m-Chloroperbenzoic acid → 2-[(4-Difluoromethoxy-3-methyl-2-pyridyl)methylsulfinyl]benzimidazole

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Reaction Steps

In chloroform (20 ml) - methanol (10 ml) was dissolved 2-[(4-difluoromethoxy-3-methyl-2-pyridyl)methylthio]benzimidazole (2.0 g). To the solution was added dropwise, under ice-cooling, a solution of m-chloroperbenzoic acid (MCPBA) (80%, 1.5 g in chloroform (20 ml). The reaction mixture was washed with a saturated aqueous solution of sodium hydrogencarbonate and water, in that order, then dried (MgSO4). The solvent was distilled off. The residual solid was subjected to a silica gel column chromatography. From the portion eluted with ethyl acetate - methanol (100:3, v/v), was obtained 2-[(4-difluoromethoxy-3-methyl-2-pyridyl)methylsulfinyl]benzimidazole (1.5 g, 71%). Recrystallization from ethyl acetate--ether gave colorless needles, m.p. 157°-158° C. (decomp.).

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