反应详情

To a solution of 4-benzyloxy-3-ethyl-5-methyl-benzoic acid tert.butyl ester (9.02 g, 27.6 mmol) in THF (50 mL) and ethanol (50 mL), Pd/C (400 mg, 10% Pd) is added. The slurry is stirred at rt for 24 h under 1 bar of H2. The catalyst is removed by filtration, the filtrate is concentrated, dissolved again in THF (50 mL) and ethanol (50 mL), and again treated with Pd/C (400 mg, 10% Pd). The slurry is stirred at rt for 24 h under 1 bar of H2. The catalyst is again removed by filtration and the filtrate is concentrated and dried to give 3-ethyl-4-hydroxy-5-methyl-benzoic acid tert.butyl ester (7.13 g) as a pale yellow oil; LC-MS: tR=1.01 min; 1H NMR (CDCl3): δ1.28 (t, J=7.8 Hz, 3H), 1.61 (s, 9H), 2.30 (s, 3H), 2.67 (q, J=7.5 Hz, 2H), 5.13 (s br, 1H), 7.67 (s, 1H), 7.69 (s, 1H).

1. customThe catalyst is removed by filtration
2. concentrationthe filtrate is concentrated
3. dissolutiondissolved again in THF (50 mL)
4. additionethanol (50 mL), and again treated with Pd/C (400 mg, 10% Pd)
5. stirringThe slurry is stirred at rt for 24 h under 1 bar of H2
6. customThe catalyst is again removed by filtration
7. concentrationthe filtrate is concentrated
8. customdried