US Patent 7772400 Optical resolution method of amlodipine

The present invention relates to a method for optical resolution of amlodipines by using isopropanol solvent and optically active O,O′-dibenzoyl tartaric acid as chiral reagent. More particularly, the present invention relates to a method comprising (a) obtaining (R)- or (S)-amlodipine dibenzoyl tartrate salt or solvate thereof by reacting (R,S)-amlodipines with optically active O,O′-dibenzoyl tartaric acid in isopropanol solvent, and (b) treating the (R)- or (S)-amlodipine salt with a base, thus obtaining optically active amlodipine.