Chlorosuccinimide → ethyl 5-bromo-8-carbamoyl-6-chloro-9H-carbazole-2-carboxylate

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Reaction Steps

A mixture of ethyl 5-bromo-8-carbamoyl-9H-carbazole-2-carboxylate [synthesized according to the procedure described in U.S. Pat. No. 8,084,620, Intermediate 48-1] (0.100 g, 0.277 mmol) and NCS (recrystallized from toluene; 0.037 g, 0.277 mmol) in CCl4 (10 mL) and DMF (2 mL) was stirred at room temperature for 112 h. The mixture was filtered, and the collected precipitate was washed with CCl4 and dried overnight under vacuum. The residue was purified by column chromatography on silica gel (40 g), eluting with hexanes, then with EtOAc-hexanes (30%, then 50%), to give ethyl 5-bromo-8-carbamoyl-6-chloro-9H-carbazole-2-carboxylate as a fluffy white solid (0.071 g, 65% yield). Mass spectrum m/z 395, 397, (M+H)+. 1H NMR (400 MHz, DMSO-d6) δ 12.13 (s, 1H), 8.77 (d, J=8.6 Hz, 1H), 8.53 (d, J=1.1 Hz, 1H), 8.36 (br. s., 1H), 8.29 (s, 1H), 7.89 (dd, J=8.4, 1.5 Hz, 1H), 7.74 (br. s., 1H), 4.38 (q, J=7.0 Hz, 2H), 1.38 (t, J=7.0 Hz, 3H).

Provenance & Evidence