Dimethylformamide → 3-(3-dimethylamino-propyl)-6,6-dimethyl-4,5,6,7-tetrahydro-1H-indole-2-carbaldehyde

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Reaction Steps

Phosphorus oxychloride (0.5 mL, 5.1 mmol) was added dropwise to ice-cooled dimethylformamide (1.1 mL, 14.1 mmol) and then stirred at room temperature for 30 minutes. A solution of [3-(6,6-dimethyl-4,5,6,7-tetrahydro-1H-indol-3-yl)-propyl]-dimethyl-amine (1.1 g, 4.6 mmol) in dimethylformamide (2 mL) was added dropwise at −5° C. The mixture was stirred at room temperature overnight. Ice cubes were added to the reaction mixture followed by the addition of 10 N potassium hydroxide to pH 11–12 and stirring for one hour. The mixture was extracted with ethyl acetate and the extract washed with brine and concentrated. The residue was chromatographed (5%-10% methanol in dichloromethane) to give 650 mg of 3-(3-dimethylamino-propyl)-6,6-dimethyl-4,5,6,7-tetrahydro-1H-indole-2-carbaldehyde as a brown solid. 1H-NMR (360 MHz, dimethylsulfoxide-d6) δ 11.25 (br s, 1H, NH), 9.41 (s, 1H, CHO), 2.62 (t, 2H, CH2), 2.36 (t, 2H, CH2), 2.30 (s, 2H, CH2), 2.21 (t, 2H, CH2), 2.12 (s, 6H, 2×CH3), 1.60 (m, 2H, CH2), 1.46 (t, 2H, CH2), 0.93 (s, 6H, 2×CH3). MS m/z 262 [M+].

Provenance & Evidence