US Patent 7696351 Process for the preparation of S-(+)-clopidogrel by optical resolution

The present invention relates to a process for the preparation of S-(+)-clopidogrel by an optical resolution and, more particularly, to a process for the preparation of S-(+)-clopidogrel represented by the following formula 1 with high optical purity by converting a clopidogrel racemic carboxylic acid into a diastereomeric salt using a (+)-cinchonine for optical resolution, extracting an S-(+)-clopidogrel carboxylic acid from the diastereomeric salt using a suitable solvent under an acidic condition and then reacting the S-(+)-clopidogrel carboxylic acid with methanol.