Water → 1-{6-[4-Methoxy-3-(3,3,6,6-tetramethyl-1,8-dioxo-2,3,4,5,6,7,8,9-octahydro-1H-xanthen-9-yl)phenyl]pyridin-2-yl}-D-proline

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Reaction Steps

Lithium hydroxide (16.9 mg, 403 μmol) was added to a solution of the methyl 1-{6-[4-methoxy-3-(3,3,6,6-tetramethyl-1,8-dioxo-2,3,4,5,6,7,8,9-octahydro-1H-xanthen-9-yl)phenyl]pyridin-2-yl}-D-prolinate obtained in Example 15-2 (157 mg, 269 μmol) in a mixed solvent of THF/water (2:1, v/v) (3 mL) at room temperature. The mixture thus obtained was stirred at the same temperature as above for 30 minutes, and was further stirred at 60° C. for 1 hour. Thereafter, water and diethyl ether were added to the reaction solution, and the mixed solution was then extracted with water twice. The resultant was washed with diethyl ether. Thereafter, 1 N hydrochloric acid was added to the water layer thus obtained, so that the pH was adjusted to pH 4 or lower, and the mixed solution was then extracted with ethyl acetate three times. The organic layer thus obtained was dried over anhydrous magnesium sulfate, and the solvent was then distilled away under reduced pressure. The residue obtained was crystallized from hexane/ethyl acetate to obtain the title compound (107 mg, yield: 70%).

Provenance & Evidence