Sodium Hydroxide → (+)-Amlodipine

Participants

Reaction Steps

To a solution of the (R)-amlodipine-hemi-L-tartrate-DMSO-solvate (68.25 g) obtained in Step (2) in methylene chloride (345 mL, 5 mL/g) was added a solution of 50% sodium hydroxide (73 mL) in water (72 mL). The solution was stirred at ambient temperature for 40 minutes. The layers were separated and the organic layer extracted with water (1×150 mL) and gravity filtered through a magnesium sulphate (25 g) bed. The magnesium sulphate was washed with methylene chloride (40 mL) and the methylene chloride removed on a rotary evaporator using a water aspirator. Heptane was added to the evaporation flask as the volume allowed. Eventually, all of the methylene chloride was removed and 600 mL of heptane was added to the flask. The resulting solid was collected by suction filtration, washed with heptane and dried in vacuo at 50° C. overnight to give (R)-amlodipine free base (19.4 g, 53.4% yield) as an off-white solid.

Provenance & Evidence