Patent ID: 8106231

Claim:
A process for the preparation of (2R,3S)-3-phenylisoserine methyl ester acetate salt (I) which comprises the following steps: a) treatment of racemic threo 3-phenylisoserine amide (VI) with an enantiomerically pure organic acid to provide a corresponding acid salt of (2R,3S)-3-phenylisoserine amide; b) treatment of the acid salt of (2R,3S)-3-phenylisoserine amide with a strong inorganic acid in a protic solvent to provide a (2R,3S)-3-phenylisoserine amide inorganic acid salt; c) treatment of the (2R,3S)-3-phenylisoserine amide inorganic acid salt with hydrochloric acid in a protic solvent followed by treatment with acetic acid to crystallise (2R,3S)-3-phenylisoserine methyl ester acetate salt (I).