Water → n,n-Diphenyl-3-hydroxyimino-2-methyl-4-methylsulfonylbenzamide

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Reaction Steps

A solution of 0.7 g (6.9 mmol) of n-butyl nitrite (97%) and 2 g (5.3 mmol) of N,N-diphenyl-2,3-dimethyl-4-methylsulfonyl-benzamide in 30 ml of dimethylformamide is cooled to from −55 to −60° C., and a solution of 1.4 g (12 mmol) of potassium tert-butoxide in 10 ml of dimethylformamide is added dropwise at this temperature, over a period of 20 minutes. The reaction is monitored by HPLC. For work-up, initially 10 ml of water are added, and the mixture is then adjusted to pH 5-6 using glacial acetic acid. The mixture is then poured onto 100 ml of ice-water and the aqueous phase is extracted with ethyl acetate. The organic phase is washed with sodium bicarbonate solution, dried over magnesium sulfate and concentrated. This gives 3.0 g of a partially crystalline crude product, which is purified by silica gel chromatography using the mobile phase toluene/acetone.

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