To provide an improved method for preparing S-pantoprazole.
The improved method for preparing the S-pantoprazole is carried out as follows: 5-Difluoromethoxy-1-benzimidazole-2-thiol is reacted with 2-chloromethyl-3,4-dimethoxypyridine in the presence of a phase transfer catalyst and a base in a solvent to afford 5-(difluoromethoxy)-2-(((3,4-dimethoxypyrrolidin-2-yl)methyl)thio)-1H-benzimidazole. The resultant compound is then subjected to in-situ stereoselective oxidation in the presence of a stereoselective reaction reagent, an oxidizing agent and a base to provide the S-pantoprazole, which is, as necessary, treated with an alkaline solution to provide the pure S-pantoprazole. The S-pantoprazole is reacted with a base in a solvent to afford a pharmaceutically acceptable stable salt of the S-pantoprazole or a hydrate thereof.
BHAWAL MANIKRAO BABURAO
SHAH BIPINBHAI VIRAL
ZOPE REWAJI UMESH
MEHTA RAMANLAL SATISH
