Y. Du, D. F. Wiemer / Tetrahedron Letters 42 (2001) 6069–6072
6071
Scheme 2.
Scheme 3.
1 could not initiate metathesis with gem-disubstituted
olefins.3a
References
1. For recent reviews, see: (a) Furstner, A. Angew. Chem.,
Int. Ed. 2000, 39, 3013–3043. (b) Trnka, T. M.; Grubbs,
R H. Acc. Chem. Res. 2001, 34, 18–29.
2. (a) Fu, G. C.; Nguyen, S. T.; Grubbs, R. H. J. Am.
Chem. Soc. 1993, 115, 9856–9857; (b) Grubbs, R. H.;
Miller, S. J.; Fu, G. C. Acc. Chem. Res. 1995, 28,
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Am. Chem. Soc. 1996, 118, 100–110; (d) Armstrong, S. K.
J. Chem. Soc., Perkin Trans. 1 1998, 371–388.
Given the positive results observed with formation of
the farnesyl derivative 18, we attempted to extend this
approach to preparation of the corresponding lactam.
Because an unprotected acrylamide has been found to
undergo ring-closing metathesis in low yield,11 a p-
methoxybenzyl group was incorporated as a protecting
group. As shown in Scheme 3, condensation of farnesal
(16) with p-methoxybenzylamine afforded the interme-
diate imine 22, which was treated with allyl magnesium
bromide without isolation to afford the secondary
amine 23. After reaction with acryloyl chloride, the
resulting amide 24 was treated with Grubbs catalyst to
afford the lactam 25 in good yield.
3. (a) Kirkland, T. A.; Grubbs, R. H. J. Org. Chem. 1997,
62, 7310–7318; (b) Ulman, M.; Grubbs, R. H.
Organometallics 1998, 17, 2484–2489.
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In conclusion, metathesis of acrylate esters derived
from different terpene aldehydes, as well as an acrylam-
ide derived from farnesal, has been shown to afford
lactone and lactam products in good yield and with
excellent regioselectivity. Further studies on the appli-
cation and biological activity of these terpenoid deriva-
tives will be reported in due course.
Acknowledgements
Financial support from the Roy J. Carver Charitable
6. Ghosh, A. K.; Cappiello, J.; Shin, D. Tetrahedron Lett.
1998, 39, 4651–4654.
Trust is gratefully acknowledged.
.