Hydrogen Peroxide → Lansoprazole

Participants

Reaction Steps

2-[[3-Methyl-4-(2,2,2-trifluoroethoxy)pyrid-2-yl]methylthio]benzimidazole (monohydrate) (1.77 g) was dissolved in dichloromethane (30 ml), to which was added dropwise at 15°-20° C. a solution of hydrogen peroxide in t-butanol (2.75 ml corresponding to 0.2 g of hydrogen peroxide) containing vanadium pentaoxide (5 mg), and then allowed to react at 20°-25° C. for about one hour. After completion of the reaction, an aqueous solution of sodium thiosulfate (0.5 g/30 ml) was added to the reaction mixture, which was stirred vigorously for about 10 minutes, allowed to stand still, and separated into layers. The dichloromethane layer was washed with water (30 ml), and concentrated under reduced pressure; to the residue was added a mixture of ethanol-water (9:1, 10 ml) for crystallization. This solution was ice-cooled, and the crystals were collected by filtration and washed with an ice-cooled mixture of ethanol-water (8:2). The crystals thus obtained were treated with a mixture of ethanol-water (9:1, 10 ml), heated (65°-70° C.) and stirred for dissolution of the crystals, then the insoluble matters were removed by hot filtration. The filtrate was ice-cooled for crystallization, and the crystals were collected by filtration, washed with ice-cooled ethanol-water mixture (8:2) and dried in vacuo to give white crystals of 2-[[3-methyl-4-(2,2,2-trifluoroethoxy)pyrid-2-yl]methylsulfinyl]benzimidazole (1.64 g). (yield: 93.2%).

Provenance & Evidence