反应详情

Potassium hydroxide (10.96 g, 0.19 mmol) was added to a stirred suspension of methyl 2,4-bis-benzyloxy-5-isopropenyl-benzoate (61.0 g, 0.16 mol) in methanol (750 ml) and water (250 ml) and the mixture was stirred and held at reflux for 16 hours. Upon cooling the organic solvent was removed in vacuo and the mixture acidified to pH 2 or below by the addition of 2M hydrochloric acid (200 ml). The mixture was diluted with water (2 L) and extracted with ethyl acetate (2 L), the organic layer was separated and the solvent removed in vacuo to afford 2,4-bis-benzyloxy-5-isopropenyl-benzoic acid (58.8 g, 100%) as a colourless solid. 1H NMR (DMSO-d6) 7.52 (2H, d), 7.47-7.29 (9H, m), 6.82 (1H, s), 5.20 (2H, s), 5.17 (2H, s), 5.06 (1H, s), 5.04 (1H, s), 2.03 (3H, s). MS: [M+H]+ 375.

1. temperatureat reflux for 16 hours
2. temperatureUpon cooling the organic solvent
3. customwas removed in vacuo
4. additionthe mixture acidified to pH 2 or below by the addition of 2M hydrochloric acid (200 ml)
5. additionThe mixture was diluted with water (2 L)
6. extractionextracted with ethyl acetate (2 L)
7. customthe organic layer was separated
8. customthe solvent removed in vacuo