Ethylene Glycol → 2-Hydroxyethyl 2-bromoisobutyrate
反応式
[CH2:1]([OH:4])[CH2:2][OH:3].CCN(CC)CC.[Br:12][C:13]([CH3:18])([CH3:17])[C:14](Br)=[O:15]>C1COCC1.O.C(Cl)Cl>[OH:3][CH2:2][CH2:1][O:4][C:14](=[O:15])[C:13]([Br:12])([CH3:18])[CH3:17][CH2:1]([OH:4])[CH2:2][OH:3].CCN(CC)CC.[Br:12][C:13]([CH3:18])([CH3:17])[C:14](Br)=[O:15]>C1COCC1.O.C(Cl)Cl>[OH:3][CH2:2][CH2:1][O:4][C:14](=[O:15])[C:13]([Br:12])([CH3:18])[CH3:17]
Ethylene glycol (279 g, 4500 mmol) and Et3N (3.34 g, 33.0 mmol) were poured in a 2-necked round bottom flask. To this was added dropwise and a solution of 2-bromoisobutryl bromide (6.90 g, 30.0 mmol) in anhydrous THF (50 mL) at room temperature over ca. 1 h. The colourless solution was stirred overnight, then diluted in 500 mL of water and extracted with 3×200 mL of a mixture of Et2O/CH2Cl2 (4:1). The organic layers, reunited, were washed with 2×200 mL of water and dried over MgSO4. Evaporation of the solvent at reduced pressure (rotavapor, without heating) gave a pale yellow liquid. The latter was dissolved in ca. 30 mL of CH2Cl2 then 10 g of SiO2 were added and the solvent evaporated again until a white powder was obtained. This was poured in a column packed with SiO2, (ca 15 cm depth) previously eluted with petroleum ether/Et2O 5:1 and purified by column chromatography (elute with petroleum ether/Et2O 5:1) to eliminate the impurities. The desired product, using this solvent mixture, has an Rf ˜0 (stays on the bottom of the TLC plate). When the impurities have been eliminated, the column was eluted with 100% Et2O, to give a colourless liquid. Yield 82%. IR ν(N—H) 3388 cm−1 (broad); ν(C═O) 1731 cm−1. 1H NMR (CDCl3) δ=1.97 (s, 6H, CH3); 3.89 (t, J=4.6 Hz; 2H, OCH2CH2OH); 4.33 (t, J=4.6 Hz; 2H, OCH2CH2OH). 13C NMR (CDCl3) δ=30.45 (2C, CH3), 55.55 (1C, C(CH3)2Br); 60.66 (1C, OCH2CH2OH); 65.90 (1C, OCH2CH2OH); 171.69 (1C, C═O).
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