2,3-Dichloro-5,6-dicyano-1,4-benzoquinone → ethyl 6-bromo-8-carbamoyl-9H-carbazole-2-carboxylate

Participants

Reaction Steps

A stirred suspension of ethyl 6-bromo-8-carbamoyl-2,3,4,9-tetrahydro-1H-carbazole-2-carboxylate (3.93 g, 10.76 mmol) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (5.37 g, 23.67 mmol) in toluene (60 mL) was heated at reflux for 4 h. The reaction mixture was cooled to room temperature and the solid was filtered, washed with toluene, and air-dried. The solid was suspended in ethyl acetate, the solid filtered, washed with MeOH and air-dried to furnish 4.6 g of ethyl 6-bromo-8-carbamoyl-9H-carbazole-2-carboxylate which was taken as such to the next reaction. MS (ESI) m/z 361.1/363.1 (M+H)+. 1H NMR (DMSO-d6) δ ppm 11.76 (s, 1H), 8.60 (d, J=1.76 Hz, 1H), 8.36 (d, J=0.88 Hz, 1H), 8.25 (d, J=8.35 Hz, 1H), 8.23 (br. s., 1H), 8.13 (d, J=1.76 Hz, 1H), 7.73 (dd, J=8.24, 1.43 Hz, 1H), 7.59 (br. s., 1H), 4.29 (q, J=7.18 Hz, 2H), 1.30 (t, J=7.14 Hz, 3H).

Provenance & Evidence