Water → Methanesulfonic acid (R)-2-benzyloxy-1-[(2S,4R)-4-ethyl-5-oxotetrahydrofuran-2-yl]ethyl ester

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Reaction Steps

A solution of 25.0 g of (3R,5S)-5-[(R)-2-benzyloxy-1-hydroxyethyl]-3-ethyldihydrofuran-2-one obtained in Example (106c) (94.7 mmol) in methylene chloride (600 ml) was cooled in an ice bath. Then, 28.7 g of triethylamine (284 mmol) and 15.9 g of methanesulfonyl chloride (139 mmol) were added thereto, and the mixture was stirred at the same temperature for three hours. 500 ml of water was added to the reaction mixture, followed by extraction with methylene chloride. Then, the organic layer was washed with water and brine and dried over anhydrous magnesium sulfate. After filtration, the solvent was evaporated under reduced pressure, and the residue was purified by silica gel column chromatography (elution solvent:n-hexane/ethyl acetate=4/1-1/1) to obtain 31.2 g of the title compound (yield: 96%).

Provenance & Evidence