Patent ID: 7365206
Filing Date: 2008-04-29
Classification: C07D

Abstract:
1. A process for preparation of sulfoxide of formula 1(i) as enantiomers or enantiomerically enriched enantiomers or a salt thereof: which process comprises: a) reacting 5-Methoxy-2-[(3,5-dimethyl-4-methoxy-2-pyridyl)methyl-thio]-1H-benzimidazole or a salt thereof with (S)- or (R) camphor sulfonychloride to obtain a mixture of 1-(S or R)-camphor sulfonyl-5-methoxy-2-[(3,5-dimethyl-4-methoxy-2-pyridyl)methyl-thio]-1H-benzimidazole and 1-(S or R)-camphor sulfonyl-6-methoxy-2-[(3,5-dimethyl-4-methoxy-2-pyridyl)methyl-thio]-1H-benzimidazole; b) oxidizing the compound formed in step (a) to give a diastereomeric excess sulfoxides having one configuration at sulfur atom of sulfoxide group over that having the opposite configuration; c) separating the diastereomers formed in step (b); and d) deprotecting the separated diastereomers with an acid or base to provide a single enantiomer or enantiomerically enriched compound of (R)- or (S)-5-Methoxy-2-[(3,5-dimethyl-4-methoxy-2-pyridyl)methylsulfinyrj1-H-benzimidazole ((R)- or (S)-esomeprazole) and optionally preparing an (R)- or (S)-esomeprazole salt.