Imidazole → (11beta,16beta)-9-Fluoro-16-methyl-3,20-dioxo-11,17-bis[(trimethylsilyl)oxy]pregna-1,4-dien-21-yl acetate

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Reaction Steps

To a solution of (11β,16β)-9-fluoro-11,17-dihydroxy-16-methyl-3,20-dioxopregna-1,4-dien-21-yl acetate (18.79 g, 43.25 mmol) and imidazole (58.89 g, 864.9 mmol) in 200 mL of dry N,N-dimethylformamide was added neat trimethylsilyl chloride (55.0 mL, 433 mmol) dropwise during 15 min. The resulting pale yellow solution was stirred at room temperature for 16 hours. The solution was diluted with ethyl acetate and washed successively with water, sat. NH4Cl, water, sat. NaHCO3, water, and brine. The organic phase was dried over Na2SO4, filtered and evaporated in vacuo to yield 26 g of the title compound as a pale yellow oil.

Provenance & Evidence