反应详情

To a solution of methyl 3-tert-butyl-5-hydroxymethylbenzoate VII (9.50 g, 42.7 mmol) and carbon tetrabromide (17.25 g, 52.0 mmol) in dichloromethane (50 mL) was slowly added triphenylphosphine (13.6 g, 52.0 mmol) over the period of 20 minutes, and the mixture was stirred at room temperature for 25 minutes. The reaction mixture was concentrated under reduced pressure and the residue was suspended in ethyl acetate. The precipitate was removed by filtration and the filtrate was concentrated. The crude material was purified by a silica gel chromatography (hexanes/ethyl acetate, 4:1), and the product was re-crystallized form ethyl acetate/hexanes to afford methyl 3-bromomethyl-5-tert-butylbenzoate VIII (12.0 g, 42.1 mmol, 99%) as a white solid: 1H NMR (CDCl3) δ 1.45 (s, 9H), 3.7 (s, 3H), 4.4 (s, 2H), 7.6 (s, 1H), 7.8 (s, 1H), 8.0 (s, 1H); 13C NMR (CDCl3) δ 31.3 (3C), 33.2, 36.0, 52.3, 126.9, 127.5, 130.6, 130.7, 137.9, 152.4, 167.0.

1. customover the period of 20 minutes
2. concentrationThe reaction mixture was concentrated under reduced pressure
3. customThe precipitate was removed by filtration
4. concentrationthe filtrate was concentrated
5. customThe crude material was purified by a silica gel chromatography (hexanes/ethyl acetate, 4:1)
6. customthe product was re-crystallized form ethyl acetate/hexanes