Triethylamine → (4S)-3-[(2S,3S,6R,7S,8S)-5-oxo-3-hydroxy-2,4,4,6,8-pentamethyl-7-(2,2,2-trichloroethoxycarbonyloxy)-10-undecenoyl]-4-benzyloxazolidinone

Participants

Reaction Conditions

Reaction Steps

A solution of (4S)-3-propionyl-4-benzyloxazolidinone (91 mmol) in 200 mL of CH2Cl2 at 0° C. is treated sequentially with dibutylboron triflate (27 mL) and triethylamine (16.7 mL) at such a rate so as to keep the reaction temperature below 3° C. After stirring for 30 minutes, the mixture is cooled to −78° C. and treated with a solution of (4R,5S, 6S)-3-oxo-5-(2,2,2-trichloroethoxycarbonyloxy)-2,2,4,6-tetramethyl-8-nonenal (90 mmol) in 10 mL of CH2Cl2. After 1 hour, the mixture is allowed to warm slowly to 0° C. and stirred an additional 1 hour. The reaction is quenched by addition of 100 mL of pH 7 phosphate buffer and 300 mL of methanol. A mixture of 2:1 methanol/30% aq. H2O2 (300 mL) is then added while maintaining the temperature below 10° C. After stirring for 1 hour, the mixture is concentrated under vacuum to a slurry, which is extracted with ether. The extract is washed sequentially with 5% NaHCO3 and brine, dried over MgSO4, filtered, and evaporated. The product is isolated by silica gel chromatography.

Provenance & Evidence