To 2-tert­-butyl-5-methylphenol (16.5 g, 0.10 mol) in dry acetonitrile (500 ml) under argon was added dry TEA (55 ml), followed by dry MgCl₂ (14.4 g, 0.15 mol). The mixture was stirred for 30 min. Dry paraformaldehyde (21 g, 0.70 mol) was added, and the mixture was heated at reflux for 2 h, before being allowed to cool to rt. The product was extracted with Et₂O (7 × 100 ml), dried (MgSO₄) and filtered through celite. The solvent was then removed in vacuo. Distillation under reduced pressure (125 – 150 °C) yielded the desired product as a yellow-green oil (3.8 g, 18%).

¹H NMR 400 MHz (CDCl₃): δ ppm 12.76 (s, 1H, OH), 10.29 (s, 1H, Ar–CH=O), 7.38 (d, 1H, ArH, ³J_HH = 8 Hz), 6.64 (d, 1H, ArH, ³J_HH = 8 Hz), 2.55 (s, 3H, Ar-CH₃), 1.43 (s, 9H, C(CH₃)₃)

 ¹³C{¹H} NMR 100 MHz (CDCl₃): δ ppm 195.6 (Ar–CH=O), 162.7, 139.5, 136.2, 134.3, 120.9, 118.2 (Ar), 34.4 (C(CH₃)₃), 29.1 (C(CH₃)₃), 17.6 (Ar–CH₃)

MS (EI⁺): m/z 192 (M⁺)