PROCESS FOR THE PREPARATION OF OPTICALLY PURE OR OPTICALLY ENRICHED ENANTIOMERS OF SULPHOXIDE COMPOUNDS

A PROCESS FOR PREPARATION OF OPTICALLY PURE OR OPTICALLY ENRICHED ENANTIOMERS OF SULPHOXIDE COMPOUNDS OF FORMULA (I), SUCH AS OMEPRAZOLE AND STRUCTURALLY RELATED COMPOUNDS, AS WELL AS THEIR SALTS AND HYDRATES. THE SAID PROCESS COMPRISES A) PROVIDING, A MIXTURE OF ENANTIOMERS OF THE SULPHOXIDE COMPOUND OF FORMULA (I) AS STARTING MATERIAL, IN AN ORGANIC SOLVENT; SAID ENANTIOMERS HAVING R AND S CONFIGURATIONS AT THE SULFUR ATOM OF THE SULPHOXIDE GROUP; B) TREATING THE MIXTURE OF ENANTIOMERS, IN THE ORGANIC SOLVENT, WITH A CHIRAL HOST; C) SEPARATING THE ADDUCT FORMED BY THE ENANTIOMER AND THE CHIRAL HOST; D) IF DESIRED, REPEATING THE OPERATION OF STEP (B); E) TREATING THE ADDUCT OBTAINED IN STEP (C) OR (D) WITH METAL BASE SELECTED FROM GROUP I AND GROUP II METAL, THEREBY OBTAINING METAL SALT OF ONE OF THE OPTICAL ISOMERS OF THE SULPHOXIDE COMPOUND IN OPTICALLY PURE OR OPTICALLY ENRICHED FORM; F) OPTIONALLY, CONVERTING THE GROUP I METAL SALT OF OPTICALLY PURE OR OPTICALLY ENRICHED FORM THE OPTICAL ISOMERS OF THE SULPHOXIDE COMPOUND OBTAINED IN STEP (E) TO MAGNESIUM SALT.