3098
S.-J. ZHANG AND W.-X. HU
heated in an oil bath at 95 ꢀC, and the inner temperature was about 80 ꢂ 5 ꢀC for 8 h.
After completion, the mixture was cooled to room temperature, and 11% sulfuric
acid (25 mL) was added with continuous stirring for 0.5 h. The mixture was extracted
with dichloromethane (20 mL ꢃ 3), washed with H2O (20 mL ꢃ 3), dried over
MgSO4, and concentrated under reduced pressure to give the crude products
2a–j, which were pure enough to be characterized.
All spectral data were in agreement with those reported in the literature.[5,11]
Data
(E)-3-Pentenoic acid (2a). Colorless oil. IR (liquid film, nmax=cmꢁ1): 2971,
1712, 1417, 1292, 1223, 967. 1H NMR (400 MHz, CDCl3): d 11.36 (br, 1H, COOH),
=
5.66 (dtt, J ¼ 1.2, 6.4, 15.2 Hz, 1H, CH3ꢁCH CHꢁ), 5.57 (dtt, J ¼ 1.2, 6.4, 15.2 Hz,
=
1H, CH3ꢁCH CHꢁ), 3.11 (dt, J ¼ 1.2, 7.2 Hz, 2H, ꢁCH2ꢁCOꢁ), 1.75 (dt, J ¼ 1.2,
6.4 Hz, 3H, CH3ꢁ).
(E)-3-Hexenoic acid (2b). Colorless oil. IR (liquid film, nmax=cmꢁ1): 2965,
1
2876, 1712, 1408, 1286, 968. H NMR (400 MHz, CDCl3): d 9.82 (br, 1H, COOH),
=
5.66 (dtt, J ¼ 1.6, 6.4, 15.6 Hz, 1H, CH3ꢁCH2ꢁCH CHꢁ), 5.55 (dtt, J ¼ 1.6, 6.8,
=
15.2 Hz, 1H, CH3ꢁCH2ꢁCH CHꢁ), 3.09 (d, J ¼ 6.8 Hz, 2H, ꢁCH2ꢁCOꢁ), 2.10
(m, J ¼ 6.8 Hz, 2H, CH3ꢁCH2ꢁ), 0.99 (t, J ¼ 7.6 Hz, 3H, CH3ꢁ).
(E)-2-Hexenoic acid (2b’). Colorless oil. IR (liquid film, nmax=cmꢁ1): 2964,
2876, 1698, 1654, 1283, 982. 1H NMR (400 MHz, CDCl3): d 10.24 (br, 1H, COOH),
=
7.11 (dt, J ¼ 7.2, 15.2 Hz, 1H, ꢁCH CHꢁCOOH), 5.86 (dt, J ¼ 1.6, 15.2 Hz, 1H,
=
ꢁCH CHꢁCOOH), 2.25 (dq, J ¼ 1.6, 7.2 Hz, 2H, CH3ꢁCH2ꢁCH2ꢁ), 1.61–1.49
(m, J ¼ 7.2 Hz, 2H, CH3ꢁCH2ꢁCH2ꢁ), 0.98 (t, J ¼ 7.4 Hz, 3H, CH3ꢁ).
4-Methyl-3-pentenoic acid (2c). Colorless oil. IR (liquid film, nmax=cmꢁ1):
1
=
2969, 1709, 1384, 828. H NMR (400 MHz, CDCl3): d 5.33–5.29 (m, 1H, ꢁC CHꢁ),
3.10 (d, J ¼ 7.2 Hz, 2H, ꢁCH2ꢁCOꢁ), 1.77 (s, 3H, CH3-), 1.66 (s, 3H, CH3ꢁ).
(E)-3-Heptenoic acid (2d). Colorless oil. IR (liquid film, nmax=cmꢁ1): 2960,
1
2873, 1713, 1415, 1292, 1221, 968. H NMR (400 MHz, CDCl3): d 11.15 (br, 1H,
=
COOH), 5.64–5.59 (m, 1H, CH3ꢁCH2ꢁCH2ꢁCH CHꢁ), 5.57–5.49 (m, 1H,
=
CH3ꢁCH2ꢁCH2ꢁCH CHꢁ), 3.09 (dd, J ¼ 1.2, 6.8 Hz, 2H, ꢁCH2ꢁCOꢁ), 2.03
(q, J ¼ 6.8 Hz, 2H, CH3ꢁCH2ꢁCH2ꢁ), 1.40 (m, J ¼ 7.2 Hz, 2H, CH3ꢁCH2ꢁCH2ꢁ),
0.91 (t, J ¼ 7.4 Hz, 3H, CH3ꢁ).
(E)-5-Methyl-3-hexenoic acid (2e). Colorless oil. IR (liquid film, nmax=cmꢁ1):
2961, 2872, 1713, 1413, 1287, 1222, 970. 1H NMR (400 MHz, CDCl3): d 11.68 (br, 1H,
=
COOH), 5.58 (dtt, J ¼ 1.6, 6.4, 15.6 Hz, 1H, (CH3)2ꢁCHꢁCH CHꢁ), 5.48 (dtt,
=
J ¼ 1.2, 6.4, 15.6 Hz, 1H, (CH3)2ꢁCHꢁCH CHꢁ), 3.08 (d, J ¼ 6.4 Hz, 2H,
ꢁCH2ꢁCOꢁ), 2.31 (m, J ¼ 6.8 Hz, 1H, (CH3)2ꢁCHꢁ), 1.00 (d, J ¼ 6.8 Hz, 6H,
(CH3)2ꢁ).
(E)-3-Nonenoic acid (2f). Colorless oil. IR (liquid film, nmax=cmꢁ1): 2958,
2928, 2858, 1712, 1414, 1384, 1288, 1222, 968, 726. H NMR (400 MHz, CDCl3):
1
=
d 11.55 (br, 1H, COOH), 5.61 (dt, J ¼ 6.4, 15.2 Hz, 1H, ꢁCH CHꢁCH2ꢁCO),
=
5.51 (dt, J ¼ 6.8, 15.2 Hz, 1H, ꢁCH CHꢁCH2ꢁCO), 3.08 (d, J ¼ 6.4 Hz, 2H,