- Cyclodextrin-based artificial oxidases with high rate accelerations and selectivity
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Three cyclodextrin derivatives with one to four 2-O-formylmethyl groups attached to the secondary rim were prepared and investigated as catalysts for the oxidation of aminophenols in buffered dilute hydrogen peroxide. The derivatives were found to be Michaelis-Menten catalysts and to give rate accelerations of up to 20,000 for the oxidation of 2-aminophenol to 2-amino-phenoxazin-3-one, and 12,000 for the oxidation of 2-amino-p-cresol to 2-nitro-p-cresol. While a range of differently substituted substrates was oxidized the success of the reaction was highly dependent on the substituent pattern. The ability of one of the new artificial enzymes to oxidize selectively one aminophenol from a mixture of two was investigated giving substrate selectivities of up to 16:1.
- Zhou, You,Lindb?ck, Emil,Pedersen, Christian M.,Bols, Mikael
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p. 2304 - 2307
(2014/04/17)
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- Microwave assisted synthesis of nitro phenols from the reaction of phenols with urea nitrate under acid-free conditions
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Urea nitrate was found to be an inexpensive, acid-free, and safe nitrating agent that provides mononitration of phenols and substituted phenols in excellent yields with exclusive ortho-selectivity under microwave irradiation. Microwave assisted reactions reduced the reaction times substantially and enhanced the product yields from good to excellent within shorter reaction times.
- Verma, Sanny,Pandita, Sangeeta,Jain, Suman L.
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p. 1320 - 1322
(2014/03/21)
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- Design, synthesis and anticancer activity evaluation of diazepinomicin derivatives
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A series of diazepinomicin derivatives were synthesized and evaluated in vitro for their growth inhibitory activity against the human carcinoma cell lines. The results indicated the anticancer selectivity of this kind of compounds. Based on the results, preliminary structure-activity relationships were discussed.
- Yu, Yongguo,Wu, Jianbo,Lei, Fan,Chen, Lei,Wan, Weili,Hai, Li,Guan, Mei,Wu, Yong
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p. 369 - 373
(2013/07/26)
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- Non-steroidal dissociated glucocorticoid agonists: Indoles as A-ring mimetics and function-regulating pharmacophores
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We report a SAR of non-steroidal glucocorticoid mimetics that utilize indoles as A-ring mimetics. Detailed SAR is discussed with a focus on improving PR and MR selectivity, GR agonism, and in vitro dissociation profile. SAR analysis led to compound (R)-33 which showed high PR and MR selectivity, potent agonist activity, and reduced transactivation activity in the MMTV and aromatase assays. The compound is equipotent to prednisolone in the LPS-TNF model of inflammation. In mouse CIA, at 30 mg/kg compound (R)-33 inhibited disease progression with an efficacy similar to the 3 mg/kg dose of prednisolone.
- Betageri, Raj,Gilmore, Thomas,Kuzmich, Daniel,Kirrane, Thomas M.,Bentzien, J?rg,Wiedenmayer, Dieter,Bekkali, Younes,Regan, John,Berry, Angela,Latli, Bachir,Kukulka, Alison J.,Fadra, Tazmeen N.,Nelson, Richard M.,Goldrick, Susan,Zuvela-Jelaska, Ljiljana,Souza, Don,Pelletier, Josephine,Dinallo, Roger,Panzenbeck, Mark,Torcellini, Carol,Lee, Heewon,Pack, Edward,Harcken, Christian,Nabozny, Gerald,Thomson, David S.
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scheme or table
p. 6842 - 6851
(2011/12/22)
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- Gas-phase reaction of hydroxyl radicals with m-, o- and p-cresol
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The gas-phase reaction of oxygenated aromatic compounds m-cresol,o-cresol. and p-cresol with hydroxyl radicals has been studied by GC-MS. Experiments have been performed in a large-volume photoreactor (8000 L) at 294 ± 2 K and atmospheric pressure. The relative kinetic method was used to determine the rate constants for these reactions, with 1,3,5-trimethylbenzene as a reference compound. The rate constants obtained are kOH(m-cresol) = (5.88 ± 0.92) × 10-11 cm3 molecule-1 s-1, kOH(o-cresol) = (4.32 ± 0.52) × 10 -11 cm3 molecule-1 s-1, and k OH(p-cresol) = (4.96 ± 0.75) × 10-11 cm 3 molecule-1 s-1. The degradation products observed and their respective molar yields were methyl-1,4-benzoquinone 12.4 ± 1.2%, 5-methyl-2-nitrophenol 1.5 ± 0.3%, and 3-methyl-2-nitrophenol 1.4 ± 0.3% from m-cresol, methyl-1,4-benzoquinone 5.6 ± 0.9%, and 6-methyl-2-nitrophenol 4.7 ± 0.8% from o-cresol. and 4-methyl-2-nitrophenol 17.2 ± 2.5% from p-cresol. This kinetic and product data are compared with the literature, and the reaction mechanisms are discussed. Our results are in accordance with the previous studies (Atkinson, J Phys Chem Ref Data 1989, Monograph (1), 1-246; Atkinson and Aschmann. Int J Chem Kinet 1990, 22, 59-67; Atkinson et al., Environ Sci Technol 1992, 26, 1397-1403; Atkinson et al., J Phys Chem 1978, 82, 2759-2805; Olariu et al., Atoms Environ 2002, 36, 3685-3697; Semadeni et al., Int J Chem Kinet 1995, 27, 287-304) and confirm the methyl-1,4-benzoquinone yields determined by a different experimental technique (long-path Fourier transform infrared FT-IR (Olariu et al., 2002)).
- Coeur-Tourneur, Cecile,Henry, Francoise,Janquin, Marie-Andree,Brutier, Laurent
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p. 553 - 562
(2008/02/10)
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- Supramolecular oxidation of anilines using hydrogen peroxide as stoichiometric oxidant
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6A,6D-Di-O-(propan-2-on-1,3-diyl) α-cyclodextrin-6A,6D-dicarboxylate (2α) and 6A,6D-di-O-(propan-2-on-1,3-diyl) β-cyclodextrin-6A,6D-dicarboxylate (2β) were found to catalyze the oxidation of aromatic amines in the presence of hydrogen peroxide. The products were the corresponding nitro compounds or in some cases azo-, azoxy-, or other dimerization products. The catalysis was found to follow enzyme kinetics giving a rate increase (kcat/kuncat) of up to 1100 in the best case. Copyright
- Marinescu, Lavinia,Molbach, Merete,Rousseau, Cyril,Bols, Mikael
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p. 17578 - 17579
(2007/10/03)
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- Nitration of phenolic compounds by metal-modified montmorillonite KSF
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The nitration of phenolic compounds with 60% nitric acid (1.2 equiv) has been carried out in the presence of metal-modified montmorillonite KSF, prepared from different metals (V, Mo, W; Sc, La, Yb, Eu, In, Bi, Ti, Zr, Hf) and KSF or nitric acid treated HKSF, as catalysts. These catalysts showed good stabilities and high catalytic activities in nitration process. In addition, these catalysts can be recovered easily and reused for many times in nitration. This process is an eco-safer and environment-benign way for clean synthesis of nitrated phenolic compounds.
- Yin, Wan-Po,Shi, Min
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p. 10861 - 10867
(2007/10/03)
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- Nitrophenol derivatives oxidized by cerium(IV) ammonium nitrate (CAN) and their cytotoxicity
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Oxidation of a series of phenols with cerium(IV) ammonium nitrate (CAN) in acetonitrile undermild conditions yields the mixture of corresponding nitrophenols. In the cases of methylphenols and hydroxy-carboxylic acids, the steric effect may reduce the nitration reaction. Compounds 3 a and 4b showed selective activities to Hep 3B and Hep G2 cancer cell lines, respectively. Compound 2c showed selective activities to Hep G2 and MDA-MB-231 cancer cell lines. Further more, com pound 10b showed selective activities to Hep G2, Hep 3B, MCF-7 and MDA-MB-231 cancer cell lines.
- Pan, Wen-Bin,Wei, Li-Mei,Wei, Li-Lan,Wu, Chin-Chung,Chang, Fang-Rong,Wu, Yang-Chang
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p. 581 - 588
(2007/10/03)
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- Enantioselective synthesis of the aminoimidazole segment of dragmacidin D
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A facile enantioselective synthesis of the 2-aminoimidazole side-chain of dragmacidin D has been developed, which involved the regio- and stereoselective opening of the chiral epoxide 9 by a diindolylcuprate reagent, followed by further steps to give 5-substituted N-(1H-imidazol-2-yl)acetamide 2.
- Yang, Cai-Guang,Wang, Jun,Jiang, Biao
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p. 1063 - 1066
(2007/10/03)
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- Regioselectivity of the nitration of phenol by acetyl nitrate adsorbed on silica gel
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The reaction of phenol with acetyl nitrate in chloroform gives nitrophenol with an ortho/para ratio of 1.8. This ratio increase to 13.3 when the reaction was carried out with acetyl nitrate pre-adsorbed on dry silica gel. Silica may be acting as a template to bring phenol close to acetyl nitrate by hydrogen bonds forming a ternary complex, which undergoes a six- center rearrangement to o-nitrophenol. The formation of this ternary complex is evaluated by ab initio molecular orbital calculation.
- Augusto,Rodrigues,De Oliveira Filho, Antonio Pedro,Moran, Paulo J. S.,Custodio, Rogerio
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p. 6733 - 6738
(2007/10/03)
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- Reactions of Some 3-Methylcyclohexenones with Dimethylformamide Dimethyl Acetal
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The reactions of 3-methylcyclohexenone, 4-ethoxycarbonyl-3-methylcyclohexenone, isophorone, 2-amino-3-methylcyclohexenone and 2-nitro-3-methylcyclohexenone with dimethylformamide dimethyl acetal have been investigated, and the products characterized.
- Kasum, Bruno,Prager, Rolf H.
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- A THEORETICAL STUDY ON THE TWO-PHASE NITRATION OF PHENOLS
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The two-phase nitration of phenols is an example of nitrous acid catalysed nitration.Semi-empirical molecular orbital calculations were undertaken on the ground state, radical cation and the phenoxy radical.Unpaired electron spin density calculations can succesfully predict isomer ratios for 3-substitued phenols.Catalysis by NO+ suggests a radical recombination mechanism based on initial electron transfer to form te radical cation followed by proton loss to generate the phenoxy radical.
- Thompson, Malcolm J.,Zeegers, Petrus J.
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p. 191 - 202
(2007/10/02)
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- MONONITRATION DE PHENOLS PAR DES NITRATES METALLIQUES
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A new and practical route to mononitrphenol in high yields is described using commercially aviable hydrated metallic nitrates.According to the metallic nitrate used, this reaction can yield regiospecifically the ortho-nitrophenol or regioselectively the para-nitrophenol.This method is successfully applied to some phenolic derivatives, in particular to the preparation of 2-nitroestrone.Sodium nitrate with ferric chloride or with titane tetrachloride allows mononitration of phenol.
- Poirier, Jean-Marie,Vottero, Catherine
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p. 1415 - 1422
(2007/10/02)
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- STUDIES ON THE TWO-PHASE NITRATION OF SELECTED PHENOLS
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The two phase nitration of several phenols by aqueous acid, sodium nitrate and diethyl ether, yielded as well as the expected nitro-phenols, a benzoquinone.A variable induction period was observed which could be significantly reduced by added sodium nitrite.
- Thompson, Malcolm J.,Zeegers, Petrus J.
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p. 2471 - 2474
(2007/10/02)
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- SELECTIVE NITRATION OF PHENOLS CATALYZED BY LANTHANUM (III) NITRATE
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Phenols are easily mononitrated at room temperature by NaNO3 in a two-phase system (water - ether) in presence of HCl and a catalytic amount of La(NO3)3.The experimental conditions leave completely unaltered many other aromatic systems.
- Ouertani, M.,Girard, P.,Kagan, H.B.
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p. 4315 - 4318
(2007/10/02)
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- Photochemical Nucleophilic Substitution Reactions of Methyl Substituted Derivatives of p- and o-Nitroanisole
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Photosubstitution reactions of several methyl substituted derivatives of p- and o-nitroanisole with hydroxide ion were investigated.The methyl substituent seemed to show an uncertain (probably electronic) effect in addition to the steric effect for the replacement of both the methoxy and the nitro groups.Mainly, the replacement reaction of the nitro group is discussed.
- Sawaura, Masaki,Mukai, Toshio
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p. 3213 - 3214
(2007/10/02)
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