- Catalyst-Free 1,2-Dibromination of Alkenes Using 1,3-Dibromo-5,5-dimethylhydantoin (DBDMH) as a Bromine Source
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A direct 1,2-dibromination method of alkenes is realized using 1,3-dibromo-5,5-dimethylhydantoin (DBDMH) as a bromine source. This reaction proceeds under mild reaction conditions without the use of a catalyst and an external oxidant. Various sorts of alkene substrates are transformed into the corresponding 1,2-dibrominated products in good to excellent yields with broad substrate scope and exclusive diastereoselectivity. This method offers a green and practical approach to synthesize vicinal dibromide compounds.
- Wang, Lei,Zhai, Lele,Chen, Jinyan,Gong, Yulin,Wang, Peng,Li, Huilin,She, Xuegong
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supporting information
p. 3177 - 3183
(2022/02/23)
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- A Facile Access to trans -3-Styryl-4-hydrazinocyclopentenes via Palladium-Catalyzed Ring Opening of Diazanorbornenes with (Z)-β-Bromostyrenes/2,3-Dibromohydrocinnamic Acids
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trans -3-Styryl-4-hydrazinocyclopentenes have been synthesized via palladium-catalyzed desymmetrization of diazanorbornenes with (Z)-β-bromostyrenes. The reaction also works well with (Z)-β-bromostyrenes generated in situ from 2,3-dibromohydrocinnamic acids. The synthesized hydrazinocyclopentenes provide an easy route towards synthetic intermediates of many scaffolds of biological potential.
- Saranya,Chand, S. Sarath,Gopalan, Greeshma,Jijitha,Radhakrishnan
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p. 184 - 192
(2017/10/13)
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- Ir-Catalyzed Intramolecular Transannulation/C(sp2)-H Amination of 1,2,3,4-Tetrazoles by Electrocyclization
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An efficient strategy for the intramolecular denitrogenative transannulation/C(sp2)-H amination of 1,2,3,4-tetrazoles bearing C8-substituted arenes, heteroarenes, and alkenes is described. The process involves the generation of the metal-nitrene intermediate from tetrazole by the combination of [CpIrCl2]2 and AgSbF6. It has been shown that the reaction proceeds via an unprecedented electrocyclization process. The method has been successfully applied for the synthesis of a diverse array of α-carbolines and 7-azaindoles.
- Das, Sandip Kumar,Roy, Satyajit,Khatua, Hillol,Chattopadhyay, Buddhadeb
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supporting information
p. 8429 - 8433
(2018/07/09)
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- Chloro/bromotrimethylsilane-Cu(NO3)2·3H2O: Safe and efficient reagent system for the decarboxylative ipso-nitration and dibromination of cinnamic acids
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Further synthetic potential of halotrimethylsilane-nitrate salt mixture is revealed. A mixture of TMSX-Cu(NO3)2·3H2O system is found to be an efficient reagent system for both the decarboxylative nitration (ipso-nitration) when X?=?Cl, and dibromination of cinnamic acids, with X?=?Br, under mild conditions. The reactions are safe and simple, affording the corresponding products (E)-β-nitrostyrenes, and anti-2,3-dibromo-3-phenylpropanoic acids in high yields with high selectivity in a relatively short time. Use of hazardous and toxic nitrating systems such as acetyl nitrate and brominating agents such as molecular bromine can be avoided.
- Roshandel, Sahar,Gurung, Laxman,Mathew, Thomas,Prakash, G.K. Surya
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supporting information
p. 2842 - 2845
(2017/06/27)
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- Pd-Catalyzed C(sp3)-C(sp2) cross-coupling of Y(CH2SiMe3)3(THF)2 with vinyl bromides and triflates
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Pd-Catalyzed C(sp3)-C(sp2) cross-coupling of Y(CH2SiMe3)3(THF)2 with vinyl bromides and triflates has been developed for efficient synthesis of various allyltrimethylsilanes. The cross-coupling reaction was conducted at room temperature with low catalyst loading of either Pd(PPh3)4 or Pd(PPh3)2Cl2, and exhibited high efficiency and a broad substrate scope. In combination with the cross-coupling by the Lewis-acid catalyzed Hosomi-Sakurai reaction, a novel three-component one-pot cascade reaction was then accomplished to deliver homoallylic alcohols and ethers with high regioselectivity and diastereoselectivity. The three-component reaction defined the yttrium complex as a novel one-carbon synthon, which could either trigger bifunctionalization of alkenes or link two electrophiles and would find applications in organic synthesis.
- Cai, Guilong,Zhou, Zhibing,Wu, Wenchao,Yao, Bo,Zhang, Shaowen,Li, Xiaofang
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supporting information
p. 8702 - 8706
(2016/10/03)
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- Preparation of Vinyl Arenes by Nickel-Catalyzed Reductive Coupling of Aryl Halides with Vinyl Bromides
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This work emphasizes the synthesis of substituted vinyl arenes by reductive coupling of aryl halides with vinyl bromides under mild and easy-to-operate nickel-catalyzed reaction conditions. A broad range of aryl halides, including heteroaromatics, and vinyl bromides were employed to yielding products in moderate to excellent yields with high functional-group tolerance. The nickel-catalytic system displays good chemoselectivity between the two C(sp2)-halide coupling partners, thus demonstrating a mechanistic pathway distinct from other stepwise protocols.
- Liu, Jiandong,Ren, Qinghua,Zhang, Xinghua,Gong, Hegui
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supporting information
p. 15544 - 15548
(2016/12/09)
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- Alkoxybromination of olefins using ammonium bromide and oxone
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A mild, efficient, and highly regio- and stereoselective method for the methoxy and ethoxy bromination of olefins has been developed using NH 4Br as a bromine source and Oxone as an oxidant. Various kinds of olefins (aromatic, linear, and cyclic olefins) afforded the corresponding alkoxy brominated products in moderate to excellent yields. Taylor & Francis Group, LLC.
- Kumar, Macharla Arun,Naresh, Mameda,Rohitha, Chozhiyath Nappunni,Narender, Nama
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supporting information
p. 3121 - 3129
(2014/01/06)
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- Formation of quaternary stereogenic centers by copper-catalyzed asymmetric conjugate addition reactions of alkenylaluminums to trisubstituted enones
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Alkenylaluminums undergo asymmetric copper-catalyzed conjugate addition (ACA) to β-substituted enones allowing the formation of stereogenic all-carbon quaternary centers. Phosphinamine-copper complexes proved to be particularly active and selective compared with phosphoramidite ligands. After extensive optimization, high enantioselectivities (up to 96 % ee) were obtained for the addition of alkenylalanes to β-substituted enones. Two strategies for the generation of the requisite alkenylaluminums were explored allowing for the introduction of aryl- and alkyl-substituted alkenyl nucleophiles. Moreover, alkyl-substituted phosphinamine (SimplePhos) ligands were identified for the first time as highly efficient ligands for the Cu-catalyzed ACA. Chiral synthesis made easy: The copper-catalyzed conjugate addition of alkenylaluminum reagents to 3-substituted cyclic enones allows for the formation of all-carbon chiral quaternary centers (see scheme; CuTC=copper(I) thiophene-2-carboxylate). Chiral phosphinamine (SimplePhos) ligands were found to be highly efficient for this transformation.
- Mueller, Daniel,Alexakis, Alexandre
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supporting information
p. 15226 - 15239
(2013/11/06)
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- Regio-and stereoselective hydroxybromination and dibromination of olefins using ammonium bromide and oxone
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An efficient protocol for the synthesis of vicinal bromohydrins and dibromides from olefins is presented. Various olefins are regio-and stereoselectively hydroxybrominated and dibrominated with anti fashion, following Markonikov's rule, using eco-friendly, non-toxic, and stable reagents such as NH4Br and oxone in CH3CN/H2O (1:1) and CH3CN without employing catalyst in moderate to excellent yields. Bromohydrins are formed instantaneously.
- MacHarla, Arun Kumar,Chozhiyath Nappunni, Rohitha,Nama, Narender
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supporting information; experimental part
p. 1401 - 1405
(2012/04/04)
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- Convenient synthesis of terminal alkynes from anti-3-aryl-2,3- dibromopropanoic acids using a K2CO3/DMSO system
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A convenient, efficient, and generally applicable method was developed for the synthesis of terminal alkynes from anti-3-aryl-2,3-dibromopropanoic acids in the presence of DMSO and K2CO3.
- Cheng, Xuezhi,Jia, Jun,Kuang, Chunxiang
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experimental part
p. 2350 - 2354
(2012/02/03)
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- Dioxane dibromide-mediated solvent-free synthesis of vicinal dibromides
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Structurally varied vicinal dibromides have been synthesized in high yield and good purity through highly stereoselective anti-addition of bromine across the olefinic linkages using dioxane dibromide (DD) under solvent-free conditions. Copyright Taylor & Francis Group, LLC.
- Chaudhuri, Subrata Kumar,Roy, Sanchita,Saha, Manabendra,Bhar, Sanjay
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p. 271 - 274
(2007/10/03)
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- Synthesis of (Z)-1-bromo-1-alkenes and terminal alkynes from anti-2,3-dibromoalkanoic acids by microwave-induced reaction
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(Z)-1-Bromo-1-alkenes were stereoselectively prepared in high yields in a short reaction time by microwave irradiation of the corresponding anti-2,3-dibromoalkanoic acids in a Et3N/DMF system. A one-pot synthesis of terminal alkynes and enynes from 2,3-dibromoalkanoic acids were also developed by microwave-induced reaction.
- Kuang, Chunxiang,Yang, Qing,Senboku, Hisanori,Tokuda, Masao
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p. 4043 - 4052
(2007/10/03)
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- Rapid debromination of vic-dibromoalkanes with zinc powder in acetic acid under microwave irradiation
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Microwave irradiation of vic-dibromoalkanes in acetic acid containing zinc powder for 1-2 min gave the corresponding alkenes in high yields.
- Kuang, Chunxiang,Yang, Qing,Senboku, Hisanori,Tokuda, Masao
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p. 282 - 284
(2007/10/03)
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- cis-bromination of encapsulated alkenes
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Inside changes! In striking contrast to the trans-bromination of the free acid, bromination of the bridging cinnamato ligand in 1 proceeds highly diastereoselectively to give the syn-brominated complex 2. A possible explanation for this is that the bromination of 1 proceeds within a confined environment. Since the brominated products can be liberated from the binding pocket of the dinuclear complexes, the metal complexes can be used as reagents for the cis-bromination of olefins with anchoring RCO2- functions.
- Steinfeld, Gunther,Lozan, Vasile,Kersting, Berthold
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p. 2261 - 2263
(2007/10/03)
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- Convenient and stereoselective synthesis of (Z)-1-bromo-1-alkenes by microwave-induced reaction
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(Z)-1-Bromo-1-alkenes were stereoselectively prepared in high yields in a short reaction time (0.2-1.0 min) by microwave irradiation of the corresponding 2,3-dibromoalkanoic acids in DMF in the presence of triethylamine.
- Kuang, Chunxiang,Senboku, Hisanori,Tokuda, Masao
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p. 3893 - 3896
(2007/10/03)
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- A mild procedure for the stereospecific transformation of trans cinnamic acid derivatives to cis β-bromostyrenes
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A new mild procedure has been developed for the synthesis of cis β- bromostyrene analogs with complete Z/E selectivity and good to excellent yields (58.4 - 90.9 %). The process involves carboxyl-halo-elimination of cinnamic acid dibromides by using triethylamine in N,N-dimethylformamide at room temperature. A one-pot procedure has also been described for the direct transformation of cinnamic acids to β-bromostyrenes.
- Kim, Sun Hee,Wei, Han-Xun,Willis, Steven,Li, Guigen
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p. 4179 - 4185
(2007/10/03)
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- An environmentally benign synthesis of organic ammonium tribromides (OATB) and bromination of selected organic substrates by tetrabutylammonium tribromide (TBATB)
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Stable crystalline organic ammonium tribromides (OATB), like Me4NBr3, Et4NBr3, Bu4NBr3, cetyltrimethylammonium tribromide, PyHBr3, can be readily synthesised from the reaction of the corresponding bromides with V2O5 and aqueous H2O2. Typically, TBATB, Bu4NBr3, brominates a variety of organic substrates rather easily under mild conditions. An activated aromatic ring is selectively brominated in the presence of an olefinic double bond.
- Chaudhuri, Mihir K.,Khan, Abu T.,Patel, Bhisma K.,Dey, Deepa,Kharmawophlang, Wancydora,Lakshmiprabha,Mandal, Gagan C.
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p. 8163 - 8166
(2007/10/03)
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- AFM ON CHEMICALLY REACTING CRYSTALS
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A review is given on recent developments of atomic force microscopic (AFM) studies on chemically reacting organic crystals.Three further basic phase transformation mechanisms have been added to the previous five.Both photodimerizations and gas/solid reactions are studied in detail by scanning the surfaces of initial and chemically reacted crystals of anthracenes, thiohydantoines, α- and β-cinnamic acid, and stilbene at different faces, where technically possible.The AFM-features are correlated to known crystal structure data with the aid of semiempirical calculations in part.Thus, detailed molecular mechanisms for the far-reaching well-directed transport phenomena may be derived in most cases and the appearance of the submicroscopic features rationalized.Unimolecular terrace steps of anthracene behave as independent crystal face already.The addition of bromine and chlorine leads to new solid phases directly even though there might be formed mixtures of stereoisomers.If a submicroscopic liquid phase is formed as in the reaction of α-cinnamic acid with chlorine, the surface will be remodelled by the tip and this provides for interesting nanostructures.In many cases there are secondary phase transformations apparently from one form of mixed crystals into another form of mixed crystals either upon continuation of irradiation or just on standing of gas/solid reacted crystals for several hours. - Keywords: atomic force microscopy, solid state photochemistry, gas/solid reaction, basic mechanism, phase transformation, molecular mechanism, unimolecular step, crystal face, crystal structure, nanostructures
- Kaupp, Gerd
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p. 153 - 170
(2007/10/02)
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- Iodide-induced Debromination of Cinnamic Acid and Substituted Cinnamic Acid Dibromides in 2-Methoxyethanol
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The second order rate constants for the iodide-induced debromination of cinnamic acid and substituted cinnamic acid dibromides in 2-methoxyethanol are reported; the reactivities follow the order: p-OCH3 > o-CH3 > p-CH3 > p-NO2 > p-Cl > m-NO2 > -H > m-CH3 > m-OCH3 > o-Cl.The m-CH3 and p-Cl derivatives have higher enthalpies and lower negative entropies of activation whereas methoxy substituted derivatives are characterised by lower enthalpies and higher negative entropies of activation than the unsubstituted acid.The free energy of activation is nearly constant.
- Subramanian, K.,Mathai, I. M.
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p. 909 - 911
(2007/10/02)
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- Elimination from Diastereomeric Methyl 3-Acetoxy-2-halogeno- and 2,3-Dihalogeno-3-phenylpropanoates
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The rates of elimination of a number of erythro- and threo-PhCHYCXHCO2Me in methanolic triethylamine have been measured.The kinetic evidence together with the stereochemical results suggest that elimination of the dihalogeno-compounds occurs by an (E1cB)I process for the erythro-substrates and by a concerted pathways for the threo-isomers.In the case of the acetoxy derivatives the former mechanism seems to be operative for both stereoisomers.
- Cabaleiro, Mercedes C.,Garay, Raul O.
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p. 1473 - 1476
(2007/10/02)
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- REAGENTS AND SYNTHETIC METHODS 38. 4-(DIMETHYLAMINO)PYRIDINIUM BROMIDE PERBROMIDE AS A NEW BROMINATING AGENT FOR ORGANIC COMPOUNDS.
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A new and stable brominating agent for several organic compounds is described.
- Arrieta, A.,Ganboa, I.,Palomo, C.
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p. 939 - 946
(2007/10/02)
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- UNE NOUVELLE METHODE DE BROMATION : LE TRIBROMURE DE TETRABUTYLAMMONIUM.
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Tetrabutylammonium tribromide (TBA Br3) is used under mild conditions as bromating agent for the addition on double bonds of alkenes and for selective α-substitution of acetals in high yields.
- Fournier, M.,Fournier, F.,Berthelot, J.
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p. 157 - 158
(2007/10/02)
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