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

Participants

Reaction Conditions

Reaction Steps

A suspension of 3-ethoxycarbonyl-7,8-difluoro-1-methyl-4-oxo-1,4-dihydrobenzo[b][1,8]naphthyridine (1.3 g) and (RS)-2-benzylpiperazine (1.3 g) in dimethyl sulphoxide (25 cc) is heated to approximately 90° C. with stirring for 1 hour 45 minutes. After cooling to a temperature in the region of 20° C., the reaction mixture is treated with water (100 cc) and extracted with trichloromethane (3×30 cc). The combined organic extracts are washed with water (3×30 cc), dried over magnesium sulphate, filtered and concentrated to dryness at approximately 50° C. under reduced pressure (20 kPa). After 1 recrystallization in a mixture of dimethylformamide (4 cc) and ethanol (1 cc), (RS)-8-(3-benzyl-1-piperazinyl)-3-ethoxycarbonyl-7-fluoro-1-methyl-4-oxo-1,4-dihydrobenzo[b][1,8]naphthyridine (1.6 g) is obtained in the form of a yellow solid, m.p. 190° C.

Provenance & Evidence