Boron tribromide → 3-(2-Aminoethyl)phenol hydrochloride

Participants

Reaction Steps

To a stirred solution of 2-(3-methoxyphenyl)ethylamine (10.0 g, 66.2 mmol) in dry CH2Cl2 (100 mL) at −78° C. was added a 1 M solution of BBr3 in CH2Cl2 (200 mL, 3 eq.) and the solution was allowed to slowly warm to RT. After stirring for 3 h at RT the resulting precipitate was filtered off, washed with CH2Cl2 (200 mL) and dried. The off-white solid was dissolved in cold H2O (50 mL) and the insoluble material was filtered off. The acidic filtrate (pH 1.2) was made basic (pH 13.0) with 10 N NaOH and the resulting yellow solution was extracted with ether (100 mL) and the organic layer was discarded. The aqueous layer was re-acidified with conc. HCl to pH 1.5 and then made alkaline (pH 9-10) with conc. NH4OH. The aqueous layer was then extracted with n-butanol (2×150 mL), dried (K2CO3) and concentrated to dryness to afford a viscous oil. The oily residue was then dissolved in MeOH (10 mL) and a solution of saturated HCl/MeOH was added. The solution was concentrated to small volume and ether was added to give a precipitate. The ether was decanted off to afford the desired compound as an off white solid (6.5 g, 57%). 1H NMR (D2O) 2.79 (t, 2H, J=7.2 Hz), 3.08 (t, 2H, J=7.2 Hz), 6.60-6.78 (m, 3H), 7.11 (t, 1H, J=7.7 Hz).

Provenance & Evidence