Water → methyl 7-[(1R,2R,3R,5S)-5-acetoxy-2-((E)-4,4-difluoro-3-oxo-1-octenyl)-3-(2-tetrahydropyranyloxy)cyclopentyl]heptanate

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Reaction Steps

To a solution of dimethyl (3,3-difluoro-2-oxoheptyl)phosphonate (1) (1.113 g, 4.31 mmol) in t-butyl methyl ether (17 ml), potassium hydroxide (0.225 g, 4.00 mmol) was added and the mixture was stirred for approximately 1.2 hours at room temperature. A solution of methyl 7-[(1R,2R,3R,5S)-5-acetoxy-2-formyl-3-(2-tetrahydro pyranyloxy)cyclopentyl]heptanate (2) (0.965 g, 2.42 mmol) in t-butyl methyl ether (3 ml) solution, and water (0.32 ml) were added thereto. The mixed solution was heat refluxed for approximately 48 hours. After cooling to room temperature, water (5.6 ml) was added to the solution and the mixture was stirred, let to stand and then separated into two layers. The aqueous layer was extracted twice with ethyl acetate (4 ml). The organic layers were combined, sequentially washed with 3% aqueous sodium chloride (6 ml) and saturated aqueous sodium chloride (6 ml), and dried with anhydrous magnesium sulfate. After concentration under reduced pressure, the residue was purified by silica gel column chromatography (Fuji Silysia BW-300SP: 33 g; ethyl acetate:hexane =1:4) to give methyl 7-[(1R,2R,3R,5S)-5-acetoxy-2-((E)-4,4-difluoro-3-oxo-1-octenyl)-3-(2-tetrahydropyranyloxy)cyclopentyl]heptanate (3) (1.035 g; 1.950 mmol; yield: 80.6%).

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