Acetic Acid → Cyclohexyl-[2-(2,6-dimethoxy-pyridin-3-yl)-5,6-difluoro-benzoimidazol-1-yl]-acetic acid

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Reaction Steps

To a suspension of 12.1 g (22.02 mmol) N-benzyl-N-nitroso-2-cyclohexyl-2-[2-(2,6-dimethoxy-pyridin-3-yl)-5,6-difluoro-benzoimidazol-1-yl]-acetamide in 65 ml tetrahydrofuran and 15 ml water were added dropwise over 20 min. a solution of 9.24 g (220 mmol) lithium hydroxide monohydrate in 45 ml (440 mmol) hydrogen peroxide and 30 ml water. The reaction mixture turned into a turbid solution and a slight temperature raise was observed (cooled temporarily using an ice-bath). After 1 h the pH of the mixture was adjusted to pH 4 using acetic acid. The resulting light yellow solution was extracted three times with ethyl acetate. The combined organic layers were washed twice with saturated aqueous sodium bicarbonate solution, once with water and once with brine. The solution was dried over magnesium sulfate, filtered and evaporated. The residue was dissolved in 200 ml tert-butyl methyl ether and partially evaporated until a precipitation formed. The suspension was cooled in the refrigerator for 30 min, then the solid was filtered off, washed with 50 ml ice-cold tert-butyl methyl ether and dried in high vacuum. White solid (99%). MS (Turbo Spray): m/z=432.2 [M+H].

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