反应详情

To 4-chloro-2-fluoroaniline (2.7 g, 19.0 mmol) in H2O (12 mL), cooled to 0° C., conc. HCl (4.5 mL) was added and stirred for 10 min. NaNO2 (1.3 g, 18.8 mmol), dissolved in water (13 mL), was added slowly to the reaction mixture and stirred at 0° C. for an additional 30 min., the solids were filtered to give the diazonium salt. In another set up, to ethyl 2-oxocyclohexanecarboxylate (3 g, 19.3 mmol) in H2O (10 mL), 5N NaOH (5 mL) was added. The reaction mixture was stirred at room temperature for 24 h and washed with EtOAc (15 mL). The aqueous layer was separated, cooled to 0° C. and conc. HCl (5 mL) was added dropwise to obtain 2-oxocyclohexanecarboxylic acid (2.7 g, crude). 2-oxocyclohexanecarboxylic acid (2.7 g, 19.0 mmol) and diazonium salt (prepared above) were mixed together at 0° C. and the reaction mixture was slowly warmed to room temperature and stirred for 1 h during which time a solid precipitated out which was filtered, washed with hexane (20 mL) and air dried to give the title compound as a yellow solid (2.2 g, 45%). 1H NMR (200 MHz, CDCl3, δ in ppm) 13.64 (bs, 1H), 7.684 (t, J=8.8 Hz, 1H), 7.10 (t, J=10.0 Hz, 2H), 2.74-2.67 (m, 2H), 2.56-2.50 (m, 2H), 1.90-1.83 (m, 4H).

1. washwashed with EtOAc (15 mL)
2. customThe aqueous layer was separated
3. temperaturecooled to 0° C.
4. additionconc. HCl (5 mL) was added dropwise