- Palladium-catalyzed cross-coupling of styrenes with aryl methyl ketones in ionic liquids: Direct access to cyclopropanes
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The combined use of Pd(OAc)2, Cu(OAc)2, and dioxygen in molten tetrabutylammonium acetate (TBAA) promotes an unusual cyclopropanation reaction between aryl methyl ketones and styrenes. The process is a dehydrogenative cyclizing coupl
- Cotugno, Pietro,Monopoli, Antonio,Ciminale, Francesco,Milella, Antonella,Nacci, Angelo
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- Electrochemical oxidation-induced benzyl C–H carbonylation for the synthesis of aromatic α-diketones
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Electrochemical oxidation-induced direct carbonylation of benzyl C–H bond for the synthesis of aromatic α-diketones is described. In this process, tetrabutylammonium iodide (nBu4NI) not only acts as an electrolyte, but its iodine anion is oxidized to an iodine radical at the anode, acting as a hydrogen atom transfer agent. The iodine radical extracts the benzyl hydrogen atom and causes the carbonylation of the benzyl position, where O2 in the air is used as an oxygen source.
- Tan, Yu-Fang,Chen, Yuan,Li, Rui-Xue,Guan, Zhi,He, Yan-Hong
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- Copper-catalyzed base-accelerated direct oxidation of C-H bond to synthesize benzils, isatins, and quinoxalines with molecular oxygen as terminal oxidant
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We describe herein an efficient and general copper (II)-catalyzed base-accelerated oxidation of the C-H bond to synthesize benzils and isatins. With similar oxidation system an efficient one-pot procedure for the synthesis of quinoxaline derivatives was realized. The two protocols feature using molecular oxygen as terminal oxidant, low catalyst loading, wide substrate scope, and high functional-group tolerance.
- Yu, Jing-Wen,Mao, Shuai,Wang, Yong-Qiang
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p. 1575 - 1580
(2015/03/14)
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- Rhodium-catalyzed synthesis of 2,3-diaryl-1,4-diketones via oxidative coupling of benzyl ketones using α-thioketone oxidizing reagent
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RhH(PPh3)4 and 1,2-bis(diphenylphosphino)benzene (dppBz) catalyzed the oxidative coupling reaction of aryl benzyl ketones giving 2,3-diaryl-1,4-diketones in high yields. 3,3-Dimethyl-1-methylthio-2-butanone was used as the oxidizing
- Arisawa, Mieko,Li, Guangzhe,Yamaguchi, Masahiko
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supporting information
p. 1298 - 1301
(2013/03/13)
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- Chemoselective oxidative C(CO)-C(methyl) bond cleavage of methyl ketones to aldehydes catalyzed by CuI with molecular oxygen
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Aldehyde Termination: A novel copper-catalyzed transformation from methyl ketones into aldehydes has been accomplished. This method is applicable to a wide range of aromatic and aliphatic methyl ketones and chemoselectively produces aldehydes, accompanied by the release of hydrogen (H2) and carbon dioxide (CO2) as by-products. Copyright
- Zhang, Lin,Bi, Xihe,Guan, Xiaoxue,Li, Xingqi,Liu, Qun,Barry, Badru-Deen,Liao, Peiqiu
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supporting information
p. 11303 - 11307
(2013/11/06)
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- Copper catalyzed oxidation of organozinc halides
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A wide range of organozinc substrates may be oxidized in the presence of catalytic copper to give carbon-carbon bonds in high yield. The Royal Society of Chemistry 2006.
- Su, Xianbin,Fox, David J.,Blackwell, David T.,Tanaka, Kiyotaka,Spring, David R.
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p. 3883 - 3885
(2007/10/03)
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- One-step preparation of symmetrical 1,4-diketones from α-halo ketones in the presence of Zn-I2 as a condensation agent
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Eleven 1,4-diphenylbutane-1,4-diones have been prepared in one step from the corresponding α-halo acetophenones under the action of Zn-I 2 as a condensation agent with moderate to high yields. The mechanistic pathway of the reaction can be explained by the Wurtz-like self-condensation of α-halo ketones. Similarly, 3-chloropentane-2,4-dione gave 3,4-diacetylhexane-2,5-dione, a Wurtz-like condensation product.
- Ceylan, Mustafa,Guerdere, M. Burcu,Budak, Yakup,Kazaz, Cavit,Secen, Hasan
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p. 1750 - 1754
(2007/10/03)
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- Characterization of products derived by in situ generation of α-acyl carbenium ion from benzoin in presence of trifluoroacetic acid
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Formation of tetraphenylfuran (4), benzil (5) and 1,2-dibenzoyl-1,2-diphenyl ethane (6) instead of the expected 2,3-diphenyl-5-methylbenzofuran (1) is observed in the reaction of benzoin (3) with p-cresol in the presence of trifluoroacetic acid.
- Earnest, H.,Kamat, S. P.
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p. 1096 - 1097
(2007/10/02)
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- Radical and Ionic Reactions of (Benzoylmethyl)mercurials
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Photolysis of PhCOCH2HgCl or (PhCOCH2)2Hg yields benzoylmethyl radicals which can be trapped by anions such as Me2C=NO2-, RC(CO2Et)2-, RC(O-)=CH2 or by other electron-rich systems such as (RO)3P, N-methylpyrrole, enamines, or norbornene.Electron transfer from the adduct radicals to the mercurials yields PhCOCH2A from the anions A-, PhCOCH2P(O)(OR)2 from P(OR)3, and the phenacyl derivative from N-methylpyrrole or enamines.Easily oxidized anions such as PhCOCPh2- or PhC(CH3)=NO2- react with PhCOCH2* by electron transfer to yield the dimer derived from the anion.Addition of PhCOCH2* to norbornene yields a substituted 3-benzoylpropyl radical which cyclizes at the ortho position of the benzoyl group to give the α-tetralone derivative.
- Russell, Glen A.,Kulkarni, Shekhar V.,Khanna, Rajive K.
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p. 1080 - 1086
(2007/10/02)
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- Lewis Acid-prompted Conjugate Reduction of α,β-Unsaturated Carbonyl Compounds by 2-Phenylbenzothiazoline (2-Phenyl-2,3-dihydrobenzothiazole)
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Reduction of various α,β-unsaturated ketones (3a-g) and (4a-d) in methanol by the benzothiazoline (1) in the presence of aluminium chloride gives, in all cases, the corresponding saturated ketones (5a-g) and (6a-d)without any of the unsaturated or saturated alcohol.Reduction of α,β-unsaturated esters (7a,b) similarly gives the saturated esters (9a,b), while reaction of cinnamaldehyde (8) with compound (1) does not occur at all.Among the Lewis acids examined, aluminium chloride gives the best results.Reduction of 2'-azachalcone (21) with 2-phenylbenzothiazoline reveals that, in the reduction product, the deuterium atom is located at the β-position with respect to the carbonyl group.The result obtained from the reduction of the same substrate with compound (1) in methanol shows that no incorporation of a hydrogen atom from the solvent takes place and suggests (indirectly) that the introduced hydrogen atom at the α-position of the product comes from the benzothiazoline (1).The reaction of (Z)-1,2-dibenzoyl-1,2-diphenylethylene (30) with compound (1) in the presence of aluminium chloride stereospecifically yields meso-1,2-dibenzoyl-1,2-diphenylethane (31).This shows that the transfer of two hydrogens from compound (1) to the carbon-carbon double bond of the enone proceeds via cis-addition.Experiments with ethyl phenylpropiolate (28) also support cis-reduction for the present conjugate reduction.These results are interpreted in terms of a mechanism involving synchronous transport of a pair of hydrogens from the benzothiazoline (1); i.e a cyclic addition of the two hydrogens either in exact or nearly exact concurrence.
- Chikashita, Hidenori,Miyazaki, Makoto,Itoh, Kazuyoshi
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p. 699 - 706
(2007/10/02)
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- Mechanism of Copper-Catalyzed Oxygenation of Ketones
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Deoxybenzoin (1) is converted by a Cu(II)-py-Et3N-MeOH-O2 (py=pyridine) system to a mixture of benzil (2), bidesyl (3), and the cleavage products PhCHO and PhCOOH.A product study comparing reactivities of 1 and 2 under identical conditions established (i) that the conversion of 1 to 3 is effected by Cu(II) alone, (ii) that PhCHO is generated only from 1, in a reaction that requires both Cu(II) and O2, and (iii) that 2 undergoes C-C cleavage only in the presence of H2O, forming PhCOOH exclusively, in a reaction that requires Cu(II) but not O2. α-Methyldeoxybenzoin (5) undergoes an exceptionally slow but similar reaction ( giving the tertiary α-ketol 6 rather than diketone 2).Mechanisms for these reactions are presented, and the significance of the results is discussed.
- Sayre, L. M.,Jin, S.-J.
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p. 3498 - 3503
(2007/10/02)
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- PHOTOOXYGENATION OF SILACYCLOPENTADIENES: A NOVEL OXYGENATION PRODUCT, 2,4-DIOXA-3-SILABICYCLOHEPT-6-ENE, AND ITS CYCLOREVERSION REACTIONS
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Photooxygenation of 1,1-dimethyl-2,3,4,5-tetraphenyl-1-silacyclopentadiene afforded 2,4-dioxa-3-silabicyclohept-6-ene(III) together with dibenzoylstilbene.The former was converted to isodidesyl and didesyl by treatment on alumina.Valence bond isome
- Nakadaira, Yasuhiro,Nomura, Tamotsu,Kanouchi, Seiichi,Sato, Ryuji,Kabuto, Chizuko,Sakurai, Hideki
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p. 209 - 212
(2007/10/02)
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- THE REACTION OF CARBANIONS WITH 2-SUBSTITUTED -2-NITROPROPANES SUBSTITUTION AND DIMERIZATION OCCURRING BY RADICAL CHAIN PROCESSES INVOLVING ELECTRON TRANSFER
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The reaction of mono-enolate anions with O2NCMe2X where X=Cl, NO2, p-MePhSO2 yield coupling (RCOCH(R')(CMe2NO2) and enolate dimerization products (RCOCH(R')CH(R')COR) by free radical chain mechanisms involving bimolecular substitution or electron transfer reactions between the enolate anion and the intermediate nitro alkane radical anion (XCMe2NO2(1-)).
- Russell, Glen A.,Mudryk, Boguslaw,Ros, Francisco,Jawdosiuk, Mikolaj
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p. 1059 - 1068
(2007/10/02)
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