Potassium Hydroxide → cis-4-amino-6,7-dimethoxy-2-methyl-3,4-dihydro-2H-quinoline-1-carboxylic acid ethyl ester

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To a stirred solution of 4-hydroxyimino-6,7-dimethoxy-2-methyl-3,4-dihydro-2H-quinoline-1-carboxylic acid ethyl ester (11.0 g, 34.1 mmol) in ethanol (100 mL) and aqueous 2N KOH (102 mL, 205 mmol) was added aluminum-nickel alloy (11.7 g, 136 mmol) in portions over 15 min. The reaction was stirred for 35 min, then filtered through a pad of Celite®, rinsing with ethanol. The volatiles were removed in vacuo, and the resulting aqueous phase was extracted with ethyl acetate (3×150 mL). The combined organic phases were washed with brine, dried over sodium sulfate, filtered, and concentrated in vacuo to give 16.32 g of crude product. Purification by silica gel chromatography using 0-4% methanol in dichloromethane as eluent afforded the title compound (6.51 g, 65%): 1H NMR (CDCl3) δ1.19 (d, 3H, J=6 Hz), 1.25 (m, 1H), 1.28 (t, 3H, J=7 Hz), 2.4 (m, 1H), 3.76 (m, 1H), 3.86 (s, 3H), 3.90 (s, 3H), 4.10-4.35 (m, 2H), 4.5 (m, 1H), 6.96 (s, 1H), 7.0 (s, 1H).

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