To a refluxed solution of 6-bromo-2-methoxycarbonylmethyl-N-ethoxalyltetrahydroquinoline (40 g) and ammonium nitrate (8 g, 0.1 mol) in chloroform (100 mL) was added dropwise trifluoroacetic anhydride (56.5 mL, 0.4 mol) over 40 min. The reflux was continued for 90 min and crashed ice was added. The organic layer was separated, washed with saturated aqueous sodium bicarbonate and brine, dried over magnesium sulfate, and concentrated to give 46 g of the title compound (quant): 1H NMR (270 MHz, CDCl3) δ8.11 and 7.99 (d and d, 1H, J=2 Hz), 7.66 and 7.61 (d and d, 1H, J=2 Hz), 5.03~5.16 and 4.74~4.85 (m and m, 1H), 4.37~4.49 and 4.13 (m and q, 2H, J=7.2 Hz), 3.72 and 3.62 (s and s, 3H), 2.44~3.02 (m, 5H), 1.65~1.80 and 1.50~1.60 (m and m, 1H), 1.42 and 1.23 (t and t, 3H, J=7.2 and 7.2 Hz).
