akichika,Miura, Tsuyoshi
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p. 558 - 561
(2015/02/19)
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- Pyrimidine-derived prolinamides as recoverable bifunctional organocatalysts for enantioselective inter- and intramolecular aldol reactions under solvent-free conditions
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Chiral L-prolinamides 2 containing the (R,R)- and (S,S)-trans-cyclohexane-1,2-diamine scaffold and a 2-pyrimidinyl unit are synthesized and used as general organocatalysts for intermolecular and intramolecular aldol reactions with 1,6-hexanedioic acid as a co-catalyst under solvent-free conditions. The intermolecular reaction between ketone-aldehyde and aldehyde-aldehyde must be performed under wet conditions with catalyst (S,S)-2b at 10 °C, which affords anti-aldols with high regio-, diastereo-, and enantioselectivities. For the Hajos-Parrish-Eder-Sauer-Wiechert reaction, both diastereomers of catalyst 2 give similar results at room temperature in the absence of water to give the corresponding Wieland-Miescher ketone and derivatives. Both types of reactions were scaled up to 1 g, and the organocatalysts were recovered by extractive workup and reused without any appreciable loss in activity. DFT calculations support the stereochemical results of the intermolecular process and the bifunctional role played by the organocatalyst by providing a computational comparison of the H-bonding networks occurring with catalysts 2a and 2b. The intermolecular ketone-aldehyde and aldehyde-aldehyde aldol reactions and the Hajos-Parrish-Eder-Sauer-Wiechert versions with the employment of chiral L-prolinamides containing the (R,R)- and (S,S)-trans-cyclohexane-1,2-diamine scaffold and a 2-pyrimidinyl unit are successfully performed under solvent-free conditions; WMK = Wieland-Miescher ketone.
- Vizcaíno-Milla, Pascuala,Sansano, José M.,Nájera, Carmen,Fiser, Béla,G?mez-Bengoa, Enrique
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p. 2614 - 2621
(2015/04/27)
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- Direct enantioselective aldol reactions catalyzed by calix[4]arene-based l-proline derivatives in the water
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Two novel p-tert-butylcalix[4]arene-based chiral organocatalysts derived from l-proline have been developed to catalyze direct aldol reactions between cyclohexanone and aromatic aldehydes in water. Under the optimal conditions, high yields (up to 95%), en
- Eymur, Serkan,Akceylan, Ezgi,Sahin, Ozlem,Uyanik, Arzu,Yilmaz, Mustafa
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p. 4471 - 4477
(2014/06/10)
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- AZT-prolinamide: The nucleoside derived pyrrolidine catalysts for asymmetric aldol reactions using water as solvent
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New pyrrolidine catalysts based on a nucleoside and proline, AZT-prolinamides, were synthesized and successfully employed for the enantioselective direct aldol reaction of aldehydes with ketones. These catalysts proved to be effective in promoting the rea
- Naresh, Tumma,Kumar, Togapur Pavan,Haribabu, Kothapalli,Chandrasekhar, Srivari
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p. 1340 - 1345
(2015/01/09)
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- Synthesis of Zirconium Phosphonate Supported L -Proline as an Effective Organocatalyst for Direct Asymmetric Aldol Addition
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Stable L-proline-functionalized zirconium methyl- and/or phenylphosphonates have been prepared as amorphous solids by the precipitation of (4R)-4-[(4′-phosphonobenzyl)oxy]-L-proline and methyl- and/or phenylphosphonic acid with ZrOCl2. The supp
- Angeloni, Marco,Piermatti, Oriana,Pizzo, Ferdinando,Vaccaro, Luigi
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p. 1716 - 1726
(2015/10/05)
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- Catalytic microwave-promoted direct aldol condensation using resin-bound secondary amine
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A series of polystyrene-supported imino group-bearing catalysts were prepared. A highly efficient combination of recyclable catalysts and microwave irradiation was developed as a green protocol for the direct aldol reaction. Notably, microwaves greatly shorten the reaction times to only 20 min and improve the yield significantly. Catalyst loading was reduced as well. Different aromatic aldehydes as aldol donors were subjected to our catalyst system and afforded the corresponding products in satisfactory yields. Additionally, the polymer-supported catalysts could be recovered by simple filtration and were reusable for at least four times without significant loss of reactivity. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications for the following free supplemental resource(s): Full experimental and spectral details.]
- Liao, Fu Xu,Wang, Yu Guang,Zhu, Qing
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supporting information
p. 161 - 169
(2013/12/04)
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- Alkaline earth metal-based metal-organic framework: Hydrothermal synthesis, X-ray structure and heterogeneously catalyzed Claisen-Schmidt reaction
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Two alkaline earth metal-based carboxylate systems, [Mg(HL)(H 2O)2]n (1) and [Ca(H2L) 2]n (2) (H3L = chelidamic acid) have been hydrothermally synthesized, and characterized by single-crystal X-ray diffraction, IR, elemental analysis, and thermo-gravimetric analysis. Compound 1 has a 2D structure incorporating two water molecules. The dehydrated species, 1a, generated from 1 by removal of the coordinated water, has been characterized by thermo-gravimetric analysis, IR, elemental analysis and variable temperature powder X-ray diffraction. Both 1 and its dehydrated species 1a catalyze the Claisen-Schmidt reaction under heterogeneous conditions, but 1a is a more effective catalyst under environmentally friendly conditions. The catalyst can readily be recovered and reused in successive cycles without detectable loss of activity. Compound 2 has a 3D structure and is thermally stable up to 540 °C, but is inactive catalytically. This journal is the Partner Organisations 2014.
- Saha, Debraj,Maity, Tanmoy,Koner, Subratanath
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p. 13006 - 13017
(2014/08/18)
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- One-pot synthesis of spirooxazino derivatives via enzyme- Initiated multicomponent reactions
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A novel enzyme-initiated multicomponent reaction from readily available aldehyde, nitrostyrene, cyclohexanone and acetamide substrates was discovered, enabling the facile construction of six new C-C/-N bonds and two rings in single step, one-pot operation, for the synthesis of spirooxazino derivatives in moderate to high yields. Several methods such as isotope labelling and enzyme mutation were used to probe the possible mechanism of this complex synthesis.
- Wang, Jun-Liang,Chen, Xiao-Yang,Wu, Qi,Lin, Xian-Fu
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p. 999 - 1005
(2014/04/03)
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- "Click" post-synthetic modification of metal-organic frameworks for asymmetric aldol catalysis
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The reaction of dimethyl 5-(prop-2-ynyloxy)isophthalic acid, meso-alpha, and beta-di (4-pyridyl) glycol with ZnCl2 in a methanol aqueous solution affords MOF Zn-DPPG. The enantiomeric Zn-Fun1 and Zn-Fun2 were obtained through a strategy of in s
- Zhu, Wenting,He, Cheng,Wu, Xiao,Duan, Chunying
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- Catalytic anions embedded into avidin: Importance of their chirality and the chiral environment on the stereocontrol of the aldol reaction
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Several catalytic anions bearing a pseudo-dipeptide scaffold, in combination with a biotinylated imidazolium cation, were prepared. The assembly of these salts with avidin resulted in the formation of stable biohybrid catalysts, active in ionic liquid/aqueous media for the aldol reaction. By using natural and non-natural amino alcohols as "side chains" for the proline derivative anion, we studied the cooperativity between the anion and its position in avidin. Taking advantage of the large freedom of movement of the anion inside avidin, we also investigated the substrate scope of this type of biohybrid catalyst.
- Gauchot, Vincent,Schmitzer, Andreea R.
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p. 2694 - 2701
(2014/04/17)
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- Benzo[ d ]imidazole and aliphatic α-amino acid derived primary amines in asymmetric aldol reactions
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Starting from essential α-amino acids, four new benzo[d]imidazole and alkyl-chain-substituted primary amines were synthesized. The reaction sequence involves activation of the Boc-amino acid carboxylic acid, reaction with o-phenylenediamine, and subsequen
- Mohite, Pravinkumar Hansraj,Drabina, Pavel,Bure?, Filip
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p. 491 - 494
(2014/03/21)
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