Sodium Carbonate → 4-Chloroimidazo[1,2-a]quinoxaline

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Reaction Steps

To a stirred suspension of 2-amino-3-chloroquinoxaline (25.5 g, 141.8 mmol) in water/THF 1:1 (500 mL), at rt was added 2-bromo-1,1-diethoxyethane (83.8 g, 425.4 mmol) in one portion. After stirring at rt for 1 h, the mixture was heated to reflux for 3 h under stirring and then stirred for an additional 15 h at rt. The pH value of the mixture was adjusted to pH 8 by addition of solid sodium carbonate and the mixture was subsequently extracted with ethyl acetate (3×500 mL) and the combined organic extracts were dried with sodium sulfate. Removal of the solvent yields 4-chloro-imidazo[1,2-a]quinoxaline as an orange-white solid (63 g, 93%): 1H-NMR (300 MHz, d6-DMS): δ=9.05 (d, 1H), 8.51 (dd, 1H), 8.1 (dd, 1H), 7.99 (d, 1H), 7.89 (td, 1H), 7.76 (td, 1H) ppm. UPLC-MS: RT=0.88 min; m/z 204.6 [MH+]; required MW=203.6.

Provenance & Evidence