o-formylation of 4-tert-butylphenol

SyntheticPage 643
Published Jul 24, 2013


Reaction Scheme

Procedure

A 500 mL side arm round bottom flask with a stirrer bar was placed under argon and charged with 4-tert-butylphenol (3.00 g, 20.0 mmol) and dry acetonitrile (100 mL). To this was added dry Et3N (10.4 mL 75.0 mmol), anhydrous MgCl2 (2.86 g, 30.0 mmol) and the solution was stirred for 30 min. Dry paraformaldehyde (4.05 g 135.0 mmol) was added and a Schlenk condenser fitted to the round bottom flask. The mixture was heated to reflux under argon for ca 3h. The resulting yellow solution was allowed to cool to room temperature and was added to 5 % HCl (aq.) (200 mL) followed by stirring for 30 min. This was followed by extraction with diethyl ether (7 × 25 mL). The ether fractions were combined, washed with saturated NaCl (aq.) (3 × 20 mL) and the organic layer dried over anhydrous NaSO4 followed by filtration. All volatiles were removed under reduced pressure to yield a yellow oil which 1H NMR spectra showed to be 5-tert-butyl-2- hydroxybenzaldehyde (2.97 g, 83 %).

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