Water → (-)-4,5-difluoro-2-(S)-methyl-2,3-dihydroindole p-toluenesulfonate

Participants

Reaction Steps

(-)-4,5-difluoro-2-(S)-methyl-1-[(S)-N-p-toluenesulfonylprolyl]-2,3-dihydroindole, the compound (a) obtained in Example 1, 51.7 g, was added to the solution comprising 69 g of potassium hydroxide, 50 ml of water and 200 ml of methanol, and the mixture was refluxed by heating for 3.5 hours. After the reaction the mixture was allowed to cool to the room temperature, concentrated under reduced pressure to the 1/4 volume, to which was added 800 ml of water, and extracted twice with 400 ml of ether. The ether layer was washed with 300 ml of water and a saturated aqueous solution of sodium chloride, and the organic layer was dried over magnesium sulfate and filtered. To the filtrate was added 24 g of p-toluenesulfonic acid monohydrate, and stirred for 30 minutes. The precipitate was collected by filtration, and recrystallized from ethyl acetate-edthanol, to give 25.8 g of the title compound.

Provenance & Evidence