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

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Reaction Conditions

Reaction Steps

A suspension of 3-ethoxycarbonyl-7,8,9-trifluoro-1-methyl-4-oxo-1,4-dihydrobenzo[b][1,8]naphthyridine (1.8 g) and (RS)-2-phenylpiperazine (3.2 g) in dimethyl sulphoxide (30 cc) is heated to a temperature in the region of 100° C. with stirring for 1 hour and a half. The solution obtained, at approximately 100° C., is poured with stirring into a mixture of water (150 cc) and ice (50 g). The suspension obtained is extracted at approximately 20° C. with trichloromethane (3×40 cc). The combined organic extracts are washed with water (2×50 cc), dried over magnesium sulphate, filtered and concentrated to dryness under reduced pressure (20 kPa) at approximately 50° C. The solid obtained is recrystallized in a mixture of dimethylformamide (40 cc) and ethanol (40 cc). (RS)-3-Ethoxycarbonyl-7,9-difluoro-1-methyl-4-oxo-8-(3-phenyl-1-piperazinyl)-1,4-dihydrobenzo[b][1,8]naphthyridine (2 g) is obtained in the form of a yellow solid, m.p. 216° C.

Provenance & Evidence