p-Toluenesulfonic acid → 3-(Methylamino)phenol

Participants

Reaction Steps

3-Aminophenol (5.37 g, 49.2 mmol) in ethylformate (30 mL) was treated with p-toluenesulfonic acid (50 mg) and heated at reflux. After 18 hours, the volatiles were evaporated under reduced pressure. The residue was taken up in ethyl acetate and washed with 1N HCl, saturated NaHCO3, brine, dried (Na2SO4), filtered, and the filtrate concentrated under reduced pressure. The residue was dissolved in THF (25 mL) and treated with 1M borane tetrahydofuran complex (27.2 mL, 27.2 mmol) in THF. After 18 hours at ambient temperature, the mixture was carefully quenched by addition of 1N HCl. After stirring for 30 minutes, the solution was basified and extracted with ethyl acetate. The organic layer was separated, washed with brine, dried (Na2SO4), filtered, and the filtrate concentrated under reduced pressure. The residue was purified by flash chromatography (30% ethyl acetate/hexanes) to provide the title compound as a viscous yellow oil (1.72 g, 28% yield). 1H NMR (300 MHz, CDCl3) δ 7.03 (t, 1H), 6.13-6.24 (m, 2H), 6.11 (t, 1H), 4.54 (bs, 1H), 3.72 (bs, 1H), 2.82 (s, 3H); MS (DCI/NH3) 124 (M+H)+, 141 (M+NH4)+.

Provenance & Evidence