- Mild and highly selective palladium-catalyzed monoarylation of ammonia enabled by the use of bulky biarylphosphine ligands and palladacycle precatalysts
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A method for the Pd-catalyzed arylation of ammonia with a wide range of aryl and heteroaryl halides, including challenging five-membered heterocyclic substrates, is described. Excellent selectivity for monoarylation of ammonia to primary arylamines was achieved under mild conditions or at rt by the use of bulky biarylphosphine ligands (L6, L7, and L4) as well as their corresponding aminobiphenyl palladacycle precatalysts (3a, 3b, and 3c). As this process requires neither the use of a glovebox nor high pressures of ammonia, it should be widely applicable.
- Cheung, Chi Wai,Surry, David S.,Buchwald, Stephen L.
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supporting information
p. 3734 - 3737
(2013/08/23)
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- Studies on Anti-MRSA parenteral cephalosporins I. Synthesis and antibacterial activity of 7
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In order to improve the antibacterial activity of cefozopran (CZOP) against methicillin-resistant Staphylococcus aureus (MRSA), we initiated chemical modification to introduce a 2-(5-amino-1,2,4-thiadiazol-3-yl)-2(Z)-hydroxyimino acetyl group at the C-7 position and a 3- or 6-substituted imidazo[1,2-b]pyridazinium or 5-substituted imidazo[1,2-a]pyridinium group at the C-3' position. Although this approach successfully enhanced the anti-MRSA activity of CZOP two to eight times, a slight decrease in the activity against Gram-negative bacteria including Pseudomonas aeruginosa was involved. Among the novel derivatives, 3-(6-aminoimidazo [1,2-b]pyridazinium-1-yl) methyl-7β-[2-(5-amino -1,2,4-thiadiazol-3-yl) -2(Z)-hydroxyiminoacetamidol]-3-cephem-4-carboxylate (44a) showed an excellent balance of activity against MRSA and Gram-negative bacteria.
- Ishikawa,Iizawa,Okonogi,Miyake
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p. 1053 - 1070
(2007/10/03)
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- Cephem compounds, their production and use
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Novel cephem compounds of the general formula: STR1 wherein R1 is a lower alkyl group, and salts and esters thereof, showing excellent and balanced antibacterial activity against a broad spectrum of bacteria, especially by rectal administration, and their production and use as antimicrobial agents are described.
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