2,3-Dichloro-5,6-dicyano-1,4-benzoquinone → 8-chloro-3-ethylquinoxalin-2(1H)-one

Participants

Reaction Steps

To a solution of 8-chloro-3-ethyl-3,4-dihydroquinoxalin-2(1H)-one (1.30 Kg, 6.17 mol) in anhydrous 1,4-dioxane (15 L) was added DDQ (1.47 Kg, 6.48 mol). The reaction mixture was stirred for 3 h (the internal temperature went up to 45° C. after DDQ addition). After this time LC-MS analysis showed that the reaction was complete. The mixture was evaporated under reduced pressure to give a brown residue. To this residue was added 2M aqueous NaOH to adjust the pH to 7-8. The resulting yellow solid was collected by filtration, suspended in saturated aq. NaHCO3, stirred for 1 h, and filtered to give a light green solid. The light green solid was suspended in saturated aqueous NaHCO3, stirred, filtered and washed with saturated aqueous NaHCO3 and water to give an off-white solid. The off-white solid was suspended in water, mixed well, filtered, washed with water, air-dried overnight, and dried under high vacuum at 50° C. to give 8-chloro-3-ethylquinoxalin-2(1H)-one (1 Kg). 1H NMR (DMSO-d6) δ ppm 7.69-7.75 (m, 1H), 7.59-7.65 (m, 1H), 7.29 (t, J=8.0 Hz, 1H), 2.84 (q, J=7.4 Hz, 2H), 1.23 (t, J=7.4 Hz, 3H). Mass Spectrum (ESI) m/z=209.1 (M+1).

Provenance & Evidence