- Mapping the Surface Groups of Amine-Rich Carbon Dots Enables Covalent Catalysis in Aqueous Media
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Carbon nanodots stand as the missing link between the molecular and the nanoscale world, owing to the unique molecular-like behavior emerging from their synthetic precursors. A converging set of analytical and spectroscopic data yields a precise inventory
- Amato, Francesco,Bonchio, Marcella,Companyó, Xavier,Dell'Amico, Luca,Filippini, Giacomo,Prato, Maurizio,Ragazzon, Giulio,Rosso, Cristian,Vega-Pe?aloza, Alberto
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supporting information
p. 3022 - 3037
(2020/11/03)
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- Re-Engineering Organocatalysts for Asymmetric Friedel-Crafts Alkylation of Indoles through Computational Studies
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The discovery of efficient organocatalysts is generally carried out by thorough experimental screening of different candidates. We recently reported an efficient organocatalyst for iminium-ion-based asymmetric Diels-Alder reactions following a rational design approach. This result encouraged us to test this optimal catalyst in the mechanistically related Friedel-Crafts alkylation of indoles, but to our surprise, almost null enantioselectivity was observed. The results did not significantly improve with structurally related catalysts, and a totally unexpected facial selectivity inversion was also noticed. Using DFT calculations by modeling the competing transition structures with ONIOM, we could unravel the origins of those findings, further employed to predict the most efficient catalyst for this new transformation. The computational results were validated experimentally (up to 92:8 er), providing another successful example of a general strategy to accelerate catalyst development which still remains underexplored.
- Gerosa, Gabriela G.,Marcarino, Maribel O.,Spanevello, Rolando A.,Suárez, Alejandra G.,Sarotti, Ariel M.
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p. 9969 - 9978
(2020/09/03)
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- Alkyne Hydroheteroarylation: Enantioselective Coupling of Indoles and Alkynes via Rh-Hydride Catalysis
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We report an enantioselective coupling between alkynes and indoles. A Rh-hydride catalyst isomerizes alkynes to generate a metal-allyl species that can be trapped with both aromatic and heteroaromatic nucleophiles.
- Cruz, Faben A.,Zhu, Yamin,Tercenio, Quentin D.,Shen, Zengming,Dong, Vy M.
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p. 10641 - 10644
(2017/08/15)
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- Polystyrene or Magnetic Nanoparticles as Support in Enantioselective Organocatalysis? A Case Study in Friedel-Crafts Chemistry
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Heterogenized versions of the second-generation MacMillan imidazolidin-4-one are described for the first time. This versatile organocatalyst has been supported on 1% DVB Merrifield resin and Fe3O4 magnetic nanoparticles through a copper-catalyzed alkyne-azide cycloaddition (CuAAC) reaction. The resulting catalytic materials have been successfully applied to the asymmetric Friedel-Crafts alkylation of indoles with α,β-unsaturated aldehydes. While both catalytic systems can be easily recovered and admit repeated recycling, the polystyrene-based catalyst shows higher stability and provides better stereoselectivities.
- Ranjbar, Sara,Riente, Paola,Rodríguez-Escrich, Carles,Yadav, Jagjit,Ramineni, Kishore,Pericàs, Miquel A.
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supporting information
p. 1602 - 1605
(2016/05/02)
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- Hydrogen-bond-mediated supramolecular iminium ion catalysis
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Mod squad: Multiple small molecules appear to spontaneously self-assemble to form supramolecular amine catalysts that have high reactivity, good efficiency, and enhanced turnover numbers. These modular organocatalysts should be applicable to many iminium as well as hydrogen-bond catalytic reactions and provide new insights into asymmetric catalysis. Copyright
- Wang, Yao,Yu, Tian-Yang,Zhang, Hong-Bo,Luo, Yong-Chun,Xu, Peng-Fei
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supporting information
p. 12339 - 12342
(2013/02/23)
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- Highly stereoselective imidazolethiones mediated Friedel-Crafts alkylation of indole derivatives
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The asymmetric Friedel-Crafts alkylation of indoles with α,β-unsaturated aldehydes was promoted by the novel imidazolethiones to afford the corresponding adducts in moderate to excellent yields and high enantioselectivities under mild reaction conditions.
- Liang, Xianrui,Li, Shuangmin,Su, Weike
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supporting information; experimental part
p. 289 - 291
(2012/01/31)
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- Autocatalysis and organocatalysis with synthetic structures
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The discovery of ribozymes led to the proposal of an RNA world, where a single type of molecule was supposedly capable of selfreplication and chemical catalysis. We show here that both autocatalysis and organocatalysis can be engineered into a synthetic structure. The compound is shown to selectively accelerate its own formation and catalyze either hydrogenation or nucleophilic addition to α,β-unsaturated aldehydes. The observed reactivity indicates that the components of a purported pre-RNA world conceivably include smaller organic molecules. imidazolidinone catalysis self-replication template effects.
- Kamioka, Seiji,Ajami, Dariush,Rebek Jr., Julius
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experimental part
p. 541 - 544
(2010/09/16)
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- Enantioselective friedel-crafts alkylation of indoles with aromatic αβ-unsaturated aldehydes catalyzed by diphenylprolinol silyl Ether
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A catalytic enantioselective Friedel-Crafts alkylation of indoles with aromatic α,β-unsaturated aldehydes has been developed. The process is promoted by (S)-diphenylprolinol trimethyl silyl ether to afford, after sodium borohydride mediated reduction, 3in
- Wang, Zhi-Jing,Yang, Jian-Guo,Jin, Jun,Lv, Xin,Bao, Weiliang
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scheme or table
p. 3994 - 4000
(2010/03/24)
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- Aziridin-2-yl methanols as organocatalysts in Diels-Alder reactions and Friedel-Crafts alkylations of N-methyl-pyrrole and N-methyl-indole
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A series of enantiomerically pure aziridin-2-yl methanols have been synthesized from aziridine-2-carboxylic esters and have been tested as organocatalysts in Diels-Alder reactions and Friedel-Crafts alkylations of N-methyl-pyrrole and N-methyl-indole usin
- Bonini, Bianca F.,Capito, Elena,Comes-Franchini, Mauro,Fochi, Mariafrancesca,Ricci, Alfredo,Zwanenburg, Binne
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p. 3135 - 3143
(2007/10/03)
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- Controllable Enantioselective Friedel-Crafts Reaction between Indoles and Alkylidene Malonates Catalyzed by Pseudo-C3-Symmetric Trisoxazoline Copper(II) Complexes
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Pseudo-C3-symmetric trisoxazoline copper(II) complexes prove to be excellent catalysts in the Friedel-Crafts alkylation of indoles with alkylidene malonates. The absolute stereochemistry of this reaction is shown to be dependent on the solvent.
- Zhou, Jian,Ye, Meng-Chun,Huang, Zheng-Zheng,Tang, Yong
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p. 1309 - 1320
(2007/10/03)
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- Sidearm effect: Improvement of the enantiomeric excess in the asymmetric Michael addition of indoles to alkylidene malonates
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A pseudo-C3-trisoxazoline was designed and synthesized. The improvement of the traditional bisoxazoline into a novel trisoxazoline by a sidearm approach resulted in highly catalytic enantioselective Michael addition of indoles to alkylidene mal
- Zhou, Jian,Tang, Yong
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p. 9030 - 9031
(2007/10/03)
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- Enantioselective organocatalytic indole alkylations. Design of a new and highly effective chiral amine for iminium catalysis
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The indole framework has become widely identified as a "privileged" structure with representation in over 3000 natural isolates and 40 medicinal agents of diverse therapeutic action. A new strategy for asymmetric access to this important pharmacaphore has
- Austin, Joel F.,MacMillan, David W. C.
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p. 1172 - 1173
(2007/10/03)
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