Diisopropylamine → Ethyl (6-bromo-2-quinolinyl)acetate

Beteiligte Stoffe

Reaktionsschritte

To a solution of diisopropylamine (19.2 g, 0.19 mole) in diethyl ether (200 mL) was added 2.5 M n-butyllithium in hexane (74 mL, 0.185 mole) at −78° C. The clear solution was mixed for 30 min, and followed by addition of 6-bromo-2-methyl-quinoline (13.32 g, 0.060 mole) in ether (200 mL) slowly at −78° C. The brown solution was stirred for 0.5 hour, and ethyl chloroformate (7.45 g, 0.069 mole) in ether (50 mL) was syringed into the mixture slowly so that the internal temperature did not exceed −70° C. The yellow reaction mixture was quenched by addition of 50 mL water, allowed to warm up to rt, and diluted with ethyl acetate (300 mL). The solution was washed with 5% sodium bicarbonate aq. solution (700 mL×3), 25% brine (700 mL), dried over MgSO4, and filtered. The organic was concentrated to ˜50 mL volume, and the slurry diluted with heptane (50 mL). The slurry was stirred at 0° C. for 2 h, and the solid was collected by filtration, rinsed with a ice-cold heptane: ethyl acetate (10 mL, 2:1), dried at 50° C. under vacuum to give a yellow solid (12.0 g). Concentration of the mother liquid afforded a 2nd crop of the product (3.6 g). Total yield: 88%; mp: 100-101° C. (uncorrected); MS (ESI): 294, 296 (M+H)+; 1H-NMR (CDCl3) δ 8.02 (1H, d, J=8.5 Hz), 7.94 (1H, d, J=2.2 Hz), 7.91 (1H, d, J=8.9 Hz), 7.74 (1H, dd, J=8.9, 2.2 Hz), 7.44 (1H, d, J=8.5 Hz), 4.20 (2H, q, J=7.1 Hz), 4.01 (2H, s), 1.27 (3H, t, J=7.1 Hz); 13C-NMR (CDCl3) δ169.7, 154.9, 146.0, 135.1, 132.6, 130.5, 128.9, 127.8, 122.3, 119.9, 61.2, 44.9, 14.5.

Herkunft & Nachweise