449
(3)
We have found very few literature reports of bis-allylation of carbonyl compounds.8 We note that
previous reports of allylation of aldehydes in which lanthanide triflates were employed as catalyst make
no mention of a bis-allylation reaction, even when >1 equivalent of allyltrimethylstannane was employed.
In summary, we have demonstrated that YbCl3 is a practical Lewis acid catalyst for the allylation of
various aldehydes with allyltrimethylsilane under very mild and convenient conditions, and that exclusive
bis-allylation of certain electron-rich aldehydes is observed. Asymmetric versions of this catalyst are
currently being explored in our laboratory.
Acknowledgements
This work was performed under the auspices of the Laboratory Directed Research and Development
Program. Los Alamos National Laboratory is operated by the University of California for the US
Department of Energy under contract W-7405-ENG-36.
References
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Chem. 1998, 63, 4381. (e) Marx, A.; Yamamoto, H. Synlett 1999, 584. (f) Kwong, H.-L.; Lau, K.-M.; Lee, W.-S.; Wong,
W.-T. New J. Chem. 1999, 23, 629.
2. (a) Allylation with Sn(allyl)4 catalyzed by Sc(OTf)3: Hachiya, I.; Kobayashi, S. J. Org. Chem. 1993, 58, 6958. (b) Aspinall,
H. C.; Greeves, N.; McIver, E. G. J. Alloys Compd. 1998, 275–277, 773. (c) Yang, Y.; Wang, M.; Wang, D. J. Chem. Soc.,
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Greeves, N.; McIver, E. G. Tetrahedron Lett. 1998, 39, 9283.
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6. Fang, X.-G.; Warner, B. P.; Watkin, J. G. Synth. Commun., in press.
7. Spectroscopic data for 1: 1H NMR (300 MHz, CDCl3) δ 2.42 (t, J=7.8 Hz, 4H), 3.28 (quintet, J=7.1 Hz, 1H), 3.83 (s, 3H),
4.95 (m, 4H), 5.71 (m, 2H), 6.93 (m, 2H), 7.16 (m, 2H). 13C NMR (75 MHz, CDCl3) δ 33.7, 39.0, 55.6, 110.8, 115.1, 120.6,
1
126.5, 127.0, 128.0, 133.0, 137.5, 161.0. MS (EI, m/e) 202 (M+), 161, 146, 91. Spectroscopic data for 2a: H NMR (300
MHz, CDCl3) δ 2.40 (t, J=7.7 Hz, 4H), 3.13 (quintet, J=7.3 Hz, 1H), 4.66 (s, 1H, OH), 4.96 (m, 4H), 5.71 (m, 2H), 6.75 (d,
J=7.8 Hz, 1H), 6.91 (t, J=7.5 Hz, 1H), 7.12 (m, 2H). MS (EI, m/e) 188 (M+), 147. Spectroscopic data for 2b: 1H NMR (300
MHz, CDCl3) δ 0.32 (s, 9H), 2.39 (m, 4H), 3.20 (quintet, 1H, J=7.3 Hz), 4.97 (m, 4H), 5.71 (m, 2H), 6.79 (dd, J=8.1, 1.2
Hz, 1H), 6.94 (dt, J=7.6, 1.2 Hz, 1H), 7.07 (dd, J=7.3, 1.7 Hz, 1H), 7.12 (dt, J=7.6, 1.7 Hz, 1H). MS (EI, m/e) 260 (M+),
219, 203, 73. In addition, p-anisaldehyde (16% yield) and 2-furaldehyde (22% yield) gave exclusively double- rather than
mono-allylation products.
8. (a) Ishii, A.; Kotera, O.; Saeki, T.; Mikami, K. Synlett 1997, 1145. (b) Mayr, H.; Gorath, G. J. Am. Chem. Soc. 1995, 117,
7862.