Sulfuric Acid → Ethyl [(6S)-6-(3,5-difluorophenyl)-3,3-dimethyl-2,4-dioxopiperidin-1-yl]acetate

Participants

Reaction Conditions

Reaction Steps

To a solution of ethyl [(4S,6S)-6-(3,5-difluorophenyl)-4-hydroxy-3,3-dimethyl-2-oxopiperidin-1-yl]acetate (470 mg, 1.377 mmol, described in Intermediate 21) in acetone (24 mL) at 0° C. was added a solution of chromium (VI) trioxide (174 mg, 1.740 mmol) in H2O (0.5 mL) and H2SO4 (0.147 mL, 2.75 mmol), in three portions over 5 min and the mixture was stirred at 0° C. for 30 min. Most of the acetone was removed by concentration in vacuo, and the residue was basified with saturated aqueous NaHCO3 (75 mL) and extracted with EtOAc (2×100 mL). The combined organic layers were washed with brine (40 mL) and dried over Na2SO4, filtered, and concentrated in vacuo. The crude product was purified by silica gel chromatography, eluting with a gradient of CH2Cl2:CH3OH—100:0 to 92:8, to give the title compound. MS: m/z=340 (M+1).

Provenance & Evidence