1 - -6-fluoro-1,4-dihydroquinoline-2-carboxylic acid

Treatment of 8-fluoro-l,2-dihydro-4 7,67/-[l,4]oxazino[4,3-a]quinoline-4,6-dione with 6N aqueous NaOH and PhCH2Br under reflux overnight and with NaOMe in DMF at ambient temperature yielded l-(2-benzyloxyethyl)- and l-vinyl-6-fluoro-l, 4-dihydroquinoline-2-carboxylic acids, respectively (01SL833). 

Chloro-1 -ethyl-6-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid Piparazine... 

The suspension was heated to 90°C, while stirring. The crystals were separated and recrystallized from 2B0 cm of a mixture of DMF (1 volume) and ethanol (4 volumes). After drying in vacuo ovar phosphorus pentoxide, 29.5 g (yield 70%) of 1-ethyl-6-fluoro-4-oxo-7-pl-perazinyl-1,4-dihydroquinoline-3-carboxylic acid, melting point 222°C, were obtained. 

Norfloxacin transformation has been demonstrated by P. guepini [30] and T. viride [32]. In the first case, the metabolites identified included /V-acetyl norfloxacin as the major intermediate, desethylene-Af-acetylnorfloxacin, /V-formy I norfloxacin, and 7-amino-l-ethyl-6-fluoro-4-oxo-l,4-dihydroquinoline-3-carboxylic acid. For T. viride, 4-hydroxy-3-oxo-4-vinylcyclopent-l-enyl norfloxacin was elucidated as an intermediate. In both reports, the intermediates were analogous... 

T. versicolor Pellets incubated at 30°C under orbital agitation 2 mg L-1 >90% after 7 days 7-((2-Aminoethyl)amino)-1-ethyl-6-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid 7-amino-l-ethyl-6-fluoro-4-oxo-1,4-dihydroquinoline- 3-carboxylic acid 7-((2-scetamidoethy l)am in o) -1 -ethyl-6-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid [29]... 

Table 8. Selected Examples of Sulfanyl-Substituted 4-Oxo-l,4-dihydroquinoline-3-carboxylic Acid Derivatives by Thiolation of the Respective Fluoro Derivatives3...

Substance C R = NH-[CH2]2-NH2 systematic name is 7-[(2-aminoethyl)amino]-l-cyclopropyl-6-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid (also known as the ethylenediamine compound). 

Compound 247 was also prepared by condensation of 7-chloro-l-cyclopropyl-6-fluoro-4-oxo-l,4-dihydroquinolin-3-carboxylic acid 246 with anhydrous 244 in up to 80% (Scheme 12.59). ... 

In conclusion it is worth to mention that quinolines and their fluorinated derivatives continue to be one of the most important class of heterocyclic compounds. The medicinal chemistry remains one of the main fields for their applications, and special attention during the last decades is paid to the family of 6-fluoro-l,4-dihydroquinolin-4-oxo-3-carboxylic acids which will be discussed in a separate chapter. Derivatives of 8-hydroxyquinoline have found wide application in analytical, coordination chemistry, while their metal chelates are of interest as the basis to develop new materials. 

Abstract The data on 6-fluoro-l,4-dihydroquinolin-4-oxo-3-carboxylic acids and their structural analogues accumulated in the literature for the last 10-15 years are reviewed. Synthetic approaches to the quinolone system, as well as all kind of structural modifications by incorporating substituents into 1-8 positions or by means of annelation have been discussed. The structure-activity relationships for antibacterial fluoroquinolones, as well as the data on other types of biological activity for the family of bi- and polycyclic fluoroquinolones are presented. The formation of complexes of fluoroquinolones with metals and their applications have been considered. The bibliography - 377 references. 

Rather high antineoplastic activity of ciprofloxacin derivatives, containing a substituent in position 4 of the piperazine fragment has been shown [302], Elucidation of the structure-activity relationships for l-(2-thiazolyl)-6-fluoro-l,4-dihydro-4-oxo-l,8-naphthyridin-3-carboxylic acids has shown that several compounds of this series exhibit activity, comparable with the well-known drug etoposide [316-318], Also the data on activity of amides of 7-substituted l-(2-thia-zolyl)- and l-(2-benzothiazolyl)-l,8-naphthyridin-4-on-3-carboxylic acids have been reported [319], Ethyl l-(4-cyano-2,3,5,6-tetrafluorophenyl)-6,7,8-trifluoro-4-oxo-l,4-dihydroquinolin-3-carboxylate proved to inhibit the phosphorylation process of transcription STAT3 activator that plays an important role for cancer therapy [320],... 

Guo H, Liu J, Wang Y (2004) Preparation of 5-amino-l-cyclopropyl-6-fluoro-8-methoxy-l,4-dihydroquinolin-4-one-3-carboxylic acid derivatives as antibacterial agents. CN Patent 1491944, 28 Apr 2004... 

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