- Intramolecular palladium-catalyzed alkane C-H arylation from aryl chlorides
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The first examples of efficient and general palladium-catalyzed intramolecular C(sp3)-H arylation of (hetero)aryl chlorides, giving rise to a variety of valuable cyclobutarenes, indanes, indolines, dihydrobenzofurans, and indanones, are described. The use of aryl and heteroaryl chlorides significantly improves the scope of C(sp3)-H arylation by facilitating the preparation of reaction substrates. Careful optimization studies have shown that the palladium ligand and the base/solvent combination are crucial to obtaining the desired class of product in high yields. Overall, three sets of reaction conditions employing PtBu3, PCyp3, or PCy3 as the palladium ligand and K 2CO3/DMF or Cs2CO3/pivalic acid/mesitylene as the base/solvent combination allowed five different classes of products to be accessed using this methodology. In total, more than 40 examples of C-H arylation have been performed successfully. When several types of C(sp3)-H bond were present in the substrate, the arylation was found to occur regioselectively at primary C-H bonds vs secondary or tertiary positions. In addition, in the presence of several primary C-H bonds, selectivity trends correlate with the size of the palladacyclic intermediate, with five-membered rings being favored over six- and seven-membered rings. Regio- and diastereoselectivity issues were studied computationally in the prototypal case of indane formation. DFT(B3PW91) calculations demonstrated that C-H activation is the rate-determining step and that the creation of a C-H agostic interaction, increasing the acidity of a geminal C-H bond, is a critical factor for the regiochemistry control.
- Rousseaux, Sophie,Davi, Michael,Sofack-Kreutzer, Julien,Pierre, Cathleen,Kefalidis, Christos E.,Clot, Eric,Fagnou, Keith,Baudoin, Olivier
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supporting information; experimental part
p. 10706 - 10716
(2010/09/17)
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- 2- and 2,5-substituted phenylketoenols
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The invention relates to novel phenyl-substituted cyclic ketoenols of the formula (I) in which Het represents one of the groups ?in which A, B, D, G, X and Z are each as defined in the description, to a plurality of processes and intermediates for their preparation, and to their use as pesticides.
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Page column 78
(2010/01/31)
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- Microbial asymmetric decarboxylation of fluorine-containing arylmalonic acid derivatives
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α-Methyl-α-(trifluoromethylphenyl)malonic acids have been incubated with Alcaligenes bronchisepticus to afford optically active α-arylpropionic acids.Generally, the chemical and optical yields of the reaction products were higher when the substituents on the aromatic ring were strongly electron-withdrawing.Decarboxylation of α-fluoro-α-phenylmalonic acid with the aid of the same bacterium afforded optically active α-fluoro-α-phenylacetic acid.
- Miyamoto, Kenji,Tsuchiya, Shigeo,Ohta, Hiromichi
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p. 225 - 232
(2007/10/02)
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- Anti-mycobacterial 4-hydroxy-3-phenylpyridin-2(1H)-ones
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4-Hydroxy-3-phenylpyridin-2 (1H)-ones with different substituents either at N-1 or in the phenyl group were synthesized by reaction of ethyl β-aminocrotonates with dialkyl malonates or 'magic malonates' (2,4,6-trichlorophenyl malonates).The evaluation of these compounds on Mycobacterium tuberculosis H37Ra, Escherichia coli B and Staphylococcus aureus ATCC 25923 showed significant inhibitory effects on M tuberculosis (5g and 5s, MIC=8μg/ml).A structure-activity relationship is discussed.
- Dannhardt, G,Meindl, W,Schober, B D,Kappe, T
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p. 599 - 604
(2007/10/02)
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- DIMETHYL ARYLMALONATES FROM CERIUM(IV) AMMONIUM NITRATE PROMOTED REACTIONS OF DIMETHYL MALONATE WITH AROMATIC COMPOUNDS IN METHANOL
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Aromatic compounds undergo homolytic malonylation by reaction with cerium(IV) ammonium nitrate and dimethyl malonate in methanol at room temperature.
- Baciocchi, Enrico,Dell'Aira, Donatella,Ruzziconi, Renzo
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p. 2763 - 2766
(2007/10/02)
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