Hydrogen Peroxide → Lansoprazole

Participants

Reaction Steps

2-[[3-Methyl-4-(2,2,2-trifluoroethoxy)pyrid-2-yl]methylthio]benzimidazole (monohydrate) (20.0 g) was dissolved in ethanol (150 ml), to which was added dropwise at about 20° C. a solution of vanadium pentaoxide (30 mg) in a mixture of 35% aqueous solution of hydrogen peroxide (6.14 g) and ethanol (6 ml), and allowed to react at 18°-22° for about 2.5 hours. After completion of the reaction an aqueous solution of sodium thiosulfate (2 g/60 ml) was added to the reaction mixture, which was stirred by ice-cooling for about 1 hour. The crystals were collected by filtration and washed with an ice-cooled mixture of ethanol-water (1:1). The crystals thus obtained were treated with a mixture of ethanol-water (9:1, 100 ml), heated (70°-80° C.) and stirred so that the crystals were dissolved, 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 needles of 2-[[3-methyl-4-(2,2,2-trifluoroethoxy)pyrid-2-yl]methylsulfinyl]benzimidazole (17.8 g). (yield: 89.5%).

Provenance & Evidence