Chlorosulfonic acid → 1,4-Dimethyl-2,3-dioxo-1,2,3,4-tetrahydroquinoxaline-6-sulfonyl chloride

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Reaction Steps

Chlorosulfonic acid (3 mL) was heated to 65° C. and 1,4-dimethylquinoxaline-2,3(1H,4H)-dione (example 6-3b, 1 g, 5.5 mmol) was added in portions over 0.5 hour. The reaction mixture was stirred for 4 hours then cooled to ambient temperature and poured slowly onto ice. The resulting precipitate was filtered and washed with water to give 1,4-dimethyl-2,3-dioxo-1,2,3,4-tetrahydroquinoxaline-6-sulfonyl chloride as a white solid. 1H NMR (400 MHz, DMSO-d6): δ, ppm: 3.50 (s, 6H), 7.25 (m, 2H), 7.38 (m, 4H).

Provenance & Evidence