1: 1-cyclopropyl-6,7-difluoro-8-methoxy-1,4-dihydro-4-oxo-quinoline-3-carboxylic acid With 1,1,1,3,3,3-hexamethyl-disilazane in acetonitrile T=76 - 80°C; 1 h; Heating / reflux; 2: With boron trifluoride diethyl etherate in acetonitrile T=0 - 25°C; 2 h; 3: rac-2-methylpiperazine With triethylamine in acetonitrile T=15 - 25°C; pH=~ 9; 3 h;

water in ethanol T=70 - 80°C; 2 h;

1: With boron trifluoride-tetrahydrofuran complex; triethylamine in acetonitrile T=20°C; 25 h; 2: With methanol 5 h; Reflux; 3: With sodium hydroxide in methanol; water T=20°C; pH=7; 16 h;

T=50°C; P=10 - 20 Torr; Neat (no solvent);

sodium in methanol; water

1: acetonitrile / 1 h / 70 - 80 °C / |Inert atmosphere; |Large scale 2: 1 h / 0 - 15 °C / |Large scale 3: triethylamine / acetonitrile / 12 h / 15 - 25 °C / pH 8.5 - 9.5 / |Large scale 4: acetonitrile; methanol / 5 h / 0 - 65 °C / |Large scale View Scheme

triethylamine 1.) CH3CN, 50 deg C, 18 h, 2.) CH3CN, reflux, 18 h; Yield given. Multistep reaction;