反应 #1076773

反应方程式

sodium hydride

Sodium hydrate

5-acetyl-2,2,5-trimethyl-1,3-dioxane

5-acetyl-2,2,5-trimethyl-1,3-dioxane

sodium hydride

dimethyl carbonate

→

Methyl 2,2,5-trimethyl-b-oxo-1,3-dioxane-5-propanoate

溶剂

acetic acid

methanol

water

methanol

tetrahydrofuran

tetrahydrofuran

tetrahydrofuran

反应条件

后处理

1. 1
   洗涤the metal hydride washed three times with 300-mL portions of pentane under nitrogen
2. 2
   温度under reflux
3. 3
   workup.ADDITIONwas added dropwise (ca. 0.5 hr.)
4. 4
   其他to quench the anion
5. 5
   其他The quenched reaction
6. 6
   萃取the product extracted with ligroin
7. 7
   萃取The ligroin extract
8. 8
   洗涤was washed with saturated sodium bicarbonate solution
9. 9
   干燥dried over magnesium sulfate
10. 10
    过滤filtered
11. 11
    其他flash evaporated in vacuio
12. 12
    其他to yield 203 g of crude product
13. 13
    其他The brown-colored mobile oil was purified
14. 14
    其他to yield a water white liquid
15. 15
    workup.DISTILLATIONby distillation

实验过程

Sodium hydrate—60% in oil dispersion (100.0 g, 2.5 mol) was weighed into a 5-liter three-necked reaction flask and the metal hydride washed three times with 300-mL portions of pentane under nitrogen. The washed sodium hydride was covered with a solution of dry reagent grade tetrahydrofuran (900 mL) and dimethyl carbonate (900 g, 10.0 mol). The sodium hydride was activated by the dropwise addition of anhydrous methanol (1.5 mL) followed by a few grams of 5-acetyl-2,2,5-trimethyl-1,3-dioxane in tetrahydrofuran. The reaction mixture was held under reflux with constant stirring in a nitrogen atmosphere while 5-acetyl-2,2,5-trimethyl-1,3-dioxane dissolved in tetrahydrofuran (800 mL) was added dropwise (ca. 0.5 hr.). The reaction was stirred for another hour after which time the mixture was allowed to cool to room temperature. Anhydrous methanol (100 mL) was added to the mixture to decompose residual sodium hydride followed by glacial acetic acid (150 mL) to quench the anion. The quenched reaction was poured into one liter of cold water and the product extracted with ligroin. The ligroin extract was washed with saturated sodium bicarbonate solution, dried over magnesium sulfate, filtered, and flash evaporated in vacuio to yield 203 g of crude product. The brown-colored mobile oil was purified to yield a water white liquid by distillation; b.p. 102-5° C.; 130 g, 57% of theoretical yield; H-NMR spectra were consistent. Elemental Analysis calculated for C11H18O5: C,57.38; H, 7.88. Found: C, 57.67; H, 7.98.

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