反应详情

To a solution consisting of (S)-(+)-2-methyl-5-phenylpentanoic acid (20mb(i), 2.3 g, 12 mmol) in ethanol (200 mL) was added 4 drops of concentrated sulfuric acid. The stirring reaction mixture was brought to reflux overnight and was subsequently cooled and concentrated under vacuum. The residue was diluted with ethyl acetate and washed twice with brine. The organic layer was dried over sodium sulfate, filtered, and concentrated under vacuum to afford the title compound (2.4 g, 91%) as a clear oil; TLC Rf 0.66 (solvent system: 15:85:1 v/v/v ethyl acetate-heptane-acetic; MS (ESI+) m/z 221.2 (M+H)+; 1H-NMR (CDCl3) δ 7.29-7.25 (m, 2H), 7.21-7.13 (m, 3H), 4.12 (q, J=6.96 Hz, 2H), 2.64-2.57 (m, 2H), 2.48-2.39 (m, 1H), 1.75-1.54 (m, 3H), 1.52-1.41 (m, 1H), 1.24 (t, J=7.14 Hz, 3H) 1.16-1.11 (m, 3H); [α]Tλ=α/cl, [α]21.9D=+0.101/(0.01506 g/1.5 ml)(0.5)=+20.12° (c=1, CHCl3).

1. customThe stirring reaction mixture
2. temperatureto reflux overnight
3. temperaturewas subsequently cooled
4. concentrationconcentrated under vacuum
5. additionThe residue was diluted with ethyl acetate
6. washwashed twice with brine
7. dry with materialThe organic layer was dried over sodium sulfate
8. filtrationfiltered
9. concentrationconcentrated under vacuum