- Pummerer and Related Rearrangements in 2-Acyl-1,3-Dithiane 1-Oxides
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syn- and anti-2-Acyl-2-alkyl-1,3-dithiane 1-oxides, when treated with trifluoroacetic anhydride, undergo either an unexpected Pummerer rearrangement or equilibration in near quantitative yield, depending upon the reaction conditions; 2-acyl-1,3-dithiane 1
- Page, Philip C. Bulman,Shuttleworth, Stephen J.,McKenzie, Michael J.,Schilling, Mark B.,Tapolczay, David J.
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- Catalyst-Free and Transition-Metal-Free Approach to 1,2-Diketones via Aerobic Alkyne Oxidation
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A catalyst-free and transition-metal-free method for the synthesis of 1,2-diketones from aerobic alkyne oxidation was reported. The oxidation of various internal alkynes, especially more challenging aryl-alkyl acetylenes, proceeded smoothly with inexpensive, easily handled, and commercially available potassium persulfate and an ambient air balloon, achieving the corresponding 1,2-diketones with up to 85% yields. Meanwhile, mechanistic studies indicated a radical process, and the two oxygen atoms in the 1,2-diketons were most likely from persulfate salts and molecular oxygen, respectively, rather than water.
- Shen, Duyi,Wang, Hongyan,Zheng, Yanan,Zhu, Xinjing,Gong, Peiwei,Wang, Bin,You, Jinmao,Zhao, Yulei,Chao, Mianran
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p. 5354 - 5361
(2021/05/05)
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- Visible light-induced aerobic oxidation of diarylalkynes to α-diketones catalyzed by copper-superoxo at room temperature
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We have developed the visible light induced simple copper(ii) chloride catalyzed oxidation of diarylacetylenes to α-diketones by molecular oxygen at room temperature. The in situ generated copper(ii)-superoxo complex is a light-absorbing species that oxidizes inert diarylacetylenes to α-diketones. In contrast to reported photochemical processes, the current oxidation protocol does not require any exogenous photocatalyst or radical initiator. The green chemistry metrics evaluation signifies that the E-factor for the current oxidation process is ~2.3 times better than that of reported photochemical processes. The current reaction scores 63 on the EcoScale of 0-100, indicating an adequate synthesis process. Thus, the overall oxidation process is simple, environmentally benign, and economically feasible. This journal is
- Charpe, Vaibhav Pramod,Hwang, Kuo Chu,Sagadevan, Arunachalam
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supporting information
p. 4426 - 4432
(2020/08/10)
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- Ancillary ligands switch the activity of Ru–NHC-based oxidation precatalysts
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Herein we demonstrate how the inner-sphere coordinating ligands switch the activity of Ru–NHC-based oxidation precatalysts in the oxidative conversion of olefins to carbonyl compounds, with the help of a series of systematically varied imidazolydene-NHC (Im-NHC) and triazolydene-NHC (Tz-NHC)-based ruthenium(II)-complexes. It is shown that the catalytic activity of the para-cymene-containing precatalysts varies in the order of [(Tz-NHC)Ru(para-cymene)Cl]+ > [(Im-NHC)Ru(para-cymene)Cl]+, while the order of activity of the MeCN-containing precatalysts is found to be reversed, i.e., [(Im-NHC)Ru(MeCN)4]2+ > [(Tz-NHC)Ru(MeCN)4]2+. Along with the electronic influence of the NHC ligands, the effect of the lability of the para-cymene and MeCN ligands, and the overall charge of the complexes might be attributed toward such a switching of catalytic activity. This finding led to develop a new precatalyst with improved activity which was further utilized in selective oxidation of a series of styrene substrates containing other oxidation-sensitive functionalities.
- Gupta, Suraj K.,Mandal, Tanmoy,Gangber, Tejaswinee,Singh, Vivek,Choudhury, Joyanta
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- Visible light promoted continuous flow photocyclization of 1,2-diketones
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The continuous flow Norrish-Yang photocyclization of 1,2-diketones has been developed and used for the synthesis of a large number of functionalized 2-hydroxycyclobutanones, under blue light irradiation and employing acetone as a solvent. This eco-friendly procedure represents a valid alternative to the reactions carried out in batches thus reducing the reaction times, the formation of secondary products and simplifying the purification steps. The use of differently substituted diketone compounds has allowed us to obtain a wide range of 2 and 3-functionalized cyclobutanones, thus allowing the evaluation of the scope and limitations of this procedure.
- Frongia, Angelo,Luridiana, Alberto,Porcu, Stefania,Ricci, Pier Carlo,Secci, Francesco
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supporting information
p. 3684 - 3689
(2020/06/03)
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- ICl/AgNO3 Co-catalyzed radical oxidation of diaryl- A nd alkylarylalkynes into 1,2-diketones
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A novel ICl/AgNO3 co-catalyzed radical oxidation of diaryl- A nd alkylarylalkynes into 1,2-diketones is reported. The reaction proceeded smoothly under mild conditions and generated 1,2-diketones in moderate to good yields with a good tolerance of functional groups. Furthermore, the obtained C4-(1,2-diketoaryl)isoxazoles could react smoothly with 1,2-diaminobenzene to form C4-(3-arylquinoxalin-2-yl)isoxazoles. At last, a new one-pot strategy for the synthesis of quinoxalines from 1,2-diphenylethynes and 1,2-diaminobenzene is also reported.
- Yang, Wen,Chen, Yu,Yao, Yongqi,Yang, Xin,Lin, Qifu,Yang, Dingqiao
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p. 11080 - 11090
(2019/09/09)
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- Coordination Booster-Catalyst Assembly: Remote Osmium Outperforming Ruthenium in Boosting Catalytic Activity
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Presented herein is a set of bimetallic and trimetallic “coordination booster-catalyst” assemblies in which the coordination complexes [RuII(terpy)2] and [OsII(terpy)2] acted as boosters for enhancement of the catalytic activity of [RuII(NHC)(para-cymene)]-based catalytic site. The boosters accelerated the oxidative loss of para-cymene from the catalytic site to generate the active catalyst during the oxidation of alkenes and alkynes into corresponding aldehydes, ketones and diketones. It was found that the boosting efficiency of the [OsII(terpy)2] units was considerably higher than its congener [RuII(terpy)2] unit in these assemblies. Mechanistic studies were conducted to understand this unique improvement.
- Mandal, Tanmoy,Singh, Vivek,Choudhury, Joyanta
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supporting information
p. 4774 - 4779
(2019/11/11)
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- Magnetic magnetite nanoparticals catalyzed selective oxidation of Α-hydroxy ketones with air and one-pot synthesis of benzilic acid and phenytoin derivatives
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A clean and efficient protocol for selective oxidation of α-hydroxy ketones using magnetic magnetite nanoparticals (Fe3O4·MNPs) as catalyst with air as green oxidant has been developed. Application of Fe3O4·MNPs was also proved to be successful in one-pot synthesis of benzilic acid and phenytoin derivatives. The facile one-pot procedure enhanced the production efficiency, shortened the reaction time and minimized the chemical waste. Notably, the catalyst can be reused at least for five times without any appreciable loss of its activity.
- Li, Xiaona,Xia, Dandan,Wen, Zhiyong,Gong, Bowen,Sun, Maolin,Wu, Yue,Zhang, Jie,Sun, Jun,Wu, Yang,Bao, Kai,Zhang, Weige
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- Acid-catalyzed synthesis of functionalized arylthio cyclopropane carbaldehydes and ketones
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A general strategy for the synthesis of arylthio cyclopropyl carbaldehydes and ketones via a Br?nsted acid catalyzed arylthiol addition/ring contraction reaction sequence has been exploited. The procedure led to a wide panel of cyclopropyl carbaldehydes in generally high yields and with broad substrate scope. Mechanistic aspects and synthetic applications of this procedure were investigated.
- Porcu, Stefania,Luridiana, Alberto,Martis, Alberto,Frongia, Angelo,Sarais, Giorgia,Aitken, David J.,Boddaert, Thomas,Guillot, Regis,Secci, Francesco
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supporting information
p. 13547 - 13550
(2019/01/06)
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- Preparation method of 1,2-diketone derivative
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The invention discloses a preparation method of a 1,2-diketone derivative. The method comprises the step of enabling a raw material 1,3-diketone derivative to react with a cheap and easily obtained industrial product 2,2,6,6-tetramethyl-1-piperidinyloxy under the catalysis of copper so as to obtain the product 1,2-diketone derivative. According to the preparation method, the 1,3-diketone derivative is used as an initiator, and the raw material is easy to obtain and wide in variety; by utilizing the preparation method, the obtained product types are varied, can be directly used, and can be used for other further reactions; in addition, the reagent dosage in the reaction is less, the pollution is reduced, and the production cost is lowered; moreover the reaction conditions are mild, the reaction operation and the after-treatment process are simple, the reaction time is short, the yield is high, and the preparation method is suitable for industrial production.
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Paragraph 0030
(2016/10/08)
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- Palladium-Catalyzed Oxidative Synthesis of α-Acetoxylated Enones from Alkynes
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We report a palladium-catalyzed oxidative functionalization of alkynes to generate α-acetoxylated enones in one step. A range of functional groups are well-tolerated in this reaction. Mechanistic studies, including the use of 18O-labeled DMSO,
- Jiang, Tuo,Quan, Xu,Zhu, Can,Andersson, Pher G.,B?ckvall, Jan-E.
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supporting information
p. 5824 - 5828
(2016/05/09)
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- A remote coordination booster enhances the catalytic efficiency by accelerating the generation of an active catalyst
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A remote RuII(terpy)2 unit incorporated in conjugation with the [NHC-RuII(para-cymene)] catalytic site, acts as a "coordination booster" for enhancing the catalytic efficiency to achieve excellent performance in selective oxidative scission of various carbon-carbon multiple bonds to the corresponding aldehydes, ketones and diketones. Generation of an active catalyst via oxidative loss of para-cymene from the precatalyst was found to be accelerated by the "coordination booster" through the electronic effect.
- Gupta, Suraj K.,Choudhury, Joyanta
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supporting information
p. 3384 - 3387
(2016/03/01)
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- Dramatic Effect of Ancillary NHC Ligand in the Highly Selective Catalytic Oxidative Carbon-Carbon Multiple Bond Cleavage
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Selective and controlled oxidation of olefins to aldehydes is a commonly used important transformation in chemistry. However, chemists still use the dangerous and inconvenient ozonolysis method or the less selective, low-yielding Lemieux-Johnson protocol. In a program of developing effective catalysts for this important reaction, we disclose here that an ancillary ligand can play a dramatic role in the above catalytic phenomenon, depending on the design of the ligand precursor chosen. Proof-of-principle is demonstrated with the help of two newly designed [LnRuII-NHC] precatalysts (NHC = an imidazolydene-based NHC, Im-NHC, or a triazolydene-based NHC, Trz-NHC; Ln = para-cymene) for catalytic selective oxidation of olefins/alkynes to carbonyl compounds. With the electron-deficient Trz-NHC ligand, [(para-cymene)RuII(Im-Trz)]+ precatalyst was found to be an order of magnitude more efficient than the [(para-cymene)RuII(Im-NHC)]+ precatalyst.
- Gupta, Suraj K.,Sahoo, Sandeep K.,Choudhury, Joyanta
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supporting information
p. 2462 - 2466
(2016/08/16)
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- Organocatalytic multicomponent synthesis of polysubstituted pyrroles from 1,2-diones, aldehydes and arylamines
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We have developed an organocatalyzed three-component reaction of 1,2-diones, aldehydes and arylamines, which provides an efficient approach to access polysubstituted pyrroles. In the catalysis of 4-methylbenzenesulfonic acid monohydrate, the reactions of
- Zheng, Yin,Wang, Youming,Zhou, Zhenghong
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supporting information
p. 16652 - 16655
(2015/11/25)
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- Selective oxygenation of alkynes: A direct approach to diketones and vinyl acetate
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Arylalkynes can be converted into α-diketones with the use of a copper catalyst, and also be transformed into vinyl acetates under metal-free conditions, both in the presence of PhI(OAc)2 as an oxidant at room temperature. A series of substituted α-diketones were prepared in moderate to good yields. A variety of vinyl halides could be regio- and stereo-selectively synthesized under mild conditions, and I, Br and Cl could be all easily embedded into the alkynes. This journal is
- Xia, Xiao-Feng,Gu, Zhen,Liu, Wentao,Wang, Ningning,Wang, Haijun,Xia, Yongmei,Gao, Haiyan,Liu, Xiang
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supporting information
p. 9909 - 9913
(2015/01/09)
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- Enantioselective synthesis of 3,4-disubstituted cis- and trans-1,2,5-thiadiazolidine-1,1-dioxides as precursors for chiral 1,2-diamines
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Both, cis- and trans-3,4-disubstituted thiadiazolidines 5 and 6 can enantioselectively be obtained from thiadiazoles 2 which, in turn, are efficiently prepared from the respective 1,2-diketone by an improved protocol. An asymmetric ruthenium-catalyzed transfer hydrogenation followed by a diastereoselective hydride addition furnishes exclusively the cis-isomers 5 which, under acidic conditions, undergo a novel isomerization into the trans-isomers 6. These cyclic sulfamides can be transformed into 1,2-diamines as well as 2,3-diamino acids.
- Schüttler, Christian,Li-B?hmer, Zhen,Harms, Klaus,Von Zezschwitz, Paultheo
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supporting information
p. 800 - 803
(2013/04/24)
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- Pyrrolo[1,2-a]quinoxalines: Novel synthesis via annulation of 2-alkylquinoxalines
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In an attempt to synthesize a novel homoleptic complex 3 from 2-methyl-3-phenylquinoxaline 1 and Ir(acac)3 for application as a triplet emitter in OLEDs (organic light-emitting diodes) no cyclometalation was observed. Instead, an annulation to 1-methyl-4-phenylpyrrolo[1,2-a]quinoxaline 2 was observed. Since pyrroloquinoxalines are potentially bioactive and few paths for their synthesis are known, selected reactions and conditions were investigated, suggesting Ir(acac)3 as catalyst and proving glycerol to be a reactant.
- Ammermann, Sven,Hrib, Christian,Jones, Peter G.,Du Mont, Wolf-Walther,Kowalsky, Wolfgang,Johannes, Hans-Hermann
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supporting information
p. 5090 - 5093
(2013/01/15)
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- Catalytic oxidation of silyl enol ethers to 1,2-diketones employing nitroxyl radicals
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A novel and efficient method for the preparation of 1,2-diketones is reported. A series of -diketones were readily prepared by the nitroxyl-radical-catalyzed oxidation of silyl enol ethers using magnesium monoperoxyphthalate hexahydrate (MMPP6H) as the co-oxidant. Georg Thieme Verlag Stuttgart · New York.
- Hayashi, Masaki,Shibuya, Masatoshi,Iwabuchi, Yoshiharu
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experimental part
p. 1025 - 1030
(2012/06/04)
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- Direct carbo-acylation reactions of 2-arylpyridines with α-diketones via Pd-catalyzed C-H activation and selective C(sp2)-C(sp2) cleavage
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An efficient carbo-acylation reaction of 2-arylpyridines with α-diketones via Pd-catalyzed C-H bond activation and C-C bond cleavage in the presence of TBHP was developed that generated aryl ketones in good yields. The highly selective formation of aryl ketones was observed when 2-arylpyridines reacted with aromatic/aliphatic α-diketones.
- Zhou, Wei,Li, Hongji,Wang, Lei
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supporting information
p. 4594 - 4597
(2012/10/29)
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- Palladium-catalyzed carbonation-diketonization of terminal aromatic alkenes via carbon-nitrogen bond cleavage for the synthesis of 1,2-diketones
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A palladium-catalyzed carbonation-diketonization reaction of terminal alkenes via carbon-nitrogen bond cleavage under an atmosphere of oxygen has been developed. A series of 1,2-diketones were readily prepared from the reaction of aromatic terminal alkenes with nitroalkanes.
- Wang, Azhong,Jiang, Huanfeng,Li, Xianwei
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supporting information; experimental part
p. 6958 - 6961
(2011/10/02)
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- Iron-promoted C - C bond cleavage of 1,3-diketones: A route to 1,2-diketones under mild reaction conditions
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A conceptual method for the preparation of 1,2-diketones is reported. The selective C - C bond cleavage of 1,3-diketones affords the 1,2-diketones in high yields under mild reaction conditions in air by the use of FeCl3 as the catalyst and tert-butyl nitrite (TBN) as the oxidant without the use of solvent. The possible reaction mechanism is discussed. This protocol provides an expeditious route to the useful 1,2-diketones.
- Huang, Lehao,Cheng, Kai,Yao, Bangben,Xie, Yongju,Zhang, Yuhong
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experimental part
p. 5732 - 5737
(2011/08/22)
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- Enantioselective aerobic oxidation of α-hydroxy-ketones catalyzed by oxidovanadium(V) methoxides bearing chiral, N-salicylidene- tert -butylglycinates
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Chiral oxidovanadium(V) methoxides prepared from 3,5-disubstituted-N- salicylidene-l-tert-butylglycines and vanadyl sulfate in air-saturated MeOH serve as highly enantioselective catalysts for asymmetric aerobic oxidations and kinetic resolution of alkyl, aryl, and heteroaryl α-hydroxy-ketones with differed α-substituents at ambient temperature in toluene or TBME (tert-butyl methyl ether). The best scenarios involve the use of complexes which bear the tridendate templates derived from 3,5-diphenyl- or 3-o-biphenyl-5-nitro-salicyaldehyde. The kinetic resolution selectivities of the aerobic oxidation process are in the range of 12 to >1000 based on the selectivity factors (krel).
- Chen, Chien-Tien,Kao, Jun-Qi,Salunke, Santosh B.,Lin, Ya-Hui
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- New synthetic strategy for high-enantiopurity N-protected α-amino ketones and their derivatives by asymmetric hydrogenation
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Asymmetric hydrogenation of α-dehydroamino ketones catalyzed by a rhodium-chiral phosphorus ligand complex (up to 99% ee, 1000 TON), represents an efficient approach to chiral α-amino ketones. The reduction of α-amino ketones catalyzed by palladium on carbon (Pd/C) leads to amphetamine precursors with quantitative yield and no significant enantioselectivity loss.
- Sun, Tian,Hou, Guohua,Ma, Miaofeng,Zhang, Xumu
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p. 253 - 256
(2011/04/16)
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- Elemental iodine or diphenyl diselenide in the [bis(trifluoroacetoxy)iodo] benzene-mediated conversion of alkynes into 1,2-diketones
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Both elemental iodine and diphenyl diselenides, in the presence of [bis(trifluoroacetoxy)iodo]benzene (PIFA), promote the transformation of internal alkynes into the corresponding 1,2-diketones. The reactions carried out in the presence of iodine unfortunately did not proceed with complete conversion of the starting alkynes. On the other hand, diphenyl diselenide was more efficient and gave satisfactory transformation of the starting alkynes into 1,2-diketones in better yields. The structure of the vicinal dicarbonyl compounds were confirmed by applying a subsequent condensation reaction to construct the corresponding quinoxaline derivatives. Both elemental iodine and diphenyl diselenide in the presence of [bis(trifluoroacetoxy)iodo]benzene (PIFA) promote the transformation of internal alkynes into 1,2-diketones. The structure of the products were confirmed by transformation into the corresponding quinoxaline derivatives, two of which were studied by X-ray analysis. Copyright
- Tingoli, Marco,Mazzella, Mauro,Panunzi, Barbara,Tuzi, Angela
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experimental part
p. 399 - 404
(2011/02/28)
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- Direct synthesis of 1,2-diketones by catalytic aerobic oxidative decarboxylation of 1,3-diketones with iodine and base under irradiation of fluorescent light
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We report a catalytic direct synthesis of 1,2-diketone from 1,3-diketone through iodine/base-catalyzed aerobic photooxidation under visible-light irradiation of fluorescent lamp. Georg Thieme Verlag Stuttgart.
- Tada, Norihiro,Shomura, Motoki,Nakayama, Hiroki,Miura, Tsuyoshi,Itoh, Akichika
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experimental part
p. 1979 - 1983
(2010/10/03)
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- A convenient and practical approach to α-diketones via reactions of internal aryl alkynes with N-iodosuccinimide/water
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A convenient and practical approach to α-diketones via reactions of alkynes with N-iodosuccinimides/water at 70°C has been developed. Georg Thieme Verlag Stuttgart.
- Niu, Mingyu,Fu, Hua,Jiang, Yuyang,Zhao, Yufen
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experimental part
p. 2879 - 2882
(2009/04/06)
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- Selective oxidation of aryl ketones to α-diketones with 4-aminoperoxybenzoic acid supported on silica gel in presence of air
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4-Aminoperoxybenzoic acid supported on silica gel in presence of air was found to be a selective and convenient oxidant for the oxidation of methylene groups in aryl ketones to convert them to α-diketones. Springer-Verlag 2004.
- Ghazanfari, Dadkhoda,Najafizadeh, Fariba,Khosravi, Fereshteh
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p. 1409 - 1413
(2007/10/03)
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- A Highly Efficient Ruthenium-Catalyzed Rearrangement of α,β-Epoxyketones to 1,2-Diketones
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TpRuPPh3(CH3CN)2PF6 catalyzed the efficient rearrangement of α,β-epoxyketones to 1,2-diketones. Unlike a previously reported iron catalyst, the reaction in this case is applicable not only to 1,2-disubstituted epoxides but also to mono- and trisubstituted epoxides and tolerates oxygen functionalities. The sterically crowded and highly basic tris(1-pyrazolyl)borate (Tp) ligand of the ruthenium catalyst might account for its high selectivity toward 1,2-diketone rather than 1,3-diketone.
- Chang, Chia-Lung,Kumar, Manyam Praveen,Liu, Rai-Shung
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p. 2793 - 2796
(2007/10/03)
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- Rapid microwave-promoted solvent-free oxidation of α-methylene ketones to α-diketones
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A convenient and rapid method for the oxidation of α-methylene ketones to α-diketones has been described involving the reaction of pyridine N-oxide with α-nosyloxy ketone intermediates.
- Lee, Jong Chan,Park, Hong-Jun,Park, Jin Young
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p. 5661 - 5664
(2007/10/03)
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- Lewis acid assisted permanganate oxidations
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Lewis acids combine with permanganate in acetone solutions to form a complex that has enhanced oxidizing capabilities. The use of Lewis acids under these conditions to promote permanganate oxidations is superior to the use of Bronsted acids because the latter promote enolization of the solvent and subsequent unproductive reduction of the oxidant. The products obtained from a variety of alkenes, alkynes, arenes, sulfides, alcohols and ethers have been identified and probable reaction mechanisms proposed.
- Lai, Sheng,Lee, Donald G.
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p. 9879 - 9887
(2007/10/03)
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- Asymmetric reduction of α-keto esters and α-diketones with a bakers' yeast keto ester reductase
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Optically pure α-hydroxy esters and α-hydroxy ketones have been synthesized by the reduction of the corresponding ketones with a keto ester reductase isolated from bakers' yeast (YKER-I). The reduction of α-keto esters affords the corresponding (S)- or (R)-hydroxy esters selectively, where the stereochemical course depends on the chain length of the alkyl substituent on the carbonyl group. An α-keto short alkanoic ester affords the corresponding (S)-hydroxy ester, whereas a long alkanoate yields the corresponding (R)-hydroxy ester. The reduction of α-diketones affords the corresponding (S)-2-hydroxy ketones regio- and stereoselectively.
- Kawai, Yasushi,Hida, Kouichi,Tsujimoto, Munekazu,Kondo, Shin-Ichi,Kitano, Kazutada,Nakamura, Kaoru,Ohno, Atsuyoshi
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- Enantioselective Synthesis of α-Hydroxyketones using the DiTOX Asymmetric Building Block
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The 2-(R)- and 2-(S)-hydroxy-1-phenylbutan-1-ones have been prepared in high enantiomeric excesses and in five steps from propanal using a dithiane oxide unit as an asymmetric building block and a modified Sharpless enantioselective sulphur oxidation as the source of chirality.
- Page, Philip C. Bulman,Purdle, Mark,Lathbury, David
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p. 8929 - 8932
(2007/10/03)
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- A convenient preparation of symmetrical and unsymmetrical 1,2-diketones: Application to fluorinated phenytoin synthesis
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1,2-Diketones are efficiently produced in two steps by reaction of aldehydes with anions derived from 2-substituted dithianes followed by treatment of the resulting alcoholis with NBS in aqueous acetone; phenytoin derivatives were prepared from these diketones by a standard method involving treatment with urea and potassium hydroxide under reflux.
- Page,Graham,Park
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p. 7265 - 7274
(2007/10/02)
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- Reactions of PhCOPdX(PPh3)2 (X=I, Cl) with alkylmetals under carbon monoxide; formation of α-diketones and α-hydroxyketones under stoichiometric and catalytic conditions
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The reactions of PhCOPdX(PPh3)2 (Ia: X=I; Ib: X=Cl) with alkylmetals under carbon monoxide have been investigated.The reactivity of ethylmetals toward Ia was found to decrease in the order: Et2M (M=Zn, Cd, Hg) ca.EtZnCl ca.EtCu > EtmgBr ca.EtMnI ca.Et3Al > Et2AlCl > Et3B ca.Et4Sn (no reaction).In these reactions, the simple coupling product, PhCOEt (II) and /or the carbonylative coupling products IIIa-IIIc (IIIa: PhCOCOEt; IIIb: PhCEt(OH)COEt; IIIc PhCOCEt2(OH)) were formed depending on the nature of the ethylmetal.Et2Hg and Et3Al gave exclusively II.EtMgBr, EtCu, and EtZnCl gave both of II and III.EtMnI and Et2M (M=Zn, Cd) selectively gave III.The use of Ar2Zn (AR=Ph, p-Tol) in place of Et2Zn gave decreased yields of the carbonylative coupling products.The palladium complex Ib showed almost the same reactivity toward Et2Zn as Ia.Further to this palladium-catalyzed carbonylation reactions of PhCOCl with alkylmetals were examined.The reaction with Et2Zn catalyzed by PdCl2(PR3)2 (R=Ph, p-FC6H4) afforded III (mainly IIIb and IIIc, about 200percent/Pd).The combination of Pd(PPh3)4 and Et3Al more effactively afforded III (mainly acyloin-type reduced products, about 900percent/Pd).
- Yamashita, Hiroshi,Kobayashi, Toshi-aki,Sakakura, Toshiyasu,Tanaka, Masato
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p. 125 - 132
(2007/10/02)
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- A Facile One-Pot Synthesis of Vicinal Di- and Triketones from α-Methylene Ketones by NBS-DMSO Oxidation
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The reaction of 1,2-diarylethanones (1a-u) with N-bromosuccinimide in anhydrous dimethyl sulphoxide afforded diarylethanediones (2a-u) in excellent yields.Under similar conditions, 1-phenyl-2-butanone (3) gave 1-phenyl-1,2-butanedione (4) in fair yield in addition to a small amount of 1-phenyl-3-methylthio-1,2-butanedione (5) and 1-phenyl-1-methylthio-2-butanone (6). 4-Phenyl-2-butanone (7), 1,3-diphenyl-2-propanone (9), and 1,3-diphenyl-1,3-propanedione (10) gave the corresponding triketones monohydrate (8) and (11). 1-Indanone (12), 2-indanone (13), and 1,3-indandione (14) gave ninhydrin (15) in good yields.In the case of 3-phenyl-1-indanone (16), 3-phenyl-2-bromo-1-indanone (17), 3-phenyl-2-bromo-1-indenone (18) and 3-phenyl-1-indenone (19) were obtained. 1-Phenyl-1-propanone (20) and 1-phenyl-1-butanone (22) gave the corresponding α-(methylthio)ketones (21) and (22). 1,3,3-Triphenylpropanone (24a) and 1-phenyl-3-methyl-1-butanone (24b) yielded only the corresponding α-bromoketones (25a,b) in good yields.These α-bromoketones, however, afforded the corresponding α-diketones (26a,b) in moderate yields when α-bromoketones reacted with dimethyl sulphoxide in the presence of AgBF4.
- Tatsugi, Jiro,Izawa, Yasuji
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p. 2747 - 2763
(2007/10/02)
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- Kinetics and Mechanism of Oxidation of Propiophenone and Butyrophenone by N-Bromosaccharin in Aqueous Acetic Acid Medium
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The title reaction has been studied in aqueous acetic acid medium in presence of Hg(OAc)2.Order with respect to substrate, oxidant and +> is one in each.Added saccharin retards the rate of reaction.The reaction system did not induce polymerisation of added acrylonitrile indicating the absence of free radicals in the system.Thermodynamic parameters have been evaluated.The order of reactivity among the two substrates studied is propiophenone > butyrophenone.A suitable mechanism consistent with the observed results is proposed.
- Mohan, K. Vijaya,Rao, P. Raghunath,Sundaram, E. V.
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- OXIDATION OF ACTIVE METHYLENE COMPOUNDS BY PYRIDINIUM CHLOROCHROMATE
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1-Aryl-1,2-diketones 6 have been obtained by pyridinium chlorochromate oxidation of benzylketones 5.In the same way 2-buten-1,4-olide 2 and 3H-benzofuran-2-one 4 have been obtained.
- Bonadies, Francesco,Bonini, Carlo
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p. 1573 - 1580
(2007/10/02)
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- Studies on the Oxidative Cleavage of the CC Triple Bond during the Autoxidation of Acetylenic Hydrocarbons 1. Evidence for α-Dicarbonyl Compounds as Intermediates
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Examination of oxidation mixtures of 1-phenylprop-1-yne, 1-phenylbut-1-yne and 1-phenyl-3-methylbut-1-yne revealed the presence of hitherto not reported interesting products, especially the α-dicarbonyl compounds 1-phenylpropane-1,2-dione, 1-phenylbutane-1,2-dione and 1-phenyl-3-methylbutane-1,2-dione respectively in minor quantities.Some other typical products like benzil, benzoic anhydride and phenyl benzoate were also characterized.Although the oxidation of diphenylacetylene is very slow, benzil could be found as the main detectable product along with traces of benzoic acid.The α-diketones corresponding to the 1-phenylalk-1-ynes were oxidized at 110 deg C.In each case benzoic acid and the lower carboxylic acids as in the case of the autoxidation of the corresponding acetylenes were obtained.Benzil, benzoic anhydride and phenyl benzoate were also characterized in all the cases.Therefore, α-diketones are considered as intermediates responsible for the formation of the oxidative cleavage products of the CC triple bond.
- Rao, T. S. S.,Pritzkow, W.
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p. 474 - 482
(2007/10/02)
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- Palladium Catalyzed Reaction of Acyltins with Organic Halides
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Palladium catalyzed reaction of acyltins with organic halides were investigated.Among the halides, acyl halides and allylic halides were good substrates, and the latter gave allylic ketones in good yields.
- Kosugi, Masanori,Naka, Hiroyuki,Harada, Saburo,Sano, Hiroshi,Migita, Toshihiko
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p. 1371 - 1372
(2007/10/02)
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- A Simple and Improved Procedure for the Conversion of Alkynes to 1,2-Diketones by Indirect Electrooxidation With Ruthenium Tetroxide as a Mediator
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Indirect electrooxidation of alkynes 1 using ruthenium tetroxide as a mediator, leading to 1,2-diones 2 in 72-87percent, is described.The electrolysis is carried out in the presence of a catalytic amount of ruthenium dioxide dihydrate in a two phase system of saturated aqueous sodium chloride and carbon tetrachloride.The overoxidation of 1,2-diones to the corresponding carboxylic acid, an unavoidable drawback generally encountered in the metal oxidation of acetylenes, is suppressed greatly by maintaining the pH of the aqueous phase at 4 and conducting the reaction at 0-5 deg C.The synthetic utility of this electrochemical oxidation is exemplified by the preparation of 2i (82percent), a key intermediate for the synthesis of furaneol 4, from the commercially available 1i.
- Torii, Sigeru,Inokuchi, Tsutomu,Hirata, Youzou
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p. 377 - 379
(2007/10/02)
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