反应详情

A thick slurry of 8-chloro-3-ethylquinoxalin-2(1H)-one (1.00 Kg, 4.79 mol) in POCl3 (2.68 L, 28.8 mol) was stirred at 100° C. for 2 h. At this time LC-MS analysis showed that the reaction was complete. After the removal of most of the POCl3 under reduced pressure, the residue was poured carefully into ice-water and neutralized with a combination of 2M aq. NaOH and saturated aq. NaHCO3. The resulting suspension was extracted with DCM (3×4 L). The organic phase was washed with brine, dried over anhydrous Na2SO4, filtered, and evaporated under reduced pressure. The crude was purified by flash column chromatography eluting with hexane/EtOAc (30/1) to give 3,5-dichloro-2-ethylquinoxaline (840 g) as a white solid. 1H NMR (DMSO-d6) δ ppm 8.01-8.08 (m, 2H), 7.84 (t, J=8.0 Hz, 1H), 3.10-3.17 (d, J=7.3 Hz, 2H), 1.36 (t, J=7.3 Hz, 3H). Mass Spectrum (ESI) m/z=227.1 (M+1).

1. customAfter the removal of most of the POCl3 under reduced pressure
2. additionthe residue was poured carefully into ice-water
3. extractionThe resulting suspension was extracted with DCM (3×4 L)
4. washThe organic phase was washed with brine
5. dry with materialdried over anhydrous Na2SO4
6. filtrationfiltered
7. customevaporated under reduced pressure
8. customThe crude was purified by flash column chromatography
9. washeluting with hexane/EtOAc (30/1)