1,2-Dichloroethane → ethyl 5-bromo-8-carbamoyl-2,3,4,9-tetrahydro-1H-carbazole-2-carboxylate

Participants

Reaction Steps

A suspension of 5-bromo-2-(ethoxycarbonyl)-2,3,4,9-tetrahydro-1H-carbazole-8-carboxylic acid (Intermediate 46-1, 12.28 g, 33.5 mmol), EDC (7.71 g, 40.2 mmol), and HOBT (6.16 g, 40.2 mmol) in THF-DCM (4:1, 335 mL) was treated with 28% aqueous ammonium hydroxide (7.83 mL, 201 mmol), and the resulting suspension was stirred at rt overnight. The mixture was concentrated and the residue was suspended in water. The precipitate was collected by filtration, washed with water and EtOAc and dried to give ethyl 5-bromo-8-carbamoyl-2,3,4,9-tetrahydro-1H-carbazole-2-carboxylate (8.92 g). The filtrate was concentrated and the residue was suspended in methanol. A solid was collected by filtration, washed with methanol and air dried to afford additional product (0.39 g) for a total of 9.31 g (76%). 1H NMR (400 MHz, DMSO-d6) δ 11.08 (s, 1H) 8.02 (br. s., 1H) 7.43 (d, J=8.13 Hz, 1H) 7.39 (br. s., 1H) 7.14 (d, J=8.13 Hz, 1H) 4.02-4.17 (m, 2H) 3.07-3.18 (m, 1H) 2.97-3.06 (m, 1H) 2.86-2.98 (m, 2H) 2.77-2.86 (m, 1H) 2.09-2.19 (m, 1H) 1.72-1.86 (m, 1H) 1.20 (t, J=7.14 Hz, 3H). Mass spectrum m/z 365, 367 (M+H)+.

Provenance & Evidence