- C60-catalyzed direct C-H arylation of benzene with aryl iodides in air
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C60 at 1 mol % loading catalyzed the direct C-H arylation of benzene with aryl iodides in air to yield biaryls. The in situ generation of electron-rich C60(OH)2-, from C60 and OH-, reduced the aryl iodides to aryl radicals for arylation of benzene. The large surface area and spherical shape of C60 facilitated this process.
- Kwok, Tsz Yiu,Sonnenschein, Christoph,To, Ching Tat,Liu, Jianwen,Chan, Kin Shing
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p. 2719 - 2724
(2016/05/19)
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- KOtBu: A Privileged Reagent for Electron Transfer Reactions?
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Many recent studies have used KOtBu in organic reactions that involve single electron transfer; in the literature, the electron transfer is proposed to occur either directly from the metal alkoxide or indirectly, following reaction of the alkoxide with a solvent or additive. These reaction classes include coupling reactions of halobenzenes and arenes, reductive cleavages of dithianes, and SRN1 reactions. Direct electron transfer would imply that alkali metal alkoxides are willing partners in these electron transfer reactions, but the literature reports provide little or no experimental evidence for this. This paper examines each of these classes of reaction in turn, and contests the roles proposed for KOtBu; instead, it provides new mechanistic information that in each case supports the in situ formation of organic electron donors. We go on to show that direct electron transfer from KOtBu can however occur in appropriate cases, where the electron acceptor has a reduction potential near the oxidation potential of KOtBu, and the example that we use is CBr4. In this case, computational results support electrochemical data in backing a direct electron transfer reaction.
- Barham, Joshua P.,Coulthard, Graeme,Emery, Katie J.,Doni, Eswararao,Cumine, Florimond,Nocera, Giuseppe,John, Matthew P.,Berlouis, Leonard E. A.,McGuire, Thomas,Tuttle, Tell,Murphy, John A.
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supporting information
p. 7402 - 7410
(2016/07/06)
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- Multi SO3H supported on carbon nanotubes: A practical, reusable, and regioselective catalysts for the tert-butylation of p-cresol under solvent-free conditions
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The present study describes the synthesis, characterization, and catalytic activity of sulfonated multi-walled carbon nanotubes and sulfonated single-walled carbon nanotubes in the tert-butylation of p-cresol. The catalysts were prepared using a chemical and simple process and it characterized by scanning electron microscopy, Fourier transform infrared, and Raman spectroscopy, thermogravimetric analysis, and acid-base titration. The sulfonated multi-walled carbon nanotubes and sulfonated single-walled carbon nanotubes have been used as practical heterogeneous catalytic systems in the tert-butylation of p-cresol under solvent-free conditions. Sulfonated multi-walled carbon nanotubes with the highest total density of SO3H groups possessed high activity for p-cresol conversion and high selectivity than the sulfonated single-walled carbon nanotubes. This methodology offers some advantages of high selectivity, and high yields, easy work-up, solvent-free conditions, and reusable catalyst. Moreover, the catalytic system was used in scale-up under similar optimized reaction conditions.
- Fareghi-Alamdari, Reza,Golestanzadeh, Mohsen,Zekri, Negar,Mavedatpoor, Zeinab
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p. 537 - 549
(2015/03/05)
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- Aromatic fluoro-de-triazenation with boron trifluoride diethyl etherate under non-protic acid conditions
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Fluoro-de-triazenation of 3,3-diethyl-1-aryltriazenes can be achieved by conventional or under microwave heating in carbon tetrachloride, in the presence of boron trifluoride diethyl etherate without any protic acid to avoid corresponding unwanted byproduct formation.
- Kovac, Mitja,Anderluh, Marko,Vercouillie, Johnny,Guilloteau, Denis,Emond, Patrick,Mavel, Sylvie
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- Free porphyrin catalyzed direct C-H arylation of benzene with aryl halides
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A general procedure for free porphyrin catalyzed direct C-H arylation of benzene was demonstrated. This air tolerant, transition-metal-free process provides a promising system for cheap and efficient synthesis of biaryls in a user-friendly approach.
- Ng, Yeuk Sze,Chan, Chung Sum,Chan, Kin Shing
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supporting information; experimental part
p. 3911 - 3914
(2012/08/28)
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- Mizoroki-heck-type reaction mediated by potassium tert-butoxide
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In the absence of transition-metal catalysts, a Mizoroki-Heck-type reaction proceeded to give stilbene derivatives in a simple manner using an aryl halide, a styrene derivative, KOtBu, EtOH, and DMF (see scheme; DMF=N,N- dimethylformamide).
- Shirakawa, Eiji,Zhang, Xuejing,Hayashi, Tamio
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supporting information; experimental part
p. 4671 - 4674
(2011/06/27)
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- Practical synthesis of enantiomerically pure β2-amino acids via proline-catalyzed diastereoselective aminomethylation of aldehydes
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Proline-catalyzed diastereoselective aminomethylation of aldehydes using a chiral iminium ion, generated from a readily prepared precursor, provides α-substituted-β-amino aldehydes with 85:15 to 90: 10 dr. The α-substituted-β-amino aldehydes can be reduce
- Chi, Yonggui,English, Emily P.,Pomerantz, William C.,Horne, W. Seth,Joyce, Leo A.,Alexander, Lane R.,Fleming, William S.,Hopkins, Elizabeth A.,Gellman, Samuel H.
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p. 6050 - 6055
(2008/02/08)
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- CONCISE BETA2-AMINO ACID SYNTHESIS VIA ORGANOCATALYTIC AMINOMETHYLATION
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The present invention provides a method for the synthesis of ?2-amino acids. The method also provides methods yielding a-substituted ?-amino aldehydes and ?-substituted γ-amino alcohols. The present method according to this invention allows for increased yield and easier purification using minimal chromatography or crystallization. The methods described herein are based on an aldehyde aminomethylation which involves a Mannich reaction between an aldehyde and a formaldehyde-derived N,O-acetal (iminium precursor) and a catalyst, such as, for example, L-proline or a pyrrolidine. The invention allows for large scale, commercial preparation of ?2-amino acids.
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Page/Page column 55-56
(2010/11/28)
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- Protection of phenols as t-butyl ethers under mild conditions
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Zinc mediated selective O-y-butylation of phenols has been carried out in good to excellent yields under mild conditions. No trace of C-t-butylation was observed.
- Bandgar,Kasture
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p. 252 - 253
(2007/10/03)
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