Hydrochloric Acid → 6,7-Dimethoxy-2-isopropyl-4-oxo-3,4-dihydro-2H-quinoline-1-carboxylic acid ethyl ester

Participants

Reaction Conditions

Reaction Steps

4,6,7-Trimethoxyquinoline (0.3 g, 1.4 mmol) was dissolved in anhydrous tetrahydrofuran (6 mL). The mixture was cooled to −78° C., and isopropyl magnesium chloride (0.8 mL of a 2M solution in tetrahydrofuran, 1.6 mmol) was added. The mixture was stirred at −78° C. for 10 min, then ethyl chloroformate (0.16 mL, 1.6 mmol) was added. The reaction was warmed to room temperature and stirred overnight, then 1N HCl (6 mL) was added. After stirring for 1 h, the tetrahydrofuran was removed in vacuo, and the remaining aqueous phase was extracted with ethyl acetate (3×50 mL). The organic phases were combined and washed with water (15 mL), dried over sodium sulfate, filtered, and concentrated in vacuo to give 0.26 g crude product. Purification by silica gel chromatography using 0-40% ethyl acetate/hexanes as eluent afforded the title product (0.23 g, 51%). 1H NMR (CDCl3) δ 0.85 (d, 3H), 0.9 (d, 3H), 1.33 (t, 3H), 1.8 (m, 1H), 2.8 (dd, 1H), 2.93 (dd, 1H), 3.9 (s, 3H), 3.95 (s, 3H), 4.3 (m, 2H), 4.5 (m, 1H), 7.3 (bs, 1H), 7.37 (s, 1H).

Provenance & Evidence