The preparation and analysis of the phenyldimethylsilyllithium reagent and its reaction with silyl enol ethers

Abstract

Phenyldimethylsilyllithium is formed from lithium and phenyldimethylsilyl chloride by slow cleavage of the Si–Si bond of 1,1,2,2-tetramethyl-1,2-diphenyldisilane after the rapid formation of the disilane. 1,1,2,2-Tetramethyl-1,2-diphenyldisiloxane, produced from the silyl chloride by reaction with oxides and hydroxides on the lithium metal surface, is cleaved by dimethyl(phenyl)silyllithium to give lithium dimethyl(phenyl)silanoxide. Dimethyl(phenyl)silyllithium reacts with 1,2-dibromoethane to give dimethyl(phenyl)silyl bromide, which is so rapidly consumed by excess silyllithium reagent that it does not interfere with the double titration used to measure its concentration. Dimethyl(phenyl)silane, produced by protonation of the silyllithium reagent, is also consumed by the silyllithium reagent to give 1,1,2,2-tetramethyl-1,2-diphenyldisilane, which regenerates the silyllithium reagent, as long as lithium is still present. By-products in the preparation of dimethyl(phenyl)silyllithium include 1,3-diphenyl-1,1,2,2,3,3-hexamethyltrisilane, dimethyldiphenylsilane and 1,4-bis[dimethyl(phenyl)silyl]benzene. Dimethyl(phenyl)silyllithium displaces the silyl group from the tert-butyldimethylsilyl enol ether of cyclohexanone to give the lithium enolate under relatively mild conditions.

References

1. D. J. Ager, I. Fleming and S. K. Patel, J. Chem. Soc., Perkin Trans. 1, 1981, 2520; I. Fleming and D. Marchi, Synthesis, 1981, 560; I. Fleming, T. W. Newton and F. Roessler, J. Chem. Soc., Perkin Trans. 1, 1981, 2527; I. Fleming, M. Rowley, P. Cuadrado, A. M. González-Nogal and F. J. Pulido, Tetrahedron, 1989, 45, 413; I. Fleming, D. Higgins, N. J. Lawrence and A. P. Thomas, J. Chem. Soc., Perkin Trans. 1, 1992, 3331; I. Fleming, in Organocopper Reagents: A Practical Approach, ed. R. J. K. Taylor, OUP, Oxford, 1995, ch. 12, pp. 257–292.
2. D. Wittenberg and H. Gilman, Quart. Rev., 1959, 13, 116; M. V. George, D. J. Peterson and H. Gilman, J. Am. Chem. Soc., 1960, 82, 403; H. Gilman, R. A. Klein and H. J. S. Winkler, J. Org. Chem., 1961, 26, 2474.
3. I. Fleming and U. Ghosh, J. Chem. Soc., Perkin Trans. 1, 1994, 257; I. Fleming, M. Solay and F. Stolwijk, J. Organomet. Chem., 1996, 521, 121; S. Saito, K. Shimada, H. Yamamoto, E. Martínez de Marigorta and I. Fleming, Chem. Commun., 1997, 1299; I. Fleming, R. S. Roberts and S. C. Smith, J. Chem. Soc., Perkin Trans. 1, 1998, 1215; I. Fleming, J. Frackenpohl and H. Ila, J. Chem. Soc., Perkin Trans. 1, 1998, 1229.
4. N. Abd. Rahman, I. Fleming and A. B. Zwicky, J. Chem. Res. (S), 1992, 292; J. Chem. Res. (M), 1992, 2041.
5. H. Müller, U. Weinzierl and W. Seidel, Z. Anorg. Allg. Chem., 1991, 603, 15.
6. H. Gilman, F. K. Cartledge and S.-Y. Sim, J. Organomet. Chem., 1963, 1, 8.
7. H. Gilman and D. Aoki, J. Org. Chem., 1959, 24, 426; H. Gilman and H. J. S. Winkler, in Organometallic Chemistry, ed. H. Weiss, Reinhold, New York, 1960, pp. 270–345.
8. J. B. Lambert and M. Urdaneta-Pérez, J. Am. Chem. Soc., 1978, 100, 157.
9. Y.-P. Wan, D. H. O'Brien and F. J. Smentowski, J. Am. Chem. Soc., 1972, 94, 7680 and references cited therein.
10. I. Fleming, R. S. Roberts and S. C. Smith, Tetrahedron Lett., 1996, 38, 9395.
11. P. Knochel, M. C. P. Yeh, S. C. Berk and J. Talbert, J. Org. Chem., 1988, 53, 2390; K. Takai, T. Kakiuchi and K. Utimoto, J. Org. Chem., 1994, 59, 2671; A. Fürstner and A. Hupperts, J. Am. Chem. Soc., 1995, 117, 4468.
12. E. Erdik, Tetrahedron, 1987, 43, 2203.
13. M. V. George and H. Gilman, J. Am. Chem. Soc., 1959, 81, 3288.
14. F. P. Price, J. Am. Chem. Soc., 1947, 69, 2600; H. Gilman, B. Hofferth, H. W. Melvin and G. E. Dunn, J. Am. Chem. Soc., 1950, 72, 5767; H. Gilman and G. E. Dunn, J. Am. Chem. Soc., 1951, 73, 3404; G. Schott and C. Harzdorf, Z. Anorg. Allg. Chem., 1960, 307, 105.
15. H. Gilman and B. J. Gaj, J. Org. Chem., 1961, 26, 2471.
16. K. Krohn and K. Khanbabaee, Angew. Chem., Int. Ed. Engl., 1994, 33, 99; See also G. Wickham, H. A. Olszowy and W. Kitching, J. Org. Chem., 1982, 47, 3788 and P. F. Hudrlik, M. A. Waugh and A. M. Hudrlik, J. Organomet. Chem., 1984, 271, 69.
17. W. C. Still, J. Org. Chem., 1976, 41, 3063.
18. R. Balasubramanian and J. P. Oliver, J. Organomet. Chem., 1980, 197, C7.
19. D. Wittenberg, T. C. Wu and H. Gilman, J. Org. Chem., 1959, 24, 1349.
20. G. Stork and P. F. Hudrlik, J. Am. Chem. Soc., 1968, 90, 4464.
21. R. Calas, A. Marchand, E. Frainnet and P. Gerval, Bull. Soc. Chim. Fr., 1968, 2478.
22. J. F. Hyde, O. K. Johannson, W. H. Daudt, R. F. Fleming, H. B. Laudenslager and M. P. Roche, J. Am. Chem. Soc., 1953, 75, 5615.
23. J.-C. Bonnet and E. Marechal, Bull. Soc. Chim. Fr., 1972, 3561.
24. T. I. Ponomareva, T. A. Krasovskaya and M. V. Sobolevskii, Plast. Massy., 1963, 22; Chem. Abstr., 1963, 59, 14 017b.
25. K. E. Ruehl and K. Matyjaszewski, J. Organomet. Chem., 1991, 410, 1.
26. S. B. Nagelberg, C. E. Reinhold, B. R. Willeford, M. P. Bigwood, K. C. Molloy and J. J. Zuckerman, Organometallics, 1982, 1, 851.
27. Dictionary of Organic Compounds, 5th edn., Chapman and Hall, N. Y., 1982, D-08081.
28. A. Holt, A. W. P. Jarvie and J. J. Mallabar, J. Organomet. Chem., 1973, 59, 141.
29. I. Kopka and M. W. Rathke, J. Org. Chem., 1981, 46, 3771.