Pyridine → 4-Chloro-5,6,7,8-tetrahydrocinnoline-3-carboxylic acid ethyl ester

Participants

Reaction Steps

To a slurry of 4-oxo-1,4,5,6,7,8-hexahydrocinnoline-3-carboxylic acid ethyl ester (1 g), lithium chloride (0.19 g) and pyridine (0.36 ml) in dichloromethane (30 ml) was added p-toluenesulphonyl chloride (0.85 g). The reaction mixture was heated at reflux for 20 h. The solid was collected by filtration, and the filtrate was evaporated under reduced pressure. The residue was purified by flash chromatography using a gradient elution: CH2Cl2 (500 ml), CH2Cl2/MeOH 99:1 (500 ml), CH2Cl2/MeOH 98:2 (1 liter). The appropriate fractions were combined and evaporated under reduced pressure to give a solid (0.65 g, 61%). δH (360 MHz; CDCl3) 1.44 (3H, t, J=7 Hz, CH3), 1.89 (4H, m, CH2), 2.85 (2H, t, J=5.7 Hz, CH2), 2.62 (2H, t, J=5.7 Hz, CH2), 4.51 (2H, t, J=7 Hz, CH2), m/z (ESP+) 241/243 (MH+).

Provenance & Evidence