Synthesis of Silyl Enol Ethers by Mg/TMSCl

Tetrahedron Letters 40 (1999) 1349-1352

Synthetic utility and importance of silyl enol ethers have been well established [1-2]. The
numerous methods for their preparation have been reported [3-14] although some difficulties
have been encountered in the actual preparation, especially in the large-scale production,
owing to requirement of troublesome procedure, low temperature such as -78"C, special
equipment, carcinogenic solvent and/or expensive reagents.

In this study, we wish to present novel Mg-promoted coupling of aliphatic carbonyl
compounds with trimethylsilyl chloride (TMSCI) at room temperature to give the
corresponding silyl enol ethers in excellent to good yields. This
reaction may provide a highly convenient method for the stereoselective preparation of (Z)-isomers.

ref.
[ll Brownbridge P., Synthesis, 1983, 1 and 85.
[2] Reefs yon M.T., Angew. Chem., 94, 97 (1982).
[3] Colvin E.W., Silicon in Organic Synthesis, Butterworths, London, 1981.
[4] Pawkinko S., Organo Silicon Chemistry, Walter de Gruyter, Berlin, 1986.
[5] Weber W.P., Silicon Reagents for Organic Synthesis, Spring-Verlag, Berlin, 1983.
]6] Negishi E., Organometallics in Organic Synthesis, John Wiley & Sons, New York, Vol.l, Chap. 6, 1980.
[7] Bonafoux D., Bordeau M., Biran C., Cazeau P., and Dunogues J., J. Org. Chem., 6 1,5532 (1996).
[81 Bunafoux D., Bordeau M., Biran C., and Dunogues J., J. Organomet. Chem., 4 9 3, 27 (1995).
[9] Davis F.A., Sheppard A.C, Chen B.C., and Haque M., J. Am. Chem. Soc., I 12,6679 (1990).
[10] Takai K., Kataoka Y., Okazoe T.,and Utlmoto K., Tetrahedron Left., 29, 1065 (1988).
[ I 1
] Davis F.A., Lal G.S., and Wei J., Tertahedron Left., 2 9, 4269 (1988).
[12] Dedier J., Gerval P., and Frainnet E., J. Organomet. Chem., lS$, 183 (1980).
[13] House ]t.O., Czuba L.J., Gall M.,and Olmstead H.D., J. Org. Chem., 34, 2324 (1969).
[14] Cazeau P., Duboudin F., Moulines F., Babot O., Dunogues J., Tetrahedron., 43, 2075 (1987).
[15] Ishino Y., Maekawa It., Takeuchi H., Sukata K., and Nishiguchi I., Chem. Lett., 1995, 829.