反应详情

温度

-10 °C

A slow stream of hydrogen chloride gas was passed for 4 h through a solution of 2-benzyloxy-3-bromopropionitrile (16.75 g) in methanol (2.38 g) and ether (66 ml) which was maintained at -10° C. The mixture was allowed to stand at 5° C. overnight, and then ice was added in small portions to the mixture at 0° C. After 20 min of stirring, the mixture was poured into water and the product was extracted with ether, washed with water and aqueous sodium bicarbonate, and dried (MgSO4). After the solvent was removed, the crude product was recrystallized from ether/CH2Cl2 to afford, after a first crop of crystals of 2-benzyloxy-3-bromopropanamide, the required intermediate, methyl 2-benzyloxy-3-bromopropanoate. This bromoester was treated with DBN/potassium carbonate as described above to yield methyl α-benzyloxyacrylate, mp 44.5°-45.5° C. (from hexane); 1H NMR δ 3.80 (3H, s), 4.63 (1H, d, J 3 Hz), 4.83 (2H, s), 5.37 (1H, d, J 3 Hz), 7.33 (5H, s); IR 1740 cm-1. Ketals of alkyl pyruvates, prepared according to the directions in The Journal of Organic Chemistry, 1967, 32,1615, also may be converted to α-alkoxyacrylates by an acidic catalyst, as described in Chemische Berichte, 1911, 44, 3514.

1. additionice was added in small portions to the mixture at 0° C
2. extractionthe product was extracted with ether
3. washwashed with water and aqueous sodium bicarbonate
4. dry with materialdried (MgSO4)
5. customAfter the solvent was removed
6. customthe crude product was recrystallized from ether/CH2Cl2
7. customto afford