Boron Trichloride → (3R)-1-Benzyl-3-Ethyl-7-fluoro-4-(4-hydroxybenzoyl)-3,4-dihydroquinoxalin-2(1H)-one

Participants

Reaction Conditions

Reaction Steps

To a stirred solution of (3R)-1-benzyl-3-ethyl-7-fluoro-4-(4-methoxybenzoyl)-3,4-dihydroquinoxalin-2(1H)-one (0.17 g, 0.41 mmol) and tetrabutylammonium iodide (0.28 g, 0.76 mmol) in methylene chloride (4 mL) at −78° C. was added a 1 M solution of boron trichloride in methylene chloride (2.8 mL, 2.8 mmol). Stirring was continued at −78° C. for 5 minutes, and the reaction was warmed to 0° C., where it was stirred for 10 h. Ice water was then added and stirred thoroughly. The layers were separated. The organic layer was washed with water and brine and dried over magnesium sulfate. Evaporation of the solvent under reduced pressure gave an oil (0.26 g). The product was purified via Biotage Horizon® (SiO2, gradient from 5% EtOAc/hexane to 35% EtOAc/hexane) to quantitatively yield (3R)-1-benzyl-3-ethyl-7-fluoro-4-(4-hydroxybenzoyl)-3,4-dihydroquinoxalin-2(1H)-one as a colorless oil. [α]D25=250° (c=0.0097 G/ML, CHCl3); MS (ESI) m/z 405 ([M+H]+); MS (ESI) m/z 403 ([M−H]−); HRMS: calcd for C24H21FN2O3 0.67H2O, 416.2207; found (ESI+), 405.16006.

Provenance & Evidence