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Journal articles on the topic 'Symmetric/Asymmetric Catalysis'

Author: Grafiati

Published: 7 September 2023

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1

Wang, Xiao-Chen, Zhao-Ying Yang, and Ming Zhang. "Synthesis and Applications of Chiral Bicyclic Bisborane Catalysts." Synthesis 54, no. 06 (November 19, 2021): 1527–36. http://dx.doi.org/10.1055/a-1701-7679.

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AbstractThe development of chiral borane Lewis acid catalysts opened the door for transition-metal-free catalyzed asymmetric organic reactions. Herein, we have summarized our work on the preparation of two classes of novel chiral bicyclic bisborane Lewis acid catalysts derived from C 2-symmetric [3.3.0] dienes and [4.4] dienes, respectively. These catalysts not only form frustrated Lewis pairs with Lewis bases to catalyze asymmetric hydrogenation reactions but also activate Lewis basic functional groups in traditional Lewis acid catalyzed asymmetric reactions.1 Introduction2 Synthesis of C 2-Symmetric Fused Bicyclic Bisborane Catalysts and Their Use in Imine Hydrogenation3 Synthesis of Spiro Bicyclic Bisborane Catalysts and Their Use in N-Heteroarene Reduction4 Other Types of Asymmetric Reactions Promoted by Chiral Bicyclic Bisborane Catalysts5 Conclusion

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2

Desimoni, Giovanni, Giuseppe Faita, and Karl Anker Jørgensen. "C2-Symmetric Chiral Bis(Oxazoline) Ligands in Asymmetric Catalysis." Chemical Reviews 106, no. 9 (September 2006): 3561–651. http://dx.doi.org/10.1021/cr0505324.

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3

Henderson, Alexander S., John F. Bower, and M. Carmen Galan. "Carbohydrate-based N-heterocyclic carbenes for enantioselective catalysis." Org. Biomol. Chem. 12, no. 45 (2014): 9180–83. http://dx.doi.org/10.1039/c4ob02056a.

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Versatile syntheses of C2-linked and C₂-symmetric carbohydrate-based NHC·HCls from functionalised amino-carbohydrate derivatives are reported. The corresponding Rh complexes were evaluated in asymmetric hydrosilylation of ketones.

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4

Litwinienko, Grzegorz, Gino A. DiLabio, and K. U. Ingold. "A theoretical and experimental investigation of some unusual intermolecular hydrogen-bond IR bands — Appearances can be deceptive." Canadian Journal of Chemistry 84, no. 10 (October 1, 2006): 1371–79. http://dx.doi.org/10.1139/v06-097.

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The IR spectra of the O-H stretch for hydrogen bonds (HBs) arising from complex formation between the HB donor (HBD), 4-fluorophenol, and the HB acceptors, peroxides and ethers, frequently show asymmetry that appears to arise from two incompletely resolved bands from two different complexes, but the O-H HB bands with the HBD methanol are symmetric (M. Berthelot, F. Bessau, and C. Laurence. Eur. J. Org. Chem. 925 (1998)). The present studies show that this difference in O-H HB band shapes also is true for other phenols and alcohols. However with ethylene oxide, 4-fluorophenol gives an almost symmetric O-H HB band with a very broad maximum, while alcohols give symmetric O-H HB bands with well-defined maxima. It is shown by experiment that the unusual O-H HB band shapes for the phenols are not due to Fermi resonance and are unrelated to the enthalpies of HB complex formation. Theoretical exploration of the potential energy (PE) surfaces for complexes of 4-fluorophenol and methanol with tert-butyl methyl ether and ethylene oxide reveals that O-H HB band asymmetry or broadness cannot be ascribed to the presence of two different HB complexes. For this ether, the PE surfaces for rotation about the HB and for up-and-down motion of the HBD with respect to the COC plane of the ether are relatively symmetric for methanol, but are strongly asymmetric for 4-fluorophenol, hence the differences in the O-H HB band shapes. The PE surfaces for the epoxide are effectively symmetric, but the PE for rotation about the HB has a single broad minimum for methanol, whereas with 4-fluorophenol there are two minima owing to attractive interactions between the phenyl group and the CH2 groups of the epoxide. The previously unknown β2H values for ethylene oxide and tetramethylethylene oxide are 0.36 and 0.58, respectively.Key words: asymmetric IR O-H bands, asymmetric potential energy surfaces, hydrogen-bonded complexes, hydrogen bond enthalpy, O-H frequency shift.

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5

Ruppel, Joshua V., Xin Cui, Xue Xu, and X. Peter Zhang. "Stereoselective intramolecular cyclopropanation of α-diazoacetates via Co(ii)-based metalloradical catalysis." Org. Chem. Front. 1, no. 5 (2014): 515–20. http://dx.doi.org/10.1039/c4qo00041b.

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6

Costabile, Chiara, Stefania Pragliola, and Fabia Grisi. "C2-Symmetric N-Heterocyclic Carbenes in Asymmetric Transition-Metal Catalysis." Symmetry 14, no. 8 (August 5, 2022): 1615. http://dx.doi.org/10.3390/sym14081615.

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The last decades have witnessed a rapid growth of applications of N-heterocyclic carbenes (NHCs) in different chemistry fields. Due to their unique steric and electronic properties, NHCs have become a powerful tool in coordination chemistry, allowing the preparation of stable metal-ligand frameworks with both main group metals and transition metals. An overview on the use of five membered monodentate C2-symmetric N-heterocyclic carbenes (NHCs) as ligands for transition-metal complexes and their most relevant applications in asymmetric catalysis is offered.

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7

Castillón, Sergio, Carmen Claver, and Yolanda Díaz. "C1 and C2-symmetric carbohydrate phosphorus ligands in asymmetric catalysis." Chemical Society Reviews 34, no. 8 (2005): 702. http://dx.doi.org/10.1039/b400361f.

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8

Vogl, Erasmus M., Shigeki Matsunaga, Motomu Kanai, Takehiko Iida, and Masakatsu Shibasaki. "Linking BINOL: C2-symmetric ligands for investigations on asymmetric catalysis." Tetrahedron Letters 39, no. 43 (October 1998): 7917–20. http://dx.doi.org/10.1016/s0040-4039(98)01756-0.

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9

Al-Majid, Abdullah M., Brian L. Booth, and Jonnes T. Gomes. "C2-Symmetric Ligands for Asymmetric Catalysis based on Feist's Acid." Journal of Chemical Research, no. 2 (1998): 78–79. http://dx.doi.org/10.1039/a706185d.

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10

van Slagmaat, Christian A. M. R., Khi Chhay Chou, Lukas Morick, Darya Hadavi, Burgert Blom, and Stefaan M. A. De Wildeman. "Synthesis and Catalytic Application of Knölker-Type Iron Complexes with a Novel Asymmetric Cyclopentadienone Ligand Design." Catalysts 9, no. 10 (September 22, 2019): 790. http://dx.doi.org/10.3390/catal9100790.

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Asymmetric catalysis is an essential tool in modern chemistry, but increasing environmental concerns demand the development of new catalysts based on cheap, abundant, and less toxic iron. As a result, Knölker-type catalysts have emerged as a promising class of iron catalysts for various chemical transformations, notably the hydrogenation of carbonyls and imines, while asymmetric versions are still under exploration to achieve optimal enantio-selectivities. In this work, we report a novel asymmetric design of a Knölker-type catalyst, in which the C2-rotational symmetric cyclopentadienone ligand possesses chiral substituents on the 2- and 5-positions near the active site. Four examples of the highly modular catalyst design were synthesized via standard organic procedures, and their structures were confirmed with NMR, IR, MS, and polarimetry analysis. Density functional theory (DFT) calculations were conducted to elucidate the spatial conformation of the catalysts, and therewith to rationalize the influence of structural alterations. Transfer- and H2-mediated hydrogenations were successfully established, leading to appreciable enantiomeric excesses (ee) values up to 70%. Amongst all reported Knölker-type catalysts, our catalyst design achieves one of the highest ee values for hydrogenation of acetophenone and related compounds.

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11

Lemmens, Lenne J. M., Job A. L. Roodhuizen, Tom F. A. Greef, Albert J. Markvoort, and Luc Brunsveld. "Designed Asymmetric Protein Assembly on a Symmetric Scaffold." Angewandte Chemie International Edition 59, no. 29 (May 18, 2020): 12113–21. http://dx.doi.org/10.1002/anie.202003626.

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12

Desimoni, Giovanni, Giuseppe Faita, and Karl Anker Jørgensen. "Update 1 of:C2-Symmetric Chiral Bis(oxazoline) Ligands in Asymmetric Catalysis." Chemical Reviews 111, no. 11 (November 9, 2011): PR284—PR437. http://dx.doi.org/10.1021/cr100339a.

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13

Genet, Jean Pierre, Angela Marinetti, and Virginie Ratovelomanana-Vidal. "Recent advances in asymmetric catalysis. Synthetic applications to biologically active compounds." Pure and Applied Chemistry 73, no. 2 (January 1, 2001): 299–303. http://dx.doi.org/10.1351/pac200173020299.

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New chiral cationic ruthenium complexes have been used for the industrial synthesis of (+) -dihydrojasmonate. A new class of electron-rich C2-symmetric 2,4-disubstituted phosphetanes (CnrPHOS) was developed. Preliminary evaluation of their catalytic properties revealed high efficiency in rhodium and ruthenium-catalyzed asymmetric hydrogenations. A new stereochemical model is presented in which the phosphetane Rh-catalyzed hydrogenation follows an apparent stability-controlled mechanism.

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14

Chelucci, Giorgio. "New chiral C2-symmetric bis(oxazolinylpyridinyl)dioxolane ligands for asymmetric catalysis: palladium catalysed allylic substitution." Tetrahedron: Asymmetry 8, no. 16 (August 1997): 2667–70. http://dx.doi.org/10.1016/s0957-4166(97)00318-2.

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15

Pedersen, Stephan K., Kristina Eriksen, and Michael Pittelkow. "Symmetric, Unsymmetrical, and Asymmetric [7]‐, [10]‐, and [13]Helicenes." Angewandte Chemie International Edition 58, no. 51 (November 6, 2019): 18419–23. http://dx.doi.org/10.1002/anie.201910214.

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16

Kumari, Beena, Surya Pratap Singh, Ranga Santosh, Arnab Dutta, Sairam S. Mallajosyula, Subhas Ghosal, and Sriram Kanvah. "Branching effect on triphenylamine-CF3 cyanostilbenes: enhanced emission and aggregation in water." New Journal of Chemistry 43, no. 10 (2019): 4106–15. http://dx.doi.org/10.1039/c8nj05907a.

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17

Snider, Barry B., James F. Grabowski, Roger W. Alder, Bruce M. Foxman, and Lin Yang. "Synthesis of a hindered C2-symmetric hydrazine and diamine by a crisscross cycloaddition of citronellal azine." Canadian Journal of Chemistry 84, no. 10 (October 1, 2006): 1242–49. http://dx.doi.org/10.1139/v06-084.

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Crisscross cycloaddition of citronellal azine (6) with 2 equiv. of TFA and powdered 3 Å molecular sieves in CH2Cl2 at reflux for 22 h afforded 37% of the desired C2-symmetric hydrazine 7 and 5%–10% of diastereomer 8 in which one of the 6–5 ring fusions is cis. Methylation of the hydrazine of 7 and reduction of the resulting salt (9) with Li in NH3 cleaved the N—N bond to give secondary tertiary amine 10 in 97% yield. Eschweiler–Clarke methylation afforded the C2-symmetric bis tertiary amine 11 in 69% yield. Racemic products were obtained in initial attempts at asymmetric catalysis using 7 or 11 as asymmetric bases, using bistertiary amine 11 as a ligand analogous to sparteine for alkyllithiums, or using the lithium amide from secondary tertiary amine 10 as an asymmetric base. Apparently, the proton is buried in the core of 11, leaving a hydrophobic surface; the free counterion is not an asymmetric catalyst. Diamine 11 may be too hindered to complex to s-BuLi. Tertiary amine 11 (pKa1 = 24.7) is more basic than DBU (pKa = 24.3) in CH3CN, in good agreement with theory.Key words: crisscross cycloaddition, azine, dipolar cycloaddition, calculation of pKa.

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18

Berkessel, Albrecht, Michael Schröder, Christoph A. Sklorz, Stefania Tabanella, Nadine Vogl, Johann Lex, and Jörg M. Neudörfl. "Enantioselective Synthesis of DIANANE, a NovelC2-Symmetric Chiral Diamine for Asymmetric Catalysis†." Journal of Organic Chemistry 69, no. 9 (April 2004): 3050–56. http://dx.doi.org/10.1021/jo035841d.

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19

Reetz, Manfred T., and Andreas Gosberg. "New non-C2-symmetric phosphine-phosphonites as ligands in asymmetric metal catalysis." Tetrahedron: Asymmetry 10, no. 11 (June 1999): 2129–37. http://dx.doi.org/10.1016/s0957-4166(99)00215-3.

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20

Powell, Mark T., Alexander M. Porte, and Kevin Burgess. "On the efficacy of propeller-shaped, C3-symmetric triarylphosphines in asymmetric catalysis." Chemical Communications, no. 19 (1998): 2161–62. http://dx.doi.org/10.1039/a806811i.

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21

VOGL, E. M., S. MATSUNAGA, M. KANAI, T. IIDA, and M. SHIBASAKI. "ChemInform Abstract: Linking BINOL: C2-Symmetric Ligands for Investigations on Asymmetric Catalysis." ChemInform 30, no. 1 (June 18, 2010): no. http://dx.doi.org/10.1002/chin.199901046.

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22

Laufer, Radoslaw, Ulrich Veith, Nicholas J. Taylor, and Victor Snieckus. "(–)-Sparteine-mediated stereoselective directed ortho metalation of ferrocene diamides." Canadian Journal of Chemistry 84, no. 2 (February 1, 2006): 356–69. http://dx.doi.org/10.1139/v06-008.

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The utility of (–)-sparteine-mediated directed ortho metalation (DoM) has been investigated in stereoselective preparation of planar chiral ferrocenes derived from 1,1′-N,N,N′,N′-tetraisopropylferrocenedicarboxamide (5). In the synthesis of C2-symmetric analogs of 5, the protocol (base, solvent, and two-step DoM) was found to be crucial for obtaining high enantio- and diastereo-selectivities of the products. A variety of highly enantioenriched mono and doubly functionalized derivatives of 5 have been synthesized. The synthetic applications of these compounds as chiral ligands in asymmetric alkylation of aldehydes and asymmetric palladium-catalyzed allylic substitutions have been demonstrated.Key words: directed ortho metalation, stereoselective deprotonation, ferrocene ligands, asymmetric catalysis.

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23

Pfaltz, Andreas, Hans Adolfsson, Kenneth Wärnmark, Kari Aasbø, Martti Klinga, and Antonio Romerosa. "Design of Chiral Ligands for Asymmetric Catalysis: from C2-Symmetric Semicorrins and Bisoxazolines to Non-Symmetric Phosphinooxazolines." Acta Chemica Scandinavica 50 (1996): 189–94. http://dx.doi.org/10.3891/acta.chem.scand.50-0189.

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24

Narine, Arun A., and Peter D. Wilson. "Synthesis and evaluation of 7-hydroxyindan-1-one-derived chiral auxiliaries." Canadian Journal of Chemistry 83, no. 5 (May 1, 2005): 413–19. http://dx.doi.org/10.1139/v05-052.

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A series of novel chiral acetals were prepared from 7-hydroxyindan-1-one and a variety of substituted chiral nonracemic C2-symmetric 1,2-ethanediols (R = Me, Ph, CH2OMe, CH2OBn, CH2O(1-Np), and i-Pr). These acetals were evaluated as chiral auxiliaries for use in asymmetric synthesis. A high degree of stereochemical induction was observed in the diethylaluminum chloride-promoted DielsAlder reaction of an acrylate derivative (R = i-Pr) with cyclopentadiene (91:9 dr). This demonstrated that these acetals could serve as effective chiral directors in asymmetric substrate-directed reactions.Key words: 7-hydroxyindan-1-one, chiral nonracemic C2-symmetric 1,2-diols, acetals, chiral auxiliaries, DielsAlder reaction.

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25

Ohshima, Takashi, Takahito Kawabata, Yosuke Takeuchi, Takahiro Kakinuma, Takanori Iwasaki, Takayuki Yonezawa, Hajime Murakami, Hisao Nishiyama, and Kazushi Mashima. "C1-Symmetric Rh/Phebox-Catalyzed Asymmetric Alkynylation of α-Ketoesters." Angewandte Chemie International Edition 50, no. 28 (May 30, 2011): 6296–300. http://dx.doi.org/10.1002/anie.201100252.

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26

Kisszékelyi, Péter, Zsuzsanna Fehér, Sándor Nagy, Péter Bagi, Petra Kozma, Zsófia Garádi, Miklós Dékány, Péter Huszthy, Béla Mátravölgyi, and József Kupai. "Synthesis of C3-Symmetric Cinchona-Based Organocatalysts and Their Applications in Asymmetric Michael and Friedel–Crafts Reactions." Symmetry 13, no. 3 (March 23, 2021): 521. http://dx.doi.org/10.3390/sym13030521.

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In this work, anchoring of cinchona derivatives to trifunctional cores (hub approach) was demonstrated to obtain size-enlarged organocatalysts. By modifying the cinchona skeleton in different positions, we prepared four C3-symmetric size-enlarged cinchona derivatives (hub-cinchonas), which were tested as organocatalysts and their catalytic activities were compared with the parent cinchona (hydroquinine) catalyst. We showed that in the hydroxyalkylation reaction of indole, hydroquinine provides good enantioselectivities (up to 73% ee), while the four new size-enlarged derivatives resulted in significantly lower values (up to 29% ee) in this reaction. Anchoring cinchonas to trifunctional cores was found to facilitate nanofiltration-supported catalyst recovery using the PolarClean alternative solvent. The C3-symmetric size-enlarged organocatalysts were completely rejected by all the applied membranes, whereas the separation of hydroquinine was found to be insufficient when using organic solvent nanofiltration. Furthermore, the asymmetric catalysis was successfully demonstrated in the case of the Michael reaction of 1,3-diketones and trans-β-nitrostyrene using Hub3-cinchona (up to 96% ee) as a result of the positive effect of the C3-symmetric structure using a bulkier substrate. This equates to an increased selectivity of the catalyst in comparison to hydroquinine in the latter Michael reaction.

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27

Guiry, Patrick, and Steven O’Reilly. "Recent Applications of C 1-Symmetric Bis(oxazoline)-Containing Ligands in Asymmetric Catalysis." Synthesis 46, no. 06 (February 19, 2014): 722–39. http://dx.doi.org/10.1055/s-0033-1340829.

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28

AL-MAJID, A. M., B. L. BOOTH, and J. T. GOMES. "ChemInform Abstract: C2-Symmetric Ligands for Asymmetric Catalysis Based on Feist′s Acid." ChemInform 30, no. 10 (June 17, 2010): no. http://dx.doi.org/10.1002/chin.199910081.

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29

Trost, Barry M., Zhengying Pan, Jorge Zambrano, and Christof Kujat. "Polymer-SupportedC2-Symmetric Ligands for Palladium-Catalyzed Asymmetric Allylic Alkylation Reactions." Angewandte Chemie International Edition 41, no. 24 (December 16, 2002): 4691–93. http://dx.doi.org/10.1002/anie.200290018.

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30

Bao, Changjiang, Yanwei Li, Yanhui Li, Zhenjun Si, Yanru Zhang, Changshun Chen, Lei Wang, and Qian Duan. "A series of asymmetric and symmetric porphyrin derivatives: one-pot synthesis, nonlinear optical and optical limiting properties." New Journal of Chemistry 45, no. 35 (2021): 16030–38. http://dx.doi.org/10.1039/d1nj02632a.

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In this work, a series of asymmetric and symmetric porphyrin derivatives (structure types: A4, A3B1, trans-A2B2, cis-A2B2, A1B3, and B4) have been synthesized via a one-pot method and characterized to identify their structures and properties.

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31

Greencorn, David J., Victoria M. Sandre, Emily K. Piggott, Michael R. Hillier, A. James Mitchell, Taryn M. Reid, Michael J. McAlduff, Kulbir Singh, and D. Gerrard Marangoni. "Asymmetric cationic gemini surfactants: an improved synthetic procedure and the micellar and surface properties of a homologous series in the presence of simple salts." Canadian Journal of Chemistry 96, no. 7 (July 2018): 672–80. http://dx.doi.org/10.1139/cjc-2017-0676.

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The micellar and morphological properties of symmetric, cationic gemini surfactants have been well studied in the literature as a function of nature and type of the spacer group and the length and type of hydrophobic chain. In this paper, we have examined the effects of tail asymmetry on the properties of a series of cationic surfactants, the N-alkyl-1-N′-alkyl-2-N,N,N′,N′-tetramethyldiammonium dibromide. A novel synthetic method is used to prepare a series of these surfactants and the consequences of asymmetry on micellar properties are presented. This new method has been shown to be more efficient, with higher yields of the asymmetric surfactants than the yields of the accepted literature method. The critical micelle concentration values and the micelle sizes of the asymmetric gemini surfactants, 12-4-12, 12-4-10, 12-4-8, and 12-4-6 gemini surfactants, were obtained from conductivity and dynamic light scattering. With increasing chain asymmetry, the size of the micelle increased due to the formation of loose micelles. The addition of NaCl and Na2SO4 to the surfactant solutions increased the aggregate size, and this effect was more pronounced with increasing salt concentrations. These results are interpreted in terms of the effect these ions have on the “compactness” of the micelle structure.

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32

Karunaratne, Veranja, and David Dolphin. "Oxidation of 2-methylpyrroles with perchlorinated iron(III) metalloporphyrin catalysts: a versatile synthesis of symmetric and asymmetric dipyrromethanes." Canadian Journal of Chemistry 76, no. 10 (October 1, 1998): 1467–73. http://dx.doi.org/10.1139/v98-190.

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A variety of substituted 2-methylpyrroles (3-8) were oxidized using the metalloporphyrin catalysts iron(III) meso-tetra(2,6-dichloro-3-sulphonatophenyl)-β-octachloroporphyrin chloride 1 and iron(III) meso-tetra(2,6-dichlorophenyl)-β-octachloroporphyrin chloride 2 under very mild conditions. Treatment of the resulting allylic alcohols 3a-8a with α-free pyrroles 9 and 10 resulted in a very efficient synthesis of the corresponding dipyrromethanes 3b-8b and 3c-8c. Furthermore, the above allylic alcohols when treated with furfurylamine produced the novel (2-furylmethyl)-2-pyrrolylmethylamines 3d-8d.Key words: catalytic oxidation, metalloporphyrins, pyrroles, dipyrromethanes, polyhalogenated porphyrins.

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33

PFALTZ, A. "ChemInform Abstract: Design of Chiral Ligands for Asymmetric Catalysis: From C2-Symmetric Semicorrins and Bisoxazolines to Non-Symmetric Phosphinooxazolines." ChemInform 27, no. 29 (August 5, 2010): no. http://dx.doi.org/10.1002/chin.199629287.

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34

Aromí, Guillem, Paula Carrero Berzal, Patrick Gamez, Olivier Roubeau, Huub Kooijman, Anthony L. Spek, Willem L. Driessen, and Jan Reedijk. "A Unique Asymmetric [Mn] Triple-Stranded Helicate from a Symmetric Pentadentate Ligand." Angewandte Chemie International Edition 40, no. 18 (September 17, 2001): 3444–46. http://dx.doi.org/10.1002/1521-3773(20010917)40:18<3444::aid-anie3444>3.0.co;2-q.

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35

Kałuża, Zbigniew, Rafał Ćwiek, Mirosław Dygas, and Przemysław Kalicki. "Diamine Ligands for Asymmetric Catalysis: Facile Synthesis of C2-Symmetric Piperazines from Seebach’s Oxazolidinone." Synlett 25, no. 13 (July 8, 2014): 1883–87. http://dx.doi.org/10.1055/s-0034-1378341.

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36

Desimoni, Giovanni, Giuseppe Faita, and Karl Anker Joergensen. "ChemInform Abstract: Update 1 Of: C2-Symmetric Chiral Bis(oxazoline) Ligands in Asymmetric Catalysis." ChemInform 44, no. 52 (December 5, 2013): no. http://dx.doi.org/10.1002/chin.201352250.

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37

POWELL, M. T., A. M. PORTE, and K. BURGESS. "ChemInform Abstract: On the Efficacy of Propeller-Shaped, C3-Symmetric Triarylphosphines in Asymmetric Catalysis." ChemInform 30, no. 2 (June 18, 2010): no. http://dx.doi.org/10.1002/chin.199902114.

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38

Reetz, Manfred T., and Andreas Gosberg. "ChemInform Abstract: New Non-C2-Symmetric Phosphine-Phosphonites as Ligands in Asymmetric Metal Catalysis." ChemInform 30, no. 48 (June 12, 2010): no. http://dx.doi.org/10.1002/chin.199948039.

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39

Nakagawa, Hiroshi, Yoshihisa Sei, Kentaro Yamaguchi, Tetsuo Nagano, and Tsunehiko Higuchi. "Catalytic and asymmetric epoxidation by novel D4-symmetric chiral porphyrin derived from C2-symmetric diol." Journal of Molecular Catalysis A: Chemical 219, no. 2 (September 2004): 221–26. http://dx.doi.org/10.1016/j.molcata.2004.05.026.

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40

García-García, F. R., and K. Li. "New catalytic reactors prepared from symmetric and asymmetric ceramic hollow fibres." Applied Catalysis A: General 456 (April 2013): 1–10. http://dx.doi.org/10.1016/j.apcata.2013.01.031.

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41

León, Félix, Javier Francos, Joaquín López-Serrano, Sergio E. García-Garrido, Victorio Cadierno, and Antonio Pizzano. "Double asymmetric hydrogenation of conjugated dienes: a self-breeding chirality route for C2 symmetric 1,4-diols." Chemical Communications 55, no. 6 (2019): 786–89. http://dx.doi.org/10.1039/c8cc09391a.

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42

Yang, Gink N., Parinaz Ahangar, Xanthe L. Strudwick, Zlatko Kopecki, and Allison J. Cowin. "Overexpression of Flii during Murine Embryonic Development Increases Symmetrical Division of Epidermal Progenitor Cells." International Journal of Molecular Sciences 22, no. 15 (July 30, 2021): 8235. http://dx.doi.org/10.3390/ijms22158235.

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Epidermal progenitor cells divide symmetrically and asymmetrically to form stratified epidermis and hair follicles during late embryonic development. Flightless I (Flii), an actin remodelling protein, is implicated in Wnt/β-cat and integrin signalling pathways that govern cell division. This study investigated the effect of altering Flii on the divisional orientation of epidermal progenitor cells (EpSCs) in the basal layer during late murine embryonic development and early adolescence. The effect of altering Flii expression on asymmetric vs. symmetric division was assessed in vitro in adult human primary keratinocytes and in vivo at late embryonic development stages (E16, E17 and E19) as well as adolescence (P21 day-old) in mice with altered Flii expression (Flii knockdown: Flii+/−, wild type: WT, transgenic Flii overexpressing: FliiTg/Tg) using Western blot and immunohistochemistry. Flii+/− embryonic skin showed increased asymmetrical cell division of EpSCs with an increase in epidermal stratification and elevated talin, activated-Itgb1 and Par3 expression. FliiTg/Tg led to increased symmetrical cell division of EpSCs with increased cell proliferation rate, an elevated epidermal SOX9, Flap1 and β-cat expression, a thinner epidermis, but increased hair follicle number and depth. Flii promotes symmetric division of epidermal progenitor cells during murine embryonic development.

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Heinz, Benjamin, Moritz Balkenhohl, and Paul Knochel. "Thiolation of Pyridine-2-sulfonamides using Magnesium Thiolates." Synthesis 51, no. 23 (September 3, 2019): 4452–62. http://dx.doi.org/10.1055/s-0039-1690199.

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The thiolation of pyridine-2-sulfonamides using magnesium thiolates is reported. The ortho-functionalizations of these sulfonamides using TMPMgCl·LiCl (TMP = 2,2,6,6-tetramethylpiperidyl) followed by electrophilic quenching produced a range of 3-functionalized pyridine-2-sulfonamides, which were subsequently converted into the corresponding thioethers. Finally, symmetric or asymmetric diorganodisulfides were employed as electrophiles in a one-pot ortho-functionalization–thiolation procedure, leading to pyridine 2,3-disubstituted dithioethers.

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44

Wang, Zhi-Xian, Susie M. Miller, Oren P. Anderson, and Yian Shi. "ChemInform Abstract: A Class of C2 and Pseudo C2 Symmetric Ketone Catalysts for Asymmetric Epoxidation. Conformational Effect on Catalysis." ChemInform 31, no. 1 (June 12, 2010): no. http://dx.doi.org/10.1002/chin.200001128.

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Dube, Edith, Njemuwa Nwaji, John Mack, and Tebello Nyokong. "The photophysicochemical behavior of symmetric and asymmetric zinc phthalocyanines, surface assembled onto gold nanotriangles." New Journal of Chemistry 42, no. 17 (2018): 14290–99. http://dx.doi.org/10.1039/c8nj02746c.

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46

Eno, Meredith S., Alexander Lu, and James P. Morken. "Nickel-Catalyzed Asymmetric Kumada Cross-Coupling of Symmetric Cyclic Sulfates." Journal of the American Chemical Society 138, no. 25 (June 16, 2016): 7824–27. http://dx.doi.org/10.1021/jacs.6b03384.

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47

Wakchaure, Vijay N., and Benjamin List. "Catalytic Asymmetric Reductive Condensation of N-H Imines: Synthesis ofC2-Symmetric Secondary Amines." Angewandte Chemie International Edition 55, no. 51 (November 22, 2016): 15775–78. http://dx.doi.org/10.1002/anie.201608329.

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48

Gendrineau, Thomas, Olivier Chuzel, Hendrik Eijsberg, Jean-Pierre Genet, and Sylvain Darses. "C1-Symmetric Monosubstituted Chiral Diene Ligands in Asymmetric Rhodium-Catalyzed 1,4-Addition Reactions." Angewandte Chemie International Edition 47, no. 40 (September 22, 2008): 7669–72. http://dx.doi.org/10.1002/anie.200803230.

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Langner, Martin, and Carsten Bolm. "C1-Symmetric Sulfoximines as Ligands in Copper-Catalyzed Asymmetric Mukaiyama-Type Aldol Reactions." Angewandte Chemie International Edition 43, no. 44 (November 12, 2004): 5984–87. http://dx.doi.org/10.1002/anie.200460953.

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Morimoto, Yoshiki, Takamasa Kinoshita, and Toshiyuki Iwai. "Asymmetric total synthesis of highly symmetric squalene-derived cytotoxic polyethers." Chirality 14, no. 7 (2002): 578–86. http://dx.doi.org/10.1002/chir.10083.

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