- o-xylylene bis(triethyl ammonium tribromide) as a mild and recyclable reagent for rapid and regioselective bromination of anilines and phenols
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Background: o-Xylylene bis(triethyl ammonium tribromide) (OXBTEATB) as a recyclable and high bromine containing di-(tribromide) reagent has been employed for the bromination of various organic substrates such as phenol and aniline or its derivatives. This catalyst can be recovered and reused several times. Methods: Aryl bromides shown in Table 1, were easily produced from bromination of aromatic compounds by OXBTEATB. This high-yield process lets the reagents to be recycled and reused. Results: As shown in Table 1, substituted anilines, phenols and β-naphthol were found to be the most reactive and immediately converted to the corresponding mono-brominated products by OXBTEATB. Conclusion: OXBTEATB can be considered a solidified bromine. This novel reagent has variable solubility in different polar protic and aprotic solvents but insoluble in non-polar aprotic solvent. Subsequently, OXBTEATB can be recognized as a more useful brominating and regioselective catalyst than the liquid bromine.
- Hemati, Roya,Shahvelayati, Ashraf S.,Yadollahzadeh, Khadijeh
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p. 682 - 687
(2018/07/14)
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- Efficient synthesis of rigid ladder polymers via palladium catalyzed annulation
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We report a new method to synthesize rigid ladder polymers using efficient palladium catalyzed annulation reactions with low catalyst loading (1 mol %). Rigid ladder polymers with benzocyclobutene backbone linkages can be synthesized from copolymerization of readily accessible aryl dibromides and norbornadiene or polymerization of AB type monomers bearing norbornene and aryl bromide or triflate moieties. High molecular weight (10-40 kDa) rigid ladder polymers can be obtained with complete monomer conversions. Diverse monomers also gave different, fixed ladder polymer conformations. The ladder polymers exhibited excellent thermal stability, high carbonization yield, and large intrinsic porosity.
- Liu, Sheng,Jin, Zexin,Teo, Yew Chin,Xia, Yan
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supporting information
p. 17434 - 17437
(2015/02/05)
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- Synthesis and antioxidant activity of 5-hydroxycoumarans,c 6-hydroxychromanes and sulfur-containing derivatives on their base
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A synthesis of 5-hydroxycoumarans, 6-hydroxychromanes and their dodecylthiomethyl- substituted derivatives was accomplished based on methylphenols through the intermediate preparation of 2-allyl-4-alkoxyphenols. The sulfur-containing compounds synthesized
- Yagunov,Khol'shin,Kandalintseva,Prosenko
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p. 1395 - 1400
(2014/05/06)
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- Regioselective and high-yielding bromination of phenols and anilins using N-bromosaccharin and amberlyst-15
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A regioselective and facile conversion method for bromination of anilines and phenols using N-bromosaccharine in the presence of a catalytic amount of Amberlyst-15 lead to enhancement of the reaction rate and yielded brominated products in good to excellent yields and short reaction times.
- Baharfar,Alinezhad,Azimi,Salehian
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experimental part
p. 863 - 865
(2012/04/23)
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- Efficient and regioselective bromination of aromatic compounds with ethylenebis(N-methylimidazolium) ditribromide (EBMIDTB)
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A regioselective and highly efficient method for bromination of phenol and aniline derivatives using ethylenebis(N-methylimidazolium) ditribromide (EBMIDTB) as an efficient reagent in dichloromethane at ambient temperature is reported. The reagent can be recovered and reused several times.
- Hosseinzadeh, Rahman,Tajbakhsh, Mahmood,Mohadjerani, Maryam,Lasemi, Zahra
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experimental part
p. 868 - 876
(2010/05/18)
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- Novel Phosphinic Acid-Containing Thyromimetics
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The present invention relates to compounds of phosphonic acid-containing T3 mimetics and monoesters thereof, stereoisomers, pharmaceutically acceptable salts, co-crystals, and prodrugs thereof and pharmaceutically acceptable salts and co-crystals of the prodrugs, as well as their preparation and uses for preventing and/or treating metabolic diseases such as obesity, NASH, hypercholesterolemia and hyperlipidemia, as well as associated conditions such as atherosclerosis, coronary heart disease, impaired glucose tolerance, metabolic syndrome x and diabetes.
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Page/Page column 105-106
(2009/02/11)
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- First synthesis of nitro-substituted 2,2-diphenyl-2H-1-benzopyrans via the ipso-nitration reaction
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The first synthesis of a series of nitro-substituted 2,2-diphenyl-2H-1-benzopyrans is reported. Our synthetic approach is based on a linear synthesis in two steps from appropriate brominated 2,2-diphenyl-2H-1-benzopyrans 12-17, which requires the preliminary preparation of bromophenols 7-11. These latter were easily obtained by the reaction of phenols 1-5 with a mild and selective brominating agent tetrabutylammonium tribromide (TBA·Br3). The key intermediates 12-17 were efficiently elaborated through an univocal classic chromenization between the commercially available 1,1-diphenyl-2-yn-1-ol and the brominated phenols 6-11. The compounds 12-17 so obtained were converted into arylboronic acids 18-23 by a metalation/boronylation sequence, followed by acid hydrolysis. From advanced building blocks 18-23, the introduction of nitro group, which constitutes the ultimate step of our strategy, was achieved by an ipso-nitration reaction using the Crivello's reagent. This highly selective method provides only the ipso-nitrated products 24-29 in moderate to high yield.
- Bougdid, Lahoussine,Heynderickx, Arnault,Delbaere, Stéphanie,Moustrou, Corinne
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p. 8242 - 8249
(2008/02/05)
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- A convenient and regioselective oxidative bromination of electron-rich aromatic rings using potassium bromide and benzyltriphenylphosphonium peroxymonosulfate under nearly neutral reaction conditions
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Regioselective oxidative bromination of electron-rich aromatic rings has been studied using potassium bromide as a bromine source in the presence of benzyltriphenylphosphonium peroxymonosulfate as oxidant under nearly neutral reaction conditions. In most cases we obtained monobrominated derivatives regioselectively and in good to high yields without the aid of strong acids.
- Adibi, Hadi,Hajipour, Abdol R.,Hashemi, Majid
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p. 1255 - 1259
(2007/10/03)
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- NOVEL PHOSPHORUS-CONTAINING THYROMIMETICS
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The present invention relates to compounds of phosphonic acid containing T3 mimetics, stereoisomers, pharmaceutically acceptable salts, co-crystals, and prodrugs thereof and pharmaceutically acceptable salts and co-crystals of the prodrugs, as well as their preparation and uses for preventing and/or treating metabolic diseases such as obesity, NASH, hypercholesterolemia and hyperlipidemia, as well as associated conditions such as atherosclerosis, coronary heart disease, impaired glucose tolerance, metabolic syndromex and diabetes.
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Page/Page column 243
(2008/06/13)
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- Synthesis of soluble phenyl-substituted poly(p-phenylenevinylenes) with a low content of structural defects
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The synthesis and characterization of two new soluble poly(p-phenylenevinylenes) (PPVs) are reported. The polymers are poly(2-(2′,5′-bis(octyloxy)benzene)-1,4-phenylenevinylene) (BOP-PPV) and poly(2-(2′,5′-bis(octyloxy)benzene)-5-methoxy-1,4-phenyleneviny
- Johansson, D. Mikael,Wang, Xiangjun,Johansson, Tomas,Inganaes, Olle,Yu, Gang,Srdanov, Gordana,Andersson, Mats R.
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p. 4997 - 5003
(2007/10/03)
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- Catalysis of the Debromination of 4-Alkyl-4-bromo-2,5-cyclohexadienones in Aqueous Solution by α-Cyclodextrin
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α-Cyclodextrin (CD) has little or no effect on the rates of enolization of transient 4-bromo-2,5-cyclohexadienones (2), formed during the aqueous bromination of alkylphenols.In contrast, saturation kinetics and large catalytic effect are observed for the debromination of the title dienones (4), formed by ipso bromine attack on 4-alkylphenols (alkyl = Me, Et, i-Pr, n-pr, t-Bu, 3,4-diMe).With the exception of the n-propyl case, the extent of the catalysis kc/ku = 23-78) and the dissociation constant of the CD.dienone complexes (Kd = 2.32-4.83 mM) show surprisingly little variation for the different alkyl groups.The simplest interpretation of the results is that the CD-catalyzed debromination reaction involves attack by free bromide ion on the CD.dienone complex.However, the kinetically equivalent pathway, the reaction between the free dienone 4 and the CD complex of bromide ion, is much more consistent with the low sensitivity of the catalysis to the length and size of the different alkyl groups.For this mechanism the rate enhancements are much larger (2400-4600) and almost constant.They imply that Br- in its CD complex is a stronger nucleophile than bromide ion that is completely solvated by water.The preferred mechanism is the microscopic reverse of that postulated for the CD-catalyzed bromination of phenols.The common transition state for the ipso bromination of 5 (R=Me) and the debromination of 4 (R=Me) is strongly bound by CD (Kd ca. 4.5 1E-5 M).
- Tee, Oswald S.,Bennett, Janice M.
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p. 3226 - 3230
(2007/10/02)
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- Halogenation Using Quaternary Ammonium Polyhalides. IV. Selective Bromination of Phenols by Use of Tetraalkylammonium Tribromides
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Reaction of phenols with calculated amounts of benzyltrimethylammonium tribromide or tetrabutylammonium tribromide in dichloromethane-methanol for 0.5-1 h under mild conditions gave, selectively, the objective mono-, di-, or tribromophenols in good yields.
- Kajigaeshi, Shoji,Kakinami, Takaaki,Okamoto, Tsuyoshi,Nakamura, Hiroko,Fujikawa, Masahiro
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p. 4187 - 4189
(2007/10/02)
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- Observation of Transient Cyclohexadienones during the Aqueous Bromination of Phenols
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Transient 4-bromo-2,5-cyclohexadienone intermediates have been observed during the aqueous bromination of phenol and several methylated derivatives.They enolize to the corresponding p-bromophenols by both acid-catalyzed and water-catalyzed pathways in the pH range 0-6.Studies carried out in buffers also indicate both general acid catalysis (α ca 0.0) and general base catalysis (β=0.54).The latter is ascribed to simple rate-limiting proton abstraction, but the former is not so easily rationalized.The very low α is attributed to a termolecular transition state (water, substrate, and general acid) in which the dienone becomes more anion-like than cation like.This seemingly anomalous behaviour can be explained by the very large enol/keto ratio (ca. 1011) for phenol.
- Tee, Oswald S.,Iyengar, N. Rani
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p. 455 - 459
(2007/10/02)
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