Patent attributes
The present invention provides a new and efficient process for the preparation of the dexmethylphenidate hydrochloride with high optical purity, the process comprising:(a) reacting a solution of threo-N-Boc-ritalinic acid with (S)-1-phenylethylamine, separating precipitated solid salt of (R,R)-enriched N-Boc-ritalinic acid with (S)-1-phenylethylamnine from the reaction mixture and recrystallizing, reslurring and/or trituring of said salt;(b) mixing the solid salt of (R,R)-N-Boc-ritalinic acid and (S)-1-phenylethylamine obtained in step (a) with aqueous acid and separating (R,R)-N-Boc-ritalinic acid from the mixture; and(c) reacting the (R,R)-N-Boc-ritalinic acid prepared in step (b) with hydrogen chloride and methanol to give dexmethylphenidate hydrochloride with optical purity of at least 99% ee.
