- Visible-light-induced selective aerobic oxidation of sp3 C-H bonds catalyzed by a heterogeneous AgI/BiVO4 catalyst
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An efficient oxidation of sp3 C-H bonds to esters and ketones has been developed using AgI/BiVO4 as the photocatalyst and O2 as the oxidant in water. Various substrates can be transformed into the desired esters and ketones in moderate to good yields. The synthetic utility of this approach has been demonstrated by gram-level experiments and consecutive oxidation experiments. A plausible mechanism has been proposed.
- Jiang, Li-Ya,Ming, Jing-Jing,Wang, Lian-Yue,Jiang, Yuan-Yuan,Ren, Lan-Hui,Wang, Zi-Cheng,Cheng, Wen-Chen
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supporting information
p. 1156 - 1163
(2020/03/11)
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- Synthesis and Characterization of Acridinium Dyes for Photoredox Catalysis
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Photoredox catalysis is a rapidly evolving platform for synthetic methods development. The prominent use of acridinium salts as a sustainable option for photoredox catalysts has driven the development of more robust and synthetically useful versions based on this scaffold. However, more complicated syntheses, increased cost, and limited commercial availability have hindered the adoption of these catalysts by the greater synthetic community. By utilizing the direct conversion of a xanthylium salt into the corresponding acridinium as the key transformation, we present an efficient and scalable preparation of the most synthetically useful acridinium reported to date. This divergent strategy also enabled the preparation of a suite of novel acridinium dyes, allowing for a systematic investigation of substitution effects on their photophysical properties.
- White, Alexander R.,Wang, Leifeng,Nicewicz, David A.
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p. 827 - 832
(2019/04/25)
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- Methyl group transfer upon gas phase decomposition of protonated methyl benzoate and similar compounds
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Gas phase decompositions of protonated methyl benzoate and its conjugates have been studied by using electrospray ionization-collision induced dissociation-tandem mass spectrometry. Loss of CO2 molecule, thus transfer of methyl group, has been observed. In order to better understand this process, the theoretical calculations have been performed. For methyl benzoate conjugates, it has been found that position of substituent affects the loss of CO2 molecule, not the electron donor/withdrawing properties of the substituent. Therefore, electrospray ionization-mass spectrometry in positive ion mode may be useful for differentiation of isomers of methyl benzoate conjugates.
- Frański, Rafa?,Gierczyk, B?a?ej,Zalas, Maciej,Jankowski, Wojciech,Hoffmann, Marcin
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p. 379 - 384
(2018/05/14)
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- Solvent- and Metal-free Oxidative Esterification of Aromatic Aldehydes Using Urea-2,2-dihydroperoxypropane as a New Solid Oxidant
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Urea-2,2-dihydroperoxypropane as a noble and solid gem-dihydroperoxide derivative was used to transform various aromatic aldehydes to their corresponding benzoate derivatives in the presence of HBr under mild conditions at room temperature in high yields and short reaction times.
- Khosravi, Kaveh,Khalaji, Kobra,Naserifar, Shirin
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p. 303 - 309
(2017/03/27)
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- The dual role of ionic liquid BmimBF4, precursor of N-heterocyclic carbene and solvent, in the oxidative esterification of aldehydes
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Room temperature ionic liquid BmimBF4 (1-butyl-3- methylimidazolium tetrafluoroborate) has been utilized in the N-heterocyclic carbene-catalyzed oxidation of aldehydes to yield esters. In the presence of MnO2 as oxidant and of DBU and caesium carbonate as bases, aromatic, heteroaromatic and aliphatic esters have been isolated in good to excellent yields. The recyclability of the used ionic liquid along with the excess of inorganic reagents has been proved. The simple and cheap BmimBF4 ionic liquid played the dual role of precatalyst and solvent. This is the first time that such a reaction has been carried out with an ionic liquid as solvent.
- Chiarotto, Isabella,Feroci, Marta,Sotgiu, Giovanni,Inesi, Achille
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p. 8088 - 8095
(2013/08/23)
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- 5-ALKYNYL-PYRIMIDINES
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The present invention encompasses compounds of general formula (1) wherein R1 to R3 are defined as in claim 1, which are suitable for the treatment of diseases characterised by excessive or abnormal cell proliferation, and the use thereof for preparing a medicament having the above-mentioned properties.
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Page/Page column 17
(2012/02/06)
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- An oxidation of benzyl methyl ethers with NBS that selectively affords either aromatic aldehydes or aromatic methyl esters
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Either mono- or dibromination of benzyl methyl ethers can be achieved by controlling the amount of NBS and the temperature. Elimination of methyl bromide from the monobrominated intermediates produces aromatic aldehydes, whereas hydrolysis of the dibrominated intermediates affords aromatic methyl esters in good yields.
- Mayhoub, Abdelrahman S.,Talukdar, Arindam,Cushman, Mark
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experimental part
p. 3507 - 3510
(2010/08/06)
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- Electroreduction of organic compounds, 36 [1]. Electroreduction of chlorinated methyl benzoates
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The preparative electroreduction of the three methyl monochlorobenzoates, the six methyl dichlorobenzoates, and methyl 2,3,4-trichlorobenzoate in different solvent-supporting electrolytes (SSE) was studied. The rate of the dechlorination, which is the main reaction, is dependent on the substitution pattern. Pronounced regioselectivity is therefore observed in case of the oligochloro derivatives. Hydrogenation of the benzene ring and reduction of the methoxycarbonyl group with formation of a hydroxymethyl group are observed as side-reactions. Quantum chemical calculations on the reaction mechanism were performed. The theoretical results are in accordance with the experimental observations.
- Gassmann, Joerg,Voss, Juergen
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experimental part
p. 1291 - 1299
(2009/06/19)
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- CYCLIC COMPOUNDS
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There is provided a CRF receptor antagonist comprising a compound of the formula (I): A-W-Ar wherein, A is a group represented by the formula (A1) or (A2) (wherein, ring Aa is a 5-or 6-membered ring which may be further substituted; ring Ab is a 5-or 6-membered ring which may be further substituted; ring Ac is a 5- or 6-membered ring which may be substituted; R1 is optionally substituted alkyl, substituted amino, substituted hydroxy, etc.; X is carbonyl, -O-, -S-, etc.; Y1, Y2 and Q are independently optionally substituted carbon or nitrogen; … is a single or double bond); W is a bond, optionally substituted methylene, optionally substituted imino, -O-, -S-, etc.; Ar is optionally substituted aryl or optionally substituted heteroaryl; or a salt thereof or a prodrug thereof.
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Page/Page column 305
(2010/02/14)
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- Nucleophilic catalysis with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) for the esterification of carboxylic acids with dimethyl carbonate
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1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) is an effective nucleophilic catalyst for carboxylic acid esterification with dimethyl carbonate (DMC). The reaction pathway of this new class of nucleophilic catalysis has been studied. A plausible, multistep mech
- Shieh, Wen-Chung,Dell, Steven,Repic, Oljan
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p. 2188 - 2191
(2007/10/03)
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- Large scale microwave-accelerated esterification of carboxylic acids with dimethyl carbonate
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An environmentally friendly process for the esterification of carboxylic acids with dimethyl carbonate can be accelerated by employing a combined strategy: using 1,8-diazabicyclo[5,4,0]undec-7-ene (DBU) as the catalyst (chemical means) and microwave as the energy source (physical means). This approach provides synthetic advantages, niches, and upscalability.
- Shieh, Wen-Chung,Dell, Steven,Repi?, Oljan
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p. 5607 - 5609
(2007/10/03)
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- Relative reactivity of methyl iodide to ethyl iodide in nucleophilic substitution reactions in acetonitrile and partial desolvation accompanying activation
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Through the examination of empirical correlations involving activation parameters for nucleophilic substitution of methyl iodide and of ethyl iodide, nucleophiles have been classified into three series: (1) nucleophiles with two equivalent reaction sites, (2) nucleophiles with a chlorine atom in the para-position, and (3) nucleophiles with a single reaction site. Three types of partial desolvation processes accompanying activation have been deduced on the basis of these classifications. A major factor determining the relative reactivity of methyl iodide to ethyl iodide in the substitution reaction of an anionic nucleophile having a single reaction site in acetonitrile (kMeI/kEtI) is suggested to be partial desolvation around the nucleophilic center on going from reactant to transition-state.
- Kondo, Yasuhiko,Urade, Miyuki,Yamanishi, Yukari,Chen, Xinyu
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p. 1449 - 1454
(2007/10/03)
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- Natural formation of chlorobenzoic acids (CBA) and distinction between PCB-degraded CBA
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Mono- and dichlorobenzoic acid (CBA) could be found in samples of remote bog pond water and sediment. The 2,4-CBA always had the highest concentrations. In bog water samples the concentrations ranged between 0.11 and 0.48 μg/l. Besides 2,4-CBA most only 2,5-CBA could be found as dichlorobenzoic acid. In all samples we could detect also trichloroacetic acid (TCAA). The TCAA concentrations correlate with the CBA concentrations. As TCAA is known as a naturally produced organohalogen, this correlation can be seen as an indication to a natural formation of CBA. A confirmation of this presumption is our detection CBA in a reaction of benzoic acid with the chlorinating enzyme chloroperoxidase (CPO).
- Niedan,Schoeler
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p. 1233 - 1241
(2007/10/03)
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- KINETICS OF METHANOLYSIS OF 1-(2-HALOGENO AND 2,6-DIHALOGENOBENZOYL)-3-(4-CHLOROPHENYL)UREAS
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The methanolysis kinetics has been measured of 1-(2,6-difluorobenzoyl)-3-(4-chlorophenyl)urea (a larvicidal insecticide Dimilin) and of four other mono- and dihalogenobenzoyl derivatives.Polar and steric effects of halogen on the rate and dissociation constants is discussed.
- Kavalek, Jaromir,Kacetl, Lubomir,Kavalkova, Marcela
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p. 1363 - 1369
(2007/10/02)
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- Quantitative Determination of Compounds in Mixtures by B2E=Constant Linked Scans
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The B2E=constant linked scan is shown to be an excellent tool for quantifications with reversed geometry mass spectrometers.Deuterium-labelled analogues may be used as internal standards, thus providing very simple clean-up procedures.The principle is demonstrated with the example of chloro-substituted benzoic acid methyl esters.Possible interferences arising from isotope peaks are discussed.The method is applied to the quantification of caffeine in beverages.
- Walther, Hansjoerg,Schlunegger, Urs Peter,Friedli, Felix
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p. 572 - 575
(2007/10/02)
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