- Prevention of manganese precipitation during the continuous selective partial oxidation of methyl aromatics with molecular oxygen in supercritical water
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Presented here is an investigation of the activity and recovery of the homogeneous manganese/bromide catalyst during the continuous flow oxidation of o-xylene, as model substrate, with molecular oxygen (O2) in supercritical water (scH2O). Two strategies are discussed for preventing catalyst precipitation, mainly in the form of oxides such as manganese(IV) oxide, The first strategy involves varying the manganese:bromide ratio using either manganese(II) acetate or manganese (II) bromide in the presence of hydrobromic and other acids. The results show that the effect of acidity and bromide concentration plays an important role in preventing the manganese/bromide catalyst from precipitating. The second strategy uses aromatic carboxylic acids in combination with the manganese/bromide catalyst, particularly benzoic acid, which improves the catalyst recovery dramatically over a certain range of acid concentrations. Our studies show how the presence of an organic acid and/or its precursors is important in stabilising the catalyst. Our results are rationalised on the basis of a tentative reaction mechanism.
- Fraga-Dubreuil, Joan,Garcia-Verdugo, Eduardo,Hamley, Paul A.,Perez, Eduardo,Pearson, Ian,Thomas, W. Barry,Housley, Duncan,Partenheimer, Walt,Poliakoff, Martyn
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Read Online
- Selectivity in catalytic diol electrooxidation using a polypyridine ru(iv) complex
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1,2-, 1,3-, and 1,4-Butanediols and phthatic alcohol were oxidized electrocatalytically using the polypyridine [(bpy)(trpy)RuO]2+ complex (1) as oxidant under different conditions: concentration of 1, pH, and temperature. By controlling the number of coulombs passed through the electrolytic cell, it was possible to obtain selective reactions. 1-Hydroxy-2-butanone,1-hydroxy-3-butanone, γ-butyrolactone, phthalide, phtalic aldehyde, and phthalic acid were the products obtained by controlled potential electrolysis from these substrates, with yields ranging from 41 to 89%.
- Navarro, Marcelo,De Giovani, Wagner F.,Romero, Jose R.
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Read Online
- Facile construction of pyrrolo[1,2-: B] isoquinolin-10(5 H)-ones via a redox-amination-aromatization-Friedel-Crafts acylation cascade reaction and discovery of novel topoisomerase inhibitors
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An efficient redox-amination-aromatization-Friedel-Crafts acylation cascade process from trans-4-hydroxyproline and 2-formylbenzoic acids has been developed for the synthesis of pyrrolo[1,2-b]isoquinolin-10(5H)-ones. Compound 3h was identified as a new potent dual topoisomerase I/II inhibitor.
- Wu, Shanchao,Liu, Na,Dong, Guoqiang,Ma, Lin,Wang, Shengzheng,Shi, Wencai,Fang, Kun,Chen, Shuqiang,Li, Jian,Zhang, Wannian,Sheng, Chunquan,Wang, Wei
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Read Online
- Oxidation of benzyl alcohol by pyridinium dichromate in acetonitrile. Using the paralmeta ratio of substituent effects for mechanism elucidation
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Rate constants were measured for the oxidation reaction of benzyl alcohol and twenty-five ortho-, recta- and para-monosubstituted derivatives in the temperature range 293-323 K at intervals of 10 K. The kinetics were followed spectrophotometrically in dry acetonitrile acidified with trichloroacetic acid (TCA) using pyridinium dichromate (PDC) as oxidising agent under pseudo-first-order conditions with respect to PDC. Benzaldehyde is the only oxidation product and no reaction takes place without TCA. From good linear Eyring plots activation enthalpies Δ?H° and entropies Δ?S° are calculated. For ortho-substituted benzyl alcohols high Δ?H° values and small negative Δ?S° values point to an ortho effect on the rate-determining step. Using the tetralinear approach to substituent effects, the average value λ = 1.09 ± 0.05 for the para/meta ratio of inductive or Electra effects is obtained and negative Hammett reaction constants decreasing in magnitude with increasing temperature are found. A mechanism implicating the prior acid-catalysed formation of neutral benzyl hydrogen dichromate ester followed by intramolecular proton transfer is proposed. Modelling of parameter λ in terms of the electrostatic theory showed its experimental value to be consistent with the ratio of electric potentials generated in the immediate vicinity of the nearest chromium atom by dipolar substituents introduced in the aromatic ring on para and meta positions. At a molecular level the oxidative, rate-determining step is suggested to be triggered by the retraction or shrinkage of electron pairs from sigma bonds in Cr2VI species to non-bonding orbitals in unstable CrIV-O-CrVI species. In contrast with past interpretations, an electrochemical approach is used to explain negative values for the Hammett reaction constant.
- Kabilan,Girija,Reis, Joao Carlos R.,Segurado, Manuel A.P.,De Oliveira, Jaime D. Gomes
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Read Online
- Industrial synthesis method of o-aldehyde phenyl fatty acid
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The invention provides an industrial synthesis method of o-aldehyde phenyl fatty acid, which comprises the following steps: by using aromatic lactone or o-methylphenyl fatty acid as a raw material, carrying out halogenation reaction and hydrolysis to obtain the o-aldehyde phenyl fatty acid. In the method, halogen is used in the production process; however, if haloid acid or haloid salt formed byhydrolysis is directly discharged to the environment, the cost of a halogen source accounts for most of the cost of the whole process, and severe environmental pollution is caused; by means of the method, an activated halogen source can be obtained in real time by adding a specific oxidant in the reaction process, so that the closed cycle of halogen elements is realized by means of the subsequenthydrolysis process; therefore, a large amount of raw material cost is saved on the whole, environmental pollution is reduced, the product yield is high, and large-scale production is facilitated.
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Paragraph 0074; 0076; 0077; 0083; 0085; 0086; 0088; 0090
(2020/01/08)
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- Synthesis method of O-formyl benzoic acid
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The invention discloses a synthesis method of o-formyl benzoic acid. The synthesis method includes the following steps that (1) 20 mL of o-dimethyl benzene is taken and placed in a reactor, the reactor is heated to 130 to 135 DEG C, and DMF, a catalyst and a cocatalyst are added in turn; (2) reaction liquid is cooled to the room temperature, and an obtained clear colorless crystal is o-methyl benzonitrile; and (3) the o-methyl benzonitrile is placed in the reactor, and heated to 110 to 115 DEG C, the DMF, the catalyst and the cocatalyst are added, oxygen intake is controlled to be 900 mL/min,hydrogen intake is controlled to be 100 mL/min, reaction is conducted for 2 to 3 h, and the o-formyl benzoic acid can be obtained through hydrolysis of obtained white crystalline powder under the acidic condition. The o-methyl benzonitrile is synthesized by a one-step method of liquid phase ammoxidation of o-xylene under normal pressure, then the o-formyl benzoic acid is synthesized by further oxidation of the o-methyl benzonitrile, the yield is high, the purity of product is high, and the requirements on equipment are low.
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Paragraph 0009 0011-0012
(2019/12/25)
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- Synthesis of chiral isoindolinones via asymmetric propargylation/lactamization cascade
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A Zn-mediated propargylation/lactamization cascade reaction with chiral 2-formylbenzoate derived N-tert-butanesulfinyl imines was realized, which provided a practical and efficient method for the synthesis of chiral isoindolinones. High diastereoselectivities (up to 97:3 dr) and good reaction yields were observed for most examined cases.
- Meng, Jiao-Long,Jiao, Tang-Qian,Chen, Ya-Heng,Fu, Rui,Zhang, Shu-Sheng,Zhao, Qian,Feng, Chen-Guo,Lin, Guo-Qiang
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supporting information
p. 1564 - 1567
(2018/03/23)
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- Structure-based design of potent human dihydroorotate dehydrogenase inhibitors as anticancer agents
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It has been proven that inhibiting human dihydroorotate dehydrogenase (hDHODH) restricts the growth of rapidly proliferating cells, thus hDHODH can be developed as a promising target for the treatment of immunological disease and cancer. Here, a succession of substituted hydrazino-thiazole derivatives were designed, synthesized, and biologically evaluated through structure-based optimization, of which compound 22 was the most potent inhibitor of hDHODH with an IC50 value of 1.8 nM. Furthermore, 22 exhibited much better antiproliferative activity than brequinar, both in HCT-116 and BxPC-3 cancer cell lines. Flow cytometry analysis revealed that 22 induced S phase cell cycle arrest and promoted induction of apoptosis. All results established a proof that blocking the pyrimidine de novo synthesis pathway by inhibiting the rate-limiting enzyme hDHODH is an attractive therapy for cancer.
- Song, Wenlin,Li, Shiliang,Tong, Yi,Wang, Jiawei,Quan, Lina,Chen, Zhuo,Zhao, Zhenjiang,Xu, Yufang,Zhu, Lili,Qian, Xuhong,Li, Honglin
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supporting information
p. 1441 - 1448
(2016/07/21)
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- Cu/Fe Catalyzed Intermolecular Oxidative Amination of Benzylic C-H Bonds
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We report a Cu/Fe co-catalyzed Ritter-type C-H activation/amination reaction that allows efficient and selective intermolecular functionalization of benzylic C-H bonds. This new reaction is featured by simple reaction conditions, readily available reagents and general substrate scope, allowing facile synthesis of biologically interesting nitrogen containing heterocycles. The Cu and Fe salts were found to play distinct roles in this cooperative catalysis. With a little help: A Ritter-type intermolecular amination of benzylic C-H bonds with acetonitrile, co-catalyzed by CuII/FeIII is reported. A wide array of biologically interesting nitrogen containing heterocycles was prepared from 2-alkyl benzoic acids and heteroaromatic carboxylic acids under operationally simple conditions. The Cu and Fe salts were found to play distinct roles in this cooperative catalysis.
- Liu, Cong,Zhang, Qi,Li, Hongbo,Guo, Shuangxi,Xiao, Bin,Deng, Wei,Liu, Lei,He, Wei
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supporting information
p. 6208 - 6212
(2016/05/09)
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- Enantioselective addition of arylboronic acids to methyl 2-formylbenzoates by using a ruthenium/Me-BIPAM catalyst for synthesis of chiral 3-aryl-isobenzofuranones
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Ruthenium/Me-BIPAM-catalyzed asymmetric addition of arylboronic acids to methyl 2-formylbenzoates afforded chiral 3-aryl-isobenzofuranones. [RuCl2(p-cymene)]2/Me-BIPAM and RuCl2(PPh3)3/Me-BIPAM catalyst systems tolerate a variety of functional groups and give high yields with high enantioselectivities.
- Yohda, Masaaki,Yamamoto, Yasunori
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p. 10874 - 10880
(2015/11/17)
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- Highly enantioselective synthesis of 2,3-dihydro-1 H-imidazo[2,1-a isoindol-5(9b H)-ones via catalytic asymmetric intramolecular cascade imidization-nucleophilic addition-lactamization
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Highly enantioselective catalytic asymmetric intramolecular cascade imidization-nucleophilic addition-lactamization of N1-alkylethane-1,2-diamine with methyl 2-formylbenzoate catalyzed by a chiral phosphoric acid represents the first efficient method for the preparation of medicinally interesting chiral 2,3-dihydro-1H-imidazo[2,1-a]isoindol-5(9bH)-ones with high yields and excellent enantioselectivities. This strategy has been shown to be quite general toward various methyl 2-formylbenzoates.
- He, Yuwei,Cheng, Chuyu,Chen, Bin,Duan, Kun,Zhuang, Yue,Yuan, Bo,Zhang, Meisan,Zhou, Yougui,Zhou, Zihong,Su, Yu-Jun,Cao, Rihui,Qiu, Liqin
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supporting information
p. 6366 - 6369
(2015/01/16)
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- Gold-catalyzed amide synthesis from aldehydes and amines in aqueous medium
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An efficient gold-catalyzed amide synthesis from aldehydes and amines in aqueous medium under mild reaction conditions has been developed.
- Li, Gai-Li,Kung, Karen Ka-Yan,Wong, Man-Kin
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supporting information; experimental part
p. 4112 - 4114
(2012/06/16)
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- Zinc-catalyzed benzylic C-H bond oxidation
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A zinc-catalyzed oxidation of benzylic substrates has been developed. The corresponding carbonyl containing compounds have been produced in moderate to excellent yields. Both arenes and heteroarenes can be applied as substrates by using H2O2 as the oxidant.
- Wu, Xiao-Feng
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supporting information
p. 6123 - 6126
(2012/11/07)
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- Metal free: A novel and efficient aerobic oxidation of toluene derivatives catalyzed by N′, N″, Nprime;, -trihydroxyisocyanuric acid and dimethylglyoxime in PEG-1000-based dicationic acidic ionic liquid
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A non-metal catalytic system containing of N′, N″, Nprime;, -trihydroxyisocyanuric acid (THICA) and dimethylglyoxime (DMG) is described for the selective oxidation of toluene derivatives with dioxygen in PEG-1000-based dicationic acidic ionic liquid (PEG1000-DAIL). Several toluene derivatives were efficiently oxidized to corresponding acids under mild conditions. The oxidation followed a radical pathway and a possible mechanism was proposed. Both the catalyst and PEG1000-DAIL could be reused at least eight times without significantly decreasing the catalytic activity.
- Lu, Tingting,Mao, Yang,Yao, Kai,Xu, Jian,Lu, Ming
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p. 124 - 128
(2012/10/29)
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- Remarkable effect of PEG-1000-based dicationic ionic liquid for N-Hydroxyphthalimide-catalyzed aerobic selective oxidation of alkylaromatics
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PEG 1000-based functional dicationic acidic ionic liquid (PEG 1000-DAIL) was used for the first time as the reaction solvent for the N-Hydroxyphthalimide (NHPI)-cobalt acetate(Co(OAc)2) catalyzed aerobic oxidations of alkylaromatics to the corresponding acids. It enhanced the efficient catalytic ability of NHPI: 99.9 % conversion of toluene with 99.5 % selectivity for benzoic acid could be obtained at 80 °C in 10 h and ethylbenzene was selectively oxidized to benzoic acid. Several alkylaromatics were efficiently oxidized to their corresponding acids under mild conditions. For substituted toluene, the conversions of substrates and the selectivity of products was affected by the position and kind of substituted groups, respectively. Both the catalyst and PEG1000-DAIL could be reused at least eight times without significantly decreasing the catalytic activity.
- Lu, Tingting,Lu, Ming,Yu, Wang,Liu, Zhongjie
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p. 277 - 282
(2013/01/15)
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- Selective aerobic oxidation of para-xylene in sub- and supercritical water. Part 1. Comparison with ortho-xylene and the role of the catalyst
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The selective, continuous, aerobic oxidations of para-xylene (pX) and ortho-xylene (oX) were performed in an identical fashion in supercritical water. The xylenes were oxidized without a catalyst and with hydrobromic acid, cobalt(ii) and manganese(ii) bromide catalysts. The conversions and yields to phthalic acid (OA) from oX were always significantly higher than those for terephthalic acid (TA) from pX. The formation of CO2 was significantly higher for pX than oX despite the higher conversions to oX. These results are unexpected because the literature teaches that thermal and catalytic decarboxylation is much higher for OA than TA. The superior yields from oX are consistent with a lower steady-state concentration of hydroxyl radicals, OH due to the internal, concerted attack of the peroxides with the oX methyl group. This mechanism forms the phthalide directly from o-tolualdehyde (oTOL) which is consistent with the observation that ortho-toluic acid (OTA) is much lower in oX than para-toluic acid, PTA, in pX oxidation. This mechanism also lowers the steady-state concentration of aromatic acids consistent with the observed lower benzoic acid and CO2 yields. Overall, the results suggest that the metal catalysts can play more than one role, thereby opening up the opportunity for discovering new catalytic synergies which are explored in our next paper, Part 2 of this series.
- Perez, Eduardo,Fraga-Dubreuil, Joan,Garcia-Verdugo, Eduardo,Hamley, Paul A.,Thomas, W. Barry,Housley, Duncan,Partenheimer, Walt,Poliakoff, Martyn
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experimental part
p. 2389 - 2396
(2011/10/13)
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- Synthesis of chiral 3-substituted phthalides by a sequential organocatalytic enantioselective aldol-lactonization reaction. Three-step synthesis of (S)-(-)-3-butylphthalide
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(Chemical Equation Presented) The development of efficient methods for the facile construction of important molecular frameworks is an important goal in organic synthesis. Chiral 3-substituted phthalides are widely distributed in a large collection of natural products with broad, potent, and potentially path-pointing biological activities. In this investigation, we have uncovered an unprecedented organocatalytic asymmetric aldol-lactonization reaction of 2-formylbenzoic esters with ketones/aldehydes for convenient construction of the enantioenriched "privileged" scaffold. As a result of the sensitive nature of substrate structures of an organocatalytic enantioselective aldol reaction, after extensive optimization of reaction conditions, catalyst L-prolinamide alcohol IV is identified as the best promoter. Interestingly, it is found that in this reaction, addition of an acid additive PhCO2H can significantly enhance reaction efficiency with use of only as low as 2.5 mol % IV for the process. Moreover, due to the sensitivity of reaction conditions toward a sequential aldol-lactonization process without affecting enantioselectivity and racemization, it is essential to remove the catalyst for the subsequent facile lactonization reaction in the presence of K 2CO3. The aldol-lactonization processes serve as a powerful approach to the preparation of synthetically and biologically important 3-substitued phthalides with a high level of enantioselectivities. A 3-step catalytic asymmetric synthesis of the natural product of 3-butylphthalide is reported.
- Zhang, Haoyi,Zhang, Shilei,Liu, Lu,Luo, Guangshun,Duan, Wenhu,Wang, Wei
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supporting information; experimental part
p. 368 - 374
(2010/03/30)
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- OXIDATION REACTION FOR PRODUCING AROMATIC CARBOXYLIC ACIDS
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A method of minimising or preventing catalyst loss and/or the precipitation of metal oxide in a catalytic synthetic oxidation reaction in an aqueous solvent comprising water under supercritical or near-supercritical conditions wherein during the oxidation reaction an oxidant is present and a metal salt is present as a catalyst, said method comprising the step of adding an acidic component comprising one or more acid(s) into the reaction such that contact of at least part of said metal salt with said oxidant is in the presence of said acidic component, particularly wherein the oxidation reaction is a process for the production of an aromatic carboxylic acid, said process comprising contacting in the presence of a catalyst, within a reactor, one or more precursors of the aromatic carboxylic acid with an oxidant, such contact being effected with said precursor(s) and the oxidant in an aqueous solvent comprising water under supercritical conditions or near supercritical conditions.
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Page/Page column 32-35; sheer 8
(2008/12/06)
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- OXIDATION REACTION FOR PRODUCING AROMATIC CARBOXYLIC ACIDS
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A method of minimising or preventing catalyst loss and/or the precipitation of metal oxide in a process for the production of an aromatic carboxylic acid, said process comprising contacting in the presence of a catalyst comprising a metal salt within a reactor, one or more precursors of the aromatic carboxylic acid with an oxidant, such contact being effected with said precursor(s) and the oxidant in an aqueous solvent comprising water under supercritical conditions or near supercritical conditions, wherein (i)said method comprises the step of adding an acidic component comprising one or more acid(s) into the oxidation reaction zone; (ii) contact of at least part of said catalyst with said oxidant is in the presence of said acidic component; and (iii) said acidic component comprises one or more organic acid(s).
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Page/Page column 39-42
(2008/12/05)
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- Furan ring opening - Isocoumarine ring closure: A recyclization reaction of 2-carboxyaryldifurylmethanes
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A general method for the synthesis of isocoumarine derivatives has been developed. Bis(5-R-2-furyl)methylbenzoic acids (R = methyl, ethyl) underwent recyclization and subsequent cyclization into tetracyclic isochromene-1-one derivatives under treatment with hydrogen chloride in methanol. It has been shown that intermediate 4-(5-R-furan-2-yl)-3-(3-oxo-3-R-propyl)-isochromene-1- ones can be obtained selectively by varying a concentration of the hydrogen chloride and reaction times. In the case of R = tert-butyl only corresponding 4-[5-(tert-butyl)-2-furyl]-3-(4,4-dimethyl-3-oxopentyl)-1-isochromenones were isolated regardless of the reaction conditions.
- Abaev, Vladimir T.,Dmitriev, Artem S.,Gutnov, Andrey V.,Podelyakin, Sergey A.,Butin, Alexander V.
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p. 1195 - 1204
(2007/10/03)
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- Controlled release of perfumery alcohols by alkaline hydrolysis of 2-formyl- and 2-acetylbenzoates and their corresponding phthalides
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The controlled release of perfumery alcohols by alkaline hydrolysis of 2-formyl- and 2-acetylbenzoates and their corresponding phthalides were investigated. The rate of benzoate hydrolysis depended on the structure of alcohol released. It was suggested th
- Enggist, Paul,Rochat, Sabine,Herrmann, Andreas
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p. 438 - 440
(2007/10/03)
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- Electrosynthesis of substituted benzolactones by a nickel-catalyzed allyl transfer reaction from allyl benzoates
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Allyl-substituted benzolactones were obtained in good yields from allyl o-carbonyl benzoates in a Ni-catalyzed electrochemical reaction involving allyl cleavage, intramolecular allyl transfer to the carbonyl group and lactone formation, in a one-step procedure under mild conditions.
- Franco,Du?ach
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p. 806 - 808
(2007/10/03)
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- A New Strategy for the Preparation of Terephthalic Acid by the Aerobic Oxidation of p-Xylene Using N-Hydroxyphthalimide as a Catalyst
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A new methodology for the production of terephthalic acid (5) by the aerobic oxidation of p-xylene (1) using a combined catalytic system of N-hydroxyphthalimide (NHPI)/Co(OAc)2/Mn(OAc)2 was developed. The oxidation of 1 under a dioxygen atmosphere in the presence of a catalytic amount of NHPI/Co(OAc)2/Mn(OAc)2 at 100°C for 14 h afforded terephthalic acid in 82percent yield. Removal of Mn(OAc)2 from the catalytic system resulted in considerable reduction in the yield of 3. When the oxidation of 1 was carried out under a pressure of air (30 atm) at 150°C, the reaction was completed within 3 h to give 3 in 84percent yield. The oxidation of p-toluic acid (2), which can be prepared by the oxidation of 1 using the NHPI/Co(OAc)2 system at room temperature, by the NHPI/Co(OAc)2/Mn(OAc)2 system under pressure of air (30 aim) at 150°C gave 3 in 95percent yield. N-Acetoxyphthalimide (NAPI) was found to require a lower catalyst loading than NHPI, but oxidation with NAPI was slower. Thus, the oxidation of 1 catalyzed by NAPI (5 mol percent)/Co(OAc)2 (0.5 mol percent)/Mn(OAc)2 (0.5 mol percent) under a dioxygen atmosphere (1 atm) in acetic acid at 100°C gave 3 in 80percent yield.
- Tashiro, Yasutaka,Iwahama, Takahiro,Sakaguchi, Satoshi,Ishii, Yasutaka
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p. 220 - 225
(2007/10/03)
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- Pathway of anthracene modification under simulated solar radiation
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Exposure of polycyclic aromatic hydrocarbons (PAHs) to sunlight results in rapid structural photomodification generally via oxidation reactions. These PAH modification products are in many cases more toxic than their parent compounds. In this study, anthracene (ANT), a rapidly photooxidized PAH, was irradiated with simulated solar radiation (SSR, 100 μmol m-2 s- 1) in aqueous solution to examine the photomodification pathway. The photoproducts formed were identified by HPLC. The ANT product profile after 9 h in SSR was very complex, with more than 20 compounds detected. The photoproducts formed were anthraquinones, benzoic acids, benzaldehydes and phenols showing the process to be oxidative in nature. Some of the anthraquinones were themselves subject to photooxidation, and were thus intermediates in the product pathway. The kinetics of ANT photooxidation revealed a pseudo first-order reaction with a half-life of 2 h under the SSR source used. The kinetics of product formation allowed deduction of a probable photomodification pathway. This study indicates that PAH photooxidation products are likely to exist as complex, dynamically changing mixtures in PAH contaminated aquatic environments.
- Mallakin, Ali,George Dixon,Greenberg, Bruce M.
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p. 1435 - 1441
(2007/10/03)
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- Ring-chain tautomerism. Part 10 +. The reaction of oxocarboxylic acids with diazodiphenylmethane
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The rate coefficients for the esterification of a series of oxocarboxylic acids with diazodiphenylmethane have been determined in ethanol or 2-methoxyethanol at 30.0°C. These and the rates of reaction with model compounds have been used to estimate the equilibrium constants for ring-chain tautomerism for the oxocarboxylic acids.
- Bowden, Keith,Misic-Vukovic, Milica M.,Ranson, Richard J.
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p. 1601 - 1606
(2007/10/03)
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- Prodrugs - Part 2. Acylbenzoate esters of metronidazole
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The design and synthesis of a series of chain and cyclic acylbenzoate esters of metronidazole are described. The esters are designed to be both lipophilic and reactive in their hydrolysis reactions. The alkaline hydrolyses of the chain 2-acylbenzoates are relatively rapid, employing an intramolecular catalytic route, while the reactions of the 4-formylbenzoate and cyclic 2-formylbenzoate are also relatively rapid using the normal pathway. The anti-bacterial activity of the esters are comparable to that of metronidazole.
- Bowden,Izadi
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p. 995 - 1000
(2007/10/03)
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- Reactions of carbonyl compounds in basic solutions. Part 24. 1 The mechanism of the base-catalysed ring fission of substituted benzocyclobutene-1,2-diones
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The rate coefficients for the base-catalysed ring fission of a series of substituted benzocyclobutenediones to give the corresponding 2-formylbenzoic acids have been determined in water at 25.0 and 60.0°C. The effects of 4-substituents and 4,5-di-substituents on the rates have been correlated using a modified Hammett equation to give a reaction constant, ρ, equal to ca. 3.6 at 25.0°C. The activation parameters have been calculated. The effect of solvent composition on the rates has been studied. The kinetic solvent isotope effect, product composition and enrichment in 18O-enriched water have also been studied. All the evidence indicates a mechanistic pathway which proceeds by rapid reversible addition of hydroxide anion to the dione, followed by intramolecular nucleophilic attack on the second carbonyl group and formation of a carbanionic intermediate.
- Bowden, Keith,Horri, M. Vahid
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p. 989 - 992
(2007/10/03)
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- Reactions of carbonyl compounds in basic solutions. Part 28. The alkaline hydrolysis of 2-formylbenzonitrile, N-(2-formyl and -acetylphenyl)acetamides, N-(2-formylphenyl)-substituted benzamides, 4-(2-formylbenzoyl)morpholine, 3-(4-morpholino)- and -(N-methylanilino)-phthalides and -na
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Rate coefficients have been measured for the alkaline hydrolysis of 2-formylbenzonitrile 1, N-(2-formyl and -acetylphenyl)acetamides 2, N-(2-formylphenyl)-3-substituted benzamides 3, 4-(2-formylbenzoyl)morpholine 4, 3-(4-morpholino)- and -(N-methylanilino)-phthalides 5 and -naphthalides 6 in 70percent (v/v) dioxane-water at various temperatures.The enthalpies and entropies of activation have been evaluated.The hydrolysis of the nitrile is second order in base and that of the amides is first order in base.The relative rates of hydrolysis, activation parameters and substituent effects have been used to suggest the mechanisms of the reactions.Intramolecular catalysis by the neighbouring carbonyl group occurs in the alkaline hydrolysis of 1-4.The alkaline hydrolysis of 5 and 6 is rapid due to their lactone structures.
- Bowden, Keith,Hiscocks, Simon P.,Reddy, M. Komal
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p. 1133 - 1138
(2007/10/03)
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- Intermediates for the preparation of 1-(phenyl)-1-hydroxy-2-amino-3-fluoro propane derivatives
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A process for preparing a D-threo compound of the formula wherein R, and R1 have the meanings shown in the description, via protection of both the secondary hydroxy and the amino group of a corresponding D-threo 1-(phenyl)-2-amino-1,3-propanediol, fluorination of the protected compound and treatment of the thus obtained compound to afford a D-threo compound of the formula (II).
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- Poly(oxyalkylene) substituted xanthene colorant and method for making the same
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A diamino-xanthene colorant is provided having the following structure: STR1 where Y is a poly(oxyalkylene) substituent having a straight or branched polymer chain of at least 3 monomer units selected from ethylene oxide, propylene oxide, butylene oxide and glycidol; R1 and R2 are independently selected from H, C1-C4 alkyl, C1-C4 alkoxy, Cl, Br and I; X is selected from H, SO3 --, CO2 -- and COOR3, where R3 is C1-C4 alkyl or aryl; and each Z is independently selected from SO3 --, CO2 --, COOR4, Cl and OH, where R4 is C1-C4 alkyl or aryl, and n is 0, 1, or 2; the colorant is synthesized by condensing two moles of an N,N-bis(poly(oxyalkylene))-p-methoxyaniline and o-formylbenzene sulfonic acid.
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- Process for nucleophilic fluoroalkylation of aldehydes
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Aryl difluoromethyl sulfone adds to alkehydes under phase transfer conditions to give novel substituted alcohols of the general formula wherein R is an aryl, cycloaliphatic, sec- or tert-aliphatic, or heterocyclic group and Ar is an aryl group. The substituted alcohols of formula I are of particular utility as intermediates in the synthesis of a variety of useful end products. For example, the products of formula I may be utilized in desulfonylation reactions, oxidation reactions and fluorination reactions.
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- Nucleophilic Addition to Diazaquinones. Formation and Breakdown of Tetrahedral Intermediates in Relation to Luminol Chemiluminescence
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Nucleophilic addition to diazaquinones 2 was shown to occur at the carbonyl group.The rate constants and activation parameters for this process were determined with a large number of nucleophiles.The kinetics was rationalized in term of an equilibrium reaction between the reactants and a tetrahedral intermediate followed by the latter's breakdown.With some nucleophiles the enthalpy of activation for this process was found to be essentially zero.These cases were interpreted by assuming the formation of the tetrahedral intermediate to be the rate-determining step in the consumption of the diazaquinone.The complete mechanism of hydrolysis, azidolysis, and perhydrolysis were investigated.The stoichiometries were found to be 2a + H2O -> 2-formylbenzoic acid + N2 2a + HN3 -> phtalimide + 2N2 2a + H2O2 -> o-phthalic acid + N2 The breakdown kinetics of the tetrahedral intermediate of 2 with H2O2 was determined by chemiluminescence measurements while the lifetimes of the corresponding adducts of OH- and N3- were estimated from experiment.The initial additions of OH- and N3- were shown to generate acyldiazene species.The lattern were prone to further nucleophilic addition of OH- or N3- to the acyldiazene group.This second addition is also proposed to proceed via a tetrahedral intermediate the breakdown of which is exothermic involving the expulsion of N2.In the hydrolysis this step yields the end product (2-formyl benzoate) while in the azidolysis a second expulsion of N2 occurs which is followed by ring closure and tautomerization to yield the phthalimide.The neutral breakdown of the H2O2 adduct of 2 yields ground-state phthalate while its OH--catalyzed rupture leads to chemiexcitation.The latter process is proposed to involve as an intermediate an acyldiazene peracid anion.This species is prone to intramolecular nucleophilic addition to yield the cyclic tetrahedral intermediate.The breakdown of the latter through the expulsion of N2 generates an antiaromatic endoperoxide which transforms into excited phthalate in a pericyclic process.
- Merenyi, Gabor,Lind, Johan,Eriksen, Trygve E.
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p. 7716 - 7726
(2007/10/02)
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- Synthesis and Reactions of 2,3-Dihydro-oxazoloisoindol-5(9bH)-ones
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The synthesis and reactions with nucleophiles of 2,3-dihydro-oxazoloisoindol-5(9bH)-ones are described.
- Wharton, Clifford J.,Wrigglesworth, Roger
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p. 809 - 814
(2007/10/02)
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