Water → 6,8-difluoro-7-hydroxy-4-methylcoumarin-3-carboxylic acid ethyl ester beta-D-glucuronic acid methyl ester triacetate

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Reaction Steps

A solution of 10% NaOH in water (1.5 eq) is added to a 0.1M solution of Compound 5 (1.0 eq) in CH2Cl2, followed by the addition of 1-bromo-2,3,4-tri-O-acetyl-α-D-glucopyranuronic acid methyl ester (1.6 eq) and tetrabutylammonium bromide (1.5 eq). The reaction mixture is stirred vigorously for 16 hours, then poured into 5 volumes of water. The product is extracted with CHCl3 (2×), washed with brine, dried over anhydrous MgSO4, and concentrated in vacuo. The residue is then purified by silica gel column chromatography (eluted with CHCl3 /MeOH) to yield Compound 21.

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