- Synthesis of α-oxygenated ketones and substituted catechols via the rearrangement of N-enoxy- and N-aryloxyphthalimides
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A common approach to the synthesis of α-oxygenated carbonyl compounds and catechols is the treatment of a carbonyl compound or a phenol with an electrophilic oxygen source. As an alternative approach to these important structures, formal [3,3]-rearrangements of N-enoxyphthalimides, N-enoxyisoindolinones, and N-aryloxyphthalimides have been explored. When used in combination with an initial Chan-Lam coupling, these transformations facilitate the dioxygenation of alkenylboronic acids for the synthesis of α-oxygenated ketones and the dioxygenation of arylboronic acids for the synthesis of catechols. The rearrangements of N-enoxyisoindolinones have also been shown to be diastereoselective.
- Kroc, Michelle A.,Patil, Aditi,Carlos, Anthony,Ballantine, Josiah,Aguilar, Stephanie,Mo, Dong-Liang,Wang, Heng-Yen,Mueller, Daniel S.,Wink, Donald J.,Anderson, Laura L.
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p. 4125 - 4137
(2017/06/29)
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- Ruthenium Carboxylate Complexes as Efficient Catalysts for the Addition of Carboxylic Acids to Propargylic Alcohols
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Ruthenium complexes [Ru(CO)2(PPh3)2(O2CR)2] - 3a (R = CH2OCH3), 3b (R = iPr), 3c (R = tBu), 3d (R = 2-cC4H3O), and 3e (R = Ph) - were synthesized
- Jeschke, Janine,G?bler, Christian,Korb, Marcus,Rüffer, Tobias,Lang, Heinrich
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p. 2939 - 2947
(2015/06/30)
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- Atom Economic Ruthenium-Catalyzed Synthesis of Bulky β-Oxo Esters
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Ruthenium complexes with the formulae Ru(CO)2(PR3)2(O2CPh)2 [6a-h; R=n-Bu, p-MeO-C6H4, p-Me-C6H4, Ph, p-Cl-C6H4, m-Cl-C6H4, p-CF3-C6H4, m,m′-(CF3)2C6H3] were prepared by treatment of triruthenium dodecacarbonyl [Ru3(CO)12] with the respective phosphine and benzoic acid or by the conversion of Ru(CO)3(PR3)2 (8e-h) with benzoic acid. During the preparation of 8, ruthenium hydride complexes of type Ru(CO)(PR3)3(H)2 (9g, h) could be isolated as side products. The molecular structures of the newly synthesized complexes in the solid state are discussed. Compounds 6a-h were found to be highly effective catalysts in the addition of carboxylic acids to propargylic alcohols to give valuable β-oxo esters. The catalyst screening revealed a considerably influence of the phosphine′s electronic nature on the resulting activities. The best performances were obtained with complexes 6g and 6h, featuring electron-withdrawing phosphine ligands. Additionally, catalyst 6g is very active in the conversion of sterically demanding substrates, leading to a broad substrate scope. The catalytic preparation of simple as well as challenging substrates succeeds with catalyst 6g in yields that often exceed those of established literature systems. Furthermore, the reactions can be carried out with catalyst loadings down to 0.1mol% and reaction temperatures down to 50 C.
- Jeschke, Janine,Korb, Marcus,Rüffer, Tobias,G?bler, Christian,Lang, Heinrich
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supporting information
p. 4069 - 4081
(2016/01/25)
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- Palladium-catalyzed selective anti-markovnikov oxidation of allylic esters
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An aldol alternative: The palladium(II)-catalyzed anti-Markovnikov oxidation of allylic esters to aldehydes at room temperature provides a viable alternative to valuable cross aldol products. High regioselectivity towards the aldehyde product was achieved using the ester protecting group for the allylic alcohol. Rapid isomerization and the much higher rate of oxidation of the branched isomer result in the same product forming from both linear and branched allylic esters. Copyright
- Dong, Jia Jia,Fananas-Mastral, Martin,Alsters, Paul L.,Browne, Wesley R.,Feringa, Ben L.
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p. 5561 - 5565
(2013/06/27)
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- Preparation of α-oxygenated ketones by the dioxygenation of alkenyl boronic acids
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Two in two: Dioxygenation of alkenyl boronic acids has been achieved with N-hydroxyphthalimide. The two-step process involves etherification of an alkenyl boronic acid with N-hydroxyphthalimide followed by a [3,3] rearrangement. The dioxygenated product can then be hydrolyzed to form either the corresponding α-hydroxy ketone or the α-benzoyloxy ketone. Copyright
- Patil, Aditi S.,Mo, Dong-Liang,Wang, Heng-Yen,Mueller, Daniel S.,Anderson, Laura L.
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supporting information; experimental part
p. 7799 - 7803
(2012/09/08)
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- Ruthenium(IV)-catalyzed markovnikov addition of carboxylic acids to terminal alkynes in aqueous medium
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The dimeric bis(allyl)ruthenium(IV) complex [{RuCl(μ-Cl)( η3:η3-C10H16)}2] (C10H16 = 2,7-dimethylocta-2,6-diene-1,8-diyl) (5) and several mononuclear species trans-[RuCl2(η3: η3-C10H16)(L)] (L = two-electron-donor ligand) (6) derived from 5 have been checked as catalysts for the addition of carboxylic acids onto terminal alkynes using water as a green reaction medium. The best results in terms of activity and regioselectivity were obtained with the mononuclear derivative trans-[RuCl2(η3: η3-C10H16)(PPh3)] (6a), which was able to promote the selective Markovnikov addition of both aromatic and aliphatic carboxylic acids to a large variety of terminal alkynes, enynes, and diynes as well as propargylic alcohols. In this way, a wide number of enol esters and β-oxo esters could be synthesized in moderate to good yields under mild conditions (60 °C) in an aqueous medium.
- Cadierno, Victorio,Francos, Javier,Gimeno, Jose
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experimental part
p. 852 - 862
(2011/04/15)
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- Ruthenium-catalyzed synthesis of β-oxo esters in aqueous medium: Scope and limitations
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The ability of the hydrosoluble ruthenium(ii) complexes [RuCl 2(η6-arene)(PTA)] 3a-d, [RuCl2(η 6-arene)(PTA-Bn)] 4a-d, [RuCl2(η6-arene) (DAPTA)] 5a-d, [RuCl2(η6-arene)(TPPMS)] 6a-d (arene = C6H6, p-cymene, 1,3,5-C6H3Me 3, C6Me6) to promote the atom-economic formation of β-oxo esters, by addition of carboxylic acids to terminal propargylic alcohols in water has been explored. Scope, limitations and catalyst recycling have been evaluated using the most active catalyst [RuCl 2(η6-C6H6)(TPPMS)], 6a.
- Cadierno, Victorio,Francos, Javier,Gimeno, Jose
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experimental part
p. 135 - 143
(2010/05/18)
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- Efficient oxidation of 1,2-diols into a-hydroxyketones catalyzed by organotin compounds
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Electrochemical oxidation of 1,2-diols with a catalytic amount of an organotin compound and a bromide ion as mediators has been developed. Various cyclic and acyclic 1,2-diols were oxidized into the corresponding α-hydroxyketones in good to excellent yields without C-C bond cleavage. Also, oxidation with the use of chemical oxidants was accomplished in the presence of a catalytic amount of an organotin compound. These reactions could discriminate 1,2-diols from isolated hydoxyl groups or 1,3-diols. In the case of a conformationally restricted cyclic 1,2-diol, the axial hydroxyl group was oxidized exclusively. Mono-, di-, and trialkylated tin compounds were examined as mediators and dialkylated tin compounds showed higher catalytic activity than mono- and trisubstituted ones. Me2SnCl2 was found to be the most suitable mediator for the selective oxidation..
- Maki, Toshihide,Iikawa, Shinya,Mogami, Gen,Harasawa, Hitomi,Matsumura, Yoshihiro,Onomura, Osamu
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experimental part
p. 5364 - 5370
(2009/12/22)
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- A new approach to the synthesis of 2-aryl-4-halomethyl-5-methyl-1,3- oxazoles by highly regioselective direct halogenation with NBS or NCS/MeCN
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A simple and efficient method for the synthesis of 2-aryl-4-bromomethyl-5- methyl-1,3-oxazoles 2 and 2-aryl-4-chloromethyl-5-methyl-1,3-oxazoles 3 is described. The reaction of 2-aryl-4,5-dimethyl-1,3-oxazoles 1 with N-bromosuccinimide and N-chlorosuccini
- Yamane, Taihei,Mitsudera, Hiroyuki,Shundoh, Takatsugu
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p. 2825 - 2832
(2007/10/03)
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- Therapeutic agents
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Compounds of formula (I) which includes pharmaceutically acceptable salts thereof and stereoisomers thereof: STR1 wherein: R 1 represents H or one of the following groups (optionally substituted with one or more of halo, cyano, hydroxy or amino): C 1-6 alkyl, C 1-6 alkoxy or C 1-6 alkanoyl; R 2 and R 3 independently represent H or one of the following groups (optionally substituted with one or more of halo, cyano, hydroxy or amino): C 1-6 alkyl, C 1-6 alkoxy or C 1-6 alkanoyl, C 1-6 alkylthio, C 1-6 alkylsulphinyl or C 1-6 alkylsulphonyl; R 4 and R 5 combined together with the carbon atom to which they are attached represent C 3-6 cycloalkylidene (each alkyl or cycloalkylidene being optionally substituted with one or more of halo, cyano, hydroxy, amino or C 1-6 alkyl); and R 6, R 7 and R 8 independently represent H, halo, hydroxy, mercapto, cyano or one of the following groups (optionally substituted with one or more of halo, cyano, hydroxy or amino; and any nitrogen atom being optionally substituted with one or more C 1-6 alkyl): C 1-6 alkyl, C 1-6 alkoxy or C 1-6 alkanoyl, C 1-6 alkylthio, C 1-6 alkylsulphinyl, etc; have utility in the treatment and/or prophylaxis or seizures, neurological disorders such as epilepsy and/or conditions in which there is neurological damage such as stroke, brain trauma, head injuries and haemorrhage.
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- O-Acylation of α-Diazo Ketones. A Novel Route to Alkenediazonium and 1,3-Dioxolium Salts
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O-Acylation of α-diazo ketones with benzoyl triflate or diphenylacetyl triflate generates the corresponding β-(acyloxy)alkenediazonium salts 5 and 15.These thermolabile compounds can be trapped with isopropylamine at low temperature to give triazoles 21.Dediazoniation of 5 and 15 leads to 1,3-dioxolium salts 7 and 16 as well as small amounts of vinyl triflates 8 and 17 via intermediary vinyl cations.O-Benzoylation with benzoyl triflate has also been realized for the quinoid α-diazo ketone 9; the resulting diazonium salt 10 gives triazole 13 on treatment with isopropylamine.
- Lorenz, Wolfgang,Maas, Gerhard
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p. 375 - 381
(2007/10/02)
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- Regiospecific Synthesis of a Terminal, Oxyfunctionalized Methyl Ketone Enamines via Catalytic Aminomercuriation of Prop-2-ynyl Esters and Ethers
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Catalytic aminomercuriation of 1-substituted prop-2-ynyl esters and ethers (5) provides a mild, simple, and regiospecific route to the terminal functionalized enamines (6) despite the fact that they are potentially isomerisable to their internal form; hyd
- Barluenga, Jose,Aznar, Fernando,Liz, Ramon,Postigo, Carmen
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p. 1465 - 1467
(2007/10/02)
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