- A facile and regioselective synthesis of 1-tetralones via silver-catalyzed ring expansion
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A regioselective synthesis of 1-tetralones via silver-catalyzed ring expansion is described. A variety of 1-tetralones are furnished under mild reaction conditions from tertiary cyclobutanols regardless of the electronic properties and steric hindrance of substituents, providing a new and practical method to access diverse 1-tetralone building blocks. Preliminary experimental and DFT studies revealed that a radical-mediated sequence of C-C bond cleavage/C-C bond formation is involved.
- Yu, Jiajia,Zhao, Huijun,Liang, Shuguang,Bao, Xiaoguang,Zhu, Chen
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- 1,3-BENZODITHIOLIUM ION MEDIATED ANNULATIONS
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A mild and selective method for cyclizations onto aromatic systems using 1,3-benzodithiolium ions is described.
- Rigby, James H.,Kotnis, Atul,Kramer, James
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- AN IMPROVED PREPARATION OF VINYL IODIDES
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The oxidation of ketone hydrazones by iodine in the presence of a base to furnish vinyl iodides has been considerably improved.The three factors responsible are (1) absence of water, (2) the use of strong guanidine bases and (3) inverse addition.
- Barton, Derek H. R.,Bashiardes, George,Fourrey, Jean-Louis
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- Intermolecular Oxidative Radical Addition to Aromatic Aldehydes: Direct Access to 1,4- and 1,5-Diketones via Silver-Catalyzed Ring-Opening Acylation of Cyclopropanols and Cyclobutanols
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A novel silver-catalyzed ring-opening acylation of cyclopropanols and cyclobutanols is described. The reaction proceeds under mild and neutral conditions and provides a facile access to nonsymmetric 1,4- and 1,5-diketones in promising yields with broad substrate scope. Mechanistic studies including DFT calculations suggest the involvement of an uncommon water-assisted 1,2-HAT process, which is strongly exothermic and thus promotes addition of carbon radicals to aldehydes. In contrast to traditional reductive radical addition protocols, this work represents the first example of the intermolecular oxidative radical addition to aldehydes, thus offering a novel strategy for the direct synthesis of acyclic ketones from readily accessible aldehydes.
- Che, Chao,Qian, Zhaosheng,Wu, Mingchang,Zhao, Ying,Zhu, Gangguo
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- Chemoselective oxidation of benzylic alcohols with solid supported CrO3/TBHP under microwave irradiation
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The efficient use of microwave energy coupled with dry media technique for the oxidation of benzylic alcohols using catalytic CrO3 and TBHP has been effectively projected.
- Singh,Sharma,Chhibber,Kaur,Kad
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- An Expeditious Synthesis of 8-Methoxy-1-tetralone
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8-Methoxy-1-tetralone was synthesized in a concise and efficient manner involving a sequential palladium-mediated cross-coupling reaction (Heck), catalytic hydrogenation, and intramolecular acylation mediated by Eaton's reagent or Lewis acids. The pivotal step in the synthesis was the use of a bromine substituent at the benzenoid C4 position of the intermediate methyl 4-arylbutyric ester to ensure cyclization ortho to the methoxy moiety and obviate cyclization at the para position to the thermodynamically preferred 6-methoxy-1-tetralone, the sole product obtained in the absence of this blocking group.
- Castillo-Rangel, Norma,Pérez-Díaz, José Oscar H.,Vázquez, Alfredo
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- A new method for the conversion of enol phenyl thioethers to ketones
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Exposure of enol thioethers at ambient temperature to in situ-generated hydrogen iodide in acetonitrile containing mercuric chloride gives rise to ketones in yields ranging from 74-87%.
- Grieco, Paul A.,Dai, Yujia
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- PRACTICAL CHROMIUMVI OXIDE-CATALYZED BENZYLIC OXIDATIONS USING 70percent TERT-BUTYLHYDROPEROXIDE
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In using 70percent t.BuOOH and catalytic amounts of chromic anhydride, benzylic methylene groups are oxidized at room temperature to carbonyl functions in fair yields.
- Muzart, Jacques
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- Selective electrochemical oxidation of aromatic hydrocarbons and preparation of mono/multi-carbonyl compounds
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A selective electrochemical oxidation was developed under mild condition. Various mono-carbonyl and multi-carbonyl compounds can be prepared from different aromatic hydrocarbons with moderate to excellent yield and selectivity by virtue of this electrochemical oxidation. The produced carbonyl compounds can be further transformed into α-ketoamides, homoallylic alcohols and oximes in a one-pot reaction. In particular, a series of α-ketoamides were prepared in a one-pot continuous electrolysis. Mechanistic studies showed that 2,2,2-trifluoroethan-1-ol (TFE) can interact with catalyst species and generate the corresponding hydrogen-bonding complex to enhance the electrochemical oxidation performance. [Figure not available: see fulltext.]
- Li, Zhibin,Zhang, Yan,Li, Kuiliang,Zhou, Zhenghong,Zha, Zhenggen,Wang, Zhiyong
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p. 2134 - 2141
(2021/09/29)
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- Mechanical metal activation for Ni-catalyzed, Mn-mediated cross-electrophile coupling between aryl and alkyl bromides
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Liquid-assisted grinding has been successfully applied to eliminate the requirements of chemical activators and anhydrous solvents in nickel-catalyzed, manganese-mediated cross-electrophile coupling between aryl and alkyl bromides. In addition to the traditional reaction parameters, mechanical ones,e.g.the rotational speed of mill, the filling degree of jar and ball size, have been found to affect the catalytic efficiency remarkably, implying the involvement of the regeneration of nickel(0) species in the rate-determining steps. A combined evaluation of the reaction and mechanical parameters led to an optimal condition under which a variety ofn-alky aromatics with various functional groups could be readily obtained in good yields with a 1 mol% catalyst loading. The practical application of liquid-assisted grinding-enabled aryl/alkyl cross-electrophile coupling has been demonstrated in the gram-scale synthesis of 6-methoxytetralone.
- Wu, Sisi,Shi, Weijia,Zou, Gang
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supporting information
p. 11269 - 11274
(2021/07/02)
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- Regioselective Electrochemical Cyclobutanol Ring Expansion to 1-Tetralones
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A mild electrochemical method for the regioselective preparation of 1-tetralones under environmentally friendly conditions from readily available cyclobutanols was developed. A series of aromatic- and heteroaromatic-fused 1-tetralones was accessed through ring expansion of the functionalized cyclobutanols via electrochemical generation of alkoxy radicals and intramolecular cyclization.
- Petti, Alessia,Natho, Philipp,Lam, Kevin,Parsons, Philip J.
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p. 854 - 858
(2021/01/12)
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- Highly selective electrocatalytic oxidation of benzyl C-H using water as safe and sustainable oxygen source
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The selective oxidation of C-H bond is critical for feedstock manufacturing in chemical industry. Current strategies typically involve the use of oxygen or peroxide as the oxidation reagent under high temperature, which sets severe challenges in production sustainability and industrial safety. Herein, we demonstrate an environmental-friendly and safe electrocatalytic strategy for the selective oxidation of benzyl group to ketones at ambient conditions, while using water as the sole oxygen source. Water addition reduces the onset potential of anodic C-H oxidation, and produces 1-tetralone with satisfying conversion and excellent ketone to alcohol ratio. Layered MnO2 catalysts (with rich oxygen vacancies) further adjust the water affinity and facilitate the oxidation, leading to a significantly improved faradaic efficiency. This journal is
- Ding, Mengning,Li, Xiaoshan,Sun, Yuxia,Xie, Jin,Xu, Wentao,Yang, Miao
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supporting information
p. 7543 - 7551
(2020/11/18)
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- Green Organic Solvent-Free Oxidation of Alkylarenes with tert-Butyl Hydroperoxide Catalyzed by Water-Soluble Copper Complex
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Different benzylic compounds were efficiently oxidized to the corresponding ketones with aqueous 70% tert-butyl hydroperoxide (TBHP) and the catalytic system composed of CuCl2.2H2O and 2,2'-biquinoline-4,4'-dicarboxylic acid dipotassium salt (BQC). The catalytic system CuCl2/BQC/TBHP allows obtaining high yields at room temperature under organic solvent-free conditions. The interest of this system lies in its cost effectiveness and its benign nature towards the environment. Benzylic tertbutylperoxy ethers and benzylic alcohols were observed and suggested as the reaction intermediates. Analysis of organic products by atomic absorption did not show any contamination with copper metal. In terms of efficiency, CuCl2/BQC system is comparable or superior to the most of the catalytic systems described in the literature and which are based on toxic organic solvent.
- Ajjou, Abdelaziz Nait,Rahman, Ateeq
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p. 165 - 174
(2020/04/15)
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- Mild Deprotection of Dithioacetals by TMSCl/NaI Association in CH3CN
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A mild process using a combination of TMSCl and NaI in acetonitrile is used to regenerate carbonyl compounds from a variety of dithiane and dithiolane derivatives. This easy to handle and inexpensive protocol is also efficient to deprotect oxygenated and mixed acetals as 1,3-dioxanes, 1,3-dioxolanes and 1,3-oxathianes quantitatively. As a possible extension of this method, it was also shown that nitrogenated substrates such as hydrazones, N-tosylhydrazones, and ketimines reacted well under these conditions to give the expected ketones in high yields. The methodology proposed herein is a good alternative to the existing methods since it does not use metals, oxidants, reducing agents, acidic or basic media, and keto-products were obtained in high to excellent yields.
- Yao, Yunxin,Zhao, Guangkuan,Hamze, Abdallah,Alami, Mouad,Provot, Olivier
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supporting information
p. 5775 - 5779
(2020/08/17)
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- Ruthenium-Catalyzed Dehydrogenation of Alcohols with Carbodiimide via a Hydrogen Transfer Mechanism
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Ruthenium-catalyzed oxidative dehydrogenation of alcohols using carbodiimide as an efficient hydrogen acceptor has been developed. The protocol exhibits wide substrate scope with good to excellent yields. The results of the kinetic analysis indicated that the reaction mechanism includes the hydrogen transfer process and that the addition of carbodiimide is essential for the reaction system, and the resulting amidine also could react as a hydrogen acceptor.
- Sueki, Shunsuke,Matsuyama, Mizuki,Watanabe, Azumi,Kanemaki, Arata,Katakawa, Kazuaki,Anada, Masahiro
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p. 4878 - 4885
(2020/06/02)
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- Decarboxylative Intramolecular Arene Alkylation Using N-(Acyloxy)phthalimides, an Organic Photocatalyst, and Visible Light
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An intramolecular arene alkylation reaction has been developed using the organic photocatalyst 4CzIPN, visible light, and N-(acyloxy)phthalimides as radical precursors. Reaction conditions were optimized via high-throughput experimentation, and electron-rich and electron-deficient arenes and heteroarenes are viable reaction substrates. This reaction enables access to a diverse set of fused, partially saturated cores which are of high interest in synthetic and medicinal chemistry.
- Sherwood, Trevor C.,Xiao, Hai-Yun,Bhaskar, Roshan G.,Simmons, Eric M.,Zaretsky, Serge,Rauch, Martin P.,Knowles, Robert R.,Dhar, T. G. Murali
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p. 8360 - 8379
(2019/09/03)
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- Intramolecular Büchner reaction and oxidative aromatization with SeO2 or O2
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Intramolecular Büchner reaction of 1-diazo-5-phenylpentan-2-ones followed by oxidation with SeO2 or O2 in the presence of silica gel regioselectively gave 8-formyl-1-tetralones or one-carbon-lacking 1-tetralones, respectively.
- Morita, Shunya,Yoshimura, Tomoyuki,Matsuo, Jun-ichi
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p. 729 - 732
(2019/07/31)
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- Chemoselective oxidation and deprotection of para-methoxybenzylic position with (diacetoxyiodo)benzene in acetic-trifluoroacetic acid
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(Diacetoxyiodo)benzene in the presence of acetic–trifluoroacetic acid in THF has been developed for the chemoselective para-methoxybenzylic C–H bond oxidation to provide aryl carbonyl compounds at room temperature. The reaction condition is also applicable for the chemoselective deprotection of para-methoxybenzyl (PMB) ether in the presence of benzyl ether.
- Lin, Chun-Yu,Yang, Ping-Shin,Chou, Pang-Yu,Ong, Chi Wi
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p. 365 - 367
(2018/01/01)
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- Copper-Catalyzed Oxidative Cleavage of Electron-Rich Olefins in Water at Room Temperature
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A copper-catalyzed oxidative cleavage of electron-rich olefins into their corresponding carbonyl derivatives is described as an alternative to ozonolysis. The scope includes various precursors to aryl ketone derivatives, as well as oxidations of enol ethers bearing atypical alkyl and dialkyl substitution, the first of their kind among such metal catalyzed alkene cleavage reactions. The use of an inexpensive copper salt, room temperature conditions, an aerobic atmosphere, and water as the global reaction medium highlight the green features of this new method. Associated mechanistic investigations are also presented.
- Lippincott, Daniel J.,Trejo-Soto, Pedro J.,Gallou, Fabrice,Lipshutz, Bruce H.
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supporting information
p. 5094 - 5097
(2018/09/13)
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- Benzylic C(sp3)-H Functionalization for C-N and C-O Bond Formation via Visible Light Photoredox Catalysis
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A visible light mediated highly selective benzylic C-H bond functionalization for intermolecular C-N and C-O bond formation is reported. This cross-dehydrogenative coupling reaction demonstrates a straightforward protocol for incorporating the heteroaromatics to the benzylic position. Benzylic oxidation of various alkyl aryls to corresponding carbonyl compounds has also been reported.
- Pandey, Ganesh,Laha, Ramkrishna,Singh, Deepak
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p. 7161 - 7171
(2016/08/30)
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- Photocatalytic oxidation of benzyl alcohols by three-dimensional reduced graphene oxide/nano zinc oxide catalyst under visible light
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A three-dimensional reduced graphene oxide/nano zinc oxide (3D-RGO/ZnO) composite photocatalyst has been prepared through an in situ reduction of GO and growth of nano ZnO particles process. The 3D-RGO/ZnO catalyst displayed enhanced photocatalytic activity towards commercial ZnO nanoparticles and can be applied to the oxidation of a broad series of benzyl alcohols including primary and secondary alcohols to corresponding carbonyl compounds under the irradiation of visible light. A plausible photocatalytic mechanism referring to photo electron generation and transfer has been proposed.
- Wang, Yuxiang,Zhang, Xianlong,Wang, Lihua,Chen, Youjian
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p. 727 - 730
(2016/01/26)
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- Borontribromide-mediated C-C bond formation in cyclic ketones: A transition metal free approach
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Borontribromide (BBr3) is a well-known demethylating agent. The current investigation was focused on a new application of borontribromide as a C-C bond forming agent in cyclic ketones. In this study, borontribromide mediated C-C bond formation reactions of tetralones, chromenone, thiochromenone and indanones were explored. A methoxy group containing ketones showed selective C-C bond formation reaction instead of demethylation of the methoxy group. MM2 steric energy calculations for the final products showed that the reaction favored the formation of exo- or endo-cyclic double bond containing products, depending upon their low MM2 steric energy in a specific frame structure, as observed in X-ray crystallography. A comprehensive crystallographic and pi-stacking analysis of product 10a demonstrated the formation of 10a as an enantiomeric mixture, and its centre of inversion was stabilized by a set of three unique pi-pi interactions.
- Ahmad, Imran,Pathak, Vinay,Vasudev, Prema G.,Maurya, Hardesh K.,Gupta, Atul
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p. 24619 - 24634
(2014/07/07)
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- 2-Iodoxybenzenesulfonic acid-catalysed oxidation of primary and secondary alcohols with oxone in cetyl trimethylammonium bromide micelles at room temperature
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A mild and green protocol for alcohol oxidation using 2-iodoxybenzene sulfonic acid/oxone at room temperature in CTAB micelles has been developed. Typically, secondary benzyl alcohols were oxidised to ketones and primary benzyl alcohols to aldehydes in good yields in 2 h. Under harsher conditions (100 °C/24 h), aliphatic alcohols were oxidised to ketones or organic acids in moderate to high yields.
- Liu, Yangyang,Wang, Boliang
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p. 427 - 431
(2014/08/05)
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- The oxidation of alcohols with O-iodoxybenzoic acid (IBX) in aqueous nanomicelles at room temperature
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GMPGS-2000, a nonionic amphiphile composed of Guerbet alcohol (2-octyldodecan-1-ol), MPEG-2000 and succinic acid, has been prepared as an effective nanomicelle forming species for the oxidation of alcohols with 2-iodoxybenzoic acid (IBX) in water at room temperature.
- Xie, Aming,Zhou, Xiangxiang,Feng, Liandong,Hu, Xinyu,Dong, Wei
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p. 3514 - 3519
(2014/05/06)
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- Donor functionalized ruthenium N-heterocyclic carbene complexes in alcohol oxidation reactions
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N-Pyridyl, N′-amido functionalized imidazolium bromides were obtained in high yields as an N-heterocyclic carbene (NHC) precursor and used as bidentate or a pincer ligands to obtain ruthenium complexes via a silver NHC transmetallation route. The incorporation of a phenyl group as an amido-N substituent (R = Ph) results in a bidentate coordination mode through the C NHC and Npyridyl donors, whereas in its absence (R = H) a pincer coordination mode was observed through the Npyridyl^C NHC^Oamido donors. The ruthenium complex featuring a pincer type NCO coordination mode with a protic NH function adjacent to the coordinating Oamido atom was found to efficiently catalyse the oxidation of activated alcohols effecting quantitative conversions within 30 minutes. However the oxidation of deactivated alcohols required longer reaction times to effect the quantitative transformation. This journal is the Partner Organisations 2014.
- Naziruddin, Abbas Raja,Zhuang, Chun-Shiuan,Lin, Wan-Jung,Hwang, Wen-Shu
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p. 5335 - 5342
(2014/04/03)
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- AlCl3·6H2O/KI/CH3CN/H 2O: An efficient and versatile system for chemoselective C-O bond cleavage and formation of halides and carbonyl compounds from alcohols in hydrated media
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AlCl3·6H2O/KI/CH3CN/H 2O, an efficient and versatile system, cleaves the C-O bonds of esters, acetals, ethers, and oxathiolanes to the corresponding acids, alcohols, and carbonyl compounds chemoselectively at 80°C in hydrated media with good yields. This system also converts the alcohols (primary/secondary) to halides and oxidizes the alcohols (primary/secondary) to the corresponding carbonyl compounds in the presence of DMSO. Copyright Taylor & Francis Group, LLC.
- Gogoi, Pranjal,Konwar, Dilip,Sharma, Saikat Das,Gogoi, Prodip Kumar
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p. 1259 - 1264
(2007/10/03)
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- An efficient deprotection of dithioacetals to carbonyls using Oxone-KBr in aqueous acetonitrile
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A simple and efficient method has been developed for the chemoselective dethioacetalization of dithioacetals to aldehydes and ketones using Oxone-KBr in aqueous acetonitrile at room temperature.
- Desai,Pore,Tamhankar,Jadhav,Wadgaonkar
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p. 8559 - 8561
(2007/10/03)
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- Surfactant/I2/water: An efficient system for deprotection of oximes and imines to carbonyls under neutral conditions in water
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(Chemical Equation Presented) I2/surfactant/water system deprotecting oximes and imines to the corresponding carbonyl compounds under neutral conditions in water at 25-40°C with very high to excellent yields.
- Gogoi, Pranjal,Hazarika, Parasa,Konwar, Dilip
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p. 1934 - 1936
(2007/10/03)
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- Benzylic oxidation catalyzed by dirhodium(II,III) caprolactamate
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(Chemical Equation Presented) Dirhodium caprolactamate [Rh 2(cap)4] is an effective catalyst for benzylic oxidation with tert-butyl hydroperoxide (TBHP) under mild conditions. Sodium bicarbonate is the optimal base additive for substrate conversion. Benzylic carbonyl compounds are readily obtained, and a formal synthesis of palmarumycin CP 2 using this methodology is described.
- Catino, Arthur J.,Nichols, Jason M.,Choi, Hojae,Gottipamula, Sidhartha,Doyle, Michael P.
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p. 5167 - 5170
(2007/10/03)
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- Transition-metal- and organic-solvent-free: A highly efficient anaerobic process for selective oxidation of alcohols to aldehydes and ketones in water
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A new system, I2-KI-K2CO3-H2O, selectively oxidized alcohols to aldehydes and ketones under anaerobic condition in water at 90°C with excellent yields. The process is green, mild and inexpensive. The Royal Society of Chemistry 2005.
- Gogoi, Pranjal,Konwar, Dilip
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p. 3473 - 3475
(2007/10/03)
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- DMSO/N2H4·H2O/I2/H 2O/CH3CN: A new system for selective oxidation of alcohols in hydrated media
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A new alternative system for the oxidation of secondary alcohols to ketones with DMSO/N2H4·H2O/I2/H 2O/CH3CN in hydrated media has been developed. The system also selectively oxidizes the secondary alcoholic groups to the corresponding ketones in the presence of primary alcoholic groups present within the same molecule in moderate to very good yields at reflux temperature.
- Gogoi, Pranjal,Sarmah, Gautam Kumar,Konwar, Dilip
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p. 5153 - 5154
(2007/10/03)
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- PCC-mediated novel oxidation reactions of homobenzylic and homoallylic alcohols
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A new PCC-mediated carbon-carbon bond cleavage reaction during oxidation of homobenzylic alcohols leading to the formation of benzylic carbonyl compounds has been observed. Homobenzylic alcohols with no benzylic substitution (R1=H) gave benzylic aldehydes without further oxidation, while those with benzylic substitution (R1=Me, Et, Ar) gave benzylic ketones. In contrast, homoallylic alcohols gave products arising from double bond migration, cis- to trans-olefin isomerization and/or allylic oxidation.
- Fernandes, Rodney A.,Kumar, Pradeep
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p. 1275 - 1278
(2007/10/03)
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- Deoximation and dehydrazonation of ketoximes and ketophenylhydrazones by wet HMT in solid state under microwave conditions
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A time and energy efficient process of generation of ketones from oximes and phenylhydrazones is reported under microwave irradiation utilising inexpensive and easily available reagent - hexamethylenetetramine under solvent-free condition with high yields.
- Karchaudhuri, Nilay,De, Aparna,Mitra, Alok Kumar
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p. 1537 - 1539
(2007/10/03)
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- Intramolecular addition of acyldiazenecarboxylates onto double bonds in the synthesis of heterocycles
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Appropriate aryl-substituted unsymmetrical azodicarbonyl compounds, generated from bishydrazides by oxidation, undergo intramolecular cyclisations to furnish a variety of useful heterocycles such as N-substituted oxindoles, carbostyrils, benzazepinones, benzazocinones, benzimidazolones, benzoxazinones and pyrazolones in varying degrees of efficiency. Methods are described to remove the N-acyl groups from the heteroaromatic compounds. Under mildly acidic conditions where equal opportunities are available for an ipso or a normal cyclisation it is the former process that occurs preferentially. Evidence is presented in favour of a C-to-C migration in the ipso product for the formation of a methoxy-substituted carbostyril derivative. One of the spiro substances is shown to participate in dienone-phenol rearrangement to provide the corresponding quinolone-phenol in high yield.
- Prata, Jose V.,Clemente, Dina-Telma S.,Prabhakar, Sundaresan,Lobo, Ana M.,Mourato, Isabel,Branco, Paula S.
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p. 513 - 528
(2007/10/03)
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- A convenient oxidative demasking of 1,3-dithiolanes and dithianes to carbonyl compounds with TBHP
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Regeneration of carbonyl compounds from their 1,3-dithiolanes and dithianes was achieved using tert-butyl hydroperoxide (TBHP, aq. 70%) in high yields. Thus, an efficient, economical and experimentally simple protocol for dethioacetalization has been demonstrated.
- Barhate, Nivrutti B,Shinde, Popat D,Mahajan, Vishal A,Wakharkar, Radhika D
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p. 6031 - 6033
(2007/10/03)
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- 3,5-Dimethylpyrazolium fluorochromate(VI), C5H8N2H[CrO3F], (DmpzHFC): A convenient new reagent for oxidation of organic substrates
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A new chromium(VI) reagent, 3,5-dimethylpyrazolium fluorochromate, C5H8N2H[CrO3F] (DmpzHFC), has been developed by reacting dmpz with CrO3 and aqueous HF for the selective oxidation of primary, secondary and allylic alcohols to the corresponding carbonyl compounds, polycyclic hydrocarbons to cyclic ketones and allylic Δ5-steroids to the corresponding α,β-unsaturated ketones.
- Bora, Upasana,Chaudhuri, Mihir K,Dey, Deepa,Kalita, Dipak,Kharmawphlang, Wancydora,Mandal, Gagan C
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p. 2445 - 2448
(2007/10/03)
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- Process for the preparation of aldehydes and ketones
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A process for the preparation of vinyl, alkynyl or aryl aldehydes or vinyl, alkynyl or aryl ketones includes reacting vinyl-, alkynyl- and aryl- and -methylene compounds with the aid of a mediator and an oxidant, wherein the mediator is selected from the group of the aliphatic, heterocyclic or aromatic NO or NOH containing compounds.
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- Regeneration of ketones from semicarbazones in the solid state on wet silica supported sodium bismuthate under microwave irradiation
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Microwave irradiation of ketosemicarbazones on wet silica supported sodium bismuthate under environmentally benign solvent-free condition provides a fast, efficient and simple method for regeneration of ketones in good yields.
- Mitra, Alok Kumar,De, Aparna,Karchaudhuri, Nilay
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p. 320 - 321
(2007/10/03)
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- PYRIMIDINE DERIVATIVES
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The disclosed pyrimidine derivatives, and pharmaceutically acceptable salts thereof, exhibit useful pharmacological properties, in particular use as 5HT 2C-antagonists. The invention is also directed to formulations and methods for treatment.
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- Regeneration of ketones from oximes in solid state on wet silica supported sodium bismuthate under microwave irradiation
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Microwave irradiation of ketoximes on wet silica supported sodium bismuthate under environmentally friendly solvent-free condition provides a fast, efficient and simple method for regeneration of ketones in high yields.
- Mitra, Alok Kumar,De, Aparna,Karchaudhuri, Nilay
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p. 1345 - 1346
(2007/10/03)
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- Heterogeneous Permanganate Oxidations. 7. the Oxidation of Aliphatic Side Chains
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Alkylbenzene side chains are oxidized at the benzylic position when treated under heterogeneous conditions with permanganate adsorbed on a solid support. The products are alcohols if the benzylic carbon is tertiary, or ketones if it is secondary. Carbon-carbon bond cleavage, which usually occurs when these same compounds are oxidized by permanganate under homogeneous conditions, does not occur. A unique selectivity is observed for the oxidation of derivatives of indane, 1, and tetralin, 2, in which one of the methylenes is replaced by an oxygen. If the oxygen is in the α-position, no reaction occurs; if it is in the β-position, good yields of the corresponding lactone are obtained. A mechanism consistent with the observed selectivity has been proposed.
- Noureldin, Nazih A.,Zhao, Dongyuan,Lee, Donald G.
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p. 8767 - 8772
(2007/10/03)
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- A mild and efficient method for selective cleavage of ketals and acetals using lithium chloride in water - Dimethyl sulfoxide
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A mild anil efficient neutral aqueous method for selective cleavage of acetals and ketals to the corresponding carbonyl compounds has been established by using LiCI in H2O-DMSO at elevated temperature. While aryl and α,β-unsaturated ketals and acetals underwent smooth cleavage, diaryl, non-aryl and isolated ketals and acetals remained unaffected under the reaction conditions.
- Mandal, Pijus Kumar,Dutta, Pinak,Roy, Subhas Chandra
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p. 7271 - 7274
(2007/10/03)
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- Deblocking of dithioacetals and oxathioacetals using periodic acid under mild nonaqueous conditions
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A novel method for the deblocking of the dithioacetals and oxathioacetals is described. Periodic acid under nonaqueous conditions has been used for the deprotection of the dithio- and oxathio-derivatives to the corresponding carbonyl compounds. This simple high-yield transformation is conveniently carried out in nonaqueous medium and works well with complex sensitive aldehydes and in the presence of other protective groups.
- Shi, Xiao-Xin,Khanapure, Subhash P.,Rokach, Joshua
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p. 4331 - 4334
(2007/10/03)
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- An unusual C-C bond cleavage with chromium VI reagents: Oxidation of primary alcohols to ketones
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Oxidation of 1-hydroxymethylindanes and 1-hydroxymethyltetralins with PDC or PCC in methylene chloride affords 1-indanones and 1-tetralones.
- Bijoy,Subba Rao
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p. 2701 - 2708
(2007/10/02)
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- Electron Transfer Activation - A Selective Photooxidation Method for the Preparation of Aromatic Adehydes and Ketones
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A selective and mild photocatalytic procedure for benzylic oxydations with 9,10-dicyanoanthracene (DCA), an usual electron acceptor, in presence of methyl viologen (MV2+) and FeCl2 has been developped.Key words: Singlet Electron Transfer; benzylic oxidation; hydroperoxides
- Santamaria, Jean,Jroundi, Rachid
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p. 4291 - 4294
(2007/10/02)
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- Intramolecular Aromatic Substitution with Bisthiocarbocations. Variations of Lewis Acid, Solvent and Orthothio Substituents
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The effects of Lewis acid, solvent and orthothio substituent have been examined with regard to intramolecular electrophilic aromatic substitution (annulation) with bisthiocarbocations.A suspension of silver trifluoromethanesulfonate in dichloromethane, creating bis(arylthio)carbocations, was found to be the most effective for annulation of six-membered rings.
- Gamage, Swarna A.,Smith, Robin A. J.
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p. 815 - 824
(2007/10/02)
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- 1,3-Benzodithiolium Cation Mediated Cyclization Reactions
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General protocols for the construction of various ring systems employing cation olefin cyclizations initiated by the readily accessible 1,3-benzodithiolium ion are described.Several substituted tetralones and tetralins can be rapidly assembled by this methodology as can a variety of substituted bicyclooctane and tricyclic ring systems.The products of these transformations are amenable to interconversion into a range of functionalized species.
- Rigby, James H.,Kotnis, Atul,Kramer, James
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p. 5078 - 5088
(2007/10/02)
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- BIMETALLIC OXIDATION CATALYSTS: OXIDATIONS WITH TERT.BUTYLHYDROPEROXIDE MEDIATED BY BIS-(TRIBUTYLTIN OXIDE) DIOXOCHROMIUM (VI)
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At 40-80 deg C, t.BuOOH in conjunction with catalytic amounts of (n.Bu3SnO)2CrO2 1 oxidizes benzylic alcohols, methylenes in α-position of aryl, ethylenic or acetylenic groups into ketones, anthracene into anthraquinone, adamantane into adamantan-1-ol and 2-one.Except for propargylic oxidations, yields are generally superior to those obtained when CrO3 is used as catalyst instead of 1.
- Muzart, Jacques
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p. 2061 - 2068
(2007/10/02)
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- Mechanism of an Interesting Ring-Contraction Reaction of a Class of Carbocyclic trans-Dibromides and Stereoisomeric Bromohydrins through Solvolysis
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An efficient ring contraction of the trans-dibromides and the bromohydrins (1a-f) through solvolysis under neutral conditions to the aldehydes (3a-d) in good to excellent yields is reported.The role of substituent, influence of stereochemistry, and the effect of ring size on the case of this interesting ring contraction reaction are clearly demonstrated from the results, tabulated in Table 1; a probable mechanism for ring contraction is presented.
- Mandal, Asok N.,Bhattacharya, Sudin,Raychaudhuri, Swadesh R.,Chatterjee, Amareshwar
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p. 2856 - 2876
(2007/10/02)
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