Lithium hydroxide, monohydrate → 3-Hydroxy-6-[4-methoxy-2-methyl-3-(3,3,6,6-tetramethyl-1,8-dioxo-2,3,4,5,6,7,8,9-octahydro-1H-xanthen-9-yl)phenyl]pyridine-2-carboxylic acid

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Reaction Steps

Lithium hydroxide monohydrate (84.6 mg, 2.02 mmol) was added to a solution of the methyl 3-hydroxy-6-[4-methoxy-2-methyl-3-(3,3,6,6-tetramethyl-1,8-dioxo-2,3,4,5,6,7,8,9-octahydro-1H-xanthen-9-yl)phenyl]pyridine-2-carboxylate produced in Example 11-3 (250 mg, 0.46 mmol) in THF (5 ml) and water (2.5 ml) at room temperature, and the mixture thus obtained was then stirred at the same temperature as above for 21 hours. Thereafter, water was added to the reaction solution, and the mixed solution was then washed with diethyl ether. A 1 N aqueous solution of hydrochloric acid (2.02 ml) was added to the water layer, and the solution thus mixed was then extracted with dichloromethane seven times. The organic layer thus obtained was dried over anhydrous sodium sulfate. The solvent was distilled away under reduced pressure, and the residue thus obtained was then purified by silica gel column chromatography (methanol:dichloromethane=3:97 to 6:94, v/v). The fraction thus obtained was washed with a mixed solution of diethyl ether and hexane, followed by collection by filtration and drying, to obtain the title compound (95.6 mg, yield: 39%).

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