Triethylamine → 3,6,6-Trimethyl-1,4-dioxane-2,5-dione
反応式
[OH:1][C:2]([CH3:7])([CH3:6])[C:3]([OH:5])=[O:4].Br[CH:9]([CH3:13])[C:10](Cl)=[O:11].C(N(CC)CC)C>CC(C)=O>[CH3:13][CH:9]1[O:4][C:3](=[O:5])[C:2]([CH3:7])([CH3:6])[O:1][C:10]1=[O:11][OH:1][C:2]([CH3:7])([CH3:6])[C:3]([OH:5])=[O:4].Br[CH:9]([CH3:13])[C:10](Cl)=[O:11].C(N(CC)CC)C>CC(C)=O>[CH3:13][CH:9]1[O:4][C:3](=[O:5])[C:2]([CH3:7])([CH3:6])[O:1][C:10]1=[O:11]5 g α-hydroxyisobutyric acid (48 mmol) and 5.15 mL 2-bromopropionyl chloride (50 mmol) were stirred at 75° C. under nitrogen for 12 h. 300 mL acetone and 14 mL anhydrous triethylamine (100 mmol) were added to the mixture and the solution was stirred for 3 h at 60° C. After filtration of the triethylammonium chloride salts, acetone was distilled off and the resulting mixture was dissolved in 450 mL ethyl acetate:hexane mixture (1:1). After filtration over silica gel the solvents were distilled off, and the remaining crude product was recrystallized from ethyl acetate:hexane mixture (1:10). 1H NMR (500 MHz, CDCl3): δ 5.1 (q, 1H), 1.705 (s, 6H), 1.69 (d, 3H). 13C NMR (500 MHz, CDCl3): δ 168.58, 166.64, 80.54, 72.90, 26.23, 25.27, 17.41. ELEM. ANAL. Calcd. for C7H10O4: C, 53.16; H, 6.33. Found: C, 52.86; H, 6.39. Yield: 46%.
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