Permanganate → (S)-2(isopropylsulfonyl)-amino-3-methyl-butyric acid-N-[2-(3,4-dimethoxyphenyl)-ethyl]-amide

Participants

Reaction Steps

3.7 g of (S)-2-(isopropylsulfinyl)-amino-3-methyl-butyric acid N-[2-(3,4-dimethoxyphenyl)-ethyl]-amide (Example 3.90) are dissolved in 50 ml of acetone at room temperature. An acetone solution saturated with potassium permanganate is added dropwise to this stirred solution until the reaction mixture retains the violet colour of the permanganate; the reaction mixture is then stirred at room temperature for 45 minutes. The resulting manganese dioxide is removed by filtration over Celite. The filtrate is evaporated to dryness and the resulting residue is dissolved in 500 ml of methyl acetate. This organic phase is washed once with 200 ml of water, dried over sodium sulfate and concentrated. The resulting residue is chromatographed over silica gel with a mixture of one part of methyl acetate and one part of n-hexane. (S)-2-(isopropylsulfonyl)-amino-3-methyl-butyric acid N-[2-(3,4-dimethoxyphenyl)-ethyl]-amide, which can be further purified by recrystallization from methyl acetate/n-hexane, is obtained, melting point 86°-87° C.

Provenance & Evidence