Hydrochloric Acid → (3S)-3-ethyl-6-fluoro-4-[(4-hydroxyphenyl)sulfonyl]-1-propyl-3,4-dihydroquinoxalin-2(1H)-one

Participants

Reaction Conditions

Reaction Steps

To a solution of ethyl 4-{[(2S)-2-ethyl-7-fluoro-3-oxo-3,4-dihydroquinoxalin-1(2H)-yl]sulfonyl}phenyl carbonate (0.35 g, 0.83 mmol) in acetone (5 mL) was added cesium carbonate (0.3 g, 0.91 mmol), and 1-iodopropane (0.32 ml, 3.32 mmol). The mixture was heated at 62° C. for 2.5 hours, cooled to 25° C., and treated with a 2N aqueous solution of sodium hydroxide (3 mL). The reaction was then stirred at 25° C. for 2 hours, and was acidified to pH<2 with the addition of a 2N aqueous solution of hydrochloric acid. The resulting mixture was partitioned between ethyl acetate and a saturated aqueous solution of sodium chloride. The organic layer was separated, dried over magnesium sulfate, and concentrated. The product was purified via flash column chromatography (SiO2, 30% ethyl acetate:hexane eluted to 60% ethyl acetate:hexane) to afford 0.1 g (3S)-3-ethyl-6-fluoro-4-[(4-hydroxyphenyl)sulfonyl]-1-propyl-3,4-dihydroquinoxalin-2(1H)-one as a white solid. MS (ESI) m/z 393 ([M+H]+); MS (ESI) m/z 391 ([M−H]−); Anal. Calcd for C19H21FN2O4S: C, 58.15; H, 5.39; N, 7.14. Found: C, 57.95; H, 5.46; N, 6.66.

Provenance & Evidence