6710
S. Nakamura et al. / Tetrahedron 57 *2001) 6703±6711
1
over Na2SO4, and concentrated under reduced pressure to
leave an oil which was puri®ed by column chromatography
2silica gel 10g, hexane/ethyl acetate 97:3) to give Z-8b
234 mg, 77%) and E-8b 28 mg, 18%). The Z/E ratio was
determined to be 81:19 by the H NMR analysis. Z-8b: H
NMR d 3.73 2s, 3H), 3.83 2s, 3H), 5.83 2d, 1H, J12.7 Hz),
6.88 2d, 1H, J12.7 Hz), 6.88 2d, 2H, J8.8 Hz), 7.69 2d,
2H, J8.8 Hz); IR 2neat) 2950, 1710, 1595, 1510, 1430,
1250, 1160, 1303, 840 cm21. Anal. calcd for C11H12O3: C,
68.74; H, 6.29. Found: C, 68.62; H, 6.41. E-10b: 1H NMR d
3.79 2s, 3H), 3.84 2s, 3H), 6.302d, 1H, J15.9 Hz), 6.80±
7.702m, 6H).
4.3.8. 2-Methyl-7-phenylhept-4-en-3-one ꢀ8h). Z-8h: H
NMR
d
1.07 2d, 6H, J7.0Hz), 2.59 2hep, 1H,
J7.0 Hz), 2.70±2.80 2m, 2H), 2.90±3.00 2m, 2H), 6.04±
6.25 2m, 2H), 7.15±7.35 2m, 5H); 13C NMR d 18.0, 30.8,
35.1, 41.4, 125.9, 128.3, 128.5, 141.3, 147.5, 205.3; IR
1
1
2neat) 2950, 1680, 1610, 1450, 1050, 740, 690 cm21
;
EIMS m/z 2rel. intensity) 202 2M121, 67), 159 2100), 91
2100). Anal. calcd for C14H18O: C, 83.12; H, 8.97. Found: C,
82.99; H, 9.10.
1
4.3.9. 2-Hexylidencyclopentanone ꢀ9). Z-9: H NMR d
0.80±0.90 2m, 3H), 1.19±1.50 2m, 6H), 1.88 2tt, 2H,
J7.5, 7.5 Hz), 2.25±2.35 2m, 2H), 2.54±2.72 2m, 2H),
5.96 2tt, 1H, J2.0, 7.5 Hz); IR 2neat) 2930, 2860,
1710, 1635, 1435, 1360, 1270, 1170, 1110, 1025, 860,
1
4.3.2. Methyl cinnamate ꢀ8a). Z-8a: H NMR d 3.71 2s,
3H), 5.95 2d, 1H, J12.6 Hz), 6.96 2d, 1H, J12.6 Hz),
7.17±7.47 2m, 5H); IR 2neat) 2950, 1710, 1630, 1430,
1270, 1160, 1070, 1010, 820, 760, 690 cm21. Anal. calcd
for C101H10O2: C, 74.06; H, 6.21. Found: C, 73.96; H, 6.31.
E-8a: H NMR d 3.81 2s, 3H), 6.44 2d, 1H, J15.9 Hz),
7.10±7.75 2m, 6H).
830cm 21
. Anal. calcd for C11H18O: C, 79.47; H,
1
10.91. Found: C, 79.58; H, 10.80. E-9: H NMR d 0.80±
0.90 2m, 3H), 1.19±1.55 2m, 6H), 1.93 2tt, 2H, J7.4,
7.4 Hz), 2.14 2dt, 2H, J7.2, 7.5 Hz), 2.33 2t, 2H,
J7.4 Hz), 2.58 2dt, 1H, J2.6, 7.4 Hz), 6.55 2tt, 1H,
J2.6, 7.5 Hz).
4.3.3. Methyl 3-ꢀp-chlorophenyl)prop-2-enoate ꢀ8c). Z-
1
8c: H NMR d 3.72 2s, 3H), 5.96 2d, 1H, J12.6 Hz),
6.89 2d, 1H, J12.6 Hz), 7.25±7.73 2m, 4H); IR 2neat)
2950, 1715, 1630, 1590, 1490, 1440, 1270, 1200, 1170,
1090, 1015, 850 cm21. Anal. calcd for C10H9ClO2: C,
References
1. For Z-selective formation of a,b-unsaturated esters, see:
2a) Breuer, E.; Bannet, D. M. Tetrahedron Lett. 1977, 8,
1141±1144. 2b) Nagaoka, H.; Kishi, Y. Tetrahedron 1981,
37, 3873±3888. 2c) Still, W. C.; Gennari, C. Tetrahedron
Lett. 1983, 24, 4405±4408. 2d) Thompson, S. K.; Heathcock,
C. H. J. Org. Chem. 1990, 55, 3386±3388. 2e) Patois, C.;
Savingnac, P. Tetrahedron Lett. 1991, 32, 1317±1320.
2f) Ando, K. Tetrahedron Lett. 1995, 36, 4105±4108.
2g) Ando, K. J. Org. Chem. 1997, 62, 1934±1939.
2h) Kokin, K.; Motoyoshiya, J.; Hayashi, S.; Aoyama, H.
Synth. Commun. 1997, 27, 2387±2392. 2i) Kojima, S.; Takagi,
R.; Akiba, K. J. Am. Chem. Soc. 1997, 119, 5970±5971.
2j) Ando, K. J. Org. Chem. 1998, 63, 8411±8416. 2k) Ando,
K.; Oishi, T.; Hirama, M.; Ohno, H.; Ibuka, T. J. Org. Chem.
2000, 65, 4745±4749. For Z-selective formation of a,b-unsa-
turated nitriles, see: 2l) Zhang, T. Y.; O'Toole, J. C.; Dunigan,
J. M. Tetrahedron Lett. 1998, 39, 1461±1646. For Z-selective
formation of a,b-unsaturated ketones, see: 2m) Yu, W.; Su,
M.; Jin, Z. Tetrahedron Lett. 1999, 40, 6725±6728. For
computational investigation of Z-selective formation of a,b-
unsaturated esters, see: 2n) Motoyoshiya, J.; Kusaura, T.;
Kokin, K.; Yokoya, S.; Takaguchi, Y.; Narita, S.; Aoyama,
H. Tetrahedron 2001, 57, 1715±1721.
1
61.08; H, 4.61. Found: C, 61.25; H, 4.44. E-8c: H NMR
d 3.81 2s, 3H), 6.402d, 1H, J15.9 Hz), 7.35 2d, 2H,
J8.6 Hz), 7.45 2d, 1H, J8.6 Hz), 7.64 2d, 1H,
J15.9 Hz).
4.3.4. Methyl 5-phenylpenta-2,4-dienoate ꢀ8d). 22Z,4E)-
1
8d: H NMR d 3.77 2s, 3H), 5.74 2d, 1H, J11.4 Hz),
6.68±6.91 2m, 2H), 7.27±7.56 2m, 5H), 8.14 2dd, 1H,
J11.4, 15.6 Hz); IR 2neat) 3030, 2950, 1705, 1620,
1430, 1230, 1170, 1130, 1000, 750, 690 cm21. Anal. calcd
for C12H12O2: C, 76.57; H, 6.43. Found: C, 76.27; H, 6.73.
22E,4E)-8d: 1H NMR d 3.77 2s, 3H), 6.01 2d, 1H,
J15.9 Hz), 6.80±7.00 2m, 2H), 7.28±7.52 2m, 6H).
4.3.5. Methyl 5-phenylpent-2-enoate ꢀ8e). Z-8e: 1H NMR
d 2.70±2.802m, 2H), 2.90±3.002m, 2H), 3.702s, 3H), 5.78
2d, 1H, J11.5 Hz), 6.20±6.30 2m, 1H), 7.15±7.34 2m, 5H);
IR 2neat) 3010, 2920, 1710, 1630, 1430, 1190, 1170, 100,
810, 690 cm21. Anal. calcd for C12H14O2: C, 75.76; H, 7.42.
Found: C, 75.75; H, 7.43.
4.3.6. Methyl oct-2-enoate ꢀ8f). Z-8f: 1H NMR d 0.82±1.52
2m, 9H), 2.64 2dt, 2H, J7.0, 7.3 Hz), 3.71 2s, 3H), 5.76 2d,
1H, J11.5 Hz), 5.76 2dt, 1H, J7.3, 11.4 Hz); IR 2neat)
2930, 1720, 1640, 1435, 1405, 1200, 1170, 820, 780
730cm 21. Anal. calcd for C9H16O2: C, 69.19; H, 10.32.
Found: C, 69.02; H, 10.51.
2. Recently, the direct preparation of 2Z)-a,b-unsaturated amides
through the reaction of a-silyl enolates with various aldehydes
has been reported, see: Kojima, S.; Inai, H.; Hidaka, T.;
Ohkata, K. Chem. Commun. 2000, 1795±1796.
3. Hudrlik, P. F.; Peterson, D. J. Am. Chem. Soc. 1975, 97, 1464±
1468.
1
4.3.7. Dodec-3-en-5-yn-2-one ꢀ8g). Z-8g: H NMR d 0.89
4. For reviews, see: 2a) Chan, T. H. Acc. Chem. Res. 1977, 10,
442±448. 2b) Ager, D. Synthesis 1984, 384±398. 2c) Ager, D.
J. Org. React. 1990, 38, 1±223. 2d) Barrett, A. G. M.; Hill,
J. M.; Wallace, E. M.; Flygare, J. A. Synlett 1991, 764±
770.
2t, 3H, J6.6 Hz), 1.25±1.702m, 8H), 2.44 2dt, 2H, J1.6,
7.1 Hz), 2.49 2s, 3H), 2.70±2.80 2m, 2H), 6.10±6.25 2m,
2H); IR 2neat) 2920, 2850, 2300, 2200, 1660, 1580, 1450,
1410, 1350, 1260, 1200, 1170, 1020 cm21. Anal. calcd for
C12H18O: C, 80.85; H, 10.18. Found: C, 80.78; H, 10.25.
5. 2a) Hudrlik, P. F.; Peterson, D. Tetrahedron Lett. 1972, 1785±
1787. 2b) Utimoto, K.; Obayashi, M.; Nozaki, H. J. Org.
Chem. 1976, 41, 2940±2941. 2c) Hudrlik, P. F.; Kulkarni,
A. K. J. Am. Chem. Soc. 1981, 103, 6251±6253.
1
E-8g: H NMR d 0.87 2t, 3H, J6.5 Hz), 1.25±1.702m,
8H), 2.30±2.50 2m, 2H), 2.48 2s, 3H), 2.70±2.80 2m, 2H),
6.45±6.55 2m, 1H), 6.60±6.70 2m, 1H).