Hydrochloric Acid → 1-{2-[4-((5-Fluoro-3-indolyl)methyl)piperidino]ethyl}-2H-benzimidazolin-2-one

Participants

Reaction Conditions

Reaction Steps

6N hydrochloric acid (9.3 cc) is introduced at a temperature in the region of 20° C. into a solution of 3-isopropenyl-1-{2-[4-((5-fluoro-3-indolyl)methyl)piperidino]ethyl}-2H-benzimidazol-2-one (4 g) in ethanol (50 cc). The solution is heated to boiling for 1 hour and then cooled to a temperature in the vicinity of 20° C. The reaction medium is taken up with dichloromethane (100 cc) and distilled water (30 cc) and alkalinized to pH 9 with 5N sodium hydroxide. The organic phase is extracted with dichloromethane (3×30 cc), washed with distilled water (90 cc), dried over anhydrous magnesium sulphate, treated with vegetable charcoal, filtered and concentrated to dryness at 40° C. under reduced pressure (20 mm Hg; 2.7 kPa). The residue is recrystallized in methyl ethyl ketone (15 cc). 1-{2-[4-((5-Fluoro-3-indolyl)methyl)piperidino]ethyl}-2H-benzimidazolin-2-one (0.4 g), m.p. 220° C., is obtained.

Provenance & Evidence