2,6-Lutidine → (3S,5R,6S)-3-Allyl-6-(4-chloro-3-fluorophenyl)-5-(3-chlorophenyl)-1-((S)-1-cyclopropyl-2-hydroxyethyl)-3-methylpiperidin-2-one

Participants

Reaction Steps

A solution of (2S)-2-((2R)-3-(4-chloro-3-fluorophenyl)-2-(3-chlorophenyl)-3-hydroxypropyl)-N—((S)-1-cyclopropyl-2-hydroxyethyl)-2-methylpent-4-enamide (40.2 g, 81 mmol, Example 4, Step F) in dichloromethane (80 mL) was added p-toluenesulfonic anhydride (66.3 g, 203 mmol) in dichloromethane (220 mL) at 0° C., and the reaction mixture was stirred for 10 minutes at same the temperature. 2,6-Lutidine (43.6 mL, 374 mmol, Aldrich, St. Louis, Mo.) was added dropwise via addition funnel at 0° C. The reaction mixture was slowly warmed to room temperature, and then it was stirred at reflux. After 24 hours, sodium bicarbonate (68.3 g, 814 mmol) in water (600 mL) and 1,2-dichloroethane (300 mL) were added in succession. The reaction mixture was heated at reflux for an hour and then cooled to room temperature. The layers were separated and the aqueous layer was extracted with dichloromethane. The combined organic layer was washed with 1 N hydrochloric acid, water, and brine, then concentrated under reduced pressure. The residue was purified by flash chromatography (1.5 kg SiO2 column, gradient elution of 10% to 50% ethyl acetate in hexanes) to provide the title compound as a white solid.

Provenance & Evidence