反应详情

5-Bromo-2,2-dimethyl-1-pentanol (77.4 g, 357 mmol) was dissolved in dichloromethane (400 mL), andp-toluenesulfonic acid (6.9 g, 36 mmol) was added. The mixture was stirred under argon, chilled in an ice-bath, then was added 3,4-dihydro-2H-pyran (37.2 g, 428 mmol) and stirred, gradually letting warm to rt overnight. The reaction mixture was then filtered through neutral alumina (100 g); the alumina was rinsed with additional dichloromethane (600 mL). After evaporating to about 500 mL, the organic layer was extracted with sat. NaHCO3 (3′ 200 mL), then dried over MgSO4. The solution was concentrated under reduced pressure to produce the expected product (107.83 g, 97% yield) as a yellow oil. 1H NMR (CDCl3), d (ppm): 4.55 (m, 1H); 3.83 (m, 1H); 3.51 (m, 1H); 3.47 (d, 1 H, J=9.0); 3.38 (t, 2 H, J=6.8); 2.98 (d, 1 H, J=9.0); 1.94-1.75 (m, 2H); 1.75-1.44 (m, 6H); 1.40 (t, 2 H, J=8.5); 0.93-0.87 (m, 6H). 13C NMR (CDCl3), d (ppm): 99.0, 76.2, 61.9, 37.9, 34.6, 34.0, 30.6, 27.9, 25.6, 24.64, 24.56, 19.4. HRMS calcd. for C12H24BrO2 (MH+): 279.0960, found 279.0955.

1. temperaturechilled in an ice-bath
2. stirringstirred
3. filtrationThe reaction mixture was then filtered through neutral alumina (100 g)
4. washthe alumina was rinsed with additional dichloromethane (600 mL)
5. customAfter evaporating to about 500 mL
6. extractionthe organic layer was extracted with sat. NaHCO3 (3′ 200 mL),
7. dry with materialthen dried over MgSO4
8. concentrationThe solution was concentrated under reduced pressure