Efficient, general synthesis of silylketenes via an unusual rhodium mediated Wolff rearrangement

Abstract

Silylketenes bearing a range of substituents (alkyl, alkenyl, aryl, heteroaryl) are prepared by an unusual rhodium mediated Wolff rearrangement of the corresponding silyl diazo ketones.

References

1. A. Pommier, P. J. Kocienski and J. M. Pons, J. Chem. Soc., Perkin Trans. 1, 1998, 2105.
2. T. T. Tidwell, Ketenes, Wiley-Interscience, New York, 1995, pp. 348–354.
3. S. P. Marsden and W.-K. Pang, Tetrahedron Lett., 1998, 39, 6077.
4. S. N. Kablean, S. P. Marsden and A. M. Craig, Tetrahedron Lett., 1998, 39, 5109.
5. All of the silyl diazo ketones were prepared by C-silylation of the corresponding diazo ketones with triethylsilyl triflate, according to: T. Allspach, H. Gümbel and M. Regitz, J. Organomet. Chem., 1985, 290, 33.
6. (a) G. Maas and R. Brückmann, J. Org. Chem., 1985, 50, 2801; (b) R. Brückmann, K. Schneider and G. Maas, Tetrahedron, 1989, 45, 5517.
7. J. L. Loebach, D. M. Bennett and R. L. Danheiser, J. Am. Chem. Soc., 1998, 120, 9690; J. L. Loebach, D. M. Bennett and R. L. Danheiser, J. Org. Chem., 1998, 63, 8380.
8. S. Bien and Y. Segal, J. Org. Chem., 1977, 42, 1685; G. B. Gill, in Comprehensive Organic Synthesis, ed. B. M. Trost and I. Fleming, Pergamon, Oxford, 1991, vol. 3, p. 88.
9. The rhodium catalysed decomposition of ethyl (E)-5-aryl-2-diazo-3-oxopent-4-enoates results in products assumed to arise via Wolff rearrangement and ketene decompostition. See: E. C. Taylor and H. M. L. Taylor, Tetrahedron Lett., 1983, 24, 5453.
10. E. Colvin, Silicon in Organic Synthesis, Butterworths, London, 1981.