反应详情

To a stirring suspension of D-Mannitol (1.82 g, 10.0 mmol) in tetrahydrofuran (21 mL) and dimethylformamide (9 mL) was added p-toluenesulfonic acid monohydrate (0.02 g, 0.1 mmol,) at ambient temperature, followed by 2,2-dimethoxypropane (2.8 mL, 0.023 mol). The reaction mixture was stirred for 18 hours at room temperature, then additional 2,2-dimethoxypropane (0.3 mL, 2.4 mmol) was added. The suspension was heated to 40° C. to 45° C., and stirred for 2 hours. Sodium bicarbonate (1.8 g, 0.016 mol) was added to neutralize the acid and the mixture was stirred for 30 minutes. The excess Na2CO3 was filtered and washed with tetrahydrofuran (5 mL). The filtrate was concentrated. To the remaining light yellow oil was added toluene (15 mL) and the mixture was stirred at 3° C. to 5° C. until a light-yellow gelatinous solid formed. The solid was filtered and washed with hexane (2×5 mL). The product was dried in a vacuum oven for 18 hours to give 1,2:5,6-di-O-isopropylidene-D-mannitol (1.24 g, 47.3%) as an off-white solid, mp 110-113° C. Step B: Preparation of (S)-(+)-(2,2-dimethyl-[1,3]dioxolan-4-yl)-methanol

1. temperatureThe suspension was heated to 40° C. to 45° C.
2. stirringstirred for 2 hours
3. stirringthe mixture was stirred for 30 minutes
4. filtrationThe excess Na2CO3 was filtered
5. washwashed with tetrahydrofuran (5 mL)
6. concentrationThe filtrate was concentrated
7. additionTo the remaining light yellow oil was added toluene (15 mL)
8. stirringthe mixture was stirred at 3° C. to 5° C. until a light-yellow gelatinous solid
9. customformed
10. filtrationThe solid was filtered
11. washwashed with hexane (2×5 mL)
12. customThe product was dried in a vacuum oven for 18 hours