- Polybromide salts of tetraalkyl and N-heterocyclic cations: New entries into the structural library
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Reactions between Br2 dissolved in HBr and salts of various organic cations resulted in formation of a series of polyhalide salts: (IsoquinolH)Br3 (1), (2-BrPyH)Br3 (2), (H2(4,4′-bipy))(Br3)2 (3), Bu4NBr3 (4), (Collidinium){(Br3)(Br2)} (5) and Et4N{(Br3)(Br2)2} (6). All compounds were characterized by X-ray diffractometry; the role of supramolecular Br?Br contacts is discussed.
- Gorokh, Igor D.,Adonin, Sergey A.,Sokolov, Maxim N.,Abramov, Pavel A.,Korolkov, Ilya V.,Semitut, Evgeniy Yu.,Fedin, Vladimir P.
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- Controlling Stereoselectivity in Tribromide Mediated Oxidative Dearomatisations – Synthesis of Selective Spirofurano-naphthalones
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A series of ammonium tribromides were screened for exploring the role of ammonium counterpart attached to tribromides on generation of stereoselective spiro-furans via oxidative dearomatisation of naphthols. The proposition enlightens a suitable combination of the ammonium tribromide and solvent employed, deliver the best achieved diastereoselectivities. This in turn, has also envisioned the mechanistic aspects related to this category of reactions. The mentioned dearomative spiro-furano naphthalones has also been successfully achieved on a large-scale.
- Sarkar, Debayan,Kuila, Puspendu,Sood, Devashish
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Read Online
- A Photorobust Mo(0) Complex Mimicking [Os(2,2′-bipyridine)3]2+and Its Application in Red-to-Blue Upconversion
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Osmium(II) polypyridines are a well-known class of complexes with luminescent metal-to-ligand charge-transfer (MLCT) excited states that are currently experiencing a revival due to their application potential in organic photoredox catalysis, triplet-triplet annihilation upconversion, and phototherapy. At the same time, there is increased interest in the development of photoactive complexes made from Earth-abundant rather than precious metals. Against this background, we present a homoleptic Mo(0) complex with a new diisocyanide ligand exhibiting different bite angles and a greater extent of π-conjugation than previously reported related chelates. This new design leads to deep red emission, which is unprecedented for homoleptic arylisocyanide complexes of group 6 metals. With a 3MLCT lifetime of 56 ns, an emission band maximum at 720 nm, and a photoluminescence quantum yield of 1.5% in deaerated toluene at room temperature, the photophysical properties are reminiscent of the prototypical [Os(2,2′-bipyridine)3]2+ complex. Under 635 nm irradiation with a cw-laser, the new Mo(0) complex sensitizes triplet-triplet annihilation upconversion of 9,10-diphenylanthracene (DPA), resulting in delayed blue fluorescence with an anti-Stokes shift of 0.93 eV. The photorobustness of the Mo(0) complex and the upconversion quantum yield are high enough to generate a flux of upconverted light that can serve as a sufficiently potent irradiation source for a blue-light-driven photoisomerization reaction. These findings are relevant in the greater contexts of designing new luminophores and photosensitizers for use in red-light-driven photocatalysis, photochemical upconversion, light-harvesting, and phototherapy.
- Bilger, Jakob B.,Kerzig, Christoph,Larsen, Christopher B.,Wenger, Oliver S.
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supporting information
p. 1651 - 1663
(2021/02/01)
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- Tetrabutylammonium tribromide: An effective green reagent for the one-pot reaction of 3-acetyl-2H-chromen-2-ones with o-phenylenediamines
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An efficient and completely greener approach has been outlined for the reaction of 3-acetyl-2H-chromen-2-ones with o-phenylenediamines using tetrabutylammonium tribromide (TBATB) to obtain 3-(quinoxalin-2-yl)-2H-chromen-2-ones in one-pot. Alternatively, a step-wise method has also been demonstrated for the synthesis of 3-(quinoxalin-2-yl)-2H-chromen-2-ones, where 3-acetyl-2H-chromen-2-ones has first treated with TBATB to give 3-(2-bromoacetyl)-2H-chromen-2-one followed by its nucleophilic substitution reaction with o-phenylenediamines. Use of polyethylene glycol-600 (PEG-600) as the solvent media, mild reaction conditions and easy isolation procedure of products are the added advantages for this synthesis. Both the one-pot and step-wise methods have been compared in terms of their reaction yields and one-pot synthesis was found to be superior. All the synthesized compounds were confirmed by characterization with 1HNMR, 13CNMR, HRMS, IR spectroscopy.
- Kavitha, Kotthireddy,Srikrishna, Devulapally,Dubey, Pramod Kumar,Aparna, Pasula
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p. 172 - 185
(2018/10/26)
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- Process Development of the HCV NS5B Site D Inhibitor MK-8876
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We describe the route development and multikilogram-scale synthesis of an HCV NS5B site D inhibitor, MK-8876. The key topics covered are (1) process improvement of the two main fragments; (2) optimization of the initially troublesome penultimate step, a key bis(boronic acid) (BBA)-based borylation; (3) process development of the final Suzuki-Miyaura coupling; and (4) control of the drug substance form. These efforts culminated in a 28 kg delivery of the desired active pharmaceutical ingredient.
- Williams, Michael J.,Chen, Qinghao,Codan, Lorenzo,Dermenjian, Renee K.,Dreher, Spencer,Gibson, Andrew W.,He, Xianliang,Jin, Yan,Keen, Stephen P.,Lee, Alfred Y.,Lieberman, David R.,Lin, Wei,Liu, Guiquan,McLaughlin, Mark,Reibarkh, Mikhail,Scott, Jeremy P.,Strickfuss, Sophie,Tan, Lushi,Varsolona, Richard J.,Wen, Feng
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p. 1227 - 1238
(2016/07/23)
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- On the bromination of aromatics, alkenes and alkynes using alkylammonium bromide: Towards the mimic of bromoperoxidases reactivity
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This article describes an efficient method of bromination of organic substrates including aromatics, alkenes and alkynes with NH4VO3as a catalyst and H2O2as an oxidant agent using a non-toxic and easy-to-handle source of bromine, tetrabutylammonium bromide. The process was developed under mild reaction conditions and is an innovation from reported methods in aspects such as: i) short reaction times, ii) the ability to work at room temperature, iii) regioselectivity and good yields.
- Mendoza, Fabian,Ruíz-Guerrero, Rosario,Hernández-Fuentes, Carlos,Molina, Paulina,Norzagaray-Campos, Mariano,Reguera, Edilso
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p. 5644 - 5648
(2016/11/28)
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- Novel Metal- and Mineral-Acid-Free Synthesis of Organic Ammonium Tribromides and Application of Ethylenephenanthrolium Bistribromide for Bromination of Active Methylene Group of 1,3-Diketones and β-Ketoesters
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A novel procedure for the preparation of organic ammonium tribromides (OATBs) is described from their corresponding bromides. Quaternary ammonium bromides (QABs) and a N,N′-heterocyclic dibromide are efficiently oxidized to their corresponding monotribromides and bistribromide by m-chloroperbenzoic acid (MCPBA) in the presence of 2 and 4 equiv of KBr, respectively. The reactions are carried out in an aqueous medium without the use of any mineral acid or metal catalyst/promoters. A variety of tribromides are synthesized in very good yields including a hitherto unknown reagent, 1,10-(ethane-1, 2-diyl)phenanthrolinediium bistribromide (EPDBT). EPDBT is investigated as brominating agent and found to be highly effective for selective bromination of active methylene groups of a variety of 1,3-diketones and β-ketoesters. GRAPHICAL ABSTRACT.
- Dey, Rupa Rani,Paul, Bappi,Dhar, Siddhartha Sankar
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supporting information
p. 724 - 736
(2015/10/29)
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- Sodium hypochlorite-promoted novel synthesis of organic ammonium tribromides and application of phenanthroline hydrotribromide in chemoselective oxidation of organic sulfides by hydrogen peroxide
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A novel method of synthesis of organic ammonium tribromides (OATBs) is developed by using an inexpensive and eco-friendly sodium hypochlorite as oxidant for conversion of Br to Br3 . The OATBs thus prepared include both quaternary ammonium tribromides and N-heterocyclic tribromides. A new addition to the family of OATBs is made in the form of phenanthroline hydrotribromide. The efficacy of this new tribromide as catalyst is ascertained in the oxidative transformation of organic sulfides to their corresponding sulfoxides and sulfones by hydrogen peroxide.
- Dey, Madhudeepa,Dey, Rupa R.,Dhar, Siddhartha S.
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supporting information
p. 631 - 633
(2014/05/20)
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- Novel protocol for the synthesis of organic ammonium tribromides and investigation of 1,1′-(Ethane-1,2-diyl)dipiperidinium bis(tribromide) in the silylation of alcohols and thiols
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A novel and efficient protocol for the synthesis of organic ammonium tribromides (OATBs) is developed by using inexpensive and eco-friendly periodic acid as an oxidant for the conversion of Br-to Br3-. The method does not use any mineral acid and metal oxidants. The protocol is utilized to synthesize a new bis(tribromide) viz., 1,1′-(ethane-1,2-diyl)dipiperidinium bis(tribromide) (EDPBT). EDPBT is investigated as a catalyst in the silylation of alcohols and thiols by HMDS (hexamethyldisilazane) under solvent-free conditions.
- Dey, Rupa R.,Paul, Bappi,Dhar, Siddhartha S.,Bhattacharjee, Sushmita
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supporting information
p. 1545 - 1547
(2015/02/19)
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- Novel method of synthesis of quaternary ammonium tribromides and investigation of catalytic role of benzyltrimethylammonium tribromide in oxidation of alcohols to carbonyl compounds
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Stable crystalline organic quaternary ammonium tribromides (QATBs) have been easily synthesized by the oxidation of the corresponding organic ammonium bromides (QABs) with ammonium persulfate. The reactions have been performed under solvent-free conditions in the presence of sulfuric acid and silica as supporting agent. Two equivalents of potassium bromide have been used as the source of additional bromides for quantitative conversion of QABs to QATBs.Ammonium persulfate, a cheap and readily available oxidant, carries out the bromide oxidation to tribromide very effectively under solvent-free conditions. The synthesized QATBs have been shown to catalyze the oxidation of alcohols to carbonyl compounds with hydrogen peroxide as oxidant in good yields under mild reaction conditions. Copyright Taylor & Francis Group, LLC.
- Dey, Madhudeepa,Dhar, Siddhartha Sankar,Kalita, Mukul
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p. 1734 - 1742
(2013/05/22)
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- Facile synthesis of oxazolidinones catalyzed by n-Bu4NBr 3/n-Bu4NBr directly from olefins, chloramine-T and carbon dioxide
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A binary catalyst systemcomposed of n-Bu4NBr3/n-Bu4NBrwas developed for facile synthesis of 5-substituted 2-oxazolidinoneswith perfect regioselectivity in a single operation directly fromolefins, chloramine-T and CO2. The choice of efficient binary catalysts for two steps, i.e. aziridination and cycloaddition, and the optimization of reaction condition are keys to the one-pot synthesis of 5-substituted 2-oxazolidinones. A possiblemechanismfor the present one-pot synthesis of oxazolidinones was also proposed.
- Kong, De-Lin,He, Liang-Nian,Wang, Jin-Quan
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experimental part
p. 992 - 995
(2010/11/16)
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- PROCESS FOR PREPARING QUATERNARY AMMONIUM TRIBROMIDES
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The present invention relates to an economical and environmentally clean process for the preparation of high quality quaternary ammonium tribromides by oxidation of bromide (Br-) in an acidic medium by a biomimetic process involving transition metal ion mediated activation of hydrogen peroxide.
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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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- A New Oxidizing System for Aromatic Alcohols by the Combination of N-Oxoammonium Salt and Electrosynthesized Tetraalkylammonium Tribromide
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A combination of 2,2,6,6-tetramethyl-1-piperidinyloxyl and tetraalkylammonium tribromides (R4NBr3), which are available from the corresponding tetraalkylammonium bromides via electrooxidation with potassium bromide, has proved to be useful for oxidations of primary and secondary alcohols to the corresponding aldehydes and ketones, respectively.The oxidation reaction proceeds smoothly even with a 0.5-1.0 molpercent of N-oxyl compounds and 1.5-2.0 equivalents of tetraalkylammonium tribromides in an aqueous-organic two-phase solution buffered at pH 8.0-8.6.This recyclable oxidant/co-oxidant combination system may involve the formation of N-oxoammonium salts, actual oxidizing agents of alcohols, by the action of hypobromite species generated from R4NBr3 in the binary solution.Utility of the method is highlighted by the selective oxidation of benzylic alcohols bearing electron-releasing groups on the aromatic nucleus to the corresponding aldehydes or ketones without any bromination and overoxidation.
- Inokuchi, Tsutomu,Matsumoto, Sigeaki,Fukushima, Mitsuhiro,Torii, Sigeru
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p. 796 - 800
(2007/10/02)
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- USE OF NAFION MEMBRANES IN LABORATORY ORGANIC ELECTROSYNTHESIS
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Electrolysis of quarternary ammonium bromides and iodides in a divided cell with a Nafion membrane yields quarternary polyhalogenides at a carbon anode in water-ethanolic anolytes.The electrodialysis of tetrabutylammonium iodide in a cell with a Nafion membrane enables generation of tetrabutylammonium hydroxide.In electrolytic reduction of nitrobenzene in presence of 1,3-dibromopropane, N-phenylisoxazolidine results in approx. 60percent yield.This electrosynthesis takes place in dimethylformamide with tetrabutylammonium bromide at a glassy-carbon cathode in a divided cell.In the electroreduction of lobelanine hydrogensulfate in a divided cell in acid water-ethanolic media at a lead cathode prevalently lobelanidine has been obtained.
- Hlavaty, Jaromir,Volke, Jiri
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p. 3164 - 3170
(2007/10/02)
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- Voltametric Study of Organic Methals. I. The Determination of the Electrochemical Conditions for Crystal Growth
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The metallic crystal of organic charge-transfer complexes are grown by means of the electrolytic oxidation of tetrathiafulvalene (TTF) derivatives in the presence of trihalide anions in organic solvents.In order to obtain a crystal of good quality, the optimal conditions for the growth have been searched for based on the data on the cyclic voltammetry.In this paper, the electrochemical conditions, such as the oxidation potential, the stability of the donor monocation radicals, and the redox behavior of the anions under the oxidation potential of the donors, are discussed in relation to the chemical reactions proceeding in the solution during the crystal growth.
- Sakura, Sachiko,Imai, Hideo,Anzai, Hiroyuki,Moriya, Tetsuo
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p. 3181 - 3186
(2007/10/02)
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- Synthesis of Bromoacetyl Derivatives by Use of Tetrabutylammonium Tribromide
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Orange ccrystalline tetrabutylammonium tribromide was prepared using a simple method.The reaction of acetyl dervivatives with an eqimolar amount of the tribromide in dichloromethane-methanol at room temperature bave bromoacetyl derivatives in fairly good yields.
- Kajigaeshi, Shoji,Kakinami, Takaaki,Okamoto, Tsuyoshi,Fujisaki, Shizuo
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p. 1159 - 1160
(2007/10/02)
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- Reaction of Tertiary Aliphatic Amines with Halogens. Kinetics and Products of the Reaction of Tribenzylamine with Molecular Bromine and Tribromide Ion
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A reinvestigation of the reaction of tribenzylamine with bromine has proved that the crystalline product previously reported to be an amine*Br2 1:1 adduct of type (C6H5CH2)3NBr+Br- is actually a mixture of tribenzylammonium and NN-dibenzylbenzylidenaminium tribromides.A kinetic study carried out in 1,2-dichloroethane with the stopped-flow technique has shown the transient formation of a 1:1 tribenzylamine*Br2 charge-transfer complex having a formation constant Kf of 9.7(1.0) l mol-1 at 25 deg C.This is followed by a fast oxidation-reduction reaction leading to NN-dibenzylbenzylidenaminium bromide and HBr, which is captured by the amine to give tribenzylammonium bromide.Both bromide salts are instantaneously transformed, by association with the remaining Br2, into the corresponding tribromides, which are then consumed at a much slower rate by the oxidative cleavage of the amine.Tetrabutylammonium tribromide has been independently shown to react slowly with tribenzylamine through two processes, with respective rate constants at 25 deg C k2 Br3-=3.1(0.4) x 10-4 and k2 Br2>/=8.9 x 102 l mol-1 s-1, the former interpretable as a bromide-assisted and the latter as an unassisted elimination of HBr from the 1:1 amine*Br2 charge-transfer complex.
- Bellucci, Giuseppe,Bianchini, Roberto,Ambrosetti, Roberto
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