Hydrochloric Acid → (S)-(6-bromo-2-methyl-3,4-dihydroquinoxalin-1 (2H)-yl)(cyclopropyl)methanone

Participants

Reaction Conditions

Reaction Steps

A 200-mL round bottomed flask fitted with a nitrogen inlet, magnetic stir bar, and condenser was charged with (S)-tert-butyl 7-bromo-4-(cyclopropanecarbonyl)-3-methyl-3,4-dihydroquinoxaline-1(2H)-carboxylate (5.74 g, 14.52 mmol), ethanol (100 mL), water (25 mL), and 6 M hydrochloric acid solution (2.66 mL, 15.97 mmol). The reaction mixture was heated to 50° C. for 24 h and then cooled to room temperature. The ethanol was removed under reduced pressure, the residue was extracted into dichloromethane (100 mL), and the extract was concentrated under reduced pressure. The crude material was purified by column chromatography on silica gel (eluting with 3:2 hexanes-ethyl acetate) to afford (S)-(6-bromo-2-methyl-3,4-dihydroquinoxaline-1(2H)-yl)(cyclopropyl)methanone (4.00 g, 93%) as an off-white solid. MS (ESI, pos. ion) m/z 295, 297 [M+1]+.

Provenance & Evidence