Potassium Permanganate → 4-Benzyloxy-3-ethyl-5-methyl-benzoic acid

Participants

Reaction Steps

4-Benzyloxy-3-ethyl-5-methyl-benzaldehyde (1.4 g, 5.5 mmol) is dissolved in acetone (20 mL) and is slowly added to a cold solution of KMnO4 (1.74 g, 11 mmol) in 20% aq. acetone (25 mL). The reaction mixture is stirred at rt for 3 h, and then acetone is evaporated. The remaining aq. phase is acidified with 10% citric acid (60 mL) and is extracted with DCM (80 mL, 60 mL, 60 mL). The combined org. extracts are washed with brine, dried over MgSO4, filtered and evaporated. The crude product is purified by CC on silica gel eluting with heptane:EA (5:1 to 2:1) to give 4-benzyloxy-3-ethyl-5-methyl-benzoic acid (1.16 g) as an off-white solid; LC-MS: tR=0.56 min*; 1H NMR (CDCl3): δ 1.29 (t, J=7.5 Hz, 3H), 2.39 (s, 3H), 2.75 (q, J=7.5 Hz, 2H), 4.90 (s, 2H), 7.53-7.36 (m, 5H), 7.86 (s, 1H), 7.89 (s, 1H), 12.0 (s br, 1H).

Provenance & Evidence