2. Preparation of (S)-3-(dimethylamino)-1-(3-methoxyphenyl)-2-methylpropan-1-one (Ia): (S)-3-(dimethylamino)-1-(3-methoxyphenyl)-2-methylpropan-1-one (2R,3R)-2,3-dibenzoyloxy)succinate (968 g, 1.67 mmol, ee 98%) was suspended in a 10 L double jacketed reactor equipped with an electric impeller stirrer. tert-butyl methyl ether (6 L) in a 10 L double-jacketed reactor equipped with an electric impeller stirrer, a gas inlet tube, an R100 temperature measuring device, and an oil-based cooling/heating system. Diethylamine (384 g, 5.25 mol) was then added. The reaction mixture was stirred at 20 °C to 25 °C for 90 min, after which the solids were removed by siphoning. The filtrate was concentrated under reduced pressure at 40°C to a pressure of 4 mbar to afford (S)-3-(dimethylamino)-1-(3-methoxyphenyl)-2-methylpropan-1-one (356.7 g, 96.5%, ee 98%) as a colorless oil.
