Acetyl chloride → N-(4-Bromo-5,6,7,8-tetrahydronaphthalen-1-yl)-acetamide

Participants

Reaction Steps

To a solution of 5,6,7,8-tetrahydronaphthalen-1-amine (1 g, 6.8 mmol), triethylamine (1.9 mL, 13.6 mmol) in DCM (50 mL), is added acetyl chloride (587 mg, 7.5 mmol) dropwise. The mixture is stirred at room temperature for 2 hr. Then the mixture is concentrated and partitioned between ethyl acetate and saturated aqueous ammonium chloride. The organic layer is separated, washed with brine and dried over sodium sulfate. After concentration, the obtained N-(5,6,7,8-tetrahydronaphthalen-1-yl)acetamide (200 mg) is dissolved in acetic acid (30 mL). To this solution is added bromine (170 mg, 1.06 mmol) dropwise. The mixture is heated at 50° C. overnight. The reaction is quenched by adding sodium sulfite aqueous solution. The mixture is extracted with ethyl acetate (3×20 mL). The organic extracts are combined and washed with sodium bicarbonate aqueous solution, brine, and dried over sodium sulfate. After concentration, the crude N-(4-bromo-5,6,7,8-tetrahydronaphthalen-1-yl)acetamide is obtained as brown solid. The solid obtained is dissolved in methanol (5 mL) and concentrated HCl (15 mL). The mixture is refluxed at 95° C. overnight. After cooling to room temperature, the mixture is poured into ice water, and basified to pH=12 with conc. NaOH aqueous solution. Then the mixture is extracted with ethyl acetate (3×20 mL). The combined organic layer is dried over Na2SO4 and concentrated. The crude product is purified with silica gel chromatography (15% ethyl acetate in hexanes) to give 4-bromo-5,6,7,8-tetrahydronaphthalen-1-amine as beige solid. ESMS m/z 226 (M+H+).

Provenance & Evidence