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F. Sauter, U. Jordis, M. Rudolf, J. Wieser, K. Baumann:
"Preparation of bicyclic substituted quinolonecarboxylic acid derivatives, useful as antibacterial pharmaceuticals";
Patent: Deutschland, No. DE 3721745; submitted: 07-01-1987, granted: 01-14-1988.

Quinolones I (R1 = MeNH, 4-FC6H4, 2,4-F2C6H3; R2 = H, S atom bound to ring N via an ethylene bridge; X = H, physiol. tolerable ester group; Y = Q, Q1; R3 = H, alkyl, PhCH2, CHO, MeCOCH2, Q2) and their addn. salts with inorg. or org. acids or bases and/or their hydrates, useful as antibacterials, were prepd. by a 5-step procedure. A mixt. of I (R1 = MeNH, R2 = X = H, Y = Cl), Q1H (R3 = Me), and Me2SO was stirred 3 h at 140° to give 43% I×HCl (R1 = MeNH, R2 = X = H, Y = Q1, R3 = Me). The MIC of I (R1 = 4-FC6H4, R2 = X = H, Y = Q, R3 = Me) HCl salt (III) against Staphylococcus aureus MSSA was 0.25 and 0.5 mg/mL for 50% and 90% inhibition and for ciprofloxacin was 0.5 and 1 mg/mL. The ED50 of III against S. aureus Smith in mice was 1.1 mg/kg orally whereas that of ciprofloxacin was 4.3 mg/kg.