Water → (RS)-3-Ethoxycarbonyl-7,9-difluoro-1-(2-fluoroethyl)-4-oxo-8-(3-phenyl-1-piperazinyl)-1,4-dihydrobenzo[b][1,8]naphthyridine

Participants

Reaction Conditions

Reaction Steps

(RS)-3-Ethoxycarbonyl-7,9-difluoro-1-(2-fluoroethyl)-4-oxo-8-(3-phenyl-1-piperazinyl)-1,4-dihydrobenzo[b][1,8]naphthyridine was prepared under the following conditions: a suspension of 3-ethoxycarbonyl-1-(2-fluoroethyl)-7,8,9-trifluoro-4-oxo-1,4-dihydrobenzo[b][1,8]naphthyridine (2.8 g), (RS)-2-phenylpiperazine (1.7 g) and sodium carbonate (1.1 g) in dimethyl sulphoxide (40 cc) is heated with stirring to a temperature in the region of 100° C. for 2 hours. After cooling to approximately 20° C., the reaction mixture is poured into water (200 cc) and extracted with trichloromethane (3×100 cc). The combined organic extracts are washed with water (1×50 cc) and concentrated under reduced pressure (20 kPa) at a temperature in the region of 40° C. The oily residue is taken up with ethanol (100 cc) and concentrated again under reduced pressure under the above conditions. The solid obtained is recrystallized in ethanol (100 cc) containing dimethylformamide (20%), drained and washed with ethanol (2×20 cc). The expected product (2.4 g) is obtained in the form of a yellow solid, m.p. 208° C.

Provenance & Evidence