- Bromination of aromatic compounds using an Fe2O 3/zeolite catalyst
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The catalytic bromination of non-activated aromatic compounds has been achieved using an Fe2O3/zeolite catalyst system. FeBr 3 was identified as the catalytic species, formed in situ from HBr and Fe2O3. The catalyst was easy-to-handle and cost effective and could also be recycled. The reaction system was also amenable to the one-pot sequential bromination/C-C bond formation of benzene.
- Nishina, Yuta,Takami, Keishi
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supporting information
p. 2380 - 2383
(2013/02/21)
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- Halodeboronation of organotrifluoroborates using tetrabutylammonium tribromide or cesium triiodide
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Halodeboronation of organotrifluoroborates using commercially available tetrabutylammonium tribromide (TBATB) or cesium triiodide in aqueous medium is reported. The mild, transition metal-free method has proven to be tolerant of a wide range of functional groups. High regio- and chemoselectivity are observed. Two synthetic routes to (Z)-dibromoalkenes from alkynes, through stereodefined (Z)-2-bromoalkenyltrifluoroborates and (Z)-1,2-bis(boryl) alkenyltrifluoroborates, have been developed using the TBATB mediated bromodeboronation as the key step.
- Yao, Min-Liang,Kabalka, George W.,Blevins, David W.,Reddy, Marepally Srinivasa,Yong, Li
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experimental part
p. 3738 - 3743
(2012/06/30)
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- Chemoselective bromodeboronation of organotrifluoroborates using tetrabutylammonium tribromide: Application in (Z)-dibromoalkene syntheses
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(Chemical Equation Presented) Tetrabutylammonlum trlbromlde (TBATB) has been found to be a unique bromodeboronatlon reagent for organotrlf luoroborates. When compared to previously reported bromodeboronatlon methods, the mild and metal-free reaction conditions tolerate a wider range of functional groups. High reglo- and chemoselectlvlty are observed In the presence of both unsaturated carbon-carbon bonds and aldehyde functional groups. An efficient synthetic route to (Z)-dlbromoalkenes from terminal alkynes has been developed using the TBATB-medlated bromodeboronatlon as a key step.
- Yao, Min-Liang,Reddy, Marepally Srinivasa,Li, Yong,Walfish, Ingrid,Blevins, David W.,Kabalka, George W.
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supporting information; experimental part
p. 700 - 703
(2010/04/02)
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- Exploring Structural Opportunities: The Regioflexible Substitution of 1,3-Difluorobenzene
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To demonstrate the superiority of modern organometallic methods, the inexpensive starting material 1,3-difluorobenzene has been selectively converted into the three benzoic acids and all seven bromobenzoic acids containing the two fluorine atoms in homovicinal positions. The 2,6-difluorobenzoic acid (1) was prepared in a one-pot reaction consisting of direct metallation and carboxylation. The key step on the route to the bromobenzoic acid 4 was a deprotonation-triggered bromine migration from the 2- to the 4-position. All other products were attained through (2,6-difluorophenyl)triethylsilane (11). Consecutive deprotonation of the sites adjacent to the fluorine atoms, followed by appropriate electrophilic substitution, provided not only the acid 7 but also the dibromo and iodobromo derivatives 13 and 23. These in turn gave the isomers 14 and 24 upon base-mediated migration of the heaviest halogen, which made the acids 8 and 10 directly accessible. The regiocontrolled monodebromination of intermediate 14 afforded (4-bromo-2,6-difluoro)triethylsilane (15), which opened the route to the acids 3 and 5 (by carboxylation and protodesilylation) and to acid 9 (by carboxylation and bromodesilylation). Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Schlosser, Manfred,Heiss, Christophe
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p. 4618 - 4624
(2007/10/03)
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- Method for producing tetrakis ( fluoroaryl) borate-magnesium compound
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Fluoroaryl magnesium halide is reacted with a boron compound so that a molar ratio of the fluoroaryl magnesium halide to the boron compound is not less than 3.0 and not more than 3.7, so as to produce a tetrakis (fluoroaryl) borate·magnesium compound. With this method, there occurs no hydrogen fluoride which corrodes a producing apparatus and requires troublesome waste water treatment.
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- Electrophilic ipso substitution of trimethylsilyl groups in fluorobenzenes
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Using variants of literature methods 2,4- and 2,6- difluorophenyltrimethylsilanes have been bromodesilylated to the corresponding bromodifluorobenzenes in moderate to good yields, 3-bromo-2,6-difluorophenyltrimethylsilane afforded 1,3-dibromo-2,4-difluorobenzene whilst 1,3-difluoro-2,4-bis(trimethylsilyl)benzene yielded 3-bromo-2,6-difluorophenyltrimethylsilane. Application of either the Eaborn or Chvalovsky methods of nitrodesilylation to 4-fluorophenyltrimethylsilane, 2,4-difluorophenyltrimethylsilane and 2,6-difluorophenyltrimethylsilane afforded largely the corresponding desilylated products together with products associated with initial protodesilylation, followed by nitration of the resulting fluorobenzenes. The results obtained show that ipso desilylation in the fluoroaromatic series does follow the expected pattern previously obtained in the hydrocarbon analogues. They also show that in some cases the formation of unusually substituted fluoroarenes can be achieved more readily than by the methods previously used.
- Coe, Paul L.,Stuart, Alison M.,Moody, David J.
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- The Photolyses of 2,6- and 2,4-Difluorohalobenzenes
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Photolyses of 2,6- and 2,4-difluorobromobenzenes in acetonitrile gave isomerized and brominated products in addition to 1,3-difluorobenzene produced by the dehalogenation.The reactions were compared with similar reactions of the corresponding chloro- and iodoarenes.In general, photolytic cleavage of the C-X bond of 2,6-difluorohalo(X)benzene was shown to proceed more easily than the corresponding 2,4-difluorohalo compound.
- Song, Yong-Qi,Yuzuri, Tomoaki,Suezawa, Hiroko,Sakakibara, Kazuhisa,Hirota, Minoru,Nakada, Masahiro
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p. 1875 - 1878
(2007/10/03)
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- Triazole derivatives
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The present invention relates to a novel glycerol derivative and a process for preparing the same, and a process for preparing a triazole derivative. According to the present invention, an optical active 2-arylglycerol derivative which is a novel and useful as a synthetic intermediate of medicament can be provided and furthermore, (R)-2-(2,4-difluorophenyl)-3-(1H-1,2,4-triazole-1-yl)-propane-1,2-diol which is useful as an antifungal agent can be prepared.
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- Substituted 9,10-dihydroanthracen-9,10-imines
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Substituted 9,10-dihydroanthracen-9,10-imines are disclosed to be minor tranquilizers, anticonvulsnts, muscle relaxants, and to be useful in the treatment of extrapyramidal disorders such as Parkinson's disease; also disclosed are processes for the preparation of such compounds; pharmaceutical compositions comprising such compounds; and methods of treatment comprising administering such compounds and compositions.
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