Diethanolamine → 4-Chloro-3-(methylthio)phenol

Boron tribromide (1M in dichloromethane, 31 ml, 31 mmol) was added dropwise to a solution of 1-chloro-4-methoxy-2-(methylsulfanyl)benzene (2.88 g, 15 mmol) in dichloromethane (80 ml) at 0° C. The mixture was allowed to warm to room temperature, stirred for 72 h then cooled to 0° C. A solution of diethanolamine (10 ml) in dichloromethane (20 ml) was added dropwise (Caution—strong exotherm!) and the mixture was stirred at ambient temperature for 15 min once addition was complete, then partitioned between dichloromethane and 2N hydrochloric acid. The organic phase was washed with water, dried over MgSO4 and the solvent removed under reduced pressure. The residue was purified by flash column chromatography using ethyl acetate:cyclohexane (10:90 to 85:15) as eluant to give 4-chloro-3-(methylsulfanyl)phenol (2.12 g) as a brown oil.