- Studies on anti-MRSA parenteral cephalosporins. III. Synthesis and antibacterial activity of 7β-[2-(5-amino-1,2,4-thiadiazol-3-yl)-2(Z)- alkoxyimininoacetamido]-3-[(E)-2-(1-alkylimidazol{1,2-b]pyridazinium-6-y) thiovinyl]-3-cephem-4-carboxylates and relat
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In the course of our exploration for a novel cephalosporin derivative having excellent antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA), we modified the C-3 linked spacers of cephem derivatives bearing a 1-methylimidazo[1,
- Ishikawa,Kamiyama,Nakayama,Iizawa,Okonogi,Miyake
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p. 257 - 277
(2007/10/03)
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- Synthesis of 2-exo-methylenepenam and 3-chloro-Δ3-cephem through a sequential reductive 1,2-elimination/S-S bond fission or chloride ion-addition/cyclization of 3,4-disubstituted 2-butenoates in metal salt/metal combinations
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Synthesis of 2-exo-methylenepenam 1 through a sequential reductive 1,2-elimination/S-S bond fission/cyclization of 6 was performed by treatment with a PbBr2/Al (or a BiCl3/Al) combination in DMF, while that of 3-chloro-Δ3-cephem 2 through reductive 1,2-elimination/chloride ion-addition/cyclization was attained by use of an AlCl3/Al combination in N-methylpyrrolidone (NMP). The selective transformation of 6 to the allenecarboxylate 3 was also achieved by treatment with an AlBr3/Al combination in NMP. Cyclic voltammograms of 3,4-disubstituted 2-[2-oxo-3-(phenylacetamido)-4-[(phenylsulfonyl)thio]azetidin-1-yl]-2- butenoates (6) exhibit two irreversible reduction peaks responsible for reductive 1,2-elimination of the 3,4-disubstituted 2-butenoate moiety (at less negative potential) and for reductive S-S bond fission of the (phenylsulfonyl)thio moiety, suggesting that the reductive 1,2-elimination of 6 leading to allenecarboxylate 3 would occur prior to the reductive S-S bond cleavage.
- Tanaka,Sumida,Nishioka,Kobayashi,Tokumaru,Kameyama,Torii
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p. 3610 - 3617
(2007/10/03)
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