Dibromomethane → (Z)-2-(4-Phenylbut-3-enyl)oxirane

反応式

[C:1]1(/[CH:7]=[CH:8]\[CH2:9][CH2:10][CH:11]=[O:12])[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1.Br[CH2:14]Br.[NH4+].[Cl-]>C1COCC1>[C:1]1(/[CH:7]=[CH:8]\[CH2:9][CH2:10][CH:11]2[CH2:14][O:12]2)[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1

参加物

反応条件

温度: -78 °C

実験手順

(Z)-5-Phenylpent-4-enal (0.475 g, 2.97 mmol) and dibromomethane (0.626 g, 3.60 mmol) were taken up in THF (20 mL) and chilled to −78° C. under argon n-butyl lithium (1.6M in hexane, 2.0 mL, 3.20 mmol) was added dropwise over 5 minutes. The resulting mixture was warmed slowly to room temperature and stirred overnight. The reaction mixture was poured into saturated aqueous NH4Cl (20 mL), extracted with MTBE (2×30 mL) and solvent removed under reduced pressure. The resulting oil was purified by column chromatography (0-20% EtOAc/n-hexane, silica) to give (Z)-2-(4-Phenylbut-3-enyl)oxirane as a pale yellow oil. 1H NMR (CDCl3): δ 7.32-7.27 (m, 2H), 7.25-7.19 (m, 3H), 6.47 (d, 1H, J=11.7), 5.68 (J1=11.6, J2=7.3), 2.97-2.93 (m, 1H), 2.77-2.74 (m, 1H), 2.55-2.52 (m, 1H), 2.53-2.48 (m, 2H), 1.76-1.67 (m, 2H). Contains ca. 18% (E)-2-(4-phenylbut-3-enyl)oxirane.