836
LETTERS
SYNLETT
Chem. Jpn. 1995, 53, 987. (g) Kawatsura, M.; Dekura, F.;
Shirahama, H.; Matsuda, F. Synlett 1996, 373. (h) Kito, M.; Sakai,
T.; Haruta, N.; Shirahama, H.; Matsuda, F. Synlett 1996, 1057. (i)
Kawatsura, M.; Kishi, E.; Kito, M.; Sakai, T.; Shirahama, H.;
Matsuda, F. Synlett 1997, 479.
(2) (a) Kagan, H. B.; Namy, J. L. Tetrahedron 1986, 42, 6573.
(b) Kagan, H. B. Nouv. J. Chim. 1990, 14, 453. (c) Molander, G.
A. Chem. Rev. 1992, 92, 29. (d) Molander, G. A. Organic
Reactions 1994, 46, 211. (e) Molander, G. A.; Harris, C. R. Chem.
Rev. 1996, 96, 307.
(3) (a) Ogawa, A.; Takami, N.; Sekiguchi, M.; Ryu, I.; Kambe, N.;
Sonoda, N. J. Am. Chem. Soc., 1992, 114, 8729. (b) Ogawa, A.;
Nanke, T.; Takami, N.; Sumino, Y.; Ryu, I.; Sonoda, N. Chem.
Lett., 1994, 379. (c) Murakami, M.; Hayashi, M.; Ito, Y. Synlett,
1994, 179.(d) Yanada, R.; Bessho, K.; Yanada, K. Chem. Lett.
1994, 1279. (e) Yanada, R.; Bessho, K.; Yanada, K. Synlett 1995,
443. (f) Yanada, R.; Negoro, N.; Bessho, K.; Yanada, K. Synlett
1995, 1261. (g) Yanada, R.; Negoro, N.; Yanada, K.; Fujita, T.
Tetrahedron Lett. 1996, 37, 9313. (h) Yanada, R.; Negoro, N.;
Yanada, K.; Fujita, T. Tetrahedron Lett. 1997, 38, 3271.
(4) Enders, D.; Reinhold, U. Tetrahedron: Asymmetry 1997, 8, 1895,
and references cited therein.
(5) Examples of Grignard-type allylation to optically active imines
(N-benzylideneamino alcohol alkyl ether type): (a) Suzuki, Y.;
Takahashi, H. Chem. Pharm. Bull. 1983, 31, 2895. (b) Ukaji, Y.;
Watai, T.; Sumi, T.; Fujisawa, T. Chem. Lett. 1991, 1555.
(c) Hashimoto, Y.; Takaoki, K.; Sudo, A.; Ogasawara, T.; Saigo,
K. Chem. Lett. 1995, 235. (d) Alvaro, G.; Martelli, G.; Savoia, D.
J. Chem. Soc., Perkin Trans. 1. 1998, 775.
the bulky isopropyl group is oriented re face and obstructs the approach
of the allyl samarium species from the re face. The allyl samarium
species then approaches from the less hindered side si face to give the
(S, S) isomer 2c selectively.
In conclusion, the first diastereoselective Barbier-type allylation of
optically active imines was performed with Sm and a catalytic amount
of iodine. The induction of other substituents instead of the allyl group
is now being investigated.
(6) Addition of a catalytic amount of iodine was the best condition for
the allylation of 1c. No reaction occurred without iodine. One mol
eq. iodine to 1c gave 2c and 3c (95:5) in 24% yield accompanied
with the starting material 1c (30 %).
References and Notes
(7) (a) Bocoum, A.; Savoia, D.; Umani- Ronchi, A. J. Chem. Soc.,
Chem. Commun. 1993, 1542. (b) Basile, T.; Bocoum, A.; Savoia,
D.; Umani-Ronchi, A. J. Org. Chem. 1994, 59, 7766. (c) Alvaro,
G.; Pacioni, P.; Savoia, D. Chem. Eur. J. 1997, 3, 726.
(1) (a) Molander, G. A.; Kenny, C. Tetrahedron Lett., 1987, 28, 4367.
(b) Molander, G. A.; Kenny, C. J. Am. Chem. Soc., 1989, 111,
8236. (c) Kan, T.; Hosokawa, S.; Nara, S.; Oikawa, M.; Ito, S.;
Matsuda, F.; Shirahama, H. J. Org. Chem., 1994, 59, 5532.
(d) Kawatsura, M.; Matsuda, F.; Shirahama, H. J. Org. Chem.,
1994, 59, 6900. (e) Kawatsura, M.; Hosaka, K.; Matsuda, F.;
Shirahama, H. Synlett 1995, 729. (f) Matsuda, F. J. Synth. Org.
(8) We can not deny the mechanism in which the imine is reduced at
the first stage. But we think the formation of allyl Sm complex is
plausible because there is no imine dimer or amine, which is the
product from imine radical, under this experimental conditions.