Lithium hydroxide, monohydrate → 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

A solution of dimethyl (3,3-difluoro-2-oxoheptyl)phosphonate (1) (1.110 g, 4.299 mmol) in tetrahydrofuran (17 ml) was added with lithium hydroxide monohydrate (0.171 g, 4.08 mmol), 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-tetrahydropyranyloxy)cyclopentyl]heptanate (2) (0.962 g, 2.41 mmol) in tetrahydrofuran (3 ml) was added thereto, and the mixed solution was heat refluxed for approximately 48 hours. After cooling to room temperature, the solution was concentrated under reduced pressure. Ethyl acetate and water were added to the residue and stirred, then, the mixture was let to stand and separated into two layers. The aqueous layer was extracted twice with ethyl acetate. The organic layers were combined, sequentially washed with 3% aqueous sodium chloride and saturated aqueous sodium chloride, and then dried with anhydrous magnesium sulfate. After concentration under reduced pressure, the residue was purified by silica gel column chromatography (Fuji Silysia BW-300SP: 38 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) (0.517 g; 0.973 mmol; yield: 40.4%).

Provenance & Evidence