- Photoinduced N-demethylation of rufloxacin and its methyl ester under aerobic conditions
-
Irradiation of rufloxacin (RF) under aerobic conditions gives rise to N-demethylation of the piperazinyl ring, which is enhanced in aerated D2O. Two primary processes seem to be involved in RF N-demethylation: photoionization from 1RF and singlet oxygen generation from 3RF. Both processes may lead to the same key intermediates, namely, RF-+ and superoxide radical anion; coupling of these intermediates explains N-demethylation of RF via an iminium cation. Formation of the hydrated electron by a monophotonic process (with a quantum yield of 0.09) is detected along with 3RF (with a intersystem-crossing quantum yield πISC = 0.36) by laser flash photolysis. Studies performed on RF methyl ester give qualitatively similar results.
- Belvedere, Alessandra,Bosca, Francisco,Cuquerella, M. Consuelo,De Guidi, Guido,Miranda, Miguel A.
-
p. 252 - 258
(2007/10/03)
-
- Derivatives of pyrido-benzothiazine with high anti-microbial activity
-
Pyrido-benzothiazine compounds having anti-microbial activity are prepared by (a) reacting 3-chloro-4-fluoroaniline with potassium thiocyanate and bromine to produce 2-amino-6-fluoro-7-chlorobenzothiazole, (b) reacting 2-amino-6-fluoro-7-chlorobenzothiazole with sodium hydroxide to produce the disulfide of 2-amino-5-fluoro 6-chlorothiophenol, (c) reacting the disulfide with sodium monochloroacetate to produce 7-fluoro-8-chloro-2H-1,4-benzothiazin-3(4H)-one, (d) reducing 7-fluoro-8-chloro-2H-1,4-benzothiazin-3(4H)-one to produce 7-fluoro-8-chloro-3,4-dihydro-2H-1,4-benzothiazone, (e) reacting 7-fluoro-8-chloro-3,4-dihydro-2-H-1,4-benzothiazone with ethyl ethoxymethylenemalonate and cyclyzing the intermediate formed with polyphosphoric acid to produce ethyl 9-fluoro-10-chloro-7-oxo-2,3-dihydro-7H-pyrido[1,2,3 de] [1,4]-benzothiazine-6-carboxylate and (f) hydrolyizing the ethyl carboxylate to produce the corresponding carboxylic acid.
- -
-
-
- Quinolonecarboxylic Acids. 2. Synthesis and Antibacterial Evaluation of 7-Oxo-2,3-dihydro-7H-pyridobenzothiazine-6-carboxylic Acids
-
A series of pyridobenzothiazine acid derivatives was synthesized and their in vitro antibacterial activity was evaluated.The 1,4-benzothiazine intermediates, which by Gould-Jacobs quinoline synthesis produced pyridobenzothiazine acids, were prepared by hydrolytic basic cleavage of substituted 2-aminobenzothiazoles and successive cyclocondensation with 1-bromo-2-chloroethane or alternatively with monochloroacetic acid, hence reduction by LiAlH4.The pyridobenzothiazine acids 10c, 30, and 31 show potent antibacterial activities against Gram-positive and Gram-negative pathogens.Structure-activity relationships are discussed.The compound 9-fluoro-10-(4-methyl-1-piperazinyl)-7-oxo-2,3-dihydro-7H-pyridobenzothiazine-6-carboxylic acid (31) (MF-934) has been found to possess, together with the antibacterial activity, a weak acute toxicity and interesting pharmacokinetic characteristics in several animal species (rat, dog, monkey, man).
- Cecchetti, Violetta,Fravolini, Arnaldo,Fringuelli, Renata,Mascellani, Giuseppe,Pagella, Piergiuseppe,et al.
-
p. 465 - 473
(2007/10/02)
-