H3PW12O40: An Efficient and Green Catalyst for the Facile and Selective Oxidation of Sulfides to Sulfoxides, Applied to the Last Step of the Synthesis of Omeprazole

Omeprazole, (6-methoxy-2-((4-methoxy-3,5-dimethylpyridin-2-yl)methylsulfinyl)-1Hbenzimidazole is a well-established prescribed drug, exhibits proton pump inhibitor activity. In this work, a novel, facile, economical and selective oxidation approach using H3PW12O40 as Keggin type heteropolyacids along with H2O2 in the last step of the conventional synthesis of this compound as well as its derivatives under environmental-benign conditions, is reported. This protocol can be well adopted for pilot plant scale giving a high pure pharmacopeia grade material. Our synthetic route involves the use of various heteropolyacids as heterogeneous catalysts. Due to the obtained results, it was concluded that Keggin type heteropolyacid , is an effective catalyst for this purpose. The optimized condition for the last step of this synthesis was applied to the synthesis of lansoprazole, pantoprazole, and rabeprazole.