- Substituent and Surfactant Effects on the Photochemical Reaction of Some Aryl Benzoates in Micellar Green Environment?
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In this study, we carried out preparative and mechanistic studies on the photochemical reaction of a series of p-substituted phenyl benzoates in confined and sustainable micellar environment. The aim of this work is mainly focused to show whether the nature of the surfactant (ionic or nonionic) leads to noticeable selectivity in the photoproduct formation and whether the electronic effects of the substituents affect the chemical yields and the rate of formation of the 5-substituted-2-hydroxybenzophenone derivatives. Application of the Hammett linear free energy relationship (LFER) on the rate of formation of benzophenone derivatives, on the lower energy band of the UV-visible absorption spectra of the aryl benzoates and 5-substituted-2-hydroxybenzophenone derivatives allows a satisfactory quantification of the substituent effects. Furthermore, UV-visible and 2D-NMR (NOESY) spectroscopies have been employed to measure the binding constant Kb and the location of the aryl benzoates within the hydrophobic core of the micelle. Finally, TD-DFT calculations have been carried out to estimate the energies of the absorption bands of p-substituted phenyl benzoates and 5-substituted-2-hydroxybenzophenone derivatives providing good linear correlation with those values measured experimentally.
- Siano, Gastón,Crespi, Stefano,Bonesi, Sergio M.
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p. 1298 - 1309
(2021/05/07)
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- Selectivity in the photo-fries rearrangement of some aryl benzoates in green and sustainable media. Preparative and mechanistic studies
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Irradiation of a series of p-substituted aryl benzoates under N2 atmosphere in homogeneous and micellar media was investigated by means of steady-state condition and of time-resolved spectroscopy. A notable selectivity in favor of the 2-hydroxybenzophenone derivatives was observed in micellar media. The benzophenone derivatives were the main photoproduct. On the other hand, in homogeneous media (cyclohexane, acetonitrile, and methanol) the observed product distribution was entirely different, viz. substituted 2-hydroxybenzophenones, p-substituted phenols, benzyl and benzoic acid were found. The binding constants in the surfactant were also measured and NOESY experiments showed that the aryl benzoates were located in the hydrophobic core of the micelle. Laser flash photolysis experiments led to the characterization of both p-substituted phenoxy radical and substituted 2-benzoylcyclohexadienone transients in homogeneous and micellar environment.
- Siano, Gastón,Bonesi, Sergio M.,Crespi, Stefano,Mella, Mariella
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p. 4338 - 4352
(2019/05/01)
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- [4 + 2]-Cycloaddition and 1,4-Addition of ortho-Quinone Methides by a Chiral Crotyl Silane
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Anhydrous FeCl3 in the presence of 2,6-lutidine promotes the substrate-controlled enantioselective [4 + 2]-cycloaddition and crotylation reaction between an enantioenriched (S,E)-crotyl silane and in situ generated ortho-quinone methides (oQMs)
- Wong, Christopher R.,Hummel, Gerald,Cai, Yongqi,Schaus, Scott E.,Panek, James S.
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supporting information
p. 32 - 35
(2019/01/04)
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- Nusbiarylins, a new class of antimicrobial agents: Rational design of bacterial transcription inhibitors targeting the interaction between the NusB and NusE proteins
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Discovery of antibiotics of a novel mode of action is highly required in the fierce battlefield with multi-drug resistant bacterial infections. Previously we have validated the protein-protein interaction between bacterial NusB and NusE proteins as an unp
- Qiu, Yangyi,Chan, Shu Ting,Lin, Lin,Shek, Tsun Lam,Tsang, Tsz Fung,Zhang, Yufeng,Ip, Margaret,Chan, Paul Kay-sheung,Blanchard, Nicolas,Hanquet, Gilles,Zuo, Zhong,Yang, Xiao,Ma, Cong
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- Copper catalyzed oxidative deamination of Betti bases: An efficient approach for benzoylation/formylation of naphthols and phenols
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An efficient route for benzoylation or formylation of naphthols/phenols is developed via oxidative deamination of Betti bases. A copper salt catalyst with TBHP as an oxidant is used. Water is used as a reagent as well as solvent. The reaction proceeds through a regioselective radical pathway. Most importantly, the position of acylation is unambiguous. The method is also applicable to non-hydroxy substrates.
- Deb, Mohit L.,Pegu, Choitanya Dev,Borpatra, Paran J.,Baruah, Pranjal K.
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p. 40552 - 40559
(2016/05/24)
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- Direct C-H bond arylation of 2-hydroxybenzaldehydes with arylboronic acids via ligand-free palladium catalysis
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A mild and efficient ligand-free palladium-catalyzed direct C-H bond arylation reaction was developed to afford 2-hydroxybenzophenones in good to excellent yields from easily available 2-hydroxybenzaldehydes and arylboronic acids. The given reaction provided one of the easiest pathways for accessing 2-hydroxybenzophenones, and a variety of functional groups could be tolerated in this process.
- Weng, Fei,Wang, Chengming,Xu, Bin
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supporting information; experimental part
p. 2593 - 2596
(2010/07/04)
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- One-step reaction of friedel-crafts acylation and demethylation of aryl-methyl ethers catalyzed by ytterbium(III) triflate
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Catalytic amount of ytterbium(III) inflate [Yb(OTf)3] has been used to catalyze Friedel-Crafts acylation and demethylation of aryl-methyl ethers in one-step reaction to produce hydroxyacylphenones with moderate yields under mild conditions.
- Su, Weike,Jin, Can
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p. 4199 - 4205
(2007/10/03)
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- Preparation of hydroxybenzophenones using silica-gel supported ferric chloride
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The synthesis of commercially important hydroxybenzophenones by condensing phenols with benzotrichloride has been reported. Benzoylation is catalyzed by silica supported ferric chloride under solvent-free conditions. Hydroxybenzophenones are isolated in low to moderate yields.
- Bendale, Pravin M.,Khadilkar, Bhushan M.
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p. 1738 - 1739
(2007/10/03)
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- Fries rearrangement at atmospheric pressure using microwave irradiation
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A very safe, fast and practical Fries rearrangement with conventional AlCl3 catalyst, carried out in a modified domestic microwave oven at atmospheric pressure is reported.
- Khadilkar, Bhushan M.,Madyar, Virendra R.
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p. 1195 - 1200
(2007/10/03)
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- Hydroxylation of Nitroarenes with Alkyl Hydroperoxide Anions via Vicarious Nucleophilic Substitution of Hydrogen
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Rhone-Poulenc Polska Ltd., ul. Grzybowska 80/82, 00-844 Warszawa, Poland Garbo- and heterocyclic nitroarenes react with anions of tert-butyl and cumyl hydroperoxides in the presence of strong bases to form substituted o- and p-nitrophenols. The reaction usually proceeds in high yields and is of practical value as a method of synthesis and manufacturing of nitrophenols. Orientation of the hydroxylation can be controlled to a substantial extent by selection of the proper conditions. Basic mechanistic features of this process were clarified.
- Makosza, Mieczyslaw,Sienkiewicz, Krzysztof
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p. 4199 - 4208
(2007/10/03)
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- Structure-activity relationships of novel azomethine prodrugs of the histamine H3-receptor agonist (R)-α-methylhistamine: From alkylaryl to substituted diaryl derivatives
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This study was performed on the basis of recently developed prodrugs of the histamine H3-receptor agonist (R)-α-methylhistamine (1) to determine structure-activity relationships of azomethine prodrugs of 1, in which the primary amine functionality is bioreversibly linked to aromatic ketones. Therefore, the pro-moiety was systematically altered from alkylaryl over benzylaryl to diaryl substitution. Those compounds that emerged to be stable enough during preparation were tested for their in vitro hydrolysis rates. Apparently, bulky alkyl residues were capable of preventing previously observed intramolecular cyclization, but the obtained azomethines 12 a-c were far too unstable to serve as prodrugs. However, the benzylaryl imines 12d, e were stable compounds, but 12d decomposed too rapidly under in vitro conditions. Distinctly greater stability was provided by diaryl pro-moieties, even if strongly electron-withdrawing functionalities were introduced. Selected compounds were also tested in vivo following p.o. application to mice. Particularly the trifluoromethyl substituted imine 12i proved to be highly effective as stability and rate of conversion were well-balanced, so that brain penetration of 1 was strikingly facilitated. Thus 12i, a highly potent azomethine prodrug, may serve as an important pharmacological tool and, possibly, a therapeutic agent.
- Krause,Rouleau,Stark,Garbarg,Schwartz,Schunack
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p. 720 - 726
(2007/10/03)
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- Palladium-catalyzed coupling reaction of salicylaldehydes with aryl iodides via cleavage of the aldehyde C-H bond
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It has been found that the cross-coupling reaction of salicylaldehydes with aryl iodides smoothly proceeds by using a catalyst system of PdCl2/LiCl in the presence of Na2CO3 as base to give the corresponding 2-aroylphenols in good yields, which appears to involve cleavage of the aldehyde C-H bond.
- Satoh, Tetsuya,Itaya, Tomoaki,Miura, Masahiro,Nomura, Masakatsu
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p. 823 - 824
(2007/10/03)
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- Pyrimidinedione derivatives and antiarrhythmic agents containing same
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Pyrimidinedione derivatives of the formula: STR1 wherein R1 and R2 is so linked with each other as to make an alkylene chain and thus form a heterocyclic structure, A, R3, R4, X1, X2 and X3 are substituents, respectively, and n is 2 or 3 have a basic backbone in which a phenyl group part and a pyrimidinedione part are linked by a structure comprising an alkyl chain and a heterocyclic ring having two nitrogen atoms. These compounds are useful for a medical treatment of cardiac arrhythmias.
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- Vicarious Nucleophilic Hydroxylation of Aromatic Nitro Compounds with Organic Hydroperoxides
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Nitrobenzene, α-nitronaphthalene, m-dinitrobenzene, 1,3,5-trinitrobenzene, m-nitrobenzophenone, m-nitrobenzonitrile, methyl m-nitrobenzoate and m-nitro diphenylsulphone can be hydroxylated with cumene or tert-butyl hydroperoxide in dipolar aprotic solvents in the presence of strong bases.The hydroxyl group is introduced preferably in p-position to the nitro group.Attempts to hydroxylate benzophenone, anthraquinone, 2-ethyl anthraquinone, anthraquinone 2-sulphonate, benzonitrile and diphenyl sulphone under the same conditions failed. 1-Nitroanthraquinone delivered 1-hydroxy, 1,2-dihydroxy and 1,4-dihydroxy anthraquinone.
- Brose, Thomas,Holzscheiter, Felix,Mattersteig, Gunter,Pritzkow, Wilhelm,Voerckel, Volkmar
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p. 497 - 504
(2007/10/02)
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- Pyrimidinedione compounds, method of producing the same and antiarrythmic agents containing the same
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A pyrimidinedione derivative compound has a basic backbone in which a phenyl group part and a pyrimidinedione part are linked by a structure comprising an alkyl chain containing at least two nitrogen atoms. The pyrimidinedione derivative is useful for a medical treatment of cardiac arrhythmias.
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- Reactivity of Aromatic o-Hydroxy Oximes. I. Synthesis and Aminolysis of Acylglycine Esters of Aromatic o-Hydroxy Oximes
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Active esters (1) of glycine with o-hydroxybenzaldehyde oxime, o-hydroxyacetophenone oxime, o-hydroxybenzophenone oxime, and their 5-Cl and 5-NO2 derivatives were prepared by several methods.For aminolysis with benzylamine, esters 1 show higher reactivity than similar esters containing no hydroxyl group in the ortho position.It is suggested that esters 1 forms an intramolecular hydrogen bond between the hydrogen of the hydroxyl group at the ortho position and the hydroxyimino nitrogen so as to have its carbonyl group activated for the aminolysis; this mechanism of activation seems to be a sort of "intramolecular acid-catalysis." Among the series of esters 1, esters of o-hydroxybenzaldehyde oxime and its 5-Cl and 5-NO2 derivatives are most reactive in the aminolysis.The reactivity of esters 1 is also discussed in relation to pKa values of aromatic o-hydroxy oximes.
- Hayashi, Ikuo,Ogihara, Keizo,Shimizu, Kiyoshi
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p. 2432 - 2437
(2007/10/02)
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- 4-Phenyl-1,3-benzodioxans
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Substituted 2-aminomethyl-4-phenyl-1,3-benzodioxans and derivatives thereof have been found to possess valuable anticonvulsant and antiarrhythmia activity in mammals. For example, cis-6-chloro-2-methylaminomethyl-4-phenyl-1,3-benzodioxan hydrochloride possesses potent anticonvulsant activity while cis-2-isopropylaminomethyl-4-phenyl-1,3-benzodioxan hydrochloride has potent antiarrhythmia activity.
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