反应详情

温度

4 °C

Under an argon atmosphere, a 250-mL, round-bottomed flask equipped with a stir bar was charged with abs. ethanol (52 mL, 892 mmol, 5.0 eq). The flask was cooled to 4° C. (internal) in an ice bath. Triethyl orthoformate (29.7 mL, 178 mmol, 1.0 eq) was added followed by 3-methyl-2-butenal (17.2 mL, 178 mmol, 1.0 eq). The resulting clear, colorless solution was further cooled to 2° C. (internal). Potassium hydrogen sulfate (1.277 g, 9.38 mmol, 0.05 eq) was then added in one portion, resulting in an immediate exotherm to 10° C. The heterogeneous mixture was allowed to warm to 21° C. (internal) over 45 minutes (within 20 minutes, the mixture became slightly cloudy) and then stirred for an additional 15 minutes. The reaction mixture was then filtered and the remaining solid rinsed with abs. ethanol (5 mL). To the resulting clear, colorless solution was added anhydrous potassium carbonate (2.615 g, 18.92 mmol). The mixture was stirred for one hour before filtering off the potassium carbonate. The solid was rinsed with abs. ethanol (5 mL) and the filtrate was vacuum distilled (172 mm Hg) through a Vigereux column (13.5 cm) to produce 24.14 g (85% yield) of the title compound (boiling point 115°-119° C.).

1. customUnder an argon atmosphere, a 250-mL, round-bottomed flask equipped with a stir bar
2. additionwas charged with abs
3. temperatureThe resulting clear, colorless solution was further cooled to 2° C. (internal)
4. customresulting in an immediate exotherm to 10° C
5. temperatureto warm to 21° C. (internal) over 45 minutes (within 20 minutes
6. filtrationThe reaction mixture was then filtered
7. washthe remaining solid rinsed with abs
8. stirringThe mixture was stirred for one hour
9. filtrationbefore filtering off the potassium carbonate
10. washThe solid was rinsed with abs
11. distillationdistilled (172 mm Hg) through a Vigereux column (13.5 cm)