Lithium hydroxide, monohydrate → methyl 7-[(1R,2R,3R,5S)-5-acetoxy-2-((E)-(6S)-4,4-difluoro-6-methyl-3-oxo-1-octenyl)-3-(2-tetrahydropyranyloxy)cyclopentyl]heptanate

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Reaction Steps

To a solution of dimethyl ((5S)-3,3-difluoro-5-methyl-2-oxoheptyl)phosphonate (A) (74.7 g, 274 mmol) in t-butyl methyl ether (1120 ml), lithium hydroxide monohydrate (11.5 g, 273 mmol) was added and the mixture was stirred for one hour at room temperature. A solution of methyl 7-[(1R,2R,3R,5S)-5-acetoxy-2-formyl-3-(2-tetrahydropyranyl-oxy)cyclopentyl]heptanate (B) (64.02 g, 160.6=1) in t-butyl methyl ether (278 ml) and water (21.7 ml) were added thereto, and the mixed solution was heat refluxed for approximately 31 hours (internal temperature: approximately 53° C.). After cooling to room temperature, water (351 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 (234 ml). The organic layers were combined, washed twice with saturated aqueous sodium chloride (351 ml), and dried with anhydrous magnesium sulfate (55 g). After concentration under reduced pressure, the residue was purified by silica gel column chromatography (Fuji Silysia BW-300: 2110 g; ethyl acetate:hexane=1:4 to 1:2). The fractions containing impurities were re-purified by silica gel column chromatography (Fuji Silysia BW-300: 850 g; ethyl acetate:hexane=1:4 to 1:2) to give methyl 7-[(1R,2R,3R,5S)-5-acetoxy-2-((E)-(6S)-4,4-difluoro-6-methyl-3-oxo-1-octenyl)-3-(2-tetrahydropyranyloxy)cyclopentyl]heptanate (C) (75.03 g; 137.8 mmol; yield: 85.8%) as a pale yellow oil.

Provenance & Evidence