Ethyl 3-oxocyclohexanecarboxylate → 6-bromo-2-(ethoxycarbonyl)-2,3,4,9-tetrahydro-1H-carbazole-8-carboxylic acid

Participants

Reaction Steps

A cream colored suspension of 5-bromo-2-hydrazinylbenzoic acid dihydrochloride (6 g, 19.74 mmol) and ethyl 3-oxocyclohexanecarboxylate (3.70 g, 21.71 mmol) in glacial acetic acid, (˜0.4M) (45 mL) was heated at reflux for 4h. The reaction mixture turned in to dark yellow suspension. The reaction mixture was cooled to room temperature and it was concentrated to afford a dark yellow solid. The solid was then suspended in ethyl acetate (˜50 ml) and the solid was filtered, washed with water and ethyl acetate to give 4.14 g of 6-bromo-2-(ethoxycarbonyl)-2,3,4,9-tetrahydro-1H-carbazole-8-carboxylic acid. MS (ESI) m/z 366.3 (M+H). 1H NMR (DMSO-d6) δ ppm 13.4-12.3 (b, 1H), 10.99 (s, 1H), 7.79 (d, 1H, J=1.9 Hz) 7.69 (d, 1H, J=1.8 Hz), 4.08-4.17 (m, 2H), 3.05 (dd, 1H, J=16.5, 5.0), 2.97-2.84 (m, 2H), 2.76-2.69 (m, 1H), 2.67-2.59 (m, 1H), 2.19-2.12 (m, 1H), 1.88-1.78 (m, 1H), 1.21 (t, 3H, J=7.2).

Provenance & Evidence