反应详情

In a 250 mL round bottom flask fitted with a reflux condenser was placed 2.4 g (12 mmol) of (S)-5-hexyl-2,2-dimethyl-1,3-dioxolan-4-one in 150 mL of methanol containing 2 drops of concentrated sulfuric acid. Following heating at reflux for, 6 hours, the reaction mixture was cooled, and 0.5 g of sodium bicarbonate was added. The solvent was evaporated under reduced pressure and the residue dissolved in 200 mL of CH2Cl2. The solution was washed with 2×75 mL of water, 2×100 mL of saturated sodium bicarbonate solution, and 2×75 mL of brine, and dried (Na2SO4). The CH2Cl2 solvent was evaporated under reduced pressure to provide 2.07 g of crude product which was purified over silica gel using ethyl acetate:hexanes (1:5) to furnish 2.0 g (96%) of the title compound as a pale yellow oil: [α]D25 2.9° (C=0.8, CH3OH); IR (neat, cm-1) 3475 (br), 2925, 2857, 1739; 1H NMR (CDCl3) δ 4.19 (m, 1H), 3.79 (s, 3H), 2.73 (d, J=4.8 Hz, 1H), 1.89-1.75 (m, 1H), 1.72-1.56 (m, 1H), 1.55-1.39 (m, 2H), 1.39-1.28 (m,6H), 0.88 (t, J=6.6 Hz, 3H); HRMS calculated for C19H18O3 (M+), 174.1255, found 174.1255.

1. customIn a 250 mL round bottom flask fitted with a reflux condenser
2. temperatureFollowing heating
3. temperatureat reflux for, 6 hours
4. temperaturethe reaction mixture was cooled
5. customThe solvent was evaporated under reduced pressure
6. dissolutionthe residue dissolved in 200 mL of CH2Cl2
7. washThe solution was washed with 2×75 mL of water, 2×100 mL of saturated sodium bicarbonate solution, and 2×75 mL of brine
8. dry with materialdried (Na2SO4)
9. customThe CH2Cl2 solvent was evaporated under reduced pressure
10. customto provide 2.07 g of crude product which
11. customwas purified over silica gel