To a 1L three-necked round-bottomed flask was added 3-chlorophenol (33.6 g, 0.3 mol), anhydrous MgCl2 (85.7 g, 0.9 mmol), triethylamine (75.9 g, 0.75 mol) and anhydrous acetone (340 mL). The resulting solution was stirred at 25 °C for 30 min, followed by the addition of paraformaldehyde (45 g, 1.5 mol). The reaction mixture was heated to reflux for 5 h under nitrogen protection. When TLC monitoring showed complete consumption of the feedstock, the acetone was evaporated under reduced pressure. The residue was acidified to pH 3 with 10% hydrochloric acid solution and extracted with ethyl acetate (3 x 150 mL). The organic layers were combined, washed with water, dried over anhydrous sodium sulfate, and concentrated under reduced pressure to give a brownish-red oil (18.1 g, 43.1% yield), which can be used directly in subsequent reactions without further purification (Byun et al., 2008; Uini and Lars, 1999).
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