反应详情

温度

-78 °C

2-[2-(3-Trifluoromethylphenyl)ethyl]pent-4-enoic acid ethyl ester (529 mg, 1.76 mmol) was dissolved in CH2Cl2 and cooled to −78° C. The resulting solution was treated with ozone until a light blue color was observed. The solution was degassed with N2, then polymer-supported Ph3P (3 mmol/g, 882 mg, 2.64 mmol) was added and the mixture was stirred for 3 h at room temperature. The solid was removed by filtration and rinsed with CH2Cl2. Evaporation of the filtrate provided an oil, which was purified by flash column chromatography (hexanes/ether) to give ethyl 2-((1,2,3-trioxolan-4-yl)methyl)-4-(3-(trifluoromethyl)phenyl)butanoate as a colorless oil (151 mg, 25%) and the desired ethyl 2-(2-oxoethyl)-4-(3-(trifluoromethyl)phenyl)butanoate as a colorless oil (83 mg, 16%). A solution of ethyl 2-((1,2,3-trioxolan-4-yl)methyl)-4-(3-(trifluoromethyl)phenyl)butanoate (150 mg, 431 μmol) in CH2Cl2 (20 mL) was cooled to −78° C., then Me2S (0.3 mL, 4.1 mmol) was added and the mixture was stirred for 2 d. The reaction mixture was diluted with CH2Cl2 (300 mL), washed with water (2×100 mL), and brine (100 mL), dried over Na2SO4, filtered, and evaporated to provide additional ethyl 2-(2-oxoethyl)-4-(3-(trifluoromethyl)phenyl)butanoate (123 mg): 1H NMR (300 MHz CDCl3) δ 7.50–7.30 (m, 4H), 5.26–5.20 (m, 1H), 5.14 (d, J=1.6 Hz, 1H), 5.04 (d, J=6.3 Hz, 1H), 4.37 (q, J=7.0 Hz, 2H), 2.73–2.57 (m, 3H), 2.35–1.77 (m, 4H), 1.29 (t, J=7.1 Hz, 3H); 19F NMR (282 MHz, CDCl3) δ −63.0.

1. customThe solution was degassed with N2
2. customThe solid was removed by filtration
3. washrinsed with CH2Cl2
4. customEvaporation of the filtrate
5. customprovided an oil, which
6. customwas purified by flash column chromatography (hexanes/ether)